Publications

evidence of synergism between african cassava mosaic virus and a new double-recombinant geminivirus infecting cassava in cameroon.	stem cuttings were collected in cameroon from cassava plants displaying cassava mosaic disease (cmd) symptoms. the nature of the viruses present was determined by using the pcr with primers specific for the coat protein (cp) genes of african cassava mosaic virus (acmv) and east african cassava mosaic virus (eacmv). all samples were infected by acmv and eight of the 50 samples were infected by both acmv and an eacmv-like virus. the complete nucleotide sequences of dna-a and -b of representative a ...	2000	10640569
the role of abi1 in abscisic acid signal transduction: from gene to cell.	the semi-dominant abi1-1 mutation of arabidopsis interferes with multiple aspects of abscisic acid signal transduction resulting in reduced seed dormancy and sensitivity of root growth in aba. furthermore, the mutant transpires excessively as a result of abnormal stomatal regulation leading to a wilty phenotype. the abi1 gene has been cloned. the carboxyl-terminal domain of the predicted abi1 protein is related to the 2c class of serine-threonine phosphatases while no overt homology was found in ...	1998	10645425
potato mop-top virus rna can move long distance in the absence of coat protein: evidence from resistant, transgenic plants.	transgenic expression of a translatable version of the potato mop-top virus (pmtv) coat protein (cp) gene (encoded by rna 3) in nicotiana benthamiana prevented production of symptoms and infective virus particles. rnas 1 and 2 accumulated in inoculated and systemic leaves but, apart from small amounts of cp transgene rna transcript, no genomic-length rna 3 was found. crude leaf extracts from inoculated plants were not infective. however, when rna extracts from such transgenic plants were inocula ...	2000	10656594
replication of heterologous combinations of helper and defective rna of citrus tristeza virus.	citrus tristeza virus (ctv) populations are among the more complex of plant rna viruses with unusual mixtures of strains and defective rnas (drnas). citrus plants infected with different ctv isolates contain multiple drna molecules that differ in size and relative abundance within and between isolates. additionally, we found mixtures of heterologous drnas in populations. to examine the replication of ctv drnas, the protoplast system had to be extended to support helper-assisted amplification of ...	2000	10662631
mutations in the coat protein gene of plum pox virus suppress particle assembly, heterologous encapsidation and complementation in transgenic plants of nicotiana benthamiana.	two different motifs in the coat protein (cp) of plum pox virus (ppv) (r(3015)q(3016), d(3059)) were mutated by replacing the respective amino acids with others possessing different chemical properties. the mutated cp genes were introduced into an infectious full-length clone of ppv (p35ppv-nat) to investigate their influence on systemic infection of transgenic wild-type ppv cp-expressing and non-transgenic plants of nicotiana benthamiana. all mutants failed to establish systemic infections in n ...	2000	10675394
tagging potato leafroll virus with the jellyfish green fluorescent protein gene.	a full-length cdna corresponding to the rna genome of potato leafroll virus (plrv) was modified by inserting cdna that encoded the jellyfish green fluorescent protein (gfp) into the p5 gene near its 3' end. nicotiana benthamiana protoplasts electroporated with plasmid dna containing this cdna behind the 35s rna promoter of cauliflower mosaic virus became infected with the recombinant virus (plrv-gfp). up to 5% of transfected protoplasts showed gfp-specific fluorescence. progeny virus particles w ...	2000	10675399
virus recovery is induced in brome mosaic virus p2 transgenic plants showing synchronous complementation and rna-2-specific silencing.	nicotiana benthamiana plants expressing brome mosaic virus (bmv) p2 protein complemented replication of rnas1 + 3 but, surprisingly, supported little or no replication of rna-2. despite this, the p2 transgenic plants were able to support systemic migration of rnas-1 and -3. kinetic analyses showed identical degradation rates for rnas-2 and -3, greatly detracting from the concept of an induction of an rna-2-specific degradation system. deletion analysis identified a 200-nucleotide sequence that m ...	2000	10707350
evolutionarily related sindbis-like plant viruses maintain different levels of population diversity in a common host.	the levels of population diversity of three related sindbis-like plant viruses, tobacco mosaic virus (tmv), cucumber mosaic virus (cmv), and cowpea chlorotic mottle virus (ccmv), in infections of a common host, nicotiana benthamiana, established from genetically identical viral rna were examined. despite probably having a common evolutionary ancestor, the three viruses maintained different levels of population diversity. cmv had the highest levels of diversity, tmv had an intermediate level of d ...	2000	10708428
