Publications

spontaneous deletion enhances movement of a cucumber necrosis virus based chimera expressing the red clover necrotic mosaic virus movement protein genedagger.	summary the 35-kda movement protein (mp) gene of red clover necrotic mosaic virus (rcnmv) and 3' flanking sequence were inserted in a cucumber necrosis virus (cnv) deletion mutant lacking a large portion of the coding region for the mp. nicotiana benthamiana plants inoculated with chimeric synthetic transcripts of the resulting hybrid cdna clone (m5/rm2) developed both local and systemic symptoms and accumulated high levels of chimeric viral rna. reverse transcriptase polymerase chain reaction ( ...	2001	20572988
transgenically expressed t-rep of tomato yellow leaf curl sardinia virus acts as a trans-dominant-negative mutant, inhibiting viral transcription and replication.	we have previously shown that transgenic expression of a truncated c1 gene of tomato yellow leaf curl sardinia virus (tylcsv), expressing the first 210 amino acids of the replication-associated protein (t-rep) and potentially coexpressing the c4 protein, confers resistance to the homologous virus in nicotiana benthamiana plants. in the present study we have investigated the role of t-rep and c4 proteins in the resistance mechanism, analyzing changes in virus transcription and replication. transg ...	2001	11602699
proliferating cell nuclear antigen transcription is repressed through an e2f consensus element and activated by geminivirus infection in mature leaves.	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 app ...	2001	11402171
nuclear localization of the plant protein ser/thr phosphatase pp7.	recently we identified novel plant ser/thr phosphatases, termed pp7, which belong to the ppp family and have no known close homologs in other kingdoms. we now addressed the intracellular location of arabidopsis thaliana pp7 using gfp fusions and confocal laser scanning microscopy. pp7. gfp fusion was expressed transiently or stably in nicotiana benthamiana. pp7. gfp was found to be a predominantly nuclear protein. effects of cytoskeleton-disrupting drugs indicate that cytoskeleton may be require ...	2001	11703093
the distinct disease phenotypes of the common and yellow vein strains of tomato golden mosaic virus are determined by nucleotide differences in the 3'-terminal region of the gene encoding the movement protein.	in nicotiana benthamiana, the common strain of the bipartite geminivirus tomato golden mosaic virus (cstgmv) induces extensive chlorosis whereas the yellow vein strain (yvtgmv) produces veinal chlorosis on systemically infected leaves. in datura stramonium, cstgmv produces leaf distortion and a severe chlorotic mosaic whereas yvtgmv produces only small chlorotic lesions on systemically infected leaves. genetic recombination and site-directed mutagenesis studies using infectious clones of cstgmv ...	2001	11125157
host dna replication is induced by geminivirus infection of differentiated plant cells.	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, similar ...	2002	12468723
two e2f elements regulate the proliferating cell nuclear antigen promoter differently during leaf development.	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 ful ...	2002	12468739
spreading of rna targeting and dna methylation in rna silencing requires transcription of the target gene and a putative rna-dependent rna polymerase.	rna silencing is a sequence-specific rna degradation process that follows the recognition of double-stranded rna. here, we show that virus vectors carrying parts of a green fluorescent protein (gfp) transgene targeted rna silencing in nicotiana benthamiana and arabidopsis against the entire gfp rna. these results indicate that there was spreading of rna targeting from the initiator region into the adjacent 5' and 3' regions of the target gene. spreading was accompanied by methylation of the corr ...	2002	11971140
differential roles of geminivirus rep and ac4 (c4) in the induction of necrosis in nicotiana benthamiana.	summary the replication-associated protein (rep) of two distinct begomoviruses, the bipartite african cassava mosaic virus (acmv) and the monopartite tomato yellow leaf curl virus-china (tylcv-c), elicits a reaction resembling a hypersensitive response (hr), associated with the induction of local necrosis and a systemic burst of hydrogen peroxide production, when expressed from a potato virus x vector in nicotiana benthamiana. transient expression of the acmv rep after agrobacterium infiltration ...	2002	20569353
tomato leaf curl karnataka virus from bangalore, india, appears to be a recombinant begomovirus.	abstract the genome of tomato leaf curl virus (tolcv) from bangalore, india, a whitefly-transmitted geminivirus, was cloned (pind9) and sequenced. the circular dna of 2,759 nucleotides (u38239) is organized similarly to that of other begomoviruses with monopartite genomes. comparison of the nucleotide sequence of pind9 with other tomato-associated begomoviruses from india (tomato leaf curl bangalore virus [tolcbv, z48182]) and tomato leaf curl new delhi virus-severe (tolcndv-svr, u15015) showed ...	2002	18944261
genome structure and production of biologically active in vitro transcripts of cucurbit-infecting zucchini green mottle mosaic virus.	abstract the complete nucleotide sequence of the zucchini green mottle mosaic virus (zgmmv), a new member of the genus tobamovirus, has been determined. the genome of zgmmv is 6,513 nucleotides long and contains four open reading frames coding for proteins of 131, 189, 28, and 17 kda from the 5' to 3' end, respectively. the 5'- and 3'-non-translated regions consist of 59 and 163 residues, respectively. the sequences of the viral proteins exhibit high identity to the proteins of the members of th ...	2002	18943088
the tobacco mosaic virus resistance gene, n.	summary in this mini review we discuss recent advances in the understanding of the n gene-mediated resistance to tobacco mosaic virus (tmv). the tobacco n gene belongs to toll-interleukin-1 receptor homology/nucleotide binding/leucine rich repeat (tir-nb-lrr) class of resistance genes. it encodes two transcripts, n(s) and n(l), by alternative splicing, both of which are required to confer resistance to tmv. the structure-function analysis of the n gene indicates that the tir, nb and lrr domains ...	2002	20569323
expression in plants and immunogenicity of plant virus-based experimental rabies vaccine.	a new approach to the production and delivery of vaccine antigens is the use of engineered amino virus-based vectors. a chimeric peptide containing antigenic determinants from rabies virus glycoprotein (g protein) (amino acids 253-275) and nucleoprotein (n protein) (amino acids 404-418) was pcr-amplified and cloned as a translational fusion product with the alfalfa mosaic virus (almv) coat protein (cp). this recombinant cp was expressed in two plant virus-based expression systems. the first one ...	2002	12163267
plant-derived human papillomavirus 16 e7 oncoprotein induces immune response and specific tumor protection.	vaccine strategies for treatment of human papillomavirus-induced cervical cancer are based on either the recombinant e7 fusion oncoprotein or e7 ctl peptides. the therapeutic potential of the e7-based vaccine depends on the use of different adjuvants. in this study, we describe for the first time the expression of the human papillomavirus 16 e7 protein in nicotiana benthamiana plant using a potato virus x-derived vector. c57bl/6 mice immunized with e7-containing crude foliar extracts developed b ...	2002	12097270
