@article{verma_lin_smith_walker_hewezi_davis_hussey_baum_mitchum_2022, title={A novel sugar beet cyst nematode effector 2D01 targets the Arabidopsis HAESA receptor-like kinase}, ISSN={["1364-3703"]}, DOI={10.1111/mpp.13263}, abstractNote={Plant-parasitic cyst nematodes use a stylet to deliver effector proteins produced in oesophageal gland cells into root cells to cause disease in plants. These effectors are deployed to modulate plant defence responses and developmental programmes for the formation of a specialized feeding site called a syncytium. The Hg2D01 effector gene, coding for a novel 185-amino-acid secreted protein, was previously shown to be up-regulated in the dorsal gland of parasitic juveniles of the soybean cyst nematode Heterodera glycines, but its function has remained unknown. Genome analyses revealed that Hg2D01 belongs to a highly diversified effector gene family in the genomes of H. glycines and the sugar beet cyst nematode Heterodera schachtii. For functional studies using the model Arabidopsis thaliana-H. schachtii pathosystem, we cloned the orthologous Hs2D01 sequence from H. schachtii. We demonstrate that Hs2D01 is a cytoplasmic effector that interacts with the intracellular kinase domain of HAESA (HAE), a cell surface-associated leucine-rich repeat (LRR) receptor-like kinase (RLK) involved in signalling the activation of cell wall-remodelling enzymes important for cell separation during abscission and lateral root emergence. Furthermore, we show that AtHAE is expressed in the syncytium and, therefore, could serve as a viable host target for Hs2D01. Infective juveniles effectively penetrated the roots of HAE and HAESA-LIKE2 (HSL2) double mutant plants; however, fewer nematodes developed on the roots, consistent with a role for this receptor family in nematode infection. Taken together, our results suggest that the Hs2D01-AtHAE interaction may play an important role in sugar beet cyst nematode parasitism.}, journal={MOLECULAR PLANT PATHOLOGY}, author={Verma, Anju and Lin, Marriam and Smith, Dante and Walker, John C. and Hewezi, Tarek and Davis, Eric L. and Hussey, Richard S. and Baum, Thomas J. and Mitchum, Melissa G.}, year={2022}, month={Sep} }
 @article{davis_2022, title={Kenneth R. Barker (1932-2022) Obituary}, volume={24}, ISSN={["1388-5545"]}, DOI={10.1163/15685411-00003563}, number={10}, journal={NEMATOLOGY}, author={Davis, Eric L.}, year={2022}, month={Nov}, pages={1195–1196} }
 @article{ochola_cortada_mwaura_tariku_christensen_ng'ang'a_hassanali_pirzada_khan_pal_et al._2022, title={Wrap-and-plant technology to manage sustainably potato cyst nematodes in East Africa}, volume={2}, ISSN={["2398-9629"]}, url={https://doi.org/10.1038/s41893-022-00852-5}, DOI={10.1038/s41893-022-00852-5}, abstractNote={Abstract Renewable eco-friendly options for crop protection are fundamental in achieving sustainable agriculture. Here, we demonstrate the use of a biodegradable lignocellulosic banana-paper matrix as a seed wrap for the protection of potato plants against potato cyst nematode (PCN), Globodera rostochiensis . Potato cyst nematodes are devastating quarantine pests of potato globally. In East Africa, G. rostochiensis has recently emerged as a serious threat to potato production. Wrapping seed potatoes within the lignocellulose banana-paper matrix substantially reduced G. rostochiensis field inoculum and increased potato yields by up to fivefold in Kenya, relative to farmer practice, whether or not impregnated with ultra-low doses of the nematicide abamectin (ABM). Markedly, ABM-treated banana paper at ~1,000 times lower than conventional recommendations reduced PCN inoculum. Assays and analyses revealed that the lignocellulose matrix disrupts parasite–host chemical signalling by adsorbing critical PCN hatching and infective juvenile host location chemicals present in potato root exudate. Recovery experiments confirmed adsorption of these host location chemicals. Our study demonstrates the use of waste organic material to sustainably manage PCN, and potentially other crop root pests, while increasing potato yields.}, journal={NATURE SUSTAINABILITY}, author={Ochola, Juliet and Cortada, Laura and Mwaura, Onesmus and Tariku, Meklit and Christensen, Shawn A. and Ng'ang'a, Margaret and Hassanali, Ahmed and Pirzada, Tahira and Khan, Saad and Pal, Lokendra and et al.}, year={2022}, month={Feb} }
 @article{wang_dhroso_liu_baum_hussey_davis_wang_korkin_mitchum_2021, title={Phytonematode peptide effectors exploit a host post-translational trafficking mechanism to the ER using a novel translocation signal}, volume={229}, ISSN={["1469-8137"]}, DOI={10.1111/nph.16765}, abstractNote={Cyst nematodes induce a multicellular feeding site within roots called a syncytium. It remains unknown how root cells are primed for incorporation into the developing syncytium. Furthermore, it is unclear how CLAVATA3/EMBRYO SURROUNDING REGION (CLE) peptide effectors secreted into the cytoplasm of the initial feeding cell could have an effect on plant cells so distant from where the nematode is feeding as the syncytium expands. Here we describe a novel translocation signal within nematode CLE effectors that is recognized by plant cell secretory machinery to redirect these peptides from the cytoplasm to the apoplast of plant cells. We show that the translocation signal is functionally conserved across CLE effectors identified in nematode species spanning three genera and multiple plant species, operative across plant cell types, and can traffic other unrelated small peptides from the cytoplasm to the apoplast of host cells via a previously unknown post-translational mechanism of endoplasmic reticulum (ER) translocation. Our results uncover a mechanism of effector trafficking that is unprecedented in any plant pathogen to date, andthey illustrate how phytonematodes can deliver effector proteins into host cells and then hijack plant cellular processes for their export back out of the cell to function as external signaling molecules to distant cells.}, number={1}, journal={NEW PHYTOLOGIST}, author={Wang, Jianying and Dhroso, Andi and Liu, Xunliang and Baum, Thomas J. and Hussey, Richard S. and Davis, Eric L. and Wang, Xiaohong and Korkin, Dmitry and Mitchum, Melissa G.}, year={2021}, month={Jan}, pages={563–574} }
 @article{schwarz_li_yencho_pecota_heim_davis_2021, title={Screening Sweetpotato Genotypes for Resistance to a North Carolina Isolate of Meloidogyne enterolobii}, volume={105}, ISSN={0191-2917 1943-7692}, url={http://dx.doi.org/10.1094/PDIS-02-20-0389-RE}, DOI={10.1094/PDIS-02-20-0389-RE}, abstractNote={Potential resistance to the guava root-knot nematode, Meloidogyne enterolobii, in 91 selected sweetpotato (Ipomoea batatas [L.] Lam.) genotypes was evaluated in six greenhouse experiments. Ten thousand eggs of M. enterolobii were inoculated on each sweetpotato genotype grown in a 3:1 sand to soil mixture. Sixty days after inoculation, the percentage of total roots with nematode-induced galls was determined, and nematode eggs were extracted from roots. Significant differences (P < 0.001) between sweetpotato genotypes were found in all six tests for gall rating, total eggs, and eggs per gram of root. Resistant sweetpotato genotypes were calculated as final eggs per root system divided by the initial inoculum, where Pf/Pi < 1 (reproduction factor; final egg count divided by initial inoculum of 10,000 eggs), and statistical mean separations were confirmed by Fisher’s least significant difference t test. Our results indicated that 19 out of 91 tested sweetpotato genotypes were resistant to M. enterolobii. Some of the susceptible genotypes included ‘Covington,’ ‘Beauregard,’ ‘NCDM04-001’, and ‘Hernandez.’ Some of the resistant sweetpotato genotypes included ‘Tanzania,’ ‘Murasaki-29,’ ‘Bwanjule,’ ‘Dimbuka-Bukulula,’ ‘Jewel,’ and ‘Centennial.’ Most of the 19 resistant sweetpotato genotypes supported almost no M. enterolobii reproduction, with <20 eggs/g root of M. enterolobii. A number of segregants from a ‘Tanzania’ × ‘Beauregard’ cross demonstrated strong resistance to M. enterolobii observed in the ‘Tanzania’ parent. In collaboration with North Carolina State University sweetpotato breeding program, several genotypes evaluated in these tests are being used to incorporate the observed resistance to M. enterolobii into commercial sweetpotato cultivars.}, number={4}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Schwarz, Tanner R. and Li, Chunying and Yencho, G. Craig and Pecota, Kenneth V and Heim, Chris R. and Davis, Eric L.}, year={2021}, month={Apr}, pages={1101–1107} }
 @article{schwarz_li_ye_davis_2020, title={Distribution of Meloidogyne enterolobii in Eastern North Carolina and Comparison of Four Isolates}, volume={21}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-12-19-0093-RS}, abstractNote={The guava root-knot nematode (RKN), Meloidogyne enterolobii, is a particularly aggressive pathogen with limited known distribution in the United States. In 2011, M. enterolobii was identified on field crops in North Carolina for the first time. In collaboration with the North Carolina Department of Agriculture and Consumer Services Nematode Assay Laboratory, RKN-positive samples from the eastern half of North Carolina submitted to the laboratory were analyzed for Meloidogyne species identification using polymerase chain reaction (PCR) of individual nematodes. PCR primers specific for Meloidogyne incognita, M. javanica, M. arenaria, M. hapla, and M. enterolobii were used to analyze DNA from 203 RKN-positive samples representing a variety of field and vegetable crops grown in counties in the eastern half of North Carolina. M. incognita was the predominant species identified (32% of samples), and M. enterolobii was identified in 6% of samples including ones from sweetpotato, tobacco, and soybean crops. New detections of M. enterolobii were found in Nash, Greene, Sampson, and Harnett counties in addition to the previously identified locations in Johnston, Wayne, Columbus, and Wilson counties. Four isolates of M. enterolobii populations were collected from soybean and sweetpotato crops in Johnston, Greene, and Wilson counties and reared on ‘Rutgers’ tomato plants in the greenhouse. Potential differences in virulence among the four M. enterolobii populations were not detected in greenhouse infection assays on six selected resistant and susceptible sweetpotato genotypes in two independent tests.}, number={2}, journal={PLANT HEALTH PROGRESS}, author={Schwarz, Tanner and Li, Chunying and Ye, Weimin and Davis, Eric}, year={2020}, pages={91–96} }
 @article{ruark-seward_davis_sit_2020, title={Localization of viral and host RNA within soybean cyst nematode via fluorescence in situ hybridization}, volume={211}, ISSN={["1090-2449"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85082019323&partnerID=MN8TOARS}, DOI={10.1016/j.exppara.2020.107866}, abstractNote={Nematode-infecting RNA viruses have recently been discovered via transcriptome sequencing. In soybean cyst nematode (SCN; Heterodera glycines), seven single-stranded RNA viruses have been identified from transcriptome data and experimentally confirmed with qRT-PCR and Sanger sequencing. Presently, there is still much unknown about the relationship between these viruses and the nematode host. In this study, we localize three viruses within the soybean cyst nematode: SCN socyvirus-1 (SbCNV-1), SCN nyami-like virus (NLV), and SCN bunya-like virus (BLV). To visually locate the viruses, whole-mount fluorescence in situ hybridization (FISH) methodology was developed for SCN pre-parasitic second-stage juveniles (ppJ2s). Two SCN populations with differing viral titers (LY1 and MM21) were used as a comparison for viral probe fluorescence intensity. Viral RNAs for all three viruses were abundant in cells throughout the SCN ppJ2 body of the high titer (LY1) population but absent within the majority of the intestinal tract. A significant reduction in viral fluorescence intensity was observed in a similar body pattern in ppJ2 of the low-titer (MM21) SCN, highlighting the specificity of the FISH method. As controls, viral RNAs were colocalized with host mRNA glyceraldehyde 3-phosphate dehydrogenase (GAPDH) for full body localization and a secretory ubiquitin protein (4G06) expressed specifically within the subventral esophageal glands. In addition, viral replication was confirmed in SCN eggs and ppJ2s via qRT-PCR detection of the anti-genomic RNA strands.}, journal={EXPERIMENTAL PARASITOLOGY}, publisher={Elsevier BV}, author={Ruark-Seward, Casey L. and Davis, Eric L. and Sit, Tim L.}, year={2020}, month={Apr} }
 @article{hamamouch_winkel_li_davis_2020, title={Modulation of Arabidopsis Flavonol Biosynthesis Genes by Cyst and Root-Knot Nematodes}, volume={9}, ISSN={["2223-7747"]}, DOI={10.3390/plants9020253}, abstractNote={Although it is well established that flavonoid synthesis is induced in diverse plant species during nematode parasitism, little is known about the regulation of genes controlling flavonol biosynthesis during the plant–nematode interaction. In this study, expression of the Arabidopsis thaliana flavonol-specific transcription factor, AtMYB12, the flavonol synthase genes, AtFLS1, 2, 3, 4, and 5, and the gene encoding the central flavonoid enzyme, chalcone synthase (AtCHS), were examined in plant roots during infection by Heterodera schachtii (sugar beet cyst) and Meloidogyne incognita (root-knot) nematodes. These experiments showed that AtMYB12 was transiently upregulated at 9 dpi in syncytia associated with sugar beet cyst nematode infection and that an Atmyb12-deficient line was less susceptible to the parasite. This suggests that, rather than contributing to plant defense, this gene is essential for productive infection. However, the AtCHS and AtFLS1 genes, which are controlled by AtMYB12, did not exhibit a similar transient increase, but rather were expressly downregulated in syncytia relative to adjacent uninfected root tissue. Genetic analyses further indicated that AtFLS1 contributes to plant defense against Cyst nematode infection, while other AtFLS gene family members do not, consistent with prior reports that these other genes encode little or no enzyme activity. Together, these findings indicate a role of AtMyb12 in promoting the early stages of Cyst nematode infection, while flavonols produced through the action of AtFLS1 are essential for plant defense. On the other hand, a transient induction of AtMYB12 was not observed in galls produced during root-knot nematode infection, but this gene was instead substantially downregulated, starting at the 9 dpi sampling point, as were AtCHS and AtFLS1. In addition, both the AtMYB12- and AtFLS1-deficient lines were more susceptible to infection by this parasite. There was again little evidence for contributions from the other AtFLS gene family members, although an AtFLS5-deficient line appeared to be somewhat more susceptible to infection. Taken together, this study shows that sugar-beet cyst and root-knot nematodes modulate differently the genes involved in flavonol biosynthesis in order to successfully infect host roots and that AtFLS1 may be involved in the plant basal defense response against nematode infection.}, number={2}, journal={PLANTS-BASEL}, author={Hamamouch, Noureddine and Winkel, Brenda S. J. and Li, Chunying and Davis, Eric L.}, year={2020}, month={Feb} }
