@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{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 10 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{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{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{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{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{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}, 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{paulsson_lucia_ragauskas_li_2001, title={Photoyellowing of untreated and acetylated aspen chemithermomechanical pulp under argon, ambient, and oxygen atmospheres}, volume={21}, ISSN={["1532-2319"]}, DOI={10.1081/WCT-100108330}, abstractNote={Untreated and acetylated hydrogen peroxide-bleached aspen chemithermomechanical pulp (CTMP) was subjected to accelerated light-induced aging in various atmospheres (argon, ambient, or oxygen). The photochemical changes that took place during irradiation were followed by solid-state UV/VIS diffuse reflectance spectroscopy. The degree of photoyellowing of the untreated CTMP decreased when the air in the surrounding atmosphere was replaced with oxygen-free argon. The decrease was only moderate, indicating that atmospheric oxygen is not of sole importance for the light-induced discoloration or that only a trace amount of oxygen (strongly adsorbed to the fiber material) is necessary to cause discoloration. Acetylation clearly diminished the kinetics of photoyellowing in all atmospheres resulting in substantially less absorption in the entire visible range (λ > 400 nm). However, the development of chromophores was attenuated in an oxygen-enriched atmosphere, suggesting that oxygen is important for the color-retarding or photobleaching reactions of acetylated lignocellulosic materials. Independently of the degree of acetylation and the surrounding atmosphere, irradiation with UV/VIS fluorescent lamps generated an apparent absorption maximum around 360 nm with a shoulder at approximately 420 nm.}, number={4}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={Paulsson, M and Lucia, LA and Ragauskas, AJ and Li, C}, year={2001}, pages={343–360} }