p0 of beet western yellows virus is a suppressor of posttranscriptional gene silencing.	higher plants employ a homology-dependent rna-degradation system known as posttranscriptional gene silencing (ptgs) as a defense against virus infection. several plant viruses are known to encode proteins that can suppress ptgs. here we show that p0 of beet western yellows virus (bwyv) displays strong silencing suppressor activity in a transient expression assay based upon its ability to inhibit ptgs of green fluorescent protein (gfp) when expressed in agro-infiltrated leaves of nicotiana bentha ...	2002	12050394
subcellular localisation, protein interactions, and rna binding of potato mop-top virus triple gene block proteins.	subcellular localisation, protein interactions, and rna binding of the triple gene block proteins (tgbp) of potato mop-top virus (pmtv) were studied. the 13-kda (tgbp2) and 21-kda (tgbp3) proteins with or without green fluorescent protein fused to their n-terminus, and the 51-kda protein (tgbp1) were expressed individually from a recombinant tobacco mosaic virus (tmv) vector. fluorescent images and western immunoblotting experiments of recombinant tmv-infected nicotiana benthamiana cells suggest ...	2002	12093178
host-dependent recombination of a tomato bushy stunt virus coat protein mutant yields truncated capsid subunits that form virus-like complexes which benefit systemic spread.	this study examined the contribution of the tomato bushy stunt virus (tbsv) coat protein (cp) and its corresponding rna to systemic infection of plants. compared to results obtained with a mutant lacking the 5'-half of the cp gene, the presence of those cp-rna sequences in another mutant benefited tbsv infection on nicotiana benthamiana even though wild-type cp expression was eliminated by introduction of a small out-of-frame deletion. rt-pcr of viral rna associated with rapid infections establi ...	2002	12504582
a novel class of large and infectious defective rnas of citrus tristeza virus.	citrus tristeza virus (ctv)-infected plants contain one or more populations of defective rnas (drnas), mostly with a size range of ca. 2.0 to 5.0 kb. several ctv drnas have been characterized and found to consist mainly of the two termini of the genomic rna, with extensive internal deletions. the present paper describes a new class of large ( approximately 12.0 kb) drnas from three different ctv isolates with two unusual features. first is their composition with intact replicase genes. these drn ...	2002	12093181
inhibition of tobacco mosaic virus replication in lateral roots is dependent on an activated meristem-derived signal.	viral invasion of the root system of nicotiana benthamiana was studied noninvasively with a tobacco mosaic virus (tmv) vector expressing the green-fluorescent protein (gfp). lateral root primordia, which developed from the pericycle of primary roots, became heavily infected as they emerged from the root cortex. however, following emergence, a progressive wave of viral inhibition occurred that originated in the lateral-root meristem and progressed towards its base. excision of source and sink tis ...	2002	12099219
role of scf ubiquitin-ligase and the cop9 signalosome in the n gene-mediated resistance response to tobacco mosaic virus.	the tobacco n gene confers resistance to tobacco mosaic virus (tmv) and encodes a toll-interleukin-1 receptor/nucleotide binding/leu-rich repeat class protein. recent evidence indicates that the nicotiana benthamiana rar1 gene (nbrar1), which encodes a protein with a zinc finger motif called chord (cys- and his-rich domain), is required for the function of n. to investigate the role of nbrar1 in plant defense, we identified its interaction partners. we show that the nbrar1 protein interacts with ...	2002	12119369
characterisation of sri lankan cassava mosaic virus and indian cassava mosaic virus: evidence for acquisition of a dna b component by a monopartite begomovirus.	two bipartite begomoviruses, indian cassava mosaic virus (icmv) and sri lankan cassava mosaic virus (slcmv), have been isolated from mosaic-diseased cassava originating from central india and sri lanka, respectively. icmv was transmitted with low efficiency from cassava to nicotiana benthamiana by sap inoculation to give leaf curl symptoms. slcmv was much more virulent in this host, producing severe stunting, leaf curl, and chlorosis. these symptoms were reproduced when their cloned genomic comp ...	2002	11853400
transgenic plants expressing hc-pro show enhanced virus sensitivity while silencing of the transgene results in resistance.	nicotiana benthamiana plants were engineered to express sequences of the helper component-proteinase (hc-pro) of cowpea aphid-borne mosaic potyvirus (cabmv). the sensitivity of the transgenic plants to infection with parental and heterologous viruses was studied. the lines expressing hc-pro showed enhanced symptoms after infection with the parental cabmv isolate and also after infection with a heterologous potyvirus, potato virus y (pvy) and a comovirus, cowpea mosaic virus (cpmv). on the other ...	2002	12206307
short defective interfering rnas of tombusviruses are not targeted but trigger post-transcriptional gene silencing against their helper virus.	post-transcriptional gene silencing (ptgs) is a sequence-specific degradation mechanism that operates in almost all eukaryotic cells. in plants, double-stranded rna triggers ptgs, generating 21- to 25-nucleotide guide rnas responsible for specific degradation of cognate mrna. the double stranded rna intermediates of replicating plant viruses often induce ptgs, leading to symptom attenuation. here we demonstrate the role of ptgs in defective interfering (di) rna-mediated symptom attenuation in pl ...	2002	11884680
intramolecular complementing mutations in tobacco mosaic virus movement protein confirm a role for microtubule association in viral rna transport.	the movement protein (mp) of tobacco mosaic virus (tmv) facilitates the cell-to-cell transport of the viral rna genome through plasmodesmata (pd). a previous report described the functional reversion of a dysfunctional mutation in mp (pro81ser) by two additional amino acid substitution mutations (thr104ile and arg167lys). to further explore the mechanism underlying this intramolecular complementation event, the mutations were introduced into a virus derivative expressing the mp as a fusion to gr ...	2002	11907237
adaptation from whitefly to leafhopper transmission of an autonomously replicating nanovirus-like dna component associated with ageratum yellow vein disease.	ageratum yellow vein disease is caused by the whitefly-transmitted monopartite begomovirus ageratum yellow vein virus and a dna beta satellite component. naturally occurring symptomatic plants also contain an autonomously replicating nanovirus-like dna 1 component that relies on the begomovirus and dna beta for systemic spread and whitefly transmission but is not required for maintenance of the disease. here, we show that systemic movement of dna 1 occurs in nicotiana benthamiana when co-inocula ...	2002	11907341
the cf-9 disease resistance protein is present in an approximately 420-kilodalton heteromultimeric membrane-associated complex at one molecule per complex.	the tomato cf-9 gene confers race-specific resistance to the fungal pathogen cladosporium fulvum expressing the corresponding avirulence gene avr9. in tobacco, cf-9 confers a hypersensitive response to the avr9 peptide. to investigate cf-9 protein function in initiating defense signaling, we engineered a functional c-terminal fusion of the cf-9 gene with the tap (tandem affinity purification) tag. in addition, we established a transient expression assay in nicotiana benthamiana leaves for the pr ...	2002	11910014
efficient infection of nicotiana benthamiana by tomato bushy stunt virus is facilitated by the coat protein and maintained by p19 through suppression of gene silencing.	tomato bushy stunt virus (tbsv) is one of few rna plant viruses capable of moving systemically in some hosts in the absence of coat protein (cp). tbsv also encodes another protein (p19) that is not required for systemic movement but functions as a symptom determinant in nicotiana benthamiana. here, the role of both cp and p19 in the systemic spread has been reevaluated by utilizing transgenic n. benthamiana plants expressing the movement protein (mp) of red clover necrotic mosaic virus and chime ...	2002	11952121
mutation of three cysteine residues in tomato yellow leaf curl virus-china c2 protein causes dysfunction in pathogenesis and posttranscriptional gene-silencing suppression.	the nuclear localized c2 protein of the monopartite begomovirus tomato yellow leaf curl virus-china (tylcv-c) contributes to viral pathogenicity. here, we have investigated tylcv-c c2 protein domains that play a role in the phenotype. alignment of the c2 protein with 67 homologues from monopartite and bipartite begomoviruses revealed that a putative zinc-finger motif c36-x1-c38-x7-c46-x6-h53-x4-h58c59 and four potential phosphorylation sites (t52, s61, y68, and s74) are highly conserved. when ex ...	2002	11952122
tombusvirus p19-mediated suppression of virus-induced gene silencing is controlled by genetic and dosage features that influence pathogenicity.	the p19 protein (p19) of tomato bushy stunt virus (tbsv) is a pathogenicity determinant with host-dependent effects on virus spread and symptom induction. in addition, results in this study confirm that potato virus x-mediated delivery of p19 suppresses posttranscriptional gene silencing (ptgs). to study the relevance of this activity for tbsv biology, we evaluated whether tbsv activates virus-induced gene silencing (vigs) and if this process is suppressed by p19. tbsv vectors with the green flu ...	2002	11952130
the production of a genus-specific recombinant antibody (scfv) using a recombinant potyvirus protease.	a single chain variable fragment antibody (scfv; anti-nia scfv102) was selected from a synthetic human antibody library by using a nia protease of plum pox virus (ppv) as an antigen, which was expressed in bacteria. the nia protease forms the nuclear inclusion body a and acts as the major protease in the cleavage of the viral polyprotein into functional proteins. the nia protein was detected with anti-nia scfv102 after expression in escherichia coli cells as well as from ppv-infected nicotiana b ...	2002	12393153
expression of a phytophthora sojae necrosis-inducing protein occurs during transition from biotrophy to necrotrophy.	phytophthora sojae is an oomycete that causes stem and root rot on soybean plants. to discover pathogen factors that produce disease symptoms or activate plant defense responses, we identified putative secretory proteins from expressed sequence tags (ests) and tested selected candidates using a heterologous expression assay. from an analysis of 3035 ests originating from mycelium, zoospore, and infected soybean tissues, we identified 176 putative secreted proteins. a total of 16 different cdnas ...	2002	12410814
functional analyses of the pto resistance gene family in tomato and the identification of a minor resistance determinant in a susceptible haplotype.	pto is a member of a multigene family and encodes a serine/threonine kinase that mediates gene-for-gene resistance to strains of pseudomonas syringae pv. tomato expressing avrpto. the inferred amino acid sequence of the pto homologs from both resistant (lpimpth2 to lpimpth4) and susceptible (lescfen, lescpth2 to lescpth5) haplotypes suggested that most could encode functional serine/threonine kinases. in addition, the activation segments of the homologs are similar in sequence to that of pto, an ...	2002	11952131
initial infection of roots and leaves reveals different resistance phenotypes associated with coat protein gene-mediated resistance to potato mop-top virus.	resistance to the pomovirus potato mop-top virus (pmtv) was studied in potato (solanum tuberosum cv. saturna) and nicotiana benthamiana transformed with the coat protein (cp) gene of pmtv. the incidence of pmtv infections was reduced in tubers of the cp-transgenic potatoes grown in the field in soil infested with the viruliferous vector, spongospora subterranea. however, in those tubers that were infected, all three virus rnas were detected and virus titres were high. the cp-transgenic n. bentha ...	2002	11961276
size-dependent cell-to-cell movement of defective interfering rnas of cymbidium ringspot virus.	co-inoculation of nicotiana benthamiana plants with in vitro transcripts of both genomic and short defective interfering (di) rnas of cymbidium ringspot virus results in an accumulation of de novo generated di rna dimers. time-course analysis of di rna accumulation in the inoculated leaves showed early accumulation of di rna dimers followed by increased levels of di rna monomers. in contrast, di rna dimers were barely detectable in systems where cell-to-cell movement does not take place (protopl ...	2002	12029166
replication of potato spindle tuber viroid in cultured cells of tobacco and nicotiana benthamiana: the role of specific nucleotides in determining replication levels for host adaptation.	we have developed an electroporation protocol to inoculate cultured cells of tobacco and nicotiana benthamiana with in vitro transcripts of potato spindle tuber viroid (pstvd) to characterize viroid structural features that determine replication efficiency at the cellular level. both (+)- and (-)-strands of pstvd were detected by northern blots as early as 6 h postinoculation (h.p.i.). accumulation of the (+)-circular pstvd increased very rapidly starting at 24 h.p.i. and continued beyond 6 days ...	2002	12441088
silencing of a gene encoding a protein component of the oxygen-evolving complex of photosystem ii enhances virus replication in plants.	it has been suggested that, in addition to viral proteins, host proteins are involved in rna virus replication. in this study the rna helicase domain of the tobacco mosaic virus (tmv) replicase proteins was used as bait in the yeast two-hybrid system to identify tobacco proteins with a putative role in tmv replication. two host proteins were characterized. one protein (designated #3) belongs to a protein family of atpases associated with various activities (aaa), while the second host protein (d ...	2002	12033790
the arabidopsis atste24 is a caax protease with broad substrate specificity.	following prenylation, the proteins are subject to two prenyl-dependent modifications at their c-terminal end, which are required for their subcellular targeting. first, the three c-terminal residues of the caax box prenylation signaling motif are removed, which is followed by methylation of the free carboxyl group of the prenyl cysteine moiety. an arabidopsis homologue of the yeast caax protease ste24 (afc1) was cloned and expressed in rce1 delta ste24 delta mutant yeast to demonstrate function ...	2002	12039957
cowpea mosaic virus 32- and 60-kilodalton replication proteins target and change the morphology of endoplasmic reticulum membranes.	cowpea mosaic virus (cpmv) replicates in close association with small membranous vesicles that are formed by rearrangements of intracellular membranes. to determine which of the viral proteins are responsible for the rearrangements of membranes and the attachment of the replication complex, we have expressed individual cpmv proteins encoded by rna1 in cowpea protoplasts by transient expression and in nicotiana benthamiana plants by using the tobacco rattle virus (trv) expression vector. the 32-k ...	2002	12021362
movement of potato spindle tuber viroid reveals regulatory points of phloem-mediated rna traffic.	increasing evidence indicates that the phloem mediates traffic of selective rnas within a plant. how an rna enters, moves in, and exits the phloem is poorly understood. potato spindle tuber viroid (pstvd) is a pathogenic rna that does not encode proteins and is not encapsidated, and yet it replicates autonomously and traffics systemically within an infected plant. the viroid rna genome must interact directly with cellular factors to accomplish these functions and is, therefore, an excellent prob ...	2002	12226494
agroinfection as a rapid method for propagating cowpea mosaic virus-based constructs.	to increase the efficiency of infections with cowpea mosaic virus (cpmv)-based constructs, clones suitable for agroinfection were constructed. full-length copies of rna-1 and rna-2 were inserted between the sequence of a cauliflower mosaic virus (camv) 35s promoter and a nos terminator and were introduced into the agrobacterium tumefaciens plasmid, pbinplus. infiltration of leaves of either nicotiana benthamiana or cowpea (vigna unguiculata) with a bacterial suspension containing a mixture of th ...	2002	12270666
role of the alfalfa mosaic virus methyltransferase-like domain in negative-strand rna synthesis.	rnas 1 and 2 of the tripartite genome of alfalfa mosaic virus (amv) encode the replicase proteins p1 and p2, respectively. p1 contains a methyltransferase-like domain in its n-terminal half, which has a putative role in capping the viral rnas. six residues in this domain that are highly conserved in the methyltransferase domains of alphavirus-like viruses were mutated individually in amv p1. none of the mutants was infectious to plants. mutant rna 1 was coexpressed with wild-type (wt) rnas 2 and ...	2002	12388692
ubiquitin ligase-associated protein sgt1 is required for host and nonhost disease resistance in plants.	homologues of the yeast ubiquitin ligase-associated protein sgt1 are required for disease resistance in plants mediated by nucleotide-binding site/leucine-rich repeat (nbs-lrr) proteins. here, by silencing sgt1 in nicotiana benthamiana, we extend these findings and demonstrate that sgt1 has an unexpectedly general role in disease resistance. it is required for resistance responses mediated by nbs-lrr and other r proteins in which pathogen-derived elicitors are recognized either inside or outside ...	2002	12119413
cloning and expression of squalene synthase cdna from hot pepper (capsicum annuum l.).	we isolated and artificially expressed a cdna clone of the capsicum annuum squalene synthase (cass) gene to elucidate the pattern of alternatively regulated two-branch point enzymes. the 1,674-bp cass cdna contained an open reading frame of 411 amino acids, yielding a predicted molecular mass of about 45 kda. a deduced amino acid sequence comparison to other squalene syntheses showed identities with nicotiana tabacum (91%), nicotiana benthamiana (90%), arabidopsis thaliana (79%), and rats (40%). ...	2002	12132584
a geminivirus replication protein interacts with a protein kinase and a motor protein that display different expression patterns during plant development and infection.	the geminivirus protein al1 initiates viral dna replication, regulates its own expression, and induces plant gene transcription. to better understand how al1 interacts with host proteins during these processes, we used yeast two-hybrid library screening and a baculovirus protein interaction system to identify plant proteins that interact with al1. these studies identified a ser/thr kinase, a kinesin, and histone h3 as al1 partners. the kinase is autophosphorylated and can phosphorylate common ki ...	2002	12172024
suppression of a key gene involved in chlorophyll biosynthesis by means of virus-inducing gene silencing.	the chlh gene coding the h subunit of magnesium chelatase, an enzyme involved in chlorophyll biosynthesis, was silenced in nicotiana benthamiana plants by infection with tobacco mosaic virus vectors (ptmv-30b) containing 67,214 or 549 nt long chlh inserts. silencing of the nuclear chlh gene induced a chimeric phenotype with green and yellow/white leaves associated with alterations of chloroplast shape and ultrastructure. the symptoms became first evident around veins of young leaves, and only la ...	2002	12175014
the golgi localization of arabidopsis thaliana beta1,2-xylosyltransferase in plant cells is dependent on its cytoplasmic and transmembrane sequences.	to investigate the targeting of proteins to the plant golgi we studied arabidopsis thaliana beta1,2-xylosyltransferase (xylt), a glycosyltransferase which is unique to plants and some invertebrates. different deletion constructs of the putative cytoplasmic (c)-transmembrane (t)-stem (s) region of the enzyme were transiently expressed in the tobacco-related model plant species nicotiana benthamiana. subcellular localization of fusion proteins between cts, ct, t, or c domains and the reporter mole ...	2002	12175019
sequence-, tissue-, and delivery-specific targeting of rna during post-transcriptional gene silencing.	transgenic nicotiana benthamiana plants expressing an untranslatable version of the coat protein (cp) gene from the tamarillo mosaic virus (tamv) were either resistant to tamv infection or recovered from infection. these phenotypes were the result of a post-transcriptional gene silencing (ptgs) mechanism that targeted tamv-cp sequences for degradation. the tamv-cp sequences were degraded when present in the wild-type tamv potyvirus, in transgene mrna, or in chimeric viral vectors based on white ...	2002	12182332
virus-induced gene silencing in transgenic plants expressing the minor capsid protein of beet western yellows virus.	transgenic nicotiana benthamiana expressing the minor coat protein p74 of the phloem-limited beet western yellows virus (bwyv) exhibited an unusual spatial pattern of post-transcriptional gene silencing (ptgs) when infected with bwyv or related viruses. following infection, transgenic p74 and its mrna accumulated to only low levels, 21 to 23 nucleotide rnas homologous to the transgene appeared, and the transgene dna underwent methylation. the infecting viral rna, however, was not subject to sign ...	2002	12182337
silencing of a viral rna silencing suppressor in transgenic plants.	high expression levels of the helper component proteinase (hc(pro)), a known virus suppressor of rna silencing, were attained in nicotiana benthamiana transformed with the hc(pro) cistron of potato virus a (pva, genus potyvirus). no spontaneous silencing of the hc(pro) transgene was observed, in contrast to the pva coat protein (cp)-encoding transgene in other transgenic lines. hc(pro)-transgenic plants were initially susceptible to pva and were systemically infected by 14 days post-inoculation ...	2002	12185289
specific degradation of 3' regions of gus mrna in posttranscriptionally silenced tobacco lines may be related to 5'-3' spreading of silencing.	target regions for posttranscriptional silencing of transgenes often reside in the 3' region of the coding sequence, although there are exceptions. to resolve if the target region is determined by the gene undergoing silencing rather than by the structure of the transgene loci or the plant genetic background, we have performed detailed analyses of target regions in three spontaneously beta-glucuronidase (gus) silencing tobacco lines of different origin. from quantitative cosuppression experiment ...	2002	12212847
virus-induced gene silencing in tomato.	we have previously demonstrated that a tobacco rattle virus (trv)-based vector can be used in virus-induced gene silencing (vigs) to study gene function in nicotiana benthamiana. here we show that recombinant trv infects tomato plants and induces efficient gene silencing. using this system, we suppressed the pds, ctr1 and ctr2 genes in tomato. suppression of ctr1 led to a constitutive ethylene response phenotype and up-regulation of an ethylene response gene, chitinase b. this phenotype is simil ...	2002	12220268
subcellular location of the helper component-proteinase of cowpea aphid-borne mosaic virus.	the helper component-proteinase (hc-pro) of cowpea aphid-borne mosaic virus (cabmv) was expressed in escherichia coli and used to obtain hc-pro antiserum that was used as an analytical tool for hc-pro studies. the antiserum was used in immunofluorescence assays to study the subcellular location of hc-pro expressed with other viral proteins in cowpea protoplasts in a natural cabmv infection, or in protoplasts transfected with a transient expression construct expressing hc-pro separately from othe ...	2002	12416684
host-dependent requirement for the potato leafroll virus 17-kda protein in virus movement.	the requirement for the 17-kda protein (p17) of potato leafroll virus (plrv) in virus movement was investigated in four plant species: potato (solanum tuberosum), physalis floridana, nicotiana benthamiana, and n. clevelandii. two plrv p17 mutants were characterized, one that does not translate the p17 and another that expresses a p17 missing the first four amino acids. the p17 mutants were able to replicate and accumulate in agroinoculated leaves of potato and p. floridana, but they were unable ...	2002	12437307
long-distance movement, virulence, and rna silencing suppression controlled by a single protein in hordei- and potyviruses: complementary functions between virus families.	rna silencing is a natural defense mechanism against genetic stress factors, including viruses. a mutant hordeivirus (barley stripe mosaic virus [bsmv]) lacking the gammab gene was confined to inoculated leaves in nicotiana benthamiana, but systemic infection was observed in transgenic n. benthamiana expressing the potyviral silencing suppressor protein hcpro, suggesting that the gammab protein may be a long-distance movement factor and have antisilencing activity. this was shown for gammab prot ...	2002	12438624
virus-induced silencing of ftsh gene in nicotiana benthmiana causes a striking bleached leaf phenotype.	a recombinant potato virus x (pvx) vector, ptxs.ftsh, harboring partial sequence of ftsh gene of nicotiana benthamiana was constructed to silence the expression of endogenous ftsh homologous gene in n. benthamiana. inoculation with in vitro runoff transcript of ptxs.ftsh to n. benthamiana plants allowed silencing of ftsh, causing striking bleaching of upper leaves reminiscent of var2 mutant phenotype of arabidopsis thaliana. ftsh-silenced plants exhibited no resistance against tobacco mosaic vir ...	2002	12441644
subcellular targeting domains of abutilon mosaic geminivirus movement protein bc1.	abutilon mosaic geminivirus (abmv) encodes two movement proteins, bv1 and bc1, which mediate the intra- and intercellular transport of viral dna in plants cooperatively. it has been shown previously that singly expressed bc1, fused to green fluorescent protein (gfp), accumulates preferentially either at the cell periphery or around the nucleus in separate plant cells. to define the bc1 domains responsible for understanding the subcellular sorting, deletion mutants were fused to gfp and expressed ...	2002	12491102
tobacco rar1, eds1 and npr1/nim1 like genes are required for n-mediated resistance to tobacco mosaic virus.	the tobacco n gene confers resistance to tobacco mosaic virus (tmv) and encodes a toll-interleukin-1 receptor/nucleotide binding site/leucine-rich repeat (tir-nbs-lrr) class protein. we have developed and used a tobacco rattle virus (trv) based virus induced gene silencing (vigs) system to investigate the role of tobacco candidate genes in the n-mediated signalling pathway. to accomplish this we generated transgenic nicotiana benthamiana containing the tobacco n gene. the transgenic lines exhibi ...	2002	12028572
barley stripe mosaic virus-induced gene silencing in a monocot plant.	rna silencing of endogenous plant genes can be achieved by virus-mediated, transient expression of homologous gene fragments. this powerful, reverse genetic approach, known as virus-induced gene silencing (vigs), has been demonstrated only in dicot plant species, where it has become an important tool for functional genomics. barley stripe mosaic virus (bsmv) is a tripartite, positive-sense rna virus that infects many agriculturally important monocot species including barley, oats, wheat and maiz ...	2002	12000679
dynamics of the vigs-mediated chimeric silencing of the nicotiana benthamiana chlh gene and of the tobacco mosaic virus vector.	the chlh gene, encoding for the h subunit of the magnesium chelatase enzyme, was silenced in nicotiana bentahamiana plants by virus-induced gene silencing (vigs), using tobacco mosaic virus (tmv) expression vector. strong silencing of the chlh target gene was initiated only in the apical tissues, in which the endogenous transcription level of the target gene and the level of tmv vector rna were both very high. the virus vector was also targeted by vigs, and its suppression was correlated with th ...	2003	12575743
agrosuppression: a bioassay for the hypersensitive response suited to high-throughput screening.	we describe a novel method, agrosuppression, that addresses the need for an assay of the hypersensitive response (hr) in intact plants that is rapid and adapted to high-throughput functional screening of plant and pathogen genes. the agrosuppression assay is based on inoculation of intact plants with a mixture of agrobacterium tumefaciens strains carrying (i) a binary plasmid with one or more candidate hr-inducing genes and (ii) a tumor-inducing (oncogenic) t-dna. in the absence of hr induction, ...	2003	12580277
a naturally occurring recombinant dna-a of a typical bipartite begomovirus does not require the cognate dna-b to infect nicotiana benthamiana systemically.	species of the genus begomovirus (family geminiviridae) found in the western hemisphere typically have a bipartite genome that consists of two 2.6 kb dna genomic components, dna-a and dna-b. we have identified and cloned genomic components of a new tomato-infecting begomovirus from brazil, for which the name tomato crinkle leaf yellows virus (tcrlyv) is proposed, and a dna-a variant of tomato chlorotic mottle virus (tocmv-[mg-bt1]). sequence analysis revealed that tcrlyv was most closely related ...	2003	12604824
turnip crinkle virus coat protein mediates suppression of rna silencing in nicotiana benthamiana.	all of the protein products of turnip crinkle virus (tcv; tombusviridae, carmovirus) were tested for their ability to suppress rna silencing of a reporter gene after transient expression in agrobacterium-infiltrated nicotiana benthamiana leaves. only the capsid protein, p38, showed suppression activity, although this was not obvious when p38 was expressed as part of a tcv infection of the same tissues. when p38 was expressed from a pvx vector, symptoms with enhanced severity that correlated with ...	2003	12620795
immunodetection and fluorescent microscopy of transgenically expressed hordeivirus tgbp3 movement protein reveals its association with endoplasmic reticulum elements in close proximity to plasmodesmata.	the subcellular localization of the hydrophobic tgbp3 protein of poa semilatent virus (pslv, genus hordeivirus) was studied in transgenic plants using fluorescent microscopy to detect green fluorescent protein (gfp)-tagged protein and immunodetection with monoclonal antibodies (mabs) raised against the gfp-based fusion expressed in e. coli. in western blot analysis, mabs efficiently recognized the wild-type and gfp-fused pslv tgbp3 proteins expressed in transgenic nicotiana benthamiana, but fail ...	2003	12655101
molecular characterization of nbpaf encoding the alpha6 subunit of the 20s proteasome in nicotiana benthamiana.	the 26s proteasome involved in degradation of proteins covalently modified with polyubiquitin consists of the 20s proteasome and 19s regulatory complex. the nbpaf gene encoding the alpha6 subunit of the 20s proteasome was identified from nicotiana benthamiana. nbpaf exhibits high sequence homology with the corresponding genes from arabidopsis, human and yeast. the deduced amino acid sequence of nbpaf reveals that this protein contains the proteasome alpha-type subunits signature and nuclear loca ...	2003	12661772
the potato virus x tgbp2 protein association with the endoplasmic reticulum plays a role in but is not sufficient for viral cell-to-cell movement.	potato virus x (pvx) tgbp1, tgbp2, tgbp3, and coat protein are required for virus cell-to-cell movement. plasmids expressing gfp fused to tgbp2 were bombarded to leaf epidermal cells and gfp:tgbp2 moved cell to cell in nicotiana benthamiana leaves but not in nicotiana tabacum leaves. gfp:tgbp2 movement was observed in tgbp1-transgenic n. tabacum, indicating that tgbp2 requires tgbp1 to promote its movement in n. tabacum. in this study, gfp:tgbp2 was detected in a polygonal pattern that resembles ...	2003	12890619
two classes of subgenomic rna of grapevine virus a produced by internal controller elements.	grapevine virus a (gva), a species of the recently established genus vitivirus, consists of an approximately 7.3-kb single-stranded rna genome of positive polarity, organized into five open reading frames (orfs). the virus, which is closely associated with the grapevine rugose wood disease complex, has been poorly investigated genetically. we explored the production of viral rnas in a gva-infected nicotiana benthamiana herbaceous host and characterized one nested set of three 5'-terminal sgrnas ...	2003	12919748
the importance of alfalfa mosaic virus coat protein dimers in the initiation of replication.	deletion and substitution mutations affecting the oligomerization of alfalfa mosaic virus (amv) coat protein (cp) were studied in protoplasts to determine their effect on genome activation, an early step in amv replication. the cp mutants that formed dimers, cpdeltac9 and cpc-a(r)f, were highly active in initiating replication with 63-84% of wild-type (wt) cp activity. however, all mutants that did not form dimers, cpdeltac18, cpdeltac19, cpc-wfp, and cpc-w, were much less active with 19-33% of ...	2003	12504539
identification of grapevines infected with divergent variants of grapevine virus a using variant-specific rt-pcr.	rt-pcrs, designed for the specific detection of molecular variants of grapevine virus a (gva), were applied to analysis of the virus from various grapevines and isolates recovered from these grapevines in nicotiana benthamiana. results of sscp, cloning and sequencing revealed that the combination of these rt-pcr techniques permits reliable and rapid identification of grapevines mixed-infected with divergent variants of gva. the results suggest that such grapevines are very common among gva-infec ...	2003	12951225
individualized human scfv vaccines produced in plants: humoral anti-idiotype responses in vaccinated mice confirm relevance to the tumor ig.	we have developed a method for rapidly producing in plants the idiotype regions of the tumor-specific ig as single-chain fv (scfv) proteins for use in the treatment of non-hodgkin's lymphoma. variable region gene sequences were generated from either a tumor hybridoma or human tumor biopsy cells, and idiotype domains were joined by a novel linker and cloned into a modified tobacco mosaic virus (tmv) vector designed to secrete the scfv protein in infected nicotiana benthamiana plants. thirty-eight ...	2003	12957399
fluorescent labelling reveals spatial separation of potyvirus populations in mixed infected nicotiana benthamiana plants.	the distribution of potyviruses in mixed infected nicotiana benthamiana plants was investigated by using green and red fluorescent proteins (gfp, dsred). full-length cdna clones of plum pox virus (ppv-nat-agfps; ppv-nat-red), tobacco vein mottling virus (tvmv-gfp; tvmv-red) and clover yellow vein virus (clyvv-gfp) expressing fluorescent proteins, referred to here as labelled viruses, were used to characterize the distribution of different potyviral populations (e.g. tvmv-gfp/ppv-nat-red), as wel ...	2003	13679622
nicotiana benthamiana gp91phox homologs nbrboha and nbrbohb participate in h2o2 accumulation and resistance to phytophthora infestans.	active oxygen species (aos) are responsible for triggering defense responses in plants. respiratory burst oxidase homologs (rboh genes) have been implicated in aos generation. we have isolated two rboh cdnas, nbrboha and nbrbohb, from nicotiana benthamiana leaves. nbrboha was expressed constitutively at a low level and the transcripts were increased after mechanical stress of control leaf infiltration, whereas nbrbohb was induced specifically by the protein elicitor inf1 from the potato pathogen ...	2003	12615943
suppressor activity of potyviral and cucumoviral infections in potyvirus-induced transgene silencing.	the process known as 'recovery' by which virus-infected plants become resistant to the infection is an interesting phenomenon where both rna silencing and virus resistance fully converge. in a previous study, we showed that transgenic nicotiana benthamiana nibv3 plants, transformed with a mutated nib coding sequence from plum pox virus (ppv), showed a delayed, very specific, resistance phenotype, which was induced by the initial infection. this recovery was the consequence of the activation of a ...	2003	13679623
virus-induced gene silencing.	in the postgenomic era, large-scale functional genomic approaches are necessary for converting sequence information into functional information. a para-genetic approach, called virus-induced gene silencing (vigs), offers a rapid means of gaining insight into gene function in plants. vigs system could be used to suppress endogenous gene expression by infecting plants with a recombinant virus vector (vigs vector) carrying host-derived sequence. here, we describe the use of tobacco rattle virus (tr ...	2003	14501071
potato mop-top virus: the coat protein-encoding rna and the gene for cysteine-rich protein are dispensable for systemic virus movement in nicotiana benthamiana.	full-length genomic cdna clones of the swedish isolate of potato mop-top virus (pmtv) were transcribed in vitro using t7 rna polymerase. the combination of rna 1, 2 and 3 synthesized in the presence of m(7)gpppg cap analogue was infectious when inoculated onto nicotiana benthamiana plants. also, the combination of rna 1 (encodes the viral replicase) with rna 3 [encodes the triple gene block proteins and a small cysteine-rich protein (crp)] was infectious and both rnas moved systemically in n. be ...	2003	12655103
bovine herpes virus gd protein produced in plants using a recombinant tobacco mosaic virus (tmv) vector possesses authentic antigenicity.	a tobacco mosaic virus (tmv)-based vector was utilized for expression of a cytosolic form of the bovine herpesvirus type 1 (bhv-1) protein glycoprotein d (gdc). nicotiana benthamiana plants were harvested 7 days after inoculation with rna transcripts derived from the tmv-gdc recombinant virus. recombinant gdc protein of expected electrophoretic mobility accumulated in inoculated leaves to a concentration of about 20 micrograms/g of fresh leaf tissue. oil-based vaccines were formulated with crude ...	2003	14505899
c-terminal domain of a hevein-like protein from wasabia japonica has potent antimicrobial activity.	an antimicrobial protein, designated wjamp-1, was purified from leaves of wasabia japonica l. wjamp-1 showed antimicrobial activity against both fungi and bacteria. the deduced amino acid sequence of cdna of wjamp-1 showed 60% and 70% identity with a hevein from hevea brasiliansis and a hevein-like protein from arabidopsis thaliana, respectively. however, matured wjamp-1 lacked the hevein domain and may correspond to the c-terminal domain of hevein. southern blot analysis showed that one or two ...	2003	12668776