rapid, high-level expression of glycosylated rice alpha-amylase in transfected plants by an rna viral vector.	tobamoviral vectors have been developed for the heterologous expression of glycoproteins in plants. the rice alpha-amylase gene (os103) was placed under the transcriptional control of a tobamovirus subgenomic promoter in a rna viral vector. one to two weeks after inoculation, transfected nicotiana benthamiana plants accumulated glycosylated alpha-amylase to levels of at least 5% total soluble protein. the 46kda recombinant enzyme was purified, and its structural and biological properties were an ...	2000	10713457
subcellular sorting of small membrane-associated triple gene block proteins: tgbp3-assisted targeting of tgbp2.	we studied subcellular distribution of green fluorescent protein (gfp)-tagged movement proteins encoded by the second and the third genes of poa semilatent hordeivirus (pslv) triple gene block (tgb), 15k tgbp2 and 18k tgbp3. gfp-15k transiently expressed in nicotiana benthamiana leaf epidermal cells was associated with the endomembrane system elements. gfp-18k appeared in the membrane bodies at cell periphery. mutation analysis demonstrated that subcellular targeting of gfp-15k depended on the p ...	2000	10725204
aphid transmission studies using helper component proteins of potato virus y expressed from a vector derived from potato virus x.	the genes encoding the helper component (hc) proteins of two strains of potato virus y (pvy) were cloned and the proteins expressed from a vector derived from potato virus x (pvx). the expressed hc contained six n-terminal histidine residues to facilitate purification by metal affinity chromatography. approximately 2-4 microg/g of purified hc was obtained from leaves of nicotiana benthamiana plants systemically infected by recombinant pvx. preparations of the hc protein derived from pvy ordinary ...	2000	10725440
suppression of post-transcriptional gene silencing by a plant viral protein localized in the nucleus.	post-transcriptional gene silencing (ptgs) is a homology-dependent rna degradation process that may target rna exclusively in the cytoplasm. in plants, ptgs functions as a natural defense mechanism against viruses. we reported previously that the 2b protein encoded by cucumber mosaic cucumovirus (cmv) is a virulence determinant and a suppressor of ptgs initiation in transgenic nicotiana benthamiana. by fusion with the green fluorescent protein, we now show that the cmv 2b protein localizes to th ...	2000	10747034
clones of cotton leaf curl geminivirus induce symptoms atypical of cotton leaf curl disease.	the causative agent of cotton leaf curl disease has previously been shown to be transmissible by the whitefly bemisia tabaci (gennadius) and a begomovirus (geminiviridae) was shown to be associated with the disease. this virus was provisionally called cotton leaf curl virus (clcuv) although no causal relationship between virus and disease was shown. in the present study full-length clones of clcuv, equivalent to the dna a component of bipartite begomoviruses, were obtained. the clones of clcuv w ...	2000	10766303
complementation of the movement-deficient mutations in potato virus x: potyvirus coat protein mediates cell-to-cell trafficking of c-terminal truncation but not deletion mutant of potexvirus coat protein.	the cell-to-cell movement of the gus-tagged potato virus x (pvx) coat protein (cp) movement-deficient mutant was restored by potyviral cps of potato virus a (pva) and potato virus y (pvy) in nicotiana benthamiana leaves in transient cobombardment experiments. viral cell-to-cell movement of pvx cp mutant was complemented in nicotiana tabacum cv. sr1 transgenic plants expressing pvy cp: pvx rna and polymerase were detected in the pvx cp mutant-inoculated leaves of transgenic plants. these findings ...	2000	10772977
rotavirus vp6 expressed by pvx vectors in nicotiana benthamiana coats pvx rods and also assembles into viruslike particles.	the rotavirus major inner capsid protein (vp6) has been expressed in nicotiana benthamiana plants using vectors based on potato virus x (pvx). vp6 was expressed either as a fusion with the pvx coat protein or from an additional subgenomic promoter inserted to enable both vp6 and pvx coat protein to be expressed independently. both approaches yielded vp6, which retained the ability to form trimers. vp6 expressed from the subgenomic promoter assembled into paracrystalline sheets and tubes. express ...	2000	10793003
virus-induced silencing of a plant cellulose synthase gene.	specific cdna fragments corresponding to putative cