@article{reyes_flores-vergara_guerra-peraza_rajabu_desai_hiromoto-ruiz_ndunguru_hanley-bowdoin_kjemtrup_ascencio-ibanez_et al._2017, title={A VIGS screen identifies immunity in the Arabidopsis Pla-1 accession to viruses in two different genera of the Geminiviridae}, volume={92}, ISSN={["1365-313X"]}, DOI={10.1111/tpj.13716}, abstractNote={Summary}, number={5}, journal={PLANT JOURNAL}, author={Reyes, Maria Ines and Flores-Vergara, Miguel A. and Guerra-Peraza, Orlene and Rajabu, Cyprian and Desai, Jigar and Hiromoto-Ruiz, Yokiko H. and Ndunguru, Joseph and Hanley-Bowdoin, Linda and Kjemtrup, Susanne and Ascencio-Ibanez, Jose T. and et al.}, year={2017}, month={Dec}, pages={796–807} }
 @article{flores_reyes_robertson_kjemtrup_2015, title={Persistent Virus-Induced Gene Silencing in Asymptomatic Accessions of Arabidopsis}, volume={1284}, ISBN={["978-1-4939-2443-1"]}, ISSN={["1064-3745"]}, DOI={10.1007/978-1-4939-2444-8_15}, abstractNote={Coupled with the advantages afforded by the model plant Arabidopsis, virus-induced gene silencing (VIGS) offers a rapid means to assess gene function. The geminivirus vector based on Cabbage leaf curl virus described here has the benefits of small insert size and persistent silencing of the target gene through the life cycle of the plant. Here, we show that genetic variation in the vast collection of Arabidopsis accessions can be leveraged to ameliorate viral symptomology that accompanies the VIGS procedure. The plasticity of phenotypes under different day lengths or temperature conditions can be exploited to achieve maximum silencing efficacy in either vegetative or inflorescence tissue, according to the question being asked. Protocols and vectors for Agro-infiltration of primary leaves, subapical pricking in older plants, and microprojectile bombardment are described.}, journal={PLANT FUNCTIONAL GENOMICS: METHODS AND PROTOCOLS, 2ND EDITION}, author={Flores, Miguel A. and Reyes, Maria I. and Robertson, Dominique and Kjemtrup, Susanne}, year={2015}, pages={305–322} }
 @inbook{tuttle_haigler_robertson_2015, title={Virus-Induced Gene Silencing of Fiber-Related Genes in Cotton}, volume={1287}, ISBN={9781493924523 9781493924530}, ISSN={1064-3745 1940-6029}, url={http://dx.doi.org/10.1007/978-1-4939-2453-0_16}, DOI={10.1007/978-1-4939-2453-0_16}, abstractNote={Virus-Induced Gene Silencing (VIGS) is a useful method for transient downregulation of gene expression in crop plants. The geminivirus Cotton leaf crumple virus (CLCrV) has been modified to serve as a VIGS vector for persistent gene silencing in cotton. Here the use of Green Fluorescent Protein (GFP) is described as a marker for identifying silenced tissues in reproductive tissues, a procedure that requires the use of transgenic plants. Suggestions are given for isolating and cloning combinations of target and marker sequences so that the total length of inserted foreign DNA is between 500 and 750 bp. Using this strategy, extensive silencing is achieved with only 200–400 bp of sequence homologous to an endogenous gene, reducing the possibility of off-target silencing. Cotyledons can be inoculated using either the gene gun or Agrobacterium and will continue to show silencing throughout fruit and fiber development. CLCrV is not transmitted through seed, and VIGS is limited to genes expressed in the maternally derived seed coat and fiber in the developing seed. This complicates the use of GFP as a marker for VIGS because cotton fibers must be separated from unsilenced tissue in the seed to determine if they are silenced. Nevertheless, fibers from a large number of seeds can be rapidly screened following placement into 96-well plates. Methods for quantifying the extent of silencing using semiquantitative RT-PCR are given.}, booktitle={Methods in Molecular Biology}, publisher={Springer New York}, author={Tuttle, John R. and Haigler, Candace H. and Robertson, Dominique}, year={2015}, pages={219–234} }
 @article{tsou_lee_allen_winter-sederoff_robertson_2012, title={An ER-targeted calcium-binding peptide confers salt and drought tolerance mediated by CIPK6 in Arabidopsis}, volume={235}, ISSN={["1432-2048"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84857634774&partnerID=MN8TOARS}, DOI={10.1007/s00425-011-1522-9}, abstractNote={Different plant organelles have high internal stores of Ca(2+) compared to the cytoplasm and could play independent roles in stress responses or signal transduction. We used a GFP fusion with the C-domain of calreticulin, which shows low-affinity, high capacity Ca(2+) binding in the ER, as a calcium-binding peptide (CBP) to specifically increase stores in the ER and nucleus. Despite the presence of a signal sequence and KDEL retention sequence, our work and previous studies (Brandizzi et al. Plant Journal 34:269-281, 2003) demonstrated both ER and nuclear localization of GFP-CBP. Under normal conditions, GFP-CBP-expressing lines had ~25% more total Ca(2+) and higher levels of chlorophyll and seed yield than wild type and GFP controls. CBP-expressing plants also had better survival under intermittent drought or high salt treatments and increased root growth. One member of the CIPK (calcineurin B-like interacting protein kinase) gene family, CIPK6, was up-regulated in CBP-expressing plants, even under non-stress conditions. A null mutation in cipk6 abolished the increased stress tolerance of CBP-transgenic plants, as well as the CBP-mediated induction of two stress-associated genes, DREB1A and RD29A, under non-stress conditions. Although this suggested that it was the induction of CIPK6, rather than localized changes in Ca(2+), that resulted in increased survival under adverse conditions, CIPK6 induction still required Ca(2+). This work demonstrates that ER (or nuclear) Ca(2+) can directly participate in signal transduction to alter gene expression. The discovery of a method for increasing Ca(2+) levels without deleterious effects on plant growth may have practical applications.}, number={3}, journal={PLANTA}, author={Tsou, Pei-Lan and Lee, Sang Yoon and Allen, Nina Stromgren and Winter-Sederoff, Heike and Robertson, Dominique}, year={2012}, month={Mar}, pages={539–552} }
 @article{tuttle_haigler_robertson_2012, title={Method: low-cost delivery of the cotton leaf crumple virus-induced gene silencing system}, volume={8}, ISSN={1746-4811}, url={http://dx.doi.org/10.1186/1746-4811-8-27}, DOI={10.1186/1746-4811-8-27}, abstractNote={We previously developed a virus-induced gene silencing (VIGS) vector for cotton from the bipartite geminivirusCotton leaf crumple virus (CLCrV). The original CLCrV VIGS vector was designed for biolistic delivery by a gene gun. This prerequisite limited the use of the system to labs with access to biolistic equipment. Here we describe the adaptation of this system for delivery by Agrobacterium (Agrobacterium tumefaciens). We also describe the construction of two low-cost particle inflow guns. The biolistic CLCrV vector was transferred into two Agrobacterium binary plasmids. Agroinoculation of the binary plasmids into cotton resulted in silencing and GFP expression comparable to the biolistic vector. Two homemade low-cost gene guns were used to successfully inoculate cotton (G. hirsutum) and N. benthamiana with either the CLCrV VIGS vector or the Tomato golden mosaic virus (TGMV) VIGS vector respectively. These innovations extend the versatility of CLCrV-based VIGS for analyzing gene function in cotton. The two low-cost gene guns make VIGS experiments affordable for both research and teaching labs by providing a working alternative to expensive commercial gene guns.}, number={1}, journal={Plant Methods}, publisher={Springer Science and Business Media LLC}, author={Tuttle, John and Haigler, Candace H and Robertson, Dominique}, year={2012}, pages={27} }
 @article{tuttle_idris_brown_haigler_robertson_2008, title={Geminivirus-Mediated Gene Silencing from Cotton Leaf Crumple Virus Is Enhanced by Low Temperature in Cotton}, volume={148}, ISSN={0032-0889 1532-2548}, url={http://dx.doi.org/10.1104/pp.108.123869}, DOI={10.1104/pp.108.123869}, abstractNote={Abstract}, number={1}, journal={Plant Physiology}, publisher={American Society of Plant Biologists (ASPB)}, author={Tuttle, John R. and Idris, A.M. and Brown, Judith K. and Haigler, Candace H. and Robertson, Dominique}, year={2008}, month={Jul}, pages={41–50} }
 @article{jordan_shen_hanley-bowdoin_robertson_2007, title={Geminivirus-induced gene silencing of the tobacco retinoblastoma-related gene results in cell death and altered development}, volume={65}, ISSN={["1573-5028"]}, DOI={10.1007/s11103-007-9206-3}, abstractNote={The retinoblastoma-related protein (RBR) is required for cell cycle control and differentiation and is expressed throughout the life of plants and animals. In this study, the tomato golden mosaic virus (TGMV) geminivirus vector was used to silence NbRBR1 in Nicotiana benthamiana by microprojectile bombardment into fully developed leaves. Similar to previous results using agroinoculation of a tobacco rattle virus silencing vector [Park et al. (Plant J 42:153, 2005)], developmental defects caused by disruptions in cell size and number were seen in new growth. Leaf midvein cross-sections showed tissue-specific differences in size, cell number, and cell morphology. While cortical cell numbers decreased, size increased to maintain overall shape. In contrast, xylem parenchyma cells increased approximately three fold but remained small. Normally straight flowers often curved up to 360 degrees without a significant change in size. However, the most striking phenotype was cell death in mature cells after a delay of 3-4 weeks. Trypan blue staining confirmed cell death and demonstrated that cell death was absent in similarly treated leaves of wild type TGMV-inoculated plants. Quantitative RT-PCR confirmed that the mature TGMV:RBR-inoculated leaves still maintained reduced accumulation of RBR transcript at 4 weeks compared to controls. The results suggest that either inappropriate activation of the cell cycle is lethal in plants or that RBR has other functions, unrelated to the cell cycle. The results also demonstrate that continual transcription of RBR is necessary for cell survival.}, number={1-2}, journal={PLANT MOLECULAR BIOLOGY}, author={Jordan, Chad V. and Shen, Wei and Hanley-Bowdoin, Linda K. and Robertson, Dominique}, year={2007}, month={Sep}, pages={163–175} }
 @article{smith_woloshuk_robertson_payne_2007, title={Silencing of the aflatoxin gene cluster in a diploid strain of Aspergillus flavus is suppressed by ectopic aflR expression}, volume={176}, ISSN={["1943-2631"]}, DOI={10.1534/genetics.107.073460}, abstractNote={Abstract}, number={4}, journal={GENETICS}, author={Smith, Carrie A. and Woloshuk, Charles P. and Robertson, Dominique and Payne, Gary A.}, year={2007}, month={Aug}, pages={2077–2086} }
 @article{blevins_rajeswaran_shivaprasad_beknazariants_si-ammour_park_vazquez_robertson_meins_hohn_et al._2006, title={Four plant Dicers mediate viral small RNA biogenesis and DNA virus induced silencing}, volume={34}, ISSN={["1362-4962"]}, DOI={10.1093/nar/gkl886}, abstractNote={Like other eukaryotes, plants use DICER-LIKE (DCL) proteins as the central enzymes of RNA silencing, which regulates gene expression and mediates defense against viruses. But why do plants like Arabidopsis express four DCLs, a diversity unmatched by other kingdoms? Here we show that two nuclear DNA viruses (geminivirus CaLCuV and pararetrovirus CaMV) and a cytoplasmic RNA tobamovirus ORMV are differentially targeted by subsets of DCLs. DNA virus-derived small interfering RNAs (siRNAs) of specific size classes (21, 22 and 24 nt) are produced by all four DCLs, including DCL1, known to process microRNA precursors. Specifically, DCL1 generates 21 nt siRNAs from the CaMV leader region. In contrast, RNA virus infection is mainly affected by DCL4. While the four DCLs are partially redundant for CaLCuV-induced mRNA degradation, DCL4 in conjunction with RDR6 and HEN1 specifically facilitates extensive virus-induced silencing in new growth. Additionally, we show that CaMV infection impairs processing of endogenous RDR6-derived double-stranded RNA, while ORMV prevents HEN1-mediated methylation of small RNA duplexes, suggesting two novel viral strategies of silencing suppression. Our work highlights the complexity of virus interaction with host silencing pathways and suggests that DCL multiplicity helps mediate plant responses to diverse viral infections.}, number={21}, journal={NUCLEIC ACIDS RESEARCH}, author={Blevins, Todd and Rajeswaran, Rajendran and Shivaprasad, Padubidri V. and Beknazariants, Daria and Si-Ammour, Azeddine and Park, Hyun-Sook and Vazquez, Franck and Robertson, Dominique and Meins, Frederick, Jr. and Hohn, Thomas and et al.}, year={2006}, month={Dec}, pages={6233–6246} }
 @article{muangsan_beclin_vaucheret_robertson_2004, title={Geminivirus VIGS of endogenous genes requires SGS2/SDE1 and SGS3 and defines a new branch in the genetic pathway for silencing in plants}, volume={38}, ISSN={["1365-313X"]}, DOI={10.1111/j.1365-313X.2004.02103.x}, abstractNote={Summary}, number={6}, journal={PLANT JOURNAL}, author={Muangsan, N and Beclin, C and Vaucheret, H and Robertson, D}, year={2004}, month={Jun}, pages={1004–1014} }
 @misc{robertson_2004, title={Method of suppressing gene expression in plants}, volume={6,759,571}, number={2004 July 06}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Robertson, D.}, year={2004} }
 @misc{hanley-bowdoin_settlage_robertson_2004, title={Reprogramming plant gene expression: a prerequisite to geminivirus DNA replication}, volume={5}, ISSN={["1364-3703"]}, DOI={10.1111/J.1364-3703.2004.00214.X}, abstractNote={SUMMARY}, number={2}, journal={MOLECULAR PLANT PATHOLOGY}, author={Hanley-Bowdoin, L and Settlage, SB and Robertson, D}, year={2004}, month={Mar}, pages={149–156} }
 @misc{wyatt_tsou_robertson_boss_2004, title={Transgenic plants with increased calcium stores}, volume={6,753,462}, number={2004 June 22}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Wyatt, S. and Tsou, P.-L. and Robertson, D. and Boss, W.}, year={2004} }