 @article{wang_yeckel_kandoth_wasala_hussey_davis_baum_mitchum_2020, title={Targeted suppression of soybean BAG6-induced cell death in yeast by soybean cyst nematode effectors}, volume={21}, ISSN={["1364-3703"]}, DOI={10.1111/mpp.12970}, abstractNote={While numerous effectors that suppress plant immunity have been identified from bacteria, fungi, and oomycete pathogens, relatively little is known for nematode effectors. Several dozen effectors have been reported from the soybean cyst nematode (SCN). Previous studies suggest that a hypersensitive response-like programmed cell death is triggered at nematode feeding sites in soybean during an incompatible interaction. However, virulent SCN populations overcome this incompatibility using unknown mechanisms. A soybean BAG6 (Bcl-2 associated anthanogene 6) gene previously reported by us to be highly up-regulated in degenerating feeding sites induced by SCN in a resistant soybean line was attenuated in response to a virulent SCN population. We show that GmBAG6-1 induces cell death in yeast like its Arabidopsis homolog AtBAG6 and also in soybean. This led us to hypothesize that virulent SCN may target GmBAG6-1 as part of their strategy to overcome soybean defence responses during infection. Thus, we used a yeast viability assay to screen SCN effector candidates for their ability to specifically suppress GmBAG6-1-induced cell death. We identified several effectors that strongly suppressed cell death mediated by GmBAG6-1. Two effectors identified as suppressors showed direct interaction with GmBAG6-1 in yeast, suggesting that one mechanism of cell death suppression may occur through an interaction with this host protein.}, number={9}, journal={MOLECULAR PLANT PATHOLOGY}, author={Wang, Jianying and Yeckel, Greg and Kandoth, Pramod K. and Wasala, Lakmini and Hussey, Richard S. and Davis, Eric L. and Baum, Thomas J. and Mitchum, Melissa G.}, year={2020}, month={Sep}, pages={1227–1239} }
 @article{ruark-seward_davis_sit_2019, title={Electropermeabilization-based fluorescence in situ hybridization of whole-mount plant parasitic nematode specimens}, volume={6}, ISSN={["2215-0161"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85075266069&partnerID=MN8TOARS}, DOI={10.1016/j.mex.2019.11.009}, abstractNote={A fluorescence in situ hybridization (FISH) protocol was developed for nematodes in which nucleic acid probes are introduced within the organism via electroporation. This modification of existing FISH protocols removes numerous chemical wash steps, and thus, reduces protocol time and specimen loss while improving hybridization sensitivity. The presented work is optimized for juveniles of soybean cyst nematode (SCN; Heterodera glycines) and has been used to identify both host and associated-microbial (viral) targets. Moreover, through the use of two different long wavelength fluorophores, two probes can be colocalized within one individual. This protocol may be adapted to identify targets-of-interest within other life stages and nematode species. This protocol improves: •Hands-on protocol time (by approximately 1.5 h).•Specimen loss (fewer aspiration steps).•Hybridization (allows colocalization with two nucleic acid probes and increases sensitivity).}, journal={METHODSX}, publisher={Elsevier BV}, author={Ruark-Seward, Casey L. and Davis, Eric L. and Sit, Tim L.}, year={2019}, pages={2720–2728} }
 @article{ruark_gardner_mitchum_davis_sit_2018, title={Novel RNA viruses within plant parasitic cyst nematodes}, volume={13}, ISSN={["1932-6203"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042946067&partnerID=MN8TOARS}, DOI={10.1371/journal.pone.0193881}, abstractNote={The study of invertebrate-and particularly nematode-viruses is emerging with the advancement of transcriptome sequencing. Five single-stranded RNA viruses have now been confirmed within the economically important soybean cyst nematode (SCN; Heterodera glycines). From previous research, we know these viruses to be widespread in greenhouse and field populations of SCN. Several of the SCN viruses were also confirmed within clover (H. trifolii) and beet (H. schachtii) cyst nematodes. In the presented study, we sequenced the transcriptomes of several inbred SCN populations and identified two previously undiscovered viral-like genomes. Both of these proposed viruses are negative-sense RNA viruses and have been named SCN nyami-like virus (NLV) and SCN bunya-like virus (BLV). Finally, we analyzed publicly available transcriptome data of two potato cyst nematode (PCN) species, Globodera pallida and G. rostochiensis. From these data, a third potential virus was discovered and called PCN picorna-like virus (PLV). PCN PLV is a positive-sense RNA virus, and to the best of our knowledge, is the first virus described within PCN. The presence of these novel viruses was confirmed via qRT-PCR, endpoint PCR, and Sanger sequencing with the exception of PCN PLV due to quarantine restrictions on the nematode host. While much work needs to be done to understand the biological and evolutionary significance of these viruses, they offer insight into nematode ecology and the possibility of novel nematode management strategies.}, number={3}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Ruark, Casey L. and Gardner, Michael and Mitchum, Melissa G. and Davis, Eric L. and Sit, Tim L.}, editor={Melcher, UlrichEditor}, year={2018}, month={Mar} }
 @article{gardner_dhroso_johnson_davis_baum_korkin_mitchum_2018, title={Novel global effector mining from the transcriptome of early life stages of the soybean cyst nematode Heterodera glycines}, volume={8}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-018-20536-5}, abstractNote={Abstract Soybean cyst nematode (SCN) Heterodera glycines is an obligate parasite that relies on the secretion of effector proteins to manipulate host cellular processes that favor the formation of a feeding site within host roots to ensure its survival. The sequence complexity and co-evolutionary forces acting upon these effectors remain unknown. Here we generated a de novo transcriptome assembly representing the early life stages of SCN in both a compatible and an incompatible host interaction to facilitate global effector mining efforts in the absence of an available annotated SCN genome. We then employed a dual effector prediction strategy coupling a newly developed nematode effector prediction tool, N-Preffector, with a traditional secreted protein prediction pipeline to uncover a suite of novel effector candidates. Our analysis distinguished between effectors that co-evolve with the host genotype and those conserved by the pathogen to maintain a core function in parasitism and demonstrated that alternative splicing is one mechanism used to diversify the effector pool. In addition, we confirmed the presence of viral and microbial inhabitants with molecular sequence information. This transcriptome represents the most comprehensive whole-nematode sequence currently available for SCN and can be used as a tool for annotation of expected genome assemblies.}, journal={SCIENTIFIC REPORTS}, author={Gardner, Michael and Dhroso, Andi and Johnson, Nathan and Davis, Eric L. and Baum, Thomas J. and Korkin, Dmitry and Mitchum, Melissa G.}, year={2018}, month={Feb} }
 @article{samira_li_kliebenstein_li_davis_gillikin_long_2018, title={The bHLH transcription factor ILR3 modulates multiple stress responses in Arabidopsis}, volume={97}, ISSN={0167-4412 1573-5028}, url={http://dx.doi.org/10.1007/S11103-018-0735-8}, DOI={10.1007/S11103-018-0735-8}, number={4-5}, journal={Plant Molecular Biology}, publisher={Springer Science and Business Media LLC}, author={Samira, Rozalynne and Li, Baohua and Kliebenstein, Daniel and Li, Chunying and Davis, Eric and Gillikin, Jeffrey W. and Long, Terri A.}, year={2018}, month={Jun}, pages={297–309} }
 @article{verma_lee_morriss_odu_kenning_rizzo_spollen_lin_mcrae_givan_et al._2018, title={The novel cyst nematode effector protein 30D08 targets host nuclear functions to alter gene expression in feeding sites}, volume={219}, ISSN={["1469-8137"]}, DOI={10.1111/nph.15179}, abstractNote={Cyst nematodes deliver effector proteins into host cells to manipulate cellular processes and establish a metabolically hyperactive feeding site. The novel 30D08 effector protein is produced in the dorsal gland of parasitic juveniles, but its function has remained unknown. We demonstrate that expression of 30D08 contributes to nematode parasitism, the protein is packaged into secretory granules and it is targeted to the plant nucleus where it interacts with SMU2 (homolog of suppressor of mec-8 and unc-52 2), an auxiliary spliceosomal protein. We show that SMU2 is expressed in feeding sites and an smu2 mutant is less susceptible to nematode infection. In Arabidopsis expressing 30D08 under the SMU2 promoter, several genes were found to be alternatively spliced and the most abundant functional classes represented among differentially expressed genes were involved in RNA processing, transcription and binding, as well as in development, and hormone and secondary metabolism, representing key cellular processes known to be important for feeding site formation. In conclusion, we demonstrated that the 30D08 effector is secreted from the nematode and targeted to the plant nucleus where its interaction with a host auxiliary spliceosomal protein may alter the pre-mRNA splicing and expression of a subset of genes important for feeding site formation.}, number={2}, journal={NEW PHYTOLOGIST}, author={Verma, Anju and Lee, Chris and Morriss, Stephanie and Odu, Fiona and Kenning, Charlotte and Rizzo, Nancy and Spollen, William G. and Lin, Marriam and McRae, Amanda G. and Givan, Scott A. and et al.}, year={2018}, month={Jul}, pages={697–713} }
 @article{ruark_koenning_davis_opperman_lommel_mitchum_sit_2017, title={Soybean cyst nematode culture collections and field populations from North Carolina and Missouri reveal high incidences of infection by viruses}, volume={12}, ISSN={["1932-6203"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85011268632&partnerID=MN8TOARS}, DOI={10.1371/journal.pone.0171514}, abstractNote={Five viruses were previously discovered infecting soybean cyst nematodes (SCN; Heterodera glycines) from greenhouse cultures maintained in Illinois. In this study, the five viruses [ScNV, ScPV, ScRV, ScTV, and SbCNV-5] were detected within SCN greenhouse and field populations from North Carolina (NC) and Missouri (MO). The prevalence and titers of viruses in SCN from 43 greenhouse cultures and 25 field populations were analyzed using qRT-PCR. Viral titers within SCN greenhouse cultures were similar throughout juvenile development, and the presence of viral anti-genomic RNAs within egg, second-stage juvenile (J2), and pooled J3 and J4 stages suggests active viral replication within the nematode. Viruses were found at similar or lower levels within field populations of SCN compared with greenhouse cultures of North Carolina populations. Five greenhouse cultures harbored all five known viruses whereas in most populations a mixture of fewer viruses was detected. In contrast, three greenhouse cultures of similar descent to one another did not possess any detectable viruses and primarily differed in location of the cultures (NC versus MO). Several of these SCN viruses were also detected in Heterodera trifolii (clover cyst) and Heterodera schachtii (beet cyst), but not the other cyst, root-knot, or reniform nematode species tested. Viruses were not detected within soybean host plant tissue. If nematode infection with viruses is truly more common than first considered, the potential influence on nematode biology, pathogenicity, ecology, and control warrants continued investigation.}, number={1}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Ruark, Casey L. and Koenning, Stephen R. and Davis, Eric L. and Opperman, Charles H. and Lommel, Steven A. and Mitchum, Melissa G. and Sit, Tim L.}, editor={Rao, A.L.N.Editor}, year={2017}, month={Jan} }
 @article{pogorelko_juvale_rutter_hewezi_hussey_davis_mitchum_baum_2016, title={A cyst nematode effector binds to diverse plant proteins, increases nematode susceptibility and affects root morphology}, volume={17}, ISSN={["1364-3703"]}, DOI={10.1111/mpp.12330}, abstractNote={Cyst nematodes are plant-parasitic roundworms that are of significance in many cropping systems around the world. Cyst nematode infection is facilitated by effector proteins secreted from the nematode into the plant host. The cDNAs of the 25A01-like effector family are novel sequences that were isolated from the oesophageal gland cells of the soybean cyst nematode (Heterodera glycines). To aid functional characterization, we identified an orthologous member of this protein family (Hs25A01) from the closely related sugar beet cyst nematode H. schachtii, which infects Arabidopsis. Constitutive expression of the Hs25A01 CDS in Arabidopsis plants caused a small increase in root length, accompanied by up to a 22% increase in susceptibility to H. schachtii. A plant-expressed RNA interference (RNAi) construct targeting Hs25A01 transcripts in invading nematodes significantly reduced host susceptibility to H. schachtii. These data document that Hs25A01 has physiological functions in planta and a role in cyst nematode parasitism. In vivo and in vitro binding assays confirmed the specific interactions of Hs25A01 with an Arabidopsis F-box-containing protein, a chalcone synthase and the translation initiation factor eIF-2 β subunit (eIF-2bs), making these proteins probable candidates for involvement in the observed changes in plant growth and parasitism. A role of eIF-2bs in the mediation of Hs25A01 virulence function is further supported by the observation that two independent eIF-2bs Arabidopsis knock-out lines were significantly more susceptible to H. schachtii.}, number={6}, journal={MOLECULAR PLANT PATHOLOGY}, author={Pogorelko, Gennady and Juvale, Parijat S. and Rutter, William B. and Hewezi, Tarek and Hussey, Richard and Davis, Eric L. and Mitchum, Melissa G. and Baum, Thomas J.}, year={2016}, month={Aug}, pages={832–844} }
 @article{gardner_davis_baum_mitchum_2016, title={Effector variation among populations of the soybean cyst nematode that differ in virulence}, volume={48}, number={4}, journal={Journal of Nematology}, author={Gardner, M. and Davis, E. and Baum, T. and Mitchum, M. G.}, year={2016}, pages={323–323} }
 @article{zhang_li_davis_wang_griffin_kofsky_song_2016, title={Genome-Wide Association Study of Resistance to Soybean Cyst Nematode (Heterodera glycines) HG Type 2.5.7 in Wild Soybean (Glycine soja)}, volume={7}, ISSN={["1664-462X"]}, DOI={10.3389/fpls.2016.01214}, abstractNote={Soybean cyst nematode (SCN) is the most destructive soybean pest worldwide. Host plant resistance is the most environmentally friendly and cost-effective way of mitigating SCN damage to soybeans. However, overuse of the resistant soybean (Glycine max (L.) Merr.) cultivars from limited genetic resources has resulted in SCN race shifts in many soybean-growing areas. Thus, exploration of novel sources of SCN resistance and dissection of the genetic basis are urgently needed. In this study, we screened 235 wild soybean (Glycine soja Sieb. & Zucc.) accessions to identify genotypes resistant to SCN HG Type 2.5.7 (race 5), a less investigated type but is prevalent in the southeastern US. We also dissected the genetic basis of SCN resistance using a genome-wide association study with SNPs genotyped by SoySNP50k iSelect BeadChip. In total, 43 resistant accessions (female index < 30) were identified, with ten SNPs being significantly associated with SCN HG 2.5.7 resistance in this wild species. Furthermore, four significant SNPs were localized to linked regions of the known quantitative trait locus (QTL) rhg1 on chromosome 18. The other four SNPs on chromosome 18 and two SNPs on chromosome 19 are novel. Genes encoding disease resistance-related proteins with a leucine-rich region, a mitogen-activated protein kinase (MAPK) on chromosome 18, and a MYB transcription factor on chromosome 19 were identified as promising candidate genes. The identified SNPs and candidate genes will benefit future marker-assisted breeding and dissection of the molecular mechanisms underlying the soybean-SCN interaction.}, journal={FRONTIERS IN PLANT SCIENCE}, author={Zhang, Hengyou and Li, Chunying and Davis, Eric L. and Wang, Jinshe and Griffin, Joshua D. and Kofsky, Janice and Song, Bao-Hua}, year={2016}, month={Aug} }