peptide-mediated broad-spectrum plant resistance to tospoviruses.	plant viruses have a significant impact on agronomic losses worldwide. a new strategy for engineering virus-resistant plants by transgenic expression of a dominant interfering peptide is presented here. this peptide of 29 aa strongly interacts with the nucleocapsid proteins (n) of different tospoviruses. transgenic nicotiana benthamiana lines expressing the peptide fused to a carrier protein were challenged with five different tospoviruses that have a nucleocapsid protein interacting with the pe ...	2003	12682295
different elongation pathways in the biosynthesis of acyl groups of trichome exudate sugar esters from various solanaceous plants.	two common pathways are known for elongation of aliphatic acids via acetate in biological organisms: the fatty acid synthase (fas) and the alpha-ketoacid elongation (alphakae) pathways. the alphakae route is utilized in many biosynthetic pathways, including the tricarboxylic acid cycle, leucine biosynthesis, and in formation of coenzyme b, glucosinolates, alpha-ketoadipate, sugar-ester acyl acids, short-chain alcohols of yeast and clostridium species, 2-amino-4-methylhex-4-enoic acid, and l-gamm ...	2003	12687369
in situ characterization of cymbidium ringspot tombusvirus infection-induced posttranscriptional gene silencing in nicotiana benthamiana.	in plants, posttranscriptional gene silencing (ptgs) is an ancient and effective defense mechanism against viral infection. a number of viruses encode proteins that suppress virus-activated ptgs. the p19 protein of tombusviruses is a potent ptgs suppressor which interferes with the onset of ptgs-generated systemic signaling and is not required for viral replication or for viral movement in nicotiana benthamiana. this unique feature of p19 suppressor allowed us to analyze the mechanism of ptgs-ba ...	2003	12719602
p58(ipk), a plant ortholog of double-stranded rna-dependent protein kinase pkr inhibitor, functions in viral pathogenesis.	p58(ipk) is a cellular inhibitor of the mammalian double-stranded rna-activated protein kinase (pkr). here we provide evidence for the existence of its homolog in plants and its role in viral infection at the organism level. viral infection of p58(ipk)-silenced nicotiana benthamiana and arabidopsis knockouts leads to host death. this host cell death is associated with phosphorylation of the alpha subunit of eukaryotic translation initiation factor (eif-2alpha). loss of p58(ipk) leads to reduced ...	2003	12737801
effect of temperature on plum pox virus infection.	one of the key factors of progress of an epidemic is the duration of virus availability for a vector in plants, which could be influenced by temperature. using five epidemiologically different isolates of plum pox virus (ppv) we studied the effect of temperature on the virus infectivity, intensity of disease symptoms and virus accumulation in nicotiana benthamiana plants as determined by a double-antibody sandwich-enzyme-linked immunosorbent assay (das-elisa). no differences in infectivity and i ...	2003	12828345
plant-based heterologous expression of mal d 2, a thaumatin-like protein and allergen of apple (malus domestica), and its characterization as an antifungal protein.	mal d 2 is a thaumatin-like protein and important allergen of apple fruits that is associated with ige-mediated symptoms in apple allergic individuals. we obtained a full-length cdna clone of mal d 2 from rna isolated from ripe apple (malus domestica cv. golden delicious). the cdna's open reading frame encodes a protein of 246 amino acid residues including a signal peptide of 24 residues and two putative glycosylation sites. the deduced amino acid sequence of the mature mal d 2 protein results i ...	2003	12787673
negative-strand tospoviruses and tenuiviruses carry a gene for a suppressor of gene silencing at analogous genomic positions.	posttranscriptional silencing of a green fluorescent protein (gfp) transgene in nicotiana benthamiana plants was suppressed when these plants were infected with tomato spotted wilt virus (tswv), a plant-infecting member of the bunyaviridae: infection with tswv resulted in complete reactivation of gfp expression, similar to the case for potato virus y, but distinct from that for cucumber mosaic virus, two viruses known to carry genes encoding silencing suppressor proteins. agrobacterium-based lea ...	2003	12502849
use of green fluorescent protein to quantify the growth of colletotrichum during infection of tobacco.	to develop a quantitative assay of fungal growth inside plant tissues, strains of colletotrichum destructivum and colletotrichum orbiculare were transformed with a modified green fluorescent protein (gfp) gene fused with a glyceraldehyde-3-phosphate dehydrogenase promoter from aspergillus nidulans. transformants expressed gfp in culture and had the same growth rate and general appearance as the wild type. gfp was observed in all fungal structures during infection of leaves of nicotiana benthamia ...	2003	12609730
generation and characterisation of functional recombinant antibody fragments against rna replicase nib from plum pox virus.	a monoclonal antibody (mab 2a) able to react against the rna replicase nib from plum pox virus (ppv) was obtained and used for generating a specific scfv fragment. the vh and vl coding sequences were cloned and expressed as a fusion scfv protein to alkaline phosphatase. this fusion protein was able to recognise viral nib in both western and tissue-print elisa blots. the affinity and specificity of scfv2a for nib was similar to that of the parental mab and the region yleafy from ppv-nib was ident ...	2003	12535657
molecular analysis of the cucumber leaf spot virus genome.	full-length clones of the genome of the aureusvirus, cucumber leaf spot virus (clsv), have been constructed and infectious t7 polymerase derived synthetic transcripts have been produced. mutational analysis of the genome indicates a role for p84 in viral rna replication, the cp in systemic movement, p27 in viral cell-to-cell movement and p17 in symptom induction. a clsv mutant lacking orfs for the cp, p27 and p17 (clsv yx) was capable of replication and systemic movement in transgenic nicotiana ...	2003	12573495
gene expression analysis of plant host-pathogen interactions by supersage.	the type iii restriction endonuclease ecop15i was used in isolating fragments of 26 bp from defined positions of cdnas. we call this substantially improved variant to the conventional serial analysis of gene expression (sage) procedure "supersage." by applying supersage to magnaporthe grisea (blast)-infected rice leaves, gene expression profiles of both the rice host and blast fungus were simultaneously monitored by making use of the fully sequenced genomes of both organisms, revealing that the ...	2003	14676315
the potato virus x tgbp3 protein associates with the er network for virus cell-to-cell movement.	potato virus x (pvx) tgbp3 is required for virus cell-to-cell movement. cell-to-cell movement of tgbp3 was studied using biolistic bombardment of plasmids expressing gfp:tgbp3. tgbp3 moves between cells in nicotiana benthamiana, but requires tgbp1 to move in n. tabacum leaves. in tobacco leaves gfp:tgbp3 accumulated in a pattern resembling the endoplasmic reticulum (er). to determine if the er network is important for gfp:tgbp3 and for pvx cell-to-cell movement, a single mutation inhibiting memb ...	2003	12726734