 @misc{robertson_2004, title={VIGS vectors for gene silencing: Many targets, many tools}, volume={55}, ISSN={["1545-2123"]}, DOI={10.1146/annurev.arplant.55.031903.141803}, abstractNote={ ▪ Abstract  The discovery that plants recognize and degrade invading viral RNA caused a paradigm shift in our understanding of viral/host interactions. Combined with the discovery that plants cosuppress their own genes if they are transformed with homologous transgenes, new models for both plant intercellular communication and viral defense have emerged. Plant biologists adapted homology-based defense mechanisms triggered by incoming viruses to target individual genes for silencing in a process called virus-induced gene silencing (VIGS). Both VIGS- and dsRNA-containing transformation cassettes are increasingly being used for reverse genetics as part of an integrated approach to determining gene function. Virus-derived vectors silence gene expression without transformation and selection. However, because viruses also alter gene expression in their host, the process of VIGS must be understood. This review examines how DNA and RNA viruses have been modified to silence plant gene expression. I discuss advantages and disadvantages of VIGS in determining gene function and guidelines for the safe use of viral vectors. }, journal={ANNUAL REVIEW OF PLANT BIOLOGY}, author={Robertson, D}, year={2004}, pages={495–519} }
 @article{wyatt_tsou_robertson_2002, title={Expression of the high capacity calcium-binding domain of calreticulin increases bioavailable calcium stores in plants}, volume={11}, ISSN={["1573-9368"]}, DOI={10.1023/A:1013917701701}, abstractNote={Modulation of cytosolic calcium levels in both plants and animals is achieved by a system of Ca2+-transport and storage pathways that include Ca2+ buffering proteins in the lumen of intracellular compartments. To date, most research has focused on the role of transporters in regulating cytosolic calcium. We used a reverse genetics approach to modulate calcium stores in the lumen of the endoplasmic reticulum. Our goals were two-fold: to use the low affinity, high capacity Ca2+ binding characteristics of the C-domain of calreticulin to selectively increase Ca2+ storage in the endoplasmic reticulum, and to determine if those alterations affected plant physiological responses to stress. The C-domain of calreticulin is a highly acidic region that binds 20-50 moles of Ca2+ per mole of protein and has been shown to be the major site of Ca2+ storage within the endoplasmic reticulum of plant cells. A 377-bp fragment encoding the C-domain and ER retention signal from the maize calreticulin gene was fused to a gene for the green fluorescent protein and expressed in Arabidopsis under the control of a heat shock promoter. Following induction on normal medium, the C-domain transformants showed delayed loss of chlorophyll after transfer to calcium depleted medium when compared to seedlings transformed with green fluorescent protein alone. Total calcium measurements showed a 9-35% increase for induced C-domain transformants compared to controls. The data suggest that ectopic expression of the calreticulin C-domain increases Ca2+ stores, and that this Ca2+ reserve can be used by the plant in times of stress.}, number={1}, journal={TRANSGENIC RESEARCH}, author={Wyatt, SE and Tsou, PL and Robertson, D}, year={2002}, month={Feb}, pages={1–10} }
 @article{turnage_muangsan_peele_robertson_2002, title={Geminivirus-based vectors for gene silencing in Arabidopsis}, volume={30}, ISSN={["0960-7412"]}, DOI={10.1046/j.1365-313X.2002.01261.x}, abstractNote={Summary}, number={1}, journal={PLANT JOURNAL}, author={Turnage, MA and Muangsan, N and Peele, CG and Robertson, D}, year={2002}, month={Apr}, pages={107–114} }
 @article{nagara_hanley-bowdoin_robertson_2002, title={Host DNA replication is induced by geminivirus infection of differentiated plant cells}, volume={14}, ISSN={["1040-4651"]}, DOI={10.1105/tpc.005777}, abstractNote={The geminivirus Tomato golden mosaic virus (TGMV) replicates in differentiated plant cells using host DNA synthesis machinery. We used 5-bromo-2-deoxyuridine (BrdU) incorporation to examine DNA synthesis directly in infected Nicotiana benthamiana plants to determine if viral reprogramming of host replication controls had an impact on host DNA replication. Immunoblot analysis revealed that up to 17-fold more BrdU was incorporated into chromosomal DNA of TGMV-infected versus mock-infected, similarly treated healthy leaves. Colocalization studies of viral DNA and BrdU demonstrated that BrdU incorporation was specific to infected cells and was associated with both host and viral DNA. TGMV and host DNA synthesis were inhibited differentially by aphidicolin but were equally sensitive to hydroxyurea. Short BrdU labeling times resulted in some infected cells showing punctate foci associated with host DNA. Longer periods showed BrdU label uniformly throughout host DNA, some of which showed condensed chromatin, only in infected nuclei. By contrast, BrdU associated with viral DNA was centralized and showed uniform, compartmentalized labeling. Our results demonstrate that chromosomal DNA is replicated in TGMV-infected cells.}, number={12}, journal={PLANT CELL}, author={Nagara, S and Hanley-Bowdoin, L and Robertson, D}, year={2002}, month={Dec}, pages={2995–3007} }
 @article{wyatt_rashotte_shipp_robertson_muday_2002, title={Mutations in the gravity persistence signal loci in arabidopsis disrupt the perception and/or signal transduction of gravitropic stimuli}, volume={130}, ISSN={["1532-2548"]}, DOI={10.1104/pp.102.010579}, abstractNote={Abstract}, number={3}, journal={PLANT PHYSIOLOGY}, author={Wyatt, SE and Rashotte, AM and Shipp, MJ and Robertson, D and Muday, GK}, year={2002}, month={Nov}, pages={1426–1435} }
 @article{egelkrout_mariconti_settlage_cella_robertson_hanley-bowdoin_2002, title={Two E2F elements regulate the proliferating cell nuclear antigen promoter differently during leaf development}, volume={14}, ISSN={["1040-4651"]}, DOI={10.1105/tpc.006403}, abstractNote={E2F transcription factors regulate genes expressed at the G1/S boundary of the cell division cycle in higher eukaryotes. Although animal E2F proteins and their target promoters have been studied extensively, little is known about how these factors regulate plant promoters. An earlier study identified two E2F consensus binding sites in the promoter of a Nicotiana benthamiana gene encoding proliferating cell nuclear antigen (PCNA) and showed that the proximal element (E2F2) is required for the full repression of PCNA expression in mature leaves. In this study, we examined the distal element (E2F1) and how it interacts with the E2F2 site to regulate the PCNA promoter. Gel shift assays using plant nuclear extracts or purified Arabidopsis E2F and DP proteins showed that different complexes bind to the two E2F sites. Mutation of the E2F1 site or both sites differentially altered PCNA promoter function in transgenic plants. As reported previously for the E2F2 mutation, the E2F1 and E2F1+2 mutations partially relieved the repression of the PCNA promoter in mature leaves. In young tissues, the E2F1 mutation resulted in a threefold reduction in PCNA promoter activity, whereas the E2F1+2 mutation had no detectable effect. The activity of E2F1+2 mutants was indistinguishable from that of E2F2 mutants. These results demonstrate that both E2F elements contribute to the repression of the PCNA promoter in mature leaves, whereas the E2F1 site counters the repression activity of the E2F2 element in young leaves.}, number={12}, journal={PLANT CELL}, author={Egelkrout, EM and Mariconti, L and Settlage, SB and Cella, R and Robertson, D and Hanley-Bowdoin, L}, year={2002}, month={Dec}, pages={3225–3236} }
 @article{persson_love_tsou_robertson_thompson_boss_2002, title={When a day makes a difference. Interpreting data from endoplasmic reticulum-targeted green fluorescent protein fusions in cells grown in suspension culture}, volume={128}, ISSN={1532-2548 0032-0889}, url={http://dx.doi.org/10.1104/pp.010840}, DOI={10.1104/pp.010840}, abstractNote={The stability of the self-contained structure of green fluorescent protein (GFP) has made it the most widely utilized fluorescent marker for gene expression and subcellular localization studies ([Chalfie et al., 1994][1]; [Tsien, 1998][2]; [De Giorgi et al., 1999][3]; [Haseloff et al., 1999][4]).}, number={2}, journal={Plant Physiology}, publisher={Oxford University Press (OUP)}, author={Persson, S. and Love, J. and Tsou, P. L. and Robertson, D. and Thompson, W. F. and Boss, W. F.}, year={2002}, pages={341–344} }
 @article{staman_blum_louws_robertson_2001, title={Can simultaneous inhibition of seedling growth and stimulation of rhizosphere bacterial populations provide evidence for phytotoxin transfer from plant residues in the bulk soil to the rhizosphere of sensitive species?}, volume={27}, ISSN={["1573-1561"]}, DOI={10.1023/A:1010362221390}, abstractNote={In order to demonstrate that allelopathic interactions are occurring, one must, among other things, demonstrate that putative phytotoxins move from plant residues on or in the soil, the source, through the bulk soil to the root surface, a sink, by way of the rhizosphere. We hypothesized that the incorporation of phytotoxic plant residues into the soil would result in a simultaneous inhibition of seedling growth and a stimulation of the rhizosphere bacterial community that could utilize the putative phytotoxins as a sole carbon source. If true and consistently expressed, such as relationship would provide a means of establishing the transfer of phytotoxins from residue in the soil to the rhizosphere of a sensitive species under field conditions. Presently, direct evidence for such transfer is lacking. To test this hypothesis, cucumber seedlings were grown in soil containing various concentrations of wheat or sunflower tissue. Both tissue types contain phenolic acids, which have been implicated as allelopathic phytotoxins. The level of phytotoxicity of the plant tissues was determined by the inhibition of pigweed seedling emergence and cucumber seedling leaf area expansion. The stimulation of cucumber seedling rhizosphere bacterial communities was determined by the plate dilution frequency technique using a medium containing phenolic acids as the sole carbon source. When sunflower tissue was incorporated into autoclaved (to reduce the initial microbial populations) soil, a simultaneous inhibition of cucumber seedling growth and stimulation of the community of phenolic acid utilizing rhizosphere bacteria occurred. Thus, it was possible to observe simultaneous inhibition of cucumber seedlings and stimulation of phenolic acid utilizing rhizosphere bacteria, and therefore provide indirect evidence of phenolic acid transfer from plant residues in the soil to the root surface. However, the simultaneous responses were not sufficiently consistent to be used as a field screening tool but were dependent upon the levels of phenolic acids and the bulk soil and rhizosphere microbial populations present in the soil. It is possible that this screening procedure may be useful for phytotoxins that are more unique than phenolic acids.}, number={4}, journal={JOURNAL OF CHEMICAL ECOLOGY}, author={Staman, K and Blum, U and Louws, F and Robertson, D}, year={2001}, month={Apr}, pages={807–829} }
 @article{egelkrout_robertson_hanley-bowdoin_2001, title={Proliferating cell nuclear antigen transcription is repressed through an E2F consensus element and activated by geminivirus infection in mature leaves}, volume={13}, ISSN={["1531-298X"]}, DOI={10.1105/tpc.13.6.1437}, abstractNote={The geminivirus tomato golden mosaic virus (TGMV) amplifies its DNA genome in differentiated plant cells that lack detectable levels of DNA replication enzymes. Earlier studies showed that TGMV induces the accumulation of proliferating cell nuclear antigen (PCNA), the processivity factor for DNA polymerase delta, in mature cells of Nicotiana benthamiana. We sought to determine if PCNA protein accumulation reflects transcriptional activation of the host gene. RNA gel blot analysis detected an approximately 1200-nucleotide PCNA transcript in young leaves. The same RNA was found in mature leaves of infected but not healthy plants. Reporter gene analysis showed that a 633-bp promoter fragment of the N. benthamiana PCNA gene supports high levels of expression in cultured cells and in young but not mature leaves of healthy transgenic plants. In contrast, PCNA promoter activity was detected in both young and mature leaves of TGMV-infected plants. Developmental studies established a strong relationship between symptom severity, viral DNA accumulation, PCNA promoter activity, and endogenous PCNA mRNA levels. Mutation of an E2F consensus element in the PCNA promoter had no effect on its activity in young leaves but increased transcription in healthy mature leaves. Unlike the wild-type PCNA promoter, TGMV infection had no detectable effect on the activity of the mutant E2F promoter. Together, these results demonstrate that geminivirus infection induces the accumulation of a host replication factor by activating transcription of its gene in mature tissues, most likely by overcoming E2F-mediated repression.}, number={6}, journal={PLANT CELL}, author={Egelkrout, EM and Robertson, D and Hanley-Bowdoin, L}, year={2001}, month={Jun}, pages={1437–1452} }
 @article{peele_jordan_muangsan_turnage_egelkrout_eagle_hanley-bowdoin_robertson_2001, title={Silencing of a meristematic gene using geminivirus-derived vectors}, volume={27}, ISSN={["0960-7412"]}, DOI={10.1046/j.1365-313x.2001.01080.x}, abstractNote={Summary}, number={4}, journal={PLANT JOURNAL}, author={Peele, C and Jordan, CV and Muangsan, N and Turnage, M and Egelkrout, E and Eagle, P and Hanley-Bowdoin, L and Robertson, D}, year={2001}, month={Aug}, pages={357–366} }
 @article{persson_wyatt_love_thompson_robertson_boss_2001, title={The Ca2+ status of the endoplasmic reticulum is altered by induction of calreticulin expression in transgenic plants}, volume={126}, ISSN={["1532-2548"]}, DOI={10.1104/pp.126.3.1092}, abstractNote={Abstract}, number={3}, journal={PLANT PHYSIOLOGY}, author={Persson, S and Wyatt, SE and Love, J and Thompson, WF and Robertson, D and Boss, WF}, year={2001}, month={Jul}, pages={1092–1104} }