 @article{vang_opperman_schwarz_davis_2016, title={Spirotetramat causes an arrest of nematode juvenile development}, volume={18}, ISSN={["1388-5545"]}, DOI={10.1163/15685411-00002948}, abstractNote={Spirotetramat (Movento™, Bayer CropScience) (SPT), an effective insecticide, has also demonstrated potential activity as a nematicide. No significant effects on hatching rates of Caenorhabditis elegans , Meloidogyne incognita or Heterodera glycines were observed when eggs were soaked in a maximum concentration of 105 ppm of technical grade spirotetramat-enol (SPT-enol), the active form in plants. Synchronised first-stage juveniles of C. elegans soaked in SPT-enol concentrations as low as 30 ppm demonstrated arrested juvenile development with calculated EC 95 of 44-48 ppm. Single applications of formulated SPT (Movento 240SC) were applied to plant foliage at the labelled insecticidal rate of 87.6 g a.s. ha −1 at 1-week intervals on soybean plants inoculated with H. glycines or tomato plants inoculated with M. incognita in glasshouse tests. SPT consistently inhibited nematode development to reproductive maturity when applied at 1-2 weeks after inoculation. Optimal SPT application timings coincide with early stages of root infection, when nematodes are still in vulnerable juvenile stages.}, journal={NEMATOLOGY}, author={Vang, Leah E. and Opperman, Charles H. and Schwarz, Michael R. and Davis, Eric L.}, year={2016}, pages={121–131} }
 @article{wang_yeckel_kandoth_wasala_hussey_davis_baum_mitchum_2016, title={Suppression of soybean bag6 induced programmed cell death by soybean cyst nematode Heterodera glycines effectors}, volume={48}, number={4}, journal={Journal of Nematology}, author={Wang, J. and Yeckel, G. and Kandoth, P. K. and Wasala, L. and Hussey, R. S. and Davis, E. L. and Baum, T. J. and Mitchum, M. G.}, year={2016}, pages={381–381} }
 @article{heiken_schwarz_davis_opperman_2016, title={The Effects of fluopyram on nematodes}, volume={48}, number={4}, journal={Journal of Nematology}, author={Heiken, J. and Schwarz, M. R. and Davis, E. L. and Opperman, C. H.}, year={2016}, pages={330–331} }
 @article{noon_hewezi_maier_simmons_wei_wu_llaca_deschamps_davis_mitchum_et al._2015, title={Eighteen New Candidate Effectors of the Phytonematode Heterodera glycines Produced Specifically in the Secretory Esophageal Gland Cells During Parasitism}, volume={105}, ISSN={["1943-7684"]}, DOI={10.1094/phyto-02-15-0049-r}, abstractNote={Heterodera glycines, the soybean cyst nematode, is the number one pathogen of soybean (Glycine max). This nematode infects soybean roots and forms an elaborate feeding site in the vascular cylinder. H. glycines produces an arsenal of effector proteins in the secretory esophageal gland cells. More than 60 H. glycines candidate effectors were identified in previous gland-cell-mining projects. However, it is likely that additional candidate effectors remained unidentified. With the goal of identifying remaining H. glycines candidate effectors, we constructed and sequenced a large gland cell cDNA library resulting in 11,814 expressed sequence tags. After bioinformatic filtering for candidate effectors using a number of criteria, in situ hybridizations were performed in H. glycines whole-mount specimens to identify candidate effectors whose mRNA exclusively accumulated in the esophageal gland cells, which is a hallmark of many nematode effectors. This approach resulted in the identification of 18 new H. glycines esophageal gland-cell-specific candidate effectors. Of these candidate effectors, 11 sequences were pioneers without similarities to known proteins while 7 sequences had similarities to functionally annotated proteins in databases. These putative homologies provided the bases for the development of hypotheses about potential functions in the parasitism process.}, number={10}, journal={PHYTOPATHOLOGY}, author={Noon, Jason B. and Hewezi, Tarek and Maier, Thomas R. and Simmons, Carl and Wei, Jun-Zhi and Wu, Gusui and Llaca, Victor and Deschamps, Stephane and Davis, Eric L. and Mitchum, Melissa G. and et al.}, year={2015}, month={Oct}, pages={1362–1372} }
 @article{wubben_gavilano_baum_davis_2015, title={Sequence and spatiotemporal expression analysis of CLE-motif containing genes from the reniform nematode (Rotylenchulus reniformis Linford & Oliveira)}, volume={47}, number={2}, journal={Journal of Nematology}, author={Wubben, M. J. and Gavilano, L. and Baum, T. J. and Davis, E. L.}, year={2015}, pages={159–165} }
 @article{hewezi_juvale_piya_maier_rambani_rice_mitchum_davis_hussey_baum_2015, title={The Cyst Nematode Effector Protein 10A07 Targets and Recruits Host Posttranslational Machinery to Mediate Its Nuclear Trafficking and to Promote Parasitism in Arabidopsis}, volume={27}, ISSN={["1532-298X"]}, DOI={10.1105/tpc.114.135327}, abstractNote={Plant-parasitic cyst nematodes synthesize and secrete effector proteins that are essential for parasitism. One such protein is the 10A07 effector from the sugar beet cyst nematode, Heterodera schachtii, which is exclusively expressed in the nematode dorsal gland cell during all nematode parasitic stages. Overexpression of H. schachtii 10A07 in Arabidopsis thaliana produced a hypersusceptible phenotype in response to H. schachtii infection along with developmental changes reminiscent of auxin effects. The 10A07 protein physically associates with a plant kinase and the IAA16 transcription factor in the cytoplasm and nucleus, respectively. The interacting plant kinase (IPK) phosphorylates 10A07 at Ser-144 and Ser-231 and mediates its trafficking from the cytoplasm to the nucleus. Translocation to the nucleus is phosphorylation dependent since substitution of Ser-144 and Ser-231 by alanine resulted in exclusive cytoplasmic accumulation of 10A07. IPK and IAA16 are highly upregulated in the nematode-induced syncytium (feeding cells), and deliberate manipulations of their expression significantly alter plant susceptibility to H. schachtii in an additive fashion. An inactive variant of IPK functioned antagonistically to the wild-type IPK and caused a dominant-negative phenotype of reduced plant susceptibility. Thus, exploitation of host processes to the advantage of the parasites is one mechanism by which cyst nematodes promote parasitism of host plants.}, number={3}, journal={PLANT CELL}, author={Hewezi, Tarek and Juvale, Parijat S. and Piya, Sarbottam and Maier, Tom R. and Rambani, Aditi and Rice, J. Hollis and Mitchum, Melissa G. and Davis, Eric L. and Hussey, Richard S. and Baum, Thomas J.}, year={2015}, month={Mar}, pages={891–907} }
 @article{rutter_hewezi_maier_mitchum_davis_hussey_baum_2014, title={Members of the Meloidogyne Avirulence Protein Family Contain Multiple Plant Ligand-Like Motifs}, volume={104}, ISSN={["1943-7684"]}, DOI={10.1094/phyto-11-13-0326-r}, abstractNote={Sedentary plant-parasitic nematodes engage in complex interactions with their host plants by secreting effector proteins. Some effectors of both root-knot nematodes (Meloidogyne spp.) and cyst nematodes (Heterodera and Globodera spp.) mimic plant ligand proteins. Most prominently, cyst nematodes secrete effectors that mimic plant CLAVATA3/ESR-related (CLE) ligand proteins. However, only cyst nematodes have been shown to secrete such effectors and to utilize CLE ligand mimicry in their interactions with host plants. Here, we document the presence of ligand-like motifs in bona fide root-knot nematode effectors that are most similar to CLE peptides from plants and cyst nematodes. We have identified multiple tandem CLE-like motifs conserved within the previously identified Meloidogyne avirulence protein (MAP) family that are secreted from root-knot nematodes and have been shown to function in planta. By searching all 12 MAP family members from multiple Meloidogyne spp., we identified 43 repetitive CLE-like motifs composing 14 unique variants. At least one CLE-like motif was conserved in each MAP family member. Furthermore, we documented the presence of other conserved sequences that resemble the variable domains described in Heterodera and Globodera CLE effectors. These findings document that root-knot nematodes appear to use CLE ligand mimicry and point toward a common host node targeted by two evolutionarily diverse groups of nematodes. As a consequence, it is likely that CLE signaling pathways are important in other phytonematode pathosystems as well.}, number={8}, journal={PHYTOPATHOLOGY}, author={Rutter, William B. and Hewezi, Tarek and Maier, Tom R. and Mitchum, Melissa G. and Davis, Eric L. and Hussey, Richard S. and Baum, Thomas J.}, year={2014}, month={Aug}, pages={879–885} }
 @misc{mitchum_hussey_baum_wang_elling_wubben_davis_2013, title={Nematode effector proteins: an emerging paradigm of parasitism}, volume={199}, ISSN={["1469-8137"]}, DOI={10.1111/nph.12323}, abstractNote={Phytonematodes use a stylet and secreted effectors to modify host cells and ingest nutrients to support their growth and development. The molecular function of nematode effectors is currently the subject of intense investigation. In this review, we summarize our current understanding of nematode effectors, with a particular focus on proteinaceous stylet-secreted effectors of sedentary endoparasitic phytonematodes, for which a wealth of information has surfaced in the past 10 yr. We provide an update on the effector repertoires of several of the most economically important genera of phytonematodes and discuss current approaches to dissecting their function. Lastly, we highlight the latest breakthroughs in effector discovery that promise to shed new light on effector diversity and function across the phylum Nematoda. Contents Summary 879 I. Introduction 879 II. Nematode effector regulation and delivery into host cells 881 III. Nematode effectors as probes of plant cell biology 883 IV. Functional characterization of effectors 885 V. Cell cycle and cytoskeleton 885 VI. New approaches for effector identification 888 VII. A global perspective of nematode effector function 889 Acknowledgements 890 References 890}, number={4}, journal={NEW PHYTOLOGIST}, author={Mitchum, Melissa G. and Hussey, Richard S. and Baum, Thomas J. and Wang, Xiaohong and Elling, Axel A. and Wubben, Martin and Davis, Eric L.}, year={2013}, month={Sep}, pages={879–894} }
 @article{xue_hamamouch_li_huang_hussey_baum_davis_2013, title={The 8D05 Parasitism Gene of Meloidogyne incognita Is Required for Successful Infection of Host Roots}, volume={103}, ISSN={["1943-7684"]}, DOI={10.1094/phyto-07-12-0173-r}, abstractNote={Parasitism genes encode effector proteins that are secreted through the stylet of root-knot nematodes to dramatically modify selected plant cells into giant-cells for feeding. The Mi8D05 parasitism gene previously identified was confirmed to encode a novel protein of 382 amino acids that had only one database homolog identified on contig 2374 within the Meloidogyne hapla genome. Mi8D05 expression peaked in M. incognita parasitic second-stage juveniles within host roots and its encoded protein was limited to the subventral esophageal gland cells that produce proteins secreted from the stylet. Constitutive expression of Mi8D05 in transformed Arabidopsis thaliana plants induced accelerated shoot growth and early flowering but had no visible effects on root growth. Independent lines of transgenic Arabidopsis that expressed a double-stranded RNA complementary to Mi8D05 in host-derived RNA interference (RNAi) tests had up to 90% reduction in infection by M. incognita compared with wild-type control plants, suggesting that Mi8D05 plays a critical role in parasitism by the root-knot nematode. Yeast two-hybrid experiments confirmed the specific interaction of the Mi8D05 protein with plant aquaporin tonoplast intrinsic protein 2 (TIP2) and provided evidence that the Mi8D05 effector may help regulate solute and water transport within giant-cells to promote the parasitic interaction.}, number={2}, journal={PHYTOPATHOLOGY}, author={Xue, Bingye and Hamamouch, Noureddine and Li, Chunying and Huang, Guozhong and Hussey, Richard S. and Baum, Thomas J. and Davis, Eric L.}, year={2013}, month={Feb}, pages={175–181} }
 @article{mitchum_wang_wang_davis_2012, title={Role of Nematode Peptides and Other Small Molecules in Plant Parasitism}, volume={50}, ISSN={["1545-2107"]}, DOI={10.1146/annurev-phyto-081211-173008}, abstractNote={Molecular, genetic, and biochemical studies are demonstrating an increasingly important role of peptide signaling in nematode parasitism of plants. To date, the majority of nematode-secreted peptides identified share similarity with plant CLAVATA3/ESR (CLE) peptides, but bioinformatics analyses of nematode genomes have revealed sequences homologous to other classes of plant peptide hormones that may be utilized by these pests. Extracellular host receptors for secreted nematode peptides are beginning to be identified and their roles in parasitism elucidated. Here, we outline recent advances from studies of biologically active nematode-secreted peptides that function as molecular mimics of endogenous plant peptides to promote parasitism. Several strategies are being used to exploit this information to provide new targets for engineering nematode resistance.}, journal={ANNUAL REVIEW OF PHYTOPATHOLOGY, VOL 50}, author={Mitchum, Melissa G. and Wang, Xiaohong and Wang, Jianying and Davis, Eric L.}, year={2012}, pages={175–195} }
 @article{hamamouch_li_hewezi_baum_mitchum_hussey_vodkin_davis_2012, title={The interaction of the novel 30C02 cyst nematode effector protein with a plant beta-1,3-endoglucanase may suppress host defence to promote parasitism}, volume={63}, ISSN={["1460-2431"]}, DOI={10.1093/jxb/ers058}, abstractNote={Phytoparasitic nematodes secrete an array of effector proteins to modify selected recipient plant cells into elaborate and essential feeding sites. The biological function of the novel 30C02 effector protein of the soybean cyst nematode, Heterodera glycines, was studied using Arabidopsis thaliana as host and the beet cyst nematode, Heterodera schachtii, which contains a homologue of the 30C02 gene. Expression of Hg30C02 in Arabidopsis did not affect plant growth and development but increased plant susceptibility to infection by H. schachtii. The 30C02 protein interacted with a specific (AT4G16260) host plant β-1,3-endoglucanase in both yeast and plant cells, possibly to interfere with its role as a plant pathogenesis-related protein. Interestingly, the peak expression of 30C02 in the nematode and peak expression of At4g16260 in plant roots coincided at around 3–5 d after root infection by the nematode, after which the relative expression of At4g16260 declined significantly. An Arabidopsis At4g16260 T-DNA mutant showed increased susceptibility to cyst nematode infection, and plants that overexpressed At4g16260 were reduced in nematode susceptibility, suggesting a potential role of host β-1,3-endoglucanase in the defence response against H. schachtii infection. Arabidopsis plants that expressed dsRNA and its processed small interfering RNA complementary to the Hg30C02 sequence were not phenotypically different from non-transformed plants, but they exhibited a strong RNA interference-mediated resistance to infection by H. schachtii. The collective results suggest that, as with other pathogens, active suppression of host defence is a critical component for successful parasitism by nematodes and a vulnerable target to disrupt the parasitic cycle.}, number={10}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Hamamouch, Noureddine and Li, Chunying and Hewezi, Tarek and Baum, Thomas J. and Mitchum, Melissa G. and Hussey, Richard S. and Vodkin, Lila O. and Davis, Eric L.}, year={2012}, month={Jun}, pages={3683–3695} }