use of spring beauty latent virus to identify compatible interactions between bromovirus components required for virus infection.	spring beauty latent virus (sblv) is a member of the genus bromovirus, and is closely related to brome mosaic virus (bmv) and cowpea chlorotic mottle virus (ccmv). compatible interactions between viral components are required for successful infection of plants by bmv and ccmv. to further our understanding of interactions between bromovirus components, we used sblv to produce reassortants among the three bromoviruses. we found that sblv rna 2 functioned with heterologous bromovirus rna 1 in infec ...	2003	12771403
transient expression of arabidopsis thaliana ascorbate peroxidase 3 in nicotiana benthamiana plants infected with recombinant potato virus x.	we have explored the transient over-expression of arabidopsis thaliana ascorbate peroxidase 3 (apx3) in nicotiana benthamiana using a viral vector based on the potato virus x (pvx). plants infected with a pvx:apx3 hybrid had a similar progression of viral particles compared to control plants infected with a pvx:gfp hybrid, indicating that infection was not affected by the over-expression of heterologous apx3. our results also showed that in pvx:apx3-infected plants, the hybrid virus directed a h ...	2003	12789421
virus-induced silencing of sterol biosynthetic genes: identification of a nicotiana tabacum l. obtusifoliol-14alpha-demethylase (cyp51) by genetic manipulation of the sterol biosynthetic pathway in nicotiana benthamiana l.	obtusifoliol-14alpha-demethylase (cyp51) is implicated in plant sterol biosynthesis. an arabidopsis expressed sequence tag encoding a cyp51 was used as a probe to isolate nicotiana tabacum l. cdnas. two types of cdna clones were identified. nt cyp51-1 and nt cyp51-2 shared 97% identity together and around 75% with other plant cyp51s. the function of the encoded enzyme has been demonstrated in planta by manipulating the sterol biosynthetic pathway at the gene level. the endogenous cyp51 of nicoti ...	2003	12810855
a novel co-delivery system consisting of a tomato bushy stunt virus and a defective interfering rna for studying gene silencing.	virus induced gene silencing (vigs) and suppression are rna-specific defense and counter-defense circuits in plant-virus interactions. these phenomena have been investigated extensively with an agrobacterium-mediated transient expression system. in this study, a virus-based transient expression system was developed to study these phenomena. a tomato bushy stunt virus (tbsv) viral vector with an inactivated p19 suppressor gene, referred to as phst2-14, was chosen to express the p1 of tobacco etch ...	2003	12821195
expression of self-complementary hairpin rna under the control of the rolc promoter confers systemic disease resistance to plum pox virus without preventing local infection.	homology-dependent selective degradation of rna, or post-transcriptional gene silencing (ptgs), is involved in several biological phenomena, including adaptative defense mechanisms against plant viruses. small interfering rnas mediate the selective degradation of target rna by guiding a multicomponent rnase. expression of self-complementary hairpin rnas within two complementary regions separated by an intron elicits ptgs with high efficiency. plum pox virus (ppv) is the etiological agent of shar ...	2003	12823862
the pseudomonas syringae type iii-secreted protein hopptod2 possesses protein tyrosine phosphatase activity and suppresses programmed cell death in plants.	the bacterial plant pathogen pseudomonas syringae possesses a type iii protein secretion system that delivers many virulence proteins into plant cells. a subset of these proteins (called avr proteins) is recognized by the plant's innate immune system and triggers defences. one defence-associated response is the hypersensitive response (hr), a programmed cell death (pcd) of plant tissue. we have previously identified hopptod2 as a type iii secreted protein from p. s. pv. tomato dc3000. sequence a ...	2003	12828636
structural and mutational analyses of cis-acting sequences in the 5'-untranslated region of satellite rna of bamboo mosaic potexvirus.	the satellite rna of bamboo mosaic virus (satbamv) contains on open reading frame for a 20-kda protein that is flanked by a 5'-untranslated region (utr) of 159 nucleotides (nt) and a 3'-utr of 129 nt. a secondary structure was predicted for the 5'-utr of satbamv rna, which folds into a large stem-loop (lsl) and a small stem-loop. enzymatic probing confirmed the existence of lsl (nt 8-138) in the 5'-utr. the essential cis-acting sequences in the 5'-utr required for satbamv rna replication were de ...	2003	12832220
high-throughput viral expression of cdna-green fluorescent protein fusions reveals novel subcellular addresses and identifies unique proteins that interact with plasmodesmata.	a strategy was developed for the high-throughput localization of unknown expressed proteins in nicotiana benthamiana. libraries of random, partial cdnas fused to the 5' or 3' end of the gene for green fluorescent protein (gfp) were expressed in planta using a vector based on tobacco mosaic virus. viral populations were screened en masse on inoculated leaves using a confocal microscope fitted with water-dipping lenses. each viral infection site expressed a unique cdna-gfp fusion, allowing several ...	2003	12837943
virus-induced silencing of wipk and sipk genes reduces resistance to a bacterial pathogen, but has no effect on the inf1-induced hypersensitive response (hr) in nicotiana benthamiana.	activation of two mitogen-activated protein kinases (mapks), wound-induced protein kinase (wipk) and salicylic acid-induced protein kinase (sipk), is one of the earliest responses that occur in tobacco plants that have been wounded, treated with pathogen-derived elicitors or challenged with avirulent pathogens. we isolated cdnas for these mapks (nbwipkand nbsipk) from nicotiana benthamiana. the function of nbwipk and nbsipk in mediating the hypersensitive response (hr) triggered by infiltration ...	2003	12838412
cucumovirus- and bromovirus-encoded movement functions potentiate cell-to-cell movement of tobamo- and potexviruses.	cucumber mosaic virus (cmv, a cucumovirus) and brome mosaic virus (bmv, a bromovirus) require the coat protein (cp) in addition to the 3a movement protein (mp) for cell-to-cell movement, while cowpea chlorotic mottle virus (ccmv, a bromovirus) does not. using bombardment-mediated transcomplementation assays, we investigated whether the movement functions encoded by these viruses potentiate cell-to-cell movement of movement-defective tomato mosaic virus (tomv, a tobamovirus) and potato virus x (p ...	2003	14592759
high throughput virus-induced gene silencing implicates heat shock protein 90 in plant disease resistance.	virus-induced gene silencing was used to assess the function of random nicotiana benthamiana cdnas in disease resistance. out of 4992 cdnas tested from a normalized library, there were 79 that suppressed a hypersensitive response (hr) associated with pto-mediated resistance against pseudomonas syringae. however, only six of these clones blocked the pto-mediated suppression of p.syringae growth. the three clones giving the strongest loss of pto resistance had inserts corresponding to hsp90 and al ...	2003	14592968
synthesis of l-ascorbic acid in the phloem.	although plants are the main source of vitamin c in the human diet, we still have a limited understanding of how plants synthesise l-ascorbic acid (asa) and what regulates its concentration in different plant tissues. in particular, the enormous variability in the vitamin c content of storage organs from different plants remains unexplained. possible sources of asa in plant storage organs include in situ synthesis and long-distance transport of asa synthesised in other tissues via the phloem. in ...	2003	14633288