 @article{kong_orozco_roe_nagar_ou_feiler_durfee_miller_gruissem_robertson_et al._2000, title={A geminivirus replication protein interacts with the retinoblastoma protein through a novel domain to determine symptoms and tissue specificity of infection in plants}, volume={19}, ISSN={["0261-4189"]}, DOI={10.1093/emboj/19.13.3485}, abstractNote={Geminiviruses replicate in nuclei of mature plant cells after inducing the accumulation of host DNA replication machinery. Earlier studies showed that the viral replication factor, AL1, is sufficient for host induction and interacts with the cell cycle regulator, retinoblastoma (pRb). Unlike other DNA virus proteins, AL1 does not contain the pRb binding consensus, LXCXE, and interacts with plant pRb homo logues (pRBR) through a novel amino acid sequence. We mapped the pRBR binding domain of AL1 between amino acids 101 and 180 and identified two mutants that are differentially impacted for AL1–pRBR interactions. Plants infected with the E‐N140 mutant, which is wild‐type for pRBR binding, developed wild‐type symptoms and accumulated viral DNA and AL1 protein in epidermal, mesophyll and vascular cells of mature leaves. Plants inoculated with the KEE146 mutant, which retains 16% pRBR binding activity, only developed chlorosis along the veins, and viral DNA, AL1 protein and the host DNA synthesis factor, proliferating cell nuclear antigen, were localized to vascular tissue. These results established the importance of AL1–pRBR interactions during geminivirus infection of plants.}, number={13}, journal={EMBO JOURNAL}, author={Kong, LJ and Orozco, BM and Roe, JL and Nagar, S and Ou, S and Feiler, HS and Durfee, T and Miller, AB and Gruissem, W and Robertson, D and et al.}, year={2000}, month={Jul}, pages={3485–3495} }
 @article{bass_nagar_hanley-bowdoin_robertson_2000, title={Chromosome condensation induced by geminivirus infection of mature plant cells}, volume={113}, number={7}, journal={Journal of Cell Science}, author={Bass, H. W. and Nagar, S. and Hanley-Bowdoin, L. and Robertson, D.}, year={2000}, pages={1149–1160} }
 @article{hanley-bowdoin_settlage_orozco_nagar_robertson_2000, title={Geminiviruses - Models for plant DNA replication, transcription and cell cycle regulation ([correction to] vol 35, pg 105, 2000)}, volume={35}, number={4}, journal={Critical Reviews in Biochemistry and Molecular Biology}, author={Hanley-Bowdoin, L. and Settlage, S. B. and Orozco, B. M. and Nagar, S. and Robertson, D.}, year={2000}, pages={U4} }
 @article{hanley-bowdoin_settlage_orozco_nagar_robertson_2000, title={Geminiviruses: Models for plant DNA replication, transcription, and cell cycle regulation}, volume={35}, number={2}, journal={Critical Reviews in Biochemistry and Molecular Biology}, author={Hanley-Bowdoin, L. and Settlage, S. B. and Orozco, B. M. and Nagar, S. and Robertson, D.}, year={2000}, pages={105–140} }
 @article{hanley-bowdoin_settlage_orozco_nagar_robertson_1999, title={Geminiviruses: Models for plant DNA replication, transcription, and cell cycle regulation {review}}, volume={18}, DOI={10.1080/07352689991309162}, abstractNote={Geminiviruses have small, single-stranded DNA genomes that replicate through double-stranded intermediates in the nuclei of infected plant cells. Viral double-stranded DNA also assembles into minichromosomes and is transcribed in infected cells. Geminiviruses encode only a few proteins for their replication and transcription and rely on host enzymes for these processes. However, most plant cells, which have exited the cell cycle and undergone differentiation, do not contain the replicative enzymes necessary for viral DNA synthesis. To overcome this barrier, geminiviruses induce the accumulation of DNA replication machinery in mature plant cells, most likely by modifying cell cycle and transcriptional controls. In animals, several DNA viruses depend on host replication and transcription machinery and can alter their hosts to create an environment that facilitates efficient viral replication. Analysis of these viruses and their proteins has contributed significantly to our understanding of DNA replication, transcription, and cell cycle regulation in mammalian cells. Geminiviruses have the same potential for plant systems. Plants offer many advantages for these types of studies, including ease of transformation, well-defined cell populations and developmental programs, and greater tolerance of cell cycle perturbation and polyploidy. Our knowledge of the molecular and cellular events that mediate geminivirus infection has increased significantly during recent years. The goal of this review is to summarize recent research addressing geminivirus DNA replication and its integration with transcriptional and cell cycle regulatory processes.}, number={1}, journal={Critical Reviews in Plant Sciences}, author={Hanley-Bowdoin, L. and Settlage, S. B. and Orozco, B. M. and Nagar, S. and Robertson, D.}, year={1999}, pages={71–106} }
 @article{cox_robertson_fites_1999, title={Mapping and expression of a bifunctional thymidylate synthase, dihydrofolate reductase gene from maize}, volume={41}, ISSN={["0167-4412"]}, DOI={10.1023/A:1006324328355}, abstractNote={A bifunctional gene (ZmDHFR-TS) encoding dihydrofolate reductase (DHFR) and thymidylate synthase (TS) was cloned from a Zea mays cDNA library. Both of these enzymes are involved in nucleotide biosynthesis, specifically in the formation of thymidine monophosphate (TMP). Comparison of the deduced amino acid sequence with DHFR-TS sequences from three other plant sources revealed over 75% similarity and motifs typical of DHFR-TS proteins. Two copies of the gene were mapped to chromosomes 2 and 4. This represents the first DHFR-TS gene cloned from a monocotyledonous plant. Expression of ZmDHFR-TS was examined in developing kernels and various tissues of maize by RNA gel blot hybridization analysis in order to determine the relationship between expression of this gene and DNA synthesis. RNA transcripts for ZmDHFR-TS accumulated to high levels in developing maize kernels when endosperm cells were undergoing endoreduplication and cell division. Meristematic maize tissues had high levels of ZmDHFR-TS mRNA, but transcripts were barely detectable in RNA isolated from the root elongation zone and from mature leaf tissues.}, number={6}, journal={PLANT MOLECULAR BIOLOGY}, author={Cox, K and Robertson, D and Fites, R}, year={1999}, month={Dec}, pages={733–739} }
 @article{scott_wyatt_tsou_robertson_allen_1999, title={Model system for plant cell biology: GFP imaging in living onion epidermal cells}, volume={26}, ISSN={["1940-9818"]}, DOI={10.2144/99266st04}, abstractNote={ The ability to visualize organelle localization and dynamics is very useful in studying cellular physiological events. Until recently, this has been accomplished using a variety of staining methods. However, staining can give inaccurate information due to nonspecific staining, diffusion of the stain or through toxic effects. The ability to target green fluorescent protein (GFP) to various organelles allows for specific labeling of organelles in vivo. The disadvantages of GFP thus far have been the time and money involved in developing stable transformants or maintaining cell cultures for transient expression. In this paper, we present a rapid transient expression system using onion epidermal peels. We have localized GFP to various cellular compartments (including the cell wall) to illustrate the utility of this method and to visualize dynamics of these compartments. The onion epidermis has large, living, transparent cells in a monolayer, making them ideal for visualizing GFP. This method is easy and inexpensive, and it allows for testing of new GFP fusion proteins in a living tissue to determine deleterious effects and the ability to express before stable transformants are attempted. }, number={6}, journal={BIOTECHNIQUES}, author={Scott, A and Wyatt, S and Tsou, PL and Robertson, D and Allen, NS}, year={1999}, month={Jun}, pages={1125-+} }
 @article{kjemtrup_sampson_peele_nguyen_conkling_thompson_robertson_1998, title={Gene silencing from plant DNA carried by a Geminivirus}, volume={14}, ISSN={["0960-7412"]}, DOI={10.1046/j.1365-313X.1998.00101.x}, abstractNote={Summary}, number={1}, journal={PLANT JOURNAL}, author={Kjemtrup, S and Sampson, KS and Peele, CG and Nguyen, LV and Conkling, MA and Thompson, WF and Robertson, D}, year={1998}, month={Apr}, pages={91–100} }
 @article{robertson_weissinger_ackley_glover_sederoff_1992, title={GENETIC-TRANSFORMATION OF NORWAY SPRUCE (PICEA-ABIES (L) KARST) USING SOMATIC EMBRYO EXPLANTS BY MICROPROJECTILE BOMBARDMENT}, volume={19}, ISSN={["0167-4412"]}, DOI={10.1007/BF00040525}, abstractNote={Stable transformation of Norway spruce tissue has been obtained following bombardment of mature somatic embryos with pRT99gus, a plasmid that contains neo coding for NPTII, and gusA, coding for beta-glucuronidase, both fused to the CaMV 35S promoter. At least 8 lines have been stably transformed (over 15 months in culture) following bombardment and selection on kanamycin. Polymerase chain reaction analyses showed a high frequency of cotransformation of the gusA and neo genes. The frequency of coexpression of the selected and unselected markers was 100%. DNA/DNA hybridization of one transformed line provided conclusive evidence of stable integration and showed copy numbers of over 10 plasmid sequences per genome. None of the transformed lines has remained embryogenic.}, number={6}, journal={PLANT MOLECULAR BIOLOGY}, author={ROBERTSON, D and WEISSINGER, AK and ACKLEY, R and GLOVER, S and SEDEROFF, RR}, year={1992}, month={Sep}, pages={925–935} }