 @article{wang_replogle_hussey_baum_wang_davis_mitchum_2011, title={Identification of potential host plant mimics of CLAVATA3/ESR (CLE)-like peptides from the plant-parasitic nematode Heterodera schachtii}, volume={12}, ISSN={["1364-3703"]}, DOI={10.1111/j.1364-3703.2010.00660.x}, abstractNote={In this article, we present the cloning of two CLAVATA3/ESR (CLE)-like genes, HsCLE1 and HsCLE2, from the beet cyst nematode Heterodera schachtii, a plant-parasitic cyst nematode with a relatively broad host range that includes the model plant Arabidopsis. CLEs are small secreted peptide ligands that play important roles in plant growth and development. By secreting peptide mimics of plant CLEs, the nematode can developmentally reprogramme root cells for the formation of unique feeding sites within host roots for its own benefit. Both HsCLE1 and HsCLE2 encode small secreted polypeptides with a conserved C-terminal CLE domain sharing highest similarity to Arabidopsis CLEs 1-7. Moreover, HsCLE2 contains a 12-amino-acid CLE motif that is identical to AtCLE5 and AtCLE6. Like all other plant and nematode CLEs identified to date, HsCLEs caused wuschel-like phenotypes when overexpressed in Arabidopsis, and this activity was abolished when the proteins were expressed without the CLE motif. HsCLEs could also function in planta without a signal peptide, highlighting the unique, yet conserved function of nematode CLE variable domains in trafficking CLE peptides for secretion. In a direct comparison of HsCLE2 overexpression phenotypes with those of AtCLE5 and AtCLE6, similar shoot and root phenotypes were observed. Exogenous application of 12-amino-acid synthetic peptides corresponding to the CLE motifs of HsCLEs and AtCLE5/6 suggests that the function of this class of CLEs may be subject to complex endogenous regulation. When seedlings were grown on high concentrations of peptide (10 µm), root growth was suppressed; however, when seedlings were grown on low concentrations of peptide (0.1 µm), root growth was stimulated. Together, these findings indicate that AtCLEs1-7 may be the target peptides mimicked by HsCLEs to promote parasitism.}, number={2}, journal={MOLECULAR PLANT PATHOLOGY}, author={Wang, Jianying and Replogle, Amy and Hussey, Richard and Baum, Thomas and Wang, Xiaohong and Davis, Eric L. and Mitchum, Melissa G.}, year={2011}, month={Feb}, pages={177–186} }
 @article{replogle_wang_bleckmann_hussey_baum_sawa_davis_wang_simon_mitchum_2011, title={Nematode CLE signaling in Arabidopsis requires CLAVATA2 and CORYNE}, volume={65}, ISSN={["1365-313X"]}, DOI={10.1111/j.1365-313x.2010.04433.x}, abstractNote={Plant-parasitic cyst nematodes secrete CLAVATA3 (CLV3)/ESR (CLE)-like effector proteins. These proteins have been shown to act as ligand mimics of plant CLE peptides and are required for successful nematode infection; however, the receptors for nematode CLE-like peptides have not been identified. Here we demonstrate that CLV2 and CORYNE (CRN), members of the receptor kinase family, are required for nematode CLE signaling. Exogenous peptide assays and overexpression of nematode CLEs in Arabidopsis demonstrated that CLV2 and CRN are required for perception of nematode CLEs. In addition, promoter-reporter assays showed that both receptors are expressed in nematode-induced syncytia. Lastly, infection assays with receptor mutants revealed a decrease in both nematode infection and syncytium size. Taken together, our results indicate that perception of nematode CLEs by CLV2 and CRN is not only required for successful nematode infection but is also involved in the formation and/or maintenance of nematode-induced syncytia.}, number={3}, journal={PLANT JOURNAL}, author={Replogle, Amy and Wang, Jianying and Bleckmann, Andrea and Hussey, Richard S. and Baum, Thomas J. and Sawa, Shinichiro and Davis, Eric L. and Wang, Xiaohong and Simon, Ruediger and Mitchum, Melissa G.}, year={2011}, month={Feb}, pages={430–440} }
 @article{lee_chronis_kenning_peret_hewezi_davis_baum_hussey_bennett_mitchum_2011, title={The Novel Cyst Nematode Effector Protein 19C07 Interacts with the Arabidopsis Auxin Influx Transporter LAX3 to Control Feeding Site Development}, volume={155}, ISSN={["0032-0889"]}, DOI={10.1104/pp.110.167197}, abstractNote={Abstract Plant-parasitic cyst nematodes penetrate plant roots and transform cells near the vasculature into specialized feeding sites called syncytia. Syncytia form by incorporating neighboring cells into a single fused cell by cell wall dissolution. This process is initiated via injection of esophageal gland cell effector proteins from the nematode stylet into the host cell. Once inside the cell, these proteins may interact with host proteins that regulate the phytohormone auxin, as cellular concentrations of auxin increase in developing syncytia. Soybean cyst nematode (Heterodera glycines) Hg19C07 is a novel effector protein expressed specifically in the dorsal gland cell during nematode parasitism. Here, we describe its ortholog in the beet cyst nematode (Heterodera schachtii), Hs19C07. We demonstrate that Hs19C07 interacts with the Arabidopsis (Arabidopsis thaliana) auxin influx transporter LAX3. LAX3 is expressed in cells overlying lateral root primordia, providing auxin signaling that triggers the expression of cell wall-modifying enzymes, allowing lateral roots to emerge. We found that LAX3 and polygalacturonase, a LAX3-induced cell wall-modifying enzyme, are expressed in the developing syncytium and in cells to be incorporated into the syncytium. We observed no decrease in H. schachtii infectivity in aux1 and lax3 single mutants. However, a decrease was observed in both the aux1lax3 double mutant and the aux1lax1lax2lax3 quadruple mutant. In addition, ectopic expression of 19C07 was found to speed up lateral root emergence. We propose that Hs19C07 most likely increases LAX3-mediated auxin influx and may provide a mechanism for cyst nematodes to modulate auxin flow into root cells, stimulating cell wall hydrolysis for syncytium development.}, number={2}, journal={PLANT PHYSIOLOGY}, author={Lee, Chris and Chronis, Demosthenis and Kenning, Charlotte and Peret, Benjamin and Hewezi, Tarek and Davis, Eric L. and Baum, Thomas J. and Hussey, Richard and Bennett, Malcolm and Mitchum, Melissa G.}, year={2011}, month={Feb}, pages={866–880} }
 @article{patel_hamamouch_li_hewezi_hussey_baum_mitchum_davis_2010, title={A nematode effector protein similar to annexins in host plants}, volume={61}, ISSN={["1460-2431"]}, DOI={10.1093/jxb/erp293}, abstractNote={Nematode parasitism genes encode secreted effector proteins that play a role in host infection. A homologue of the expressed Hg4F01 gene of the root-parasitic soybean cyst nematode, Heterodera glycines, encoding an annexin-like effector, was isolated in the related Heterodera schachtii to facilitate use of Arabidopsis thaliana as a model host. Hs4F01 and its protein product were exclusively expressed within the dorsal oesophageal gland secretory cell in the parasitic stages of H. schachtii. Hs4F01 had a 41% predicted amino acid sequence identity to the nex-1 annexin of C. elegans and 33% identity to annexin-1 (annAt1) of Arabidopsis, it contained four conserved domains typical of the annexin family of calcium and phospholipid binding proteins, and it had a predicted signal peptide for secretion that was present in nematode annexins of only Heterodera spp. Constitutive expression of Hs4F01 in wild-type Arabidopsis promoted hyper-susceptibility to H. schachtii infection. Complementation of an AnnAt1 mutant by constitutive expression of Hs4F01 reverted mutant sensitivity to 75mM NaCl, suggesting a similar function of the Hs4F01 annexin-like effector in the stress response by plant cells. Yeast two-hybrid assays confirmed a specific interaction between Hs4F01 and an Arabidopsis oxidoreductase member of the 2OG-Fe(II) oxygenase family, a type of plant enzyme demonstrated to promote susceptibility to oomycete pathogens. RNA interference assays that expressed double-stranded RNA complementary to Hs4F01 in transgenic Arabidopsis specifically decreased parasitic nematode Hs4F01 transcript levels and significantly reduced nematode infection levels. The combined data suggest that nematode secretion of an Hs4F01 annexin-like effector into host root cells may mimic plant annexin function during the parasitic interaction.}, number={1}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Patel, Nrupali and Hamamouch, Noureddine and Li, Chunying and Hewezi, Tarek and Hussey, Richard S. and Baum, Thomas J. and Mitchum, Melissa G. and Davis, Eric L.}, year={2010}, month={Jan}, pages={235–248} }
 @article{barker_davis_2010, title={Anastasios (Tasso) Christos Triantaphyllou (1926-2009) obituary}, volume={12}, journal={Nematology}, author={Barker, K. R. and Davis, E. L.}, year={2010}, pages={311–312} }
 @article{wang_lee_replogle_joshi_korkin_hussey_baum_davis_wang_mitchum_2010, title={Dual roles for the variable domain in protein trafficking and host-specific recognition of Heterodera glycines CLE effector proteins}, volume={187}, ISSN={["1469-8137"]}, DOI={10.1111/j.1469-8137.2010.03300.x}, abstractNote={*Soybean cyst nematodes (Heterodera glycines) produce secreted effector proteins that function as peptide mimics of plant CLAVATA3/ESR (CLE)-like peptides probably involved in the developmental reprogramming of root cells to form specialized feeding cells called syncytia. *The site of action and mechanism of delivery of CLE effectors to host plant cells by the nematode, however, have not been established. In this study, immunologic, genetic and biochemical approaches were used to reveal the localization and site of action of H. glycines-secreted CLE proteins in planta. *We present evidence indicating that the nematode CLE propeptides are delivered to the cytoplasm of syncytial cells, but ultimately function in the apoplast, consistent with their proposed role as ligand mimics of plant CLE peptides. We determined that the nematode 12-amino-acid CLE motif peptide is not sufficient for biological activity in vivo, pointing to an important role for sequences upstream of the CLE motif in function. *Genetic and biochemical analysis confirmed the requirement of the variable domain in planta for host-specific recognition and revealed a novel role in trafficking cytoplasmically delivered CLEs to the apoplast in order to function as ligand mimics.}, number={4}, journal={NEW PHYTOLOGIST}, author={Wang, Jianying and Lee, Chris and Replogle, Amy and Joshi, Sneha and Korkin, Dmitry and Hussey, Richard and Baum, Thomas J. and Davis, Eric L. and Wang, Xiaohong and Mitchum, Melissa G.}, year={2010}, pages={1003–1017} }
 @article{sindhu_maier_mitchum_hussey_davis_baum_2009, title={Effective and specific in planta RNAi in cyst nematodes: expression interference of four parasitism genes reduces parasitic success}, volume={60}, ISSN={["1460-2431"]}, DOI={10.1093/jxb/ern289}, abstractNote={Cyst nematodes are highly evolved sedentary plant endoparasites that use parasitism proteins injected through the stylet into host tissues to successfully parasitize plants. These secretory proteins likely are essential for parasitism as they are involved in a variety of parasitic events leading to the establishment of specialized feeding cells required by the nematode to obtain nourishment. With the advent of RNA interference (RNAi) technology and the demonstration of host-induced gene silencing in parasites, a new strategy to control pests and pathogens has become available, particularly in root-knot nematodes. Plant host-induced silencing of cyst nematode genes so far has had only limited success but similarly should disrupt the parasitic cycle and render the host plant resistant. Additional in planta RNAi data for cyst nematodes are being provided by targeting four parasitism genes through host-induced RNAi gene silencing in transgenic Arabidopsis thaliana, which is a host for the sugar beet cyst nematode Heterodera schachtii. Here it is reported that mRNA abundances of targeted nematode genes were specifically reduced in nematodes feeding on plants expressing corresponding RNAi constructs. Furthermore, this host-induced RNAi of all four nematode parasitism genes led to a reduction in the number of mature nematode females. Although no complete resistance was observed, the reduction of developing females ranged from 23% to 64% in different RNAi lines. These observations demonstrate the relevance of the targeted parasitism genes during the nematode life cycle and, potentially more importantly, suggest that a viable level of resistance in crop plants may be accomplished in the future using this technology against cyst nematodes.}, number={1}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Sindhu, Anoop S. and Maier, Tom R. and Mitchum, Melissa G. and Hussey, Richard S. and Davis, Eric L. and Baum, Thomas J.}, year={2009}, month={Jan}, pages={315–324} }
 @article{rehman_butterbach_popeijus_overmars_davis_jones_goverse_bakker_smant_2009, title={Identification and characterization of the most abundant cellulases in stylet secretions from Globodera rostochiensis}, volume={99}, DOI={10.1094/PHYTO-98-2-0194}, number={2}, journal={Phytopathology}, author={Rehman, S. and Butterbach, P. and Popeijus, H. and Overmars, H. and Davis, E. L. and Jones, J. T. and Goverse, A. and Bakker, J. and Smant, G.}, year={2009}, pages={194–202} }
 @article{elling_mitreva_gai_martin_recknor_davis_hussey_nettleton_mccarter_baum_2009, title={Sequence mining and transcript profiling to explore cyst nematode parasitism}, volume={10}, ISSN={["1471-2164"]}, DOI={10.1186/1471-2164-10-58}, abstractNote={Cyst nematodes are devastating plant parasites that become sedentary within plant roots and induce the transformation of normal plant cells into elaborate feeding cells with the help of secreted effectors, the parasitism proteins. These proteins are the translation products of parasitism genes and are secreted molecular tools that allow cyst nematodes to infect plants.We present here the expression patterns of all previously described parasitism genes of the soybean cyst nematode, Heterodera glycines, in all major life stages except the adult male. These insights were gained by analyzing our gene expression dataset from experiments using the Affymetrix Soybean Genome Array GeneChip, which contains probeset sequences for 6,860 genes derived from preparasitic and parasitic H. glycines life stages. Targeting the identification of additional H. glycines parasitism-associated genes, we isolated 633 genes encoding secretory proteins using algorithms to predict secretory signal peptides. Furthermore, because some of the known H. glycines parasitism proteins have strongest similarity to proteins of plants and microbes, we searched for predicted protein sequences that showed their highest similarities to plant or microbial proteins and identified 156 H. glycines genes, some of which also contained a signal peptide. Analyses of the expression profiles of these genes allowed the formulation of hypotheses about potential roles in parasitism. This is the first study combining sequence analyses of a substantial EST dataset with microarray expression data of all major life stages (except adult males) for the identification and characterization of putative parasitism-associated proteins in any parasitic nematode.We have established an expression atlas for all known H. glycines parasitism genes. Furthermore, in an effort to identify additional H. glycines genes with putative functions in parasitism, we have reduced the currently known 6,860 H. glycines genes to a pool of 788 most promising candidate genes (including known parasitism genes) and documented their expression profiles. Using our approach to pre-select genes likely involved in parasitism now allows detailed functional analyses in a manner not feasible for larger numbers of genes. The generation of the candidate pool described here is an important enabling advance because it will significantly facilitate the unraveling of fascinating plant-animal interactions and deliver knowledge that can be transferred to other pathogen-host systems. Ultimately, the exploration of true parasitism genes verified from the gene pool delineated here will identify weaknesses in the nematode life cycle that can be exploited by novel anti-nematode efforts.}, journal={BMC GENOMICS}, author={Elling, Axel A. and Mitreva, Makedonka and Gai, Xiaowu and Martin, John and Recknor, Justin and Davis, Eric L. and Hussey, Richard S. and Nettleton, Dan and McCarter, James P. and Baum, Thomas J.}, year={2009}, month={Jan} }
 @article{hewezi_howe_maier_hussey_mitchum_davis_baum_2008, title={Cellulose Binding Protein from the Parasitic Nematode Heterodera schachtii Interacts with Arabidopsis Pectin Methylesterase: Cooperative Cell Wall Modification during Parasitism}, volume={20}, ISSN={["1532-298X"]}, DOI={10.1105/tpc.108.063065}, abstractNote={Plant-parasitic cyst nematodes secrete a complex of cell wall-digesting enzymes, which aid in root penetration and migration. The soybean cyst nematode Heterodera glycines also produces a cellulose binding protein (Hg CBP) secretory protein. To determine the function of CBP, an orthologous cDNA clone (Hs CBP) was isolated from the sugar beet cyst nematode Heterodera schachtii, which is able to infect Arabidopsis thaliana. CBP is expressed only in the early phases of feeding cell formation and not during the migratory phase. Transgenic Arabidopsis expressing Hs CBP developed longer roots and exhibited enhanced susceptibility to H. schachtii. A yeast two-hybrid screen identified Arabidopsis pectin methylesterase protein 3 (PME3) as strongly and specifically interacting with Hs CBP. Transgenic plants overexpressing PME3 also produced longer roots and exhibited increased susceptibility to H. schachtii, while a pme3 knockout mutant showed opposite phenotypes. Moreover, CBP overexpression increases PME3 activity in planta. Localization studies support the mode of action of PME3 as a cell wall-modifying enzyme. Expression of CBP in the pme3 knockout mutant revealed that PME3 is required but not the sole mechanism for CBP overexpression phenotype. These data indicate that CBP directly interacts with PME3 thereby activating and potentially targeting this enzyme to aid cyst nematode parasitism.}, number={11}, journal={PLANT CELL}, author={Hewezi, Tarek and Howe, Peter and Maier, Tom R. and Hussey, Richard S. and Mitchum, Melissa Goellner and Davis, Eric L. and Baum, Thomas J.}, year={2008}, month={Nov}, pages={3080–3093} }
 @misc{mitchum_wang_davis_2008, title={Diverse and conserved roles of CLE peptides}, volume={11}, ISSN={["1879-0356"]}, DOI={10.1016/j.pbi.2007.10.010}, abstractNote={The function of plant CLAVATA3 (CLV3)/ENDOSPERM SURROUNDING REGION (ESR) (CLE) peptides in shoot meristem differentiation has been expanded in recent years to implicate roles in root growth and vascular development among different CLE family members. Recent evidence suggests that nematode pathogens within plant roots secrete ligand mimics of plant CLE peptides to modify selected host cells into multinucleate feeding sites. This discovery demonstrated an unprecedented adaptation of an animal gene product to functionally mimic a plant peptide involved in cellular signaling for parasitic benefit. This review highlights the diverse and conserved role of CLE peptides in these different contexts.}, number={1}, journal={CURRENT OPINION IN PLANT BIOLOGY}, author={Mitchum, Melissa G. and Wang, Xiaohong and Davis, Eric L.}, year={2008}, month={Feb}, pages={75–81} }
 @article{abad_gouzy_aury_castagnone-sereno_danchin_deleury_perfus-barbeoch_anthouard_artiguenave_blok_et al._2008, title={Genome sequence of the metazoan plant-parasitic nematode Meloidogyne incognita}, volume={26}, ISSN={["1546-1696"]}, DOI={10.1038/nbt.1482}, abstractNote={Plant-parasitic nematodes are major agricultural pests worldwide and novel approaches to control them are sorely needed. We report the draft genome sequence of the root-knot nematode Meloidogyne incognita, a biotrophic parasite of many crops, including tomato, cotton and coffee. Most of the assembled sequence of this asexually reproducing nematode, totaling 86 Mb, exists in pairs of homologous but divergent segments. This suggests that ancient allelic regions in M. incognita are evolving toward effective haploidy, permitting new mechanisms of adaptation. The number and diversity of plant cell wall-degrading enzymes in M. incognita is unprecedented in any animal for which a genome sequence is available, and may derive from multiple horizontal gene transfers from bacterial sources. Our results provide insights into the adaptations required by metazoans to successfully parasitize immunocompetent plants, and open the way for discovering new antiparasitic strategies.}, number={8}, journal={NATURE BIOTECHNOLOGY}, author={Abad, Pierre and Gouzy, Jerome and Aury, Jean-Marc and Castagnone-Sereno, Philippe and Danchin, Etienne G. J. and Deleury, Emeline and Perfus-Barbeoch, Laetitia and Anthouard, Veronique and Artiguenave, Francois and Blok, Vivian C. and et al.}, year={2008}, month={Aug}, pages={909–915} }
 @misc{davis_hussey_mitchum_baum_2008, title={Parasitism proteins in nematode-plant interactions}, volume={11}, ISSN={["1879-0356"]}, DOI={10.1016/j.pbi.2008.04.003}, abstractNote={The current battery of candidate parasitism proteins secreted by nematodes to modify plant tissues for parasitism includes cell-wall-modifying enzymes of potential prokaryotic origin, multiple regulators of host cell cycle and metabolism, proteins that can localize to the plant cell nucleus, potential suppressors of host defense, mimics of plant molecules, and a relatively large cadre of predicted novel nematode parasitism proteins. Phenotypic effects of expressing nematode parasitism proteins in transformed plant tissues, protein–protein interaction assays, and RNA-mediated interference (RNAi) analyses are currently providing exciting evidence of the biological role of candidate nematode secreted parasitism proteins and identifying potential novel means of developing transgenic resistance to nematodes in crops.}, number={4}, journal={CURRENT OPINION IN PLANT BIOLOGY}, author={Davis, Eric L. and Hussey, Richard S. and Mitchum, Melissa G. and Baum, Thomas J.}, year={2008}, month={Aug}, pages={360–366} }
 @article{patel_hamamouch_li_hussey_mitchum_baum_wang_davis_2008, title={Similarity and functional analyses of expressed parasitism genes in Heterodera schachtii and Heterodera glycines}, volume={40}, number={4}, journal={Journal of Nematology}, author={Patel, N. and Hamamouch, N. and Li, C. Y. and Hussey, R. and Mitchum, M. and Baum, T. and Wang, X. H. and Davis, E. L.}, year={2008}, pages={299–310} }
 @article{elling_davis_hussey_baum_2007, title={Active uptake of cyst nematode parasitism proteins into the plant cell nucleus}, volume={37}, ISSN={["1879-0135"]}, DOI={10.1016/j.ijpara.2007.03.012}, abstractNote={Cyst nematodes produce parasitism proteins that contain putative nuclear localisation signals (NLSs) and, therefore, are predicted to be imported into the nucleus of the host plant cell. The in planta localisation patterns of eight soybean cyst nematode (Heterodera glycines) parasitism proteins with putative NLSs were determined by producing these proteins as translational fusions with the GFP and GUS reporter proteins. Two parasitism proteins were found to be imported into the nuclei of onion epidermal cells as well as Arabidopsis protoplasts. One of these two parasitism proteins was further transported into the nucleoli. Mutations introduced into the NLS domains of these two proteins abolished nuclear import and caused a cytoplasmic accumulation. Furthermore, we observed active nuclear uptake for three additional parasitism proteins, however, only when these proteins were synthesised as truncated forms. Two of these proteins were further transported into nucleoli. We hypothesise that nuclear uptake and nucleolar localisation are important mechanisms for H. glycines to modulate the nuclear biology of parasitised cells of its host plant.}, number={11}, journal={INTERNATIONAL JOURNAL FOR PARASITOLOGY}, author={Elling, Axel A. and Davis, Eric L. and Hussey, Richard S. and Baum, Thomas J.}, year={2007}, month={Sep}, pages={1269–1279} }
 @article{mccuiston_hudson_subbotin_davis_warfield_2007, title={Conventional and PCR detection of Aphelenchoides fragariae in diverse ornamental host plant species}, volume={39}, number={4}, journal={Journal of Nematology}, author={McCuiston, J. L. and Hudson, L. C. and Subbotin, S. A. and Davis, E. L. and Warfield, C. Y.}, year={2007}, pages={343–355} }
 @article{elling_mitreva_recknor_gai_martin_maier_mcdermott_hewezi_bird_davis_et al._2007, title={Divergent evolution of arrested development in the dauer stage of Caenorhabditis elegans and the infective stage of Heterodera glycines}, volume={8}, ISSN={["1474-760X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42949087595&partnerID=MN8TOARS}, DOI={10.1186/gb-2007-8-10-r211}, abstractNote={The soybean cyst nematode Heterodera glycines is the most important parasite in soybean production worldwide. A comprehensive analysis of large-scale gene expression changes throughout the development of plant-parasitic nematodes has been lacking to date. We report an extensive genomic analysis of H. glycines, beginning with the generation of 20,100 expressed sequence tags (ESTs). In-depth analysis of these ESTs plus approximately 1,900 previously published sequences predicted 6,860 unique H. glycines genes and allowed a classification by function using InterProScan. Expression profiling of all 6,860 genes throughout the H. glycines life cycle was undertaken using the Affymetrix Soybean Genome Array GeneChip. Our data sets and results represent a comprehensive resource for molecular studies of H. glycines. Demonstrating the power of this resource, we were able to address whether arrested development in the Caenorhabditis elegans dauer larva and the H. glycines infective second-stage juvenile (J2) exhibits shared gene expression profiles. We determined that the gene expression profiles associated with the C. elegans dauer pathway are not uniformly conserved in H. glycines and that the expression profiles of genes for metabolic enzymes of C. elegans dauer larvae and H. glycines infective J2 are dissimilar. Our results indicate that hallmark gene expression patterns and metabolism features are not shared in the developmentally arrested life stages of C. elegans and H. glycines, suggesting that developmental arrest in these two nematode species has undergone more divergent evolution than previously thought and pointing to the need for detailed genomic analyses of individual parasite species.}, number={10}, journal={GENOME BIOLOGY}, author={Elling, Axel A. and Mitreva, Makedonka and Recknor, Justin and Gai, Xiaowu and Martin, John and Maier, Thomas R. and McDermott, Jeffrey P. and Hewezi, Tarek and Bird, David Mck and Davis, Eric L. and et al.}, year={2007} }
 @article{sukno_mccuiston_wong_wang_thon_hussey_baum_davis_2007, title={Quantitative detection of double-stranded RNA-mediated gene silencing of parasitism genes in Heterodera glycines}, volume={39}, number={2}, journal={Journal of Nematology}, author={Sukno, S. A. and McCuiston, J. and Wong, M. Y. and Wang, X. H. and Thon, M. R. and Hussey, R. and Baum, T. and Davis, E.}, year={2007}, pages={145–152} }
 @article{wang_replogle_davis_mitchum_2007, title={The tobacco Cel7 gene promoter is auxin-responsive and locally induced in nematode feeding sites of heterologous plants}, volume={8}, ISSN={["1364-3703"]}, DOI={10.1111/J.1364-3703.2007.00403.X}, abstractNote={Emerging evidence suggests that plant cell-wall-modifying enzymes induced by root-parasitic nematodes play important roles in feeding cell formation. We previously identified a tobacco endo-β-1,4-glucanase (cellulase) gene, NtCel7, that was strongly induced in both root-knot and cyst nematode feeding cells. To characterize further the developmental and nematode-responsive regulation of NtCel7, we isolated the NtCel7 promoter and analysed its expression over a time course of nematode infection and in response to auxin, gibberellin, ethylene and sucrose in soybean and tomato hairy roots and in Arabidopsis containing the NtCel7 promoter fused to the β-glucuronidase (GUS) reporter gene. Histochemical analyses of transgenic plant materials revealed that the NtCel7 promoter exhibited a unique organ-specific expression pattern during plant development suggestive of important roles for NtCel7 in both vegetative and reproductive growth. In all plant species tested, strong GUS expression was observed in root tips and lateral root primordia of uninfected roots with weaker expression in the root vasculature. Further analyses of transgenic Arabidopsis plants revealed expression in shoot and root meristems and the vasculature of most organs during plant development. We also determined that the NtCel7 promoter was induced by auxin, but not gibberellin, ethylene or sucrose. Moreover, strong GUS activity was observed in both cyst and root-knot nematode-induced feeding sites in transgenic roots of soybean, tomato and Arabidopsis. The conserved developmental and nematode-responsive expression of the NtCel7 promoter in heterologous plants indicates that motifs of this regulatory element play a fundamental role in regulating NtCel7 gene expression within nematode feeding sites and that this regulation may be mediated by auxin.}, number={4}, journal={MOLECULAR PLANT PATHOLOGY}, author={Wang, Xiaohong and Replogle, Amy and Davis, Eric L. and Mitchum, Melissa G.}, year={2007}, month={Jul}, pages={423–436} }
 @article{huang_dong_allen_davis_baum_hussey_2006, title={A root-knot nematode secretory peptide functions as a ligand for a plant transcription factor}, volume={19}, ISSN={["1943-7706"]}, DOI={10.1094/mpmi-19-0463}, abstractNote={Parasitism genes expressed in the esophageal gland cells of root-knot nematodes encode proteins that are secreted into host root cells to transform the recipient cells into enlarged multinucleate feeding cells called giant-cells. Expression of a root-knot nematode parasitism gene which encodes a novel 13-amino-acid secretory peptide in plant tissues stimulated root growth. Two SCARECROW-like transcription factors of the GRAS protein family were identified as the putative targets for this bioactive nematode peptide in yeast two-hybrid analyses and confirmed by in vitro and in vivo coimmunoprecipitations. This discovery is the first demonstration of a direct interaction of a nematode-secreted parasitism peptide with a plant-regulatory protein, which may represent an early signaling event in the root-knot nematode-host interaction.}, number={5}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Huang, GZ and Dong, RH and Allen, R and Davis, EL and Baum, TJ and Hussey, RS}, year={2006}, month={May}, pages={463–470} }
 @misc{davis_goellner_2006, title={Endoglucanase gene promoter upregulated by the root-knot nematode}, volume={7,119,254}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, E. L. and Goellner, M.}, year={2006} }
 @article{huang_allen_davis_baum_hussey_2006, title={Engineering broad root-knot resistance in transgenic plants by RNAi silencing of a conserved and essential root-knot nematode parasitism gene}, volume={103}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.0604698103}, abstractNote={Secreted parasitism proteins encoded by parasitism genes expressed in esophageal gland cells mediate infection and parasitism of plants by root-knot nematodes (RKN). Parasitism gene 16D10 encodes a conserved RKN secretory peptide that stimulates root growth and functions as a ligand for a putative plant transcription factor. We used in vitro and in vivo RNA interference approaches to silence this parasitism gene in RKN and validate that the parasitism gene has an essential function in RKN parasitism of plants. Ingestion of 16D10 dsRNA in vitro silenced the target parasitism gene in RKN and resulted in reduced nematode infectivity. In vivo expression of 16D10 dsRNA in Arabidopsis resulted in resistance effective against the four major RKN species. Because no known natural resistance gene has this wide effective range of RKN resistance, bioengineering crops expressing dsRNA that silence target RKN parasitism genes to disrupt the parasitic process represents a viable and flexible means of developing novel durable RKN-resistant crops and could provide crops with unprecedented broad resistance to RKN.}, number={39}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Huang, Guozhong and Allen, Rex and Davis, Eric L. and Baum, Thomas J. and Hussey, Richard S.}, year={2006}, month={Sep}, pages={14302–14306} }
 @article{sukno_shimerling_mccuiston_tsabary_shani_shoseyov_davis_2006, title={Expression and regulation of the Arabidopsis thaliana cel1 Endo 1,4 beta glucanase gene during compatible plant-nematode interactions}, volume={38}, number={3}, journal={Journal of Nematology}, author={Sukno, S. and Shimerling, O. and McCuiston, J. and Tsabary, G. and Shani, Z. and Shoseyov, C. and Davis, E. L.}, year={2006}, pages={354–361} }
 @article{wang_mitchum_gao_li_diab_baum_hussey_davis_2005, title={A parasitism gene from a plant-parasitic nematode with function similar to CLAVATA3/ESR (CLE) of Arabidopsis thaliana}, volume={6}, ISSN={["1364-3703"]}, DOI={10.1111/J.1364-3703.2005.00270.X}, abstractNote={SUMMARY The Hg-SYV46 parasitism gene is expressed exclusively in the dorsal oesophageal gland cell of parasitic stages of the soybean cyst nematode, Heterodera glycines, and it encodes a secretory protein that contains a C-terminal motif of the CLAVATA3/ESR-related (CLE) family in Arabidopsis thaliana. In shoot and floral meristems of Arabidopsis, the stem cells secret CLV3, a founding member of the CLE protein family, that activates the CLV1/CLV2 receptor complex and negatively regulates WUSCHEL expression to restrict the size of the stem cell population. Mis-expression of Hg-SYV46 in Arabidopsis (ecotype Columbia-0) under control of the CaMV35S promoter resulted in a wus-like phenotype including premature termination of the shoot apical meristem and the development of flowers lacking the central gynoecium. The wus-like phenotype observed was similar to reports of over-expression of CLV3 and CLE40 in Arabidopsis, as was down-regulation of WUS expression in the shoot apices of 35S::Hg-SYV46/Col-0 plants. Expression of 35S::Hg-SYV46 in a clv3-1 mutant of Arabidopsis was able partially or fully to rescue the mutant phenotype, probably dependent upon localization and level of transgene expression. A short root phenotype, as reported for over-expression of CLV3, CLE40 and CLE19 in roots, was also produced in primary 35S::Hg-SYV46/Col-0 transgenic plants. The results suggest a functional similarity of HG-SYV46 to plant-secreted CLE ligands that may play a role in the differentiation or division of feeding cells induced in plant roots by parasitic nematodes.}, number={2}, journal={MOLECULAR PLANT PATHOLOGY}, author={Wang, XH and Mitchum, MG and Gao, BL and Li, CY and Diab, H and Baum, TJ and Hussey, RS and Davis, EL}, year={2005}, month={Mar}, pages={187–191} }
 @article{huang_dong_allen_davis_baum_hussey_2005, title={Developmental expression and molecular analysis of two Meloidogyne incognita pectate lyase genes}, volume={35}, ISSN={["0020-7519"]}, DOI={10.1016/j.ijpara.2005.01.006}, abstractNote={Proteinaceous secretions from the oesophageal glands of plant-parasitic nematodes have crucial roles in nematode parasitism of plants. Two cDNAs (designated Mi-pel-1 and Mi-pel-2) encoding pectate lyases were isolated from the root-knot nematode, Meloidogyne incognita, oesophageal gland-cell subtractive cDNA libraries, and the corresponding genomic DNAs were subsequently cloned. Southern blot analyses revealed that homologues to these pectate lyase genes were broadly distributed in Meloidogyne species, and present as members of a small multigene family. Mi-pel-1 and Mi-pel-2 encoded, respectively, predicted proteins of 271 and 280 amino acids, each of which was preceded by a signal peptide for secretion. Interestingly, these pectate lyases showed diversity at the amino acid level, with only 31% identity and 49% similarity. These pectate lyases were classified into the same family of pectate lyases with those of other phytoparasitic nematodes that contain four conserved regions characteristic of the class III pectate lyases of microbes. In situ mRNA hybridisation analyses showed the transcripts of Mi-pel-1 and Mi-pel-2 accumulated exclusively within the subventral oesophageal gland cells of M. incognita. RT-PCR analysis confirmed that their transcriptions were strong at the pre-parasitic and early parasitic second-stage juveniles, and not detectable at the late parasitic stages of the nematodes. These results indicated that these pectate lyases, like cellulases, could be secreted into plant tissues to facilitate the penetration and intercellular migration of M. incognita during the early stages of plant parasitism.}, number={6}, journal={INTERNATIONAL JOURNAL FOR PARASITOLOGY}, author={Huang, GZ and Dong, RH and Allen, R and Davis, EL and Baum, TJ and Hussey, RS}, year={2005}, month={May}, pages={685–692} }
 @misc{davis_goellner_2005, title={Endoglucanase gene promoter upregulated by nematodes}, volume={6,906,241}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, E. L. and Goellner, M.}, year={2005} }
 @article{davis_mitchum_2005, title={Nematodes. Sophisticated parasites of legumes}, volume={137}, ISSN={["1532-2548"]}, DOI={10.1104/pp.104.054973}, abstractNote={From an agronomic perspective, the interactions of phytoparasitic nematodes with leguminous crops can be devastating ([Barker, 1998][1]). On a cellular and molecular level, the complexities of the interactions of these microscopic worms with legumes are comparable to those of well-known symbionts ([}, number={4}, journal={PLANT PHYSIOLOGY}, author={Davis, EL and Mitchum, MG}, year={2005}, month={Apr}, pages={1182–1188} }
 @article{huang_dong_allen_davis_baum_hussey_2005, title={Two chorismate mutase genes from the root-knot nematode Meloidogyne incognita}, volume={6}, ISSN={["1364-3703"]}, DOI={10.1111/j.1364-3703.2004.00257.x}, abstractNote={Parasitism genes encoding secretory proteins expressed in the oesophageal glands of phytoparasitic nematodes play critical roles in nematode invasion of host plants, establishment of feeding sites and suppression of host defences. Two chorismate mutase (CM) genes potentially having a role in one or more of these processes were identified from a Meloidogyne incognita oesophageal gland-cell subtractive cDNA library. These M. incognita enzymes (designated as MI-CM-1 and MI-CM-2) with amino-terminal signal peptides, were significantly similar to chorismate mutases in M. javanica and bacteria. The complementation of an Escherichia coli CM-deficient mutant by the expression of Mi-cm-1 or Mi-cm-2 confirmed their CM activity. In-situ mRNA hybridization showed that the transcripts of Mi-cm-1 and Mi-cm-2 accumulated specifically in the two subventral oesophageal gland cells of M. incognita. RT-PCR analysis confirmed that their transcript abundances were high in the early parasitic juvenile stages, and low (Mi-cm-1) or undetectable (Mi-cm-2) in later parasitic stages of the nematode. Southern blot analysis revealed that these CM genes were members of a small multigene family in Meloidogyne species. The widespread presence of CMs in the specialized sedentary endoparasitic nematode species suggests that this multifunctional enzyme may be a key factor in modulating plant parasitism.}, number={1}, journal={MOLECULAR PLANT PATHOLOGY}, author={Huang, GZ and Dong, RH and Allen, R and Davis, EL and Baum, TJ and Hussey, RS}, year={2005}, month={Jan}, pages={23–30} }
 @article{gao_allen_davis_baum_hussey_2004, title={Developmental expression and biochemical properties of a beta-1,4-endoglucanase family in the soybean cyst nematode, Heterodera glycines}, volume={5}, ISSN={["1364-3703"]}, DOI={10.1111/J.1364-3703.2004.00209.X}, abstractNote={SUMMARY The soybean cyst nematode, Heterodera glycines, produces beta-1,4-endoglucanases (cellulases) that are secreted during infection of soybean. The gene structures of three, hg-eng-4, hg-eng-5 and hg-eng-6, of the six beta-1,4-endoglucanase genes, all family 5 glycosyl hydrolases previously identified from H. glycines, are presented here. Furthermore, we present the detailed expression analyses of beta-1,4-endoglucanase genes as well as the biochemical properties of four H. glycines endoglucanase enzymes. Two of the endoglucanases, HG-ENG-5 and HG-ENG-6, differed significantly in their amino acid sequence of the catalytic domains and their gene structure from that of the other four beta-1,4-endoglucanases. Quantitative real-time RT-PCR revealed distinct developmental expression differences among the hg-eng family members during the early stages of parasitism and relatively low expression levels in late parasitic stages, with the exception of the adult male stage for some eng genes. Recombinant HG-ENGs degraded carboxymethylcellulose and optimum enzyme activity ranged from pH 5.5 for HG-ENG-5 to pH 8 for HG-ENG-6. EDTA, Ca(2+), Co(2+), Mg(2+) and Fe(2+) did not affect enzyme activity of any ENG protein, whereas Zn(2+), Cu(2+) and Mn(2+) inhibited enzyme activity from 23% to 73% in some cases. In tests with 12 different polysaccharide substrates, enzyme activity was restricted to beta-1,4 linkages with all ENG proteins tested. Only HG-ENG-5 and HG-ENG-6 had relatively high activity on xylan and slightly degraded microcrystalline cellulose. Together, these data reveal distinct differences in expression and biochemistry of cyst nematode parasitism genes and proteins, respectively, and cast light on the intricate interactions between a parasitic animal and its plant host.}, number={2}, journal={MOLECULAR PLANT PATHOLOGY}, author={Gao, BL and Allen, R and Davis, EL and Baum, TJ and Hussey, RS}, year={2004}, month={Mar}, pages={93–104} }
 @misc{davis_hussey_baum_2004, title={Getting to the roots of parasitism by nematodes}, volume={20}, ISSN={["1471-5007"]}, DOI={10.1016/j.pt.2004.01.005}, abstractNote={Most phytoparasitic nematodes infect plant roots and some species have evolved sophisticated interactive relationships with host cells to sustain a sedentary parasitic habit. The recent isolation of multiple 'parasitism genes' expressed specifically within the esophageal gland cells of sedentary phytonematodes suggests that an arsenal of different secreted parasitism proteins from the nematode might have direct effects on recipient host cells. These include cell wall modifications and potential interactions with signal transduction receptors in the extracellular space, as well as direct introduction of proteins into host cells that might influence cellular metabolism, the cell cycle, selective protein degradation, a localized defense response and regulatory activity within the host cell nucleus.}, number={3}, journal={TRENDS IN PARASITOLOGY}, author={Davis, EL and Hussey, RS and Baum, TJ}, year={2004}, month={Mar}, pages={134–141} }
 @article{davis_hussey_baum_2004, title={Getting to the roots of parasitism by nematodes.}, volume={20}, number={3}, journal={Trends in Parasitology}, author={Davis, E. L. and Hussey, R. S. and Baum, T. J.}, year={2004}, pages={134–141} }
 @article{gao_allen_davis_baum_hussey_2004, title={Molecular characterisation and developmental expression of a cellulose-binding protein gene in the soybean cyst nematode Heterodera glycines}, volume={34}, ISSN={["1879-0135"]}, DOI={10.1016/j.ijpara.2004.09.001}, abstractNote={Secretory proteins encoded by ‘parasitism genes’ expressed in the oesophageal gland cells of plant-parasitic nematodes play key roles in nematode infection and parasitism of host plants. A cellulose-binding protein-encoding cDNA, designated Hg-cbp-1, was cloned from a Heterodera glycines oesophageal gland-cell long-distance PCR cDNA library. The cDNA hybridised to genomic DNA of H. glycines in Southern blots, and the genomic sequence of Hg-cbp-1 contained only one intron. The Hg-cbp-1 cDNA contained an open reading frame encoding 132 amino acids, with a predicted signal peptide sequence for secretion and a cellulose-binding domain. Bacterial expressed recombinant HG-CBP-1, minus the signal peptide sequence, had no hydrolytic activity on carboxymethyl-cellulose but was able to bind to cellulose. The developmental expression of Hg-cbp-1, determined by real-time reverse transcriptase PCR, showed that Hg-cbp-1 is expressed throughout the parasitic cycle of H. glycines, with a relatively higher expression level in developing parasitic stages.}, number={12}, journal={INTERNATIONAL JOURNAL FOR PARASITOLOGY}, author={Gao, B and Allen, R and Davis, EL and Baum, TJ and Hussey, RS}, year={2004}, month={Nov}, pages={1377–1383} }
 @article{mitchum_sukno_wang_shani_tsabary_shoseyov_davis_2004, title={The promoter of the Arabidopsis thaliana Cel1 endo-1,4-beta glucanase gene is differentially expressed in plant feeding cells induced by root-knot and cyst nematodes}, volume={5}, ISSN={["1364-3703"]}, DOI={10.1111/J.1364-3703.2004.00216.X}, abstractNote={Transgenic tobacco and Arabidopsis thaliana carrying the Arabidopsis endo-1,4-β-glucanase (EC 3.2.1.4) Cel1 promoter fused to the β-glucuronidase (GUS) reporter gene were infected with the root-knot nematode, Meloidogyne incognita, and either the tobacco cyst nematode, Globodera tabacum (tobacco), or beet cyst nematode, Heterodera schachtii (Arabidopsis). Cel1-driven GUS expression was detected in cell elongation zones of noninfected plants and within feeding sites (giant-cells) induced in roots of both plant hosts by M. incognita. The first detectable signs of Cel1 expression within developing giant-cells occurred at the onset of giant-cell formation and continued throughout the M. incognita life cycle. UidA (Gus) transcripts were detectable within giant-cells induced in tobacco roots at 11–13 days postinoculation with M. incognita as determined by in situ mRNA hybridization. By contrast, expression of the Cel1 promoter was not detected within developing syncytia induced in tobacco or Arabidopsis roots by G. tabacum and H. schachtii, respectively, at any time point. The results demonstrate specific regulation of cell wall-degrading enzymes that may be required for cell wall modifications during feeding cell formation by sedentary endoparasitic nematodes. Differential expression of Cel1 by cyst and root-knot nematodes further supports underlying mechanistic differences in giant-cell and syncytium formation.}, number={3}, journal={MOLECULAR PLANT PATHOLOGY}, author={Mitchum, MG and Sukno, S and Wang, XH and Shani, Z and Tsabary, G and Shoseyov, O and Davis, EL}, year={2004}, month={May}, pages={175–181} }
 @article{huang_dong_maier_allen_davis_baum_hussey_2004, title={Use of solid-phase subtractive hybridization for the identification of parasitism gene candidates from the root-knot nematode Meloidogyne incognita}, volume={5}, ISSN={["1364-3703"]}, DOI={10.1111/j.1364-3703.2004.00220.x}, abstractNote={A solid-phase subtractive strategy was used to clone parasitism gene candidates (PGCs) expressed in the oesophageal gland cells of Meloidogyne incognita. Nematode intestinal first-strand cDNA was synthesized directly on magnetic beads and used to enrich for gland-specific sequences by high stringency hybridization to gland-cell mRNA. A gland-specific cDNA library was created from the nonhybridizing gland-cell mRNA by long-distance reverse transcription polymerase chain reaction. Subtraction of the gland cDNA library (1000 clones) with previously cloned M. incognita parasitism genes removed 89 cDNA clones and promoted efficient identification of new PGCs. Sequencing of 711 cDNA clones from the subtracted library revealed that deduced protein sequences of 67 cDNAs were preceded by a signal peptide for secretion, a key criterion for parasitism genes. In situ hybridization with probes from the cDNA clones encoding signal peptides showed that seven cDNA clones were specifically expressed in the subventral gland cells and four in the dorsal gland cell of M. incognita. BLASTP analyses revealed the predicted proteins of five cDNAs to be novel sequences. The six PGCs with similarities to known proteins included a pectate lyase, three beta-1,4-endoglucanases and two chorismate mutases. This subtractive protocol provides an efficient and reliable approach for identifying PGCs encoding oesophageal gland cell secretory proteins that may have a role in M. incognita parasitism of plants.}, number={3}, journal={MOLECULAR PLANT PATHOLOGY}, author={Huang, GZ and Dong, RH and Maier, T and Allen, R and Davis, EL and Baum, TJ and Hussey, RS}, year={2004}, month={May}, pages={217–222} }
 @article{huang_gao_maier_allen_davis_baum_hussey_2003, title={A profile of putative parasitism genes expressed in the esophageal gland cells of the root-knot nematode Meloidogyne incognita}, volume={16}, ISSN={["1943-7706"]}, DOI={10.1094/MPMI.2003.16.5.376}, abstractNote={Identifying parasitism genes encoding proteins secreted from a nematode's esophageal gland cells and injected through its stylet into plant tissue is the key to understanding the molecular basis of nematode parasitism of plants. Meloidogyne incognita parasitism genes were cloned by microaspirating the cytoplasm from the esophageal gland cells of different parasitic stages to provide mRNA to create a gland cell-specific cDNA library by long-distance reverse-transcriptase polymerase chain reaction. Of 2,452 cDNA clones sequenced, deduced protein sequences of 185 cDNAs had a signal peptide for secretion and, thus, could have a role in root-knot nematode parasitism of plants. High-throughput in situ hybridization with cDNA clones encoding signal peptides resulted in probes of 37 unique clones specifically hybridizing to transcripts accumulating within the subventral (13 clones) or dorsal (24 clones) esophageal gland cells of M. incognita. In BLASTP analyses, 73% of the predicted proteins were novel proteins. Those with similarities to known proteins included a pectate lyase, acid phosphatase, and hypothetical proteins from other organisms. Our cell-specific analysis of genes encoding secretory proteins provided, for the first time, a profile of putative parasitism genes expressed in the M. incognita esophageal gland cells throughout the parasitic cycle.}, number={5}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Huang, GZ and Gao, BL and Maier, T and Allen, R and Davis, EL and Baum, TJ and Hussey, RS}, year={2003}, month={May}, pages={376–381} }
 @misc{davis_yan_2003, title={Chemoreceptors in plant parasitic nematodes}, volume={6,521,438}, number={2003 Feb. 18}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, E. L. and Yan, Y.-T.}, year={2003} }
 @misc{davis_goellner_2003, title={Endoglucanase gene promoter upregulated by the root-knot nematode}, volume={6,593,513}, number={2003 July 15}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, E. L. and Goellner, M.}, year={2003} }
 @article{guimaraes_leal-bertioli_curtis_davis_bertioli_2003, title={Isolation of two cDNAS encoding a tropomyosin and an intermediate filament protein from the soybean cyst nematode Heterodera glycines}, volume={33}, number={1}, journal={Nematropica}, author={Guimaraes, P. M. and Leal-Bertioli, S. C. M. and Curtis, R. H. and Davis, E. L. and Bertioli, D. J.}, year={2003}, pages={87–95} }
 @article{gao_allen_maier_davis_baum_hussey_2003, title={The parasitome of the phytonematode Heterodera glycines}, volume={16}, ISSN={["1943-7706"]}, DOI={10.1094/MPMI.2003.16.8.720}, abstractNote={Parasitism genes expressed in the esophageal gland cells of phytonematodes encode secretions that control the complex process of plant parasitism. In the soybean cyst nematode, Heterodera glycines, the parasitome, i.e., the secreted products of parasitism genes, facilitate nematode migration in soybean roots and mediate the modification of root cells into elaborate feeding cells required to support the growth and development of the nematode. With very few exceptions, the identities of these secretions are unknown, and the mechanisms of cyst nematode parasitism, therefore, remain obscure. The most direct and efficient approach for cloning parasitism genes and rapidly advancing our understanding of the molecular interactions during nematode parasitism of plants is to create gland cell-specific cDNA libraries using cytoplasm microaspirated from the esophageal gland cells of various parasitic stages. By combining expressed sequence tag analysis of a gland cell cDNA library with high throughput in situ expression localization of clones encoding secretory proteins, we obtained the first comprehensive parasitome profile for a parasitic nematode. We identified 51 new H. glycines gland-expressed candidate parasitism genes, of which 38 genes constitute completely novel sequences. Individual parasitome members showed distinct gland cell expression patterns throughout the parasitic cycle. The parasitome complexity discovered paints a more elaborate picture of host cellular events under specific control by the nematode parasite than previously hypothesized.}, number={8}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Gao, BL and Allen, R and Maier, T and Davis, EL and Baum, TJ and Hussey, RS}, year={2003}, month={Aug}, pages={720–726} }
 @article{gao_allen_maier_mcdermott_davis_baum_hussey_2002, title={Characterisation and developmental expression of a chitinase gene in Heterodera glycines}, volume={32}, ISSN={["0020-7519"]}, DOI={10.1016/S0020-7519(02)00110-8}, abstractNote={A chitinase full-length cDNA (designated Hg-chi-1) was isolated from a Heterodera glycines oesophageal gland cell-specific long-distance PCR cDNA library. The cDNA hybridised to genomic DNA of H. glycines in Southern blots. The Hg-chi-1 cDNA contained an open reading frame encoding 350 amino acids with the first 23 amino acids being a putative signal peptide for secretion. Hg-CHI-1 contained a chitinase 18 family catalytic domain, and chitinolytic activity of recombinant Hg-CHI-1 was confirmed in glycol-chitin substrate gel electrophoresis. In situ mRNA hybridisation analyses showed that transcripts of Hg-chi-1 accumulated specifically in the subventral oesophageal gland cells of parasitic stages of H. glycines, but Hg-chi-1 expression was not detected in eggs or hatched pre-parasitic second-stage juveniles, suggesting that this chitinase does not have a role in egg hatching of H. glycines. The biological function of Hg-CHI-1 in H. glycines remains to be determined.}, number={10}, journal={INTERNATIONAL JOURNAL FOR PARASITOLOGY}, author={Gao, BL and Allen, R and Maier, T and McDermott, JP and Davis, EL and Baum, TJ and Hussey, RS}, year={2002}, month={Sep}, pages={1293–1300} }
 @article{yan_davis_2002, title={Characterisation of guanylyl cyclase genes in the soyabean cyst nematode Heterodera glycines}, volume={32}, ISSN={["1879-0135"]}, DOI={10.1016/S0020-7519(01)00315-0}, abstractNote={Parasitism by the soybean cyst nematode, Heterodera glycines, has become one of the major limiting factors in soybean production world-wide. A partial HG-gcy-1 cDNA clone was obtained by screening a H. glycines cDNA library with a probe derived from the HG-gcy1 genomic sequence, and HG-gcy-1 full-length cDNA was obtained by nested PCR and 5' rapid amplification of cDNA ends (5' RACE). Two additional, full-length guanylyl cyclase cDNA clones from H. glycines, named HG-gcy-2 and HG-gcy-3, were recovered directly by screening the H. glycines cDNA library with a probe derived from sequence of the HG-gcy-1 catalytic domain. The encoded proteins of all three HG-gcy genes had an extracellular ligand-binding domain, a single membrane-spanning domain, an intracellular protein kinase-like domain, and a guanylyl cyclase catalytic domain. The three HG-GCY proteins had conserved cysteine residues to form disulfide bridges within the extracellular domain similar to the predicted ligand-binding domains of other known membrane-bound guanylyl cyclases. mRNA in situ hybridisation detected the expression of HG-gcy-1 and HG-gcy-2 transcripts in specific and different sensory neurons within H. glycines specimens. HG-gcy-3 transcripts were not localised in H. glycines specimens by in situ hybridisation. The discovery of the three guanylyl cyclase genes in H. glycines is the first of its kind in a plant-parasitic nematode and may be representative of a conserved gene family used for chemosensory recognition in parasitic nematodes.}, number={1}, journal={INTERNATIONAL JOURNAL FOR PARASITOLOGY}, author={Yan, YT and Davis, EL}, year={2002}, month={Jan}, pages={65–72} }
 @article{de boer_mcdermott_davis_hussey_popeijus_smant_baum_2002, title={Cloning of a putative pectate lyase gene expressed in the subventral esophageal glands of Heterodera glycines}, volume={34}, number={1}, journal={Journal of Nematology}, author={De Boer, J. M. and McDermott, J. P. and Davis, E. L. and Hussey, R. S. and Popeijus, H. and Smant, G. and Baum, T. J.}, year={2002}, pages={9–11} }
 @article{cervantes-flores_yencho_davis_2002, title={Efficient evaluation of resistance to three root-knot nematode species in selected sweetpotato cultivars}, volume={37}, number={2}, journal={HortScience}, author={Cervantes-Flores, J. C. and Yencho, G. C. and Davis, E. L.}, year={2002}, pages={390–392} }
 @article{cervantes-flores_yencho_davis_2002, title={Host reactions of sweetpotato genotypes to root-knot nematodes and variation in virulence of Meloidogyne incognita populations}, volume={37}, number={7}, journal={HortScience}, author={Cervantes-Flores, J. C. and Yencho, G. C. and Davis, E. L.}, year={2002}, pages={1112–1116} }
 @article{gao_allen_maier_davis_baum_hussey_2002, title={Identification of a new beta-1,4-endoglucanase gene expressed in the esophageal subventral gland cells of Heterodera glycines}, volume={34}, number={1}, journal={Journal of Nematology}, author={Gao, B. and Allen, R. and Maier, T. and Davis, E. L. and Baum, T. J. and Hussey, R. S.}, year={2002}, pages={12–15} }
 @article{de boer_mcdermott_wang_maier_qu_hussey_davis_baum_2002, title={The use of DNA microarrays for the developmental expression analysis of cDNAs from the oesophageal gland cell region of Heterodera glycines}, volume={3}, ISSN={["1364-3703"]}, DOI={10.1046/j.1364-3703.2002.00122.x}, abstractNote={Summary A microarray was printed containing cDNAs from a library made from cytoplasm microaspirated from the oesophageal gland cell region of parasitic stages of the soybean cyst nematode, Heterodera glycines. The array contained both previously described clones (Wang et al. Mol. Plant-Microbe Interact. 2001, 14, 536-544) and uncharacterized cDNAs. Fluorescent probes for array hybridization were prepared using RNA polymerase amplification of nematode mRNA. Developmental expression profiles of the arrayed cDNAs were determined by hybridizing the microarray with probes from parasitic and non-parasitic H. glycines life stages. Distinct patterns of developmental expression were ascertained for the previously described gland expressed genes. In addition, four H. glycines cDNAs (SCN1018, SCN1020, SCN1028 and SCN1167) were identified that showed up-regulation in one or more parasitic life stages. Clone SCN1018 encodes a C-type lectin domain and is expressed in the hypodermis of females. Clone SCN1020 encodes a probable S-adenosylmethionine synthetase. Clone SCN1028 encodes a piwi protein with high similarity to the germ-line-specific protein R06C7.1 of Caenorhabditis elegans. The sequence of SCN1167 had no similarity to known genes. This paper describes the first use of cDNA microarrays to analyse genes of a plant-parasitic nematode and establishes a functional method to mine nematode cDNA libraries.}, number={4}, journal={MOLECULAR PLANT PATHOLOGY}, author={De Boer, JM and McDermott, JP and Wang, XH and Maier, T and Qu, F and Hussey, RS and Davis, EL and Baum, TJ}, year={2002}, month={Jul}, pages={261–270} }
 @article{goellner_wang_davis_2001, title={Endo-beta-1,4-glucanase expression in compatible plant-nematode interactions}, volume={13}, ISSN={["1532-298X"]}, DOI={10.1105/tpc.13.10.2241}, number={10}, journal={PLANT CELL}, author={Goellner, M and Wang, XH and Davis, EL}, year={2001}, month={Oct}, pages={2241–2255} }
 @article{yan_smant_davis_2001, title={Functional screening yields a new beta-1,4-endoglucanase gene from Heterodera glycines that may be the product of recent gene duplication}, volume={14}, ISSN={["1943-7706"]}, DOI={10.1094/MPMI.2001.14.1.63}, abstractNote={Clones with secreted cellulolytic activity were identified when a cDNA library constructed from poly A(+) RNA of preparasitic second-stage juveniles of Heterodera glycines, the soybean cyst nematode, was expressed in the Escherichia coli SOLR strain and overlaid with a carboxymethylcellulose (CMC) substrate. Twenty CMC-degrading clones were analyzed, and all were either identical or strongly similar to a β-1,4-endoglucanase gene (HG-eng-2), previously isolated from H. glycines. A subgroup of identical “HG-eng-2-like” clones had considerable differences in the 5′ untranslated region compared with HG-eng-2 and were designated HG-eng-3. One H. glycines genomic clone contained HG-eng-2 and HG-eng-3 full-length genes, separated by a distance of approximately 8 kb, and a second genomic clone contained two copies of HG-eng-2, separated by approximately 6.5 kb, suggesting the presence of endoglucanase gene clusters in H. glycines. The HG-eng-2 and HG-eng-3 genes were in opposite transcriptional orientation, with considerable nucleotide differences in their 5′ flanking regions. The highly conserved nucleotide sequence in the introns and exons and their close proximity within the genome suggest that HG-eng-2 and HG-eng-3 are the products of recent gene duplication and inversion.}, number={1}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Yan, YT and Smant, G and Davis, E}, year={2001}, month={Jan}, pages={63–71} }
 @article{gao_allen_maier_davis_baum_hussey_2001, title={Identification of putative parasitism genes expressed in the esophageal gland cells of the soybean cyst nematode Heterodera glycines}, volume={14}, ISSN={["0894-0282"]}, DOI={10.1094/MPMI.2001.14.10.1247}, abstractNote={Cloning parasitism genes encoding secretory proteins expressed in the esophageal gland cells is the key to understanding the molecular basis of nematode parasitism of plants. Suppression subtractive hybridization (SSH) with the microaspirated contents from Heterodera glycines esophageal gland cells and intestinal region was used to isolate genes expressed preferentially in the gland cells of parasitic stages. Twenty-three unique cDNA sequences from a SSH cDNA library were identified and hybridized to the genomic DNA of H. glycines in Southern blots. Full-length cDNAs of 21 clones were obtained by screening a gland-cell long-distance polymerase chain reaction cDNA library. Deduced proteins of 10 clones were preceded by a signal peptide for secretion, and PSORT II computer analysis predicted eight proteins as extracellular, one as nuclear, and one as plasmalemma localized. In situ hybridization showed that four of the predicted extracellular clones were expressed specifically in the dorsal gland cell, one in the subventral gland cells, and three in the intestine in H. glycines. The predicted nuclear clone and the plasmalemma-localized clone were expressed in the subventral gland cells and the dorsal gland cell, respectively. SSH is an efficient method for cloning putative parasitism genes encoding esophageal gland cell secretory proteins that may have a role in H. glycines parasitism of soybean.}, number={10}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Gao, BL and Allen, R and Maier, T and Davis, EL and Baum, TJ and Hussey, RS}, year={2001}, month={Oct}, pages={1247–1254} }
 @article{gao_allen_maier_davis_baum_hussey_2001, title={Molecular characterisation and expression of two venom allergen-like protein genes in Heterodera glycines}, volume={31}, ISSN={["0020-7519"]}, DOI={10.1016/S0020-7519(01)00300-9}, abstractNote={Secretory proteins encoded by genes expressed in the oesophageal gland cells of plant-parasitic nematodes have key roles in nematode parasitism of plants. Two venom allergen-like protein cDNAs (designated hg-vap-1 and hg-vap-2)were isolated from Heterodera glycines gland cell cDNA libraries. Both cDNAs hybridised to genomic DNA of H. glycines in Southern blots. The hg-vap-1 cDNA contained an open reading frame encoding 215 amino acids with the first 25 amino acids being a putative secretion signal. The hg-vap-2 cDNA contained an open reading frame encoding 212 amino acids with the first 19 amino acids being a putative secretion signal. Genes of hg-vap-1 and hg-vap-2 contained four introns, which ranged in size from 44 to 574 bp, and five exons ranging in size from 43 to 279 bp. In situ hybridisation analyses showed that mRNAs of both vap genes accumulated specifically in the subventral gland cells of H. glycines during parasitism. The gland cell-specific expression and presence of predicted secretion signal peptides in both VAPs suggest that these proteins are secreted from the nematode and may play a role in the infection of host plants by this parasite.}, number={14}, journal={INTERNATIONAL JOURNAL FOR PARASITOLOGY}, author={Gao, B and Allen, R and Maier, T and Davis, EL and Baum, TJ and Hussey, RS}, year={2001}, month={Dec}, pages={1617–1625} }
 @article{wang_allen_ding_goellner_maier_boer_baum_hussey_davis_2001, title={Signal peptide-selection of cDNA cloned directly from the esophageal gland cells of the soybean cyst nematode Heterodera glycines}, volume={14}, ISSN={["1943-7706"]}, DOI={10.1094/mpmi.2001.14.4.536}, abstractNote={Secretions from the esophageal gland cells of plant-parasitic nematodes play critical roles in the nematode-parasitic cycle. A novel method to isolate cDNA encoding putative nematode secretory proteins was developed that utilizes mRNA for reverse transcription-polymerase chain reaction derived from microaspiration of the esophageal gland cell contents of parasitic stages of the soybean cyst nematode Heterodera glycines. The resulting H. glycines gland cell cDNA was cloned into the pRK18 vector, and plasmid DNA was transformed into a mutated yeast host for specific selection of cDNA inserts that encode proteins with functional signal peptides. Of the 223 cDNA clones recovered from selection in yeast, 97% of the clones encoded a predicted signal peptide. Fourteen unique cDNA clones hybridized to genomic DNA of H. glycines on Southern blots and, among them, nine cDNA clones encoded putative extracellular proteins, as predicted by PSORT II computer analysis. Four cDNA clones hybridized to transcripts within the dorsal esophageal gland cell of parasitic stages of H. glycines, and in situ hybridization within H. glycines was not detected for eight cDNA clones. The protocol provides a direct means to isolate potential plant-parasitic nematode esophageal gland secretory protein genes.}, number={4}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Wang, XH and Allen, R and Ding, XF and Goellner, M and Maier, T and Boer, JM and Baum, TJ and Hussey, RS and Davis, EL}, year={2001}, month={Apr}, pages={536–544} }
 @article{goellner_smant_de boer_baum_davis_2000, title={Isolation of beta-1,4-endoglucanase genes from Globodera tabacum and their expression during parasitism}, volume={32}, number={2}, journal={Journal of Nematology}, author={Goellner, M. and Smant, G. and De Boer, J. M. and Baum, T. J. and Davis, E. L.}, year={2000}, pages={154–165} }
 @article{boer_yan_wang_smant_hussey_davis_baum_1999, title={Developmental expression of secretory beta-1,4-endoglucanases in the subventral esophageal glands of Heterodera glycines}, volume={12}, ISSN={["0894-0282"]}, DOI={10.1094/MPMI.1999.12.8.663}, abstractNote={Two β-1,4-endoglucanases (EGases), Hg-eng-1 and Hg-eng-2, were recently cloned from the soybean cyst nematode, Heterodera glycines, and their expression was shown in the subventral esophageal glands of hatched second-stage juveniles (J2). We examined the expression of these EGases in the subventral glands of all post-embryonic life stages of H. glycines by in situ hybridization and immunolocalization. The first detectable accumulation of EGase mRNAs occurred in the subventral glands of unhatched J2. EGase transcripts remained detectable in J2 after hatching and during subsequent root invasion. However, in late parasitic J2 and third-stage juveniles (J3), the percentage of individuals that showed EGase transcripts decreased. In female fourth-stage juveniles and adult females, EGase transcripts were no longer detected in the subventral glands. EGase hybridization signal reappeared in unhatched males coiled within the J3 cuticle, and transcripts were also present in the subventral glands of migratory adult males. Immunofluorescence labeling showed that EGase translation products are most abundantly present in the subventral glands of preparasitic J2, migratory parasitic J2, and adult males. The presence of EGases predominantly in the migratory stages suggests that the enzymes are used by the nematodes to soften the walls of root cells during penetration and intracellular migration.}, number={8}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Boer, JM and Yan, YT and Wang, XH and Smant, G and Hussey, RS and Davis, EL and Baum, TJ}, year={1999}, month={Aug}, pages={663–669} }
 @article{wang_meyers_yan_baum_smant_hussey_davis_1999, title={In planta localization of a beta-1,4-endoglucanase secreted by Heterodera glycines}, volume={12}, ISSN={["0894-0282"]}, DOI={10.1094/MPMI.1999.12.1.64}, abstractNote={Polyclonal sera specific to β-1,4-endoglucanases (cellulases) synthesized in the subventral esophageal gland cells of the soybean cyst nematode, Heterodera glycines, were used to provide the first identification of a nematode esophageal gland protein that is secreted into host plant tissue. Sera generated to proteins encoded by Hg-eng-1 and Hg-eng-2 (endoglucanases) did not cross-react with soybean root proteins on Western blots (immunoblots) or in immunofluorescence microscopy of noninoculated (control) soybean root sections. In cross sections of soybean roots at 24 h after inoculation of roots with second-stage juveniles of H. glycines, HG-ENG-1 was localized within the nematode's subventral gland cells and was not detected in root tissue. HG-ENG-2 was localized within the subventral gland cells and was secreted from the juvenile's cortical tissue at 24 h after inoculation of roots with second-stage juveniles of H. glycines. HG-ENG-2 was localized along the juvenile's migratory path through the root cortex.}, number={1}, journal={MOLECULAR PLANT-MICROBE INTERACTIONS}, author={Wang, XH and Meyers, D and Yan, YT and Baum, T and Smant, G and Hussey, R and Davis, E}, year={1999}, month={Jan}, pages={64–67} }
 @article{smant_stokkermans_yan_boer_baum_wang_hussey_gommers_henrissat_davis_et al._1998, title={Endogenous cellulases in animals: Isolation of beta-1,4-endoglucanase genes from two species of plant-parasitic cyst nematodes}, volume={95}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.95.9.4906}, abstractNote={beta-1,4-Endoglucanases (EGases, EC 3.2.1.4) degrade polysaccharides possessing beta-1,4-glucan backbones such as cellulose and xyloglucan and have been found among extremely variegated taxonomic groups. Although many animal species depend on cellulose as their main energy source, most omnivores and herbivores are unable to produce EGases endogenously. So far, all previously identified EGase genes involved in the digestive system of animals originate from symbiotic microorganisms. Here we report on the synthesis of EGases in the esophageal glands of the cyst nematodes Globodera rostochiensis and Heterodera glycines. From each of the nematode species, two cDNAs were characterized and hydrophobic cluster analysis revealed that the four catalytic domains belong to family 5 of the glycosyl hydrolases (EC 3.2.1, 3.2.2, and 3.2.3). These domains show 37-44% overall amino acid identity with EGases from the bacteria Erwinia chrysanthemi, Clostridium acetobutylicum, and Bacillus subtilis. One EGase with a bacterial type of cellulose-binding domain was identified for each nematode species. The leucine-rich hydrophobic core of the signal peptide and the presence of a polyadenylated 3' end precluded the EGases from being of bacterial origin. Cyst nematodes are obligatory plant parasites and the identified EGases presumably facilitate the intracellular migration through plant roots by partial cell wall degradation.}, number={9}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Smant, G and Stokkermans, JPWG and Yan, YT and Boer, JM and Baum, TJ and Wang, XH and Hussey, RS and Gommers, FJ and Henrissat, B and Davis, EL and et al.}, year={1998}, month={Apr}, pages={4906–4911} }
 @article{yan_smant_stokkermans_qin_helder_baum_schots_davis_1998, title={Genomic organization of four beta-1,4-endoglucanase genes in plant-parasitic cyst nematodes and its evolutionary implications}, volume={220}, ISSN={["0378-1119"]}, DOI={10.1016/S0378-1119(98)00413-2}, abstractNote={The genomic organization of genes encoding β-1,4-endoglucanases (cellulases) from the plant-parasitic cyst nematodes Heterodera glycines and Globodera rostochiensis (HG-eng1, Hg-eng2, GR-eng1, and GR-eng2) was investigated. HG-eng1 and GR-eng1 both contained eight introns and structural domains of 2151 and 2492 bp, respectively. HG-eng2 and GR-eng2 both contained seven introns and structural domains of 2324 and 2388 bp, respectively. No significant similarity in intron sequence or size was observed between HG-eng1 and HG-eng2, whereas the opposite was true between GR-eng1 and GR-eng2. Intron positions among all four cyst nematode cellulase genes were conserved identically in relation to the predicted amino acid sequence. HG-eng1, GR-eng1, and GR-eng2 had several introns demarcated by 5′-GC…AG-3′ in the splice sites, and all four nematode cellulase genes had the polyadenylation and cleavage signal sequence 5′-GAUAAA-3′—both rare occurences in eukaryotic genes. The 5′- flanking regions of each nematode cellulase gene, however, had signature sequences typical of eukaryotic promoter regions, including a TATA box, bHLH-type binding sites, and putative silencer, repressor, and enhancer elements. Database searches and subsequent phylogenetic comparison of the catalytic domain of the nematode cellulases placed the nematode genes in one group, with Family 5, subfamily 2, glycosyl hydrolases from Scotobacteria and Bacilliaceae as the most homologous groups. The overall amino acid sequence identity among the four nematode cellulases was from 71 to 83%, and the amino acid sequence identity to bacterial Family 5 cellulases ranged from 33 to 44%. The eukaryotic organization of the four cyst nematode cellulases suggests that they share a common ancestor, and their strong homology to prokaryotic glycosyl hydrolases may be indicative of an ancient horizontal gene transfer.}, number={1-2}, journal={GENE}, author={Yan, YT and Smant, G and Stokkermans, J and Qin, L and Helder, J and Baum, T and Schots, A and Davis, E}, year={1998}, month={Oct}, pages={61–70} }
 @article{de boer_yan_smant_davis_baum_1998, title={In-situ hybridization to messenger RNA in Heterodera glycines}, volume={30}, number={3}, journal={Journal of Nematology}, author={De Boer, J. M. and Yan, Y. and Smant, G. and Davis, E. L. and Baum, T. J.}, year={1998}, pages={309–312} }
 @article{davis_meyers_burton_burton_1998, title={Resistance to root-knot, reinform, and soybean cyst nematodes in soybean breeding lines}, volume={30}, number={4, Suppl.}, journal={Journal of Nematology}, author={Davis, E. L. and Meyers, D. M. and Burton, J. W. and Burton, K. R.}, year={1998}, pages={530–541} }
 @article{davis_meyers_dullum_feitelson_1997, title={Nematicidal activity of fatty acid esters on soybean cyst and root-knot nematodes}, volume={29}, number={4, suppl.}, journal={Journal of Nematology}, author={Davis, E. L. and Meyers, D. M. and Dullum, C. J. and Feitelson, J. S.}, year={1997}, pages={677–684} }
 @article{davis_koenning_burton_barker_1996, title={Greenhouse evaluation of selected soybean germplasm for resistance to North Carolina populations of Heterodera glycines, Rotylenchulus reniformis, and Meloidogyne species}, volume={28}, number={4}, journal={Journal of Nematology}, author={Davis, E. L. and Koenning, S. R. and Burton, J. W. and Barker, K. R.}, year={1996}, pages={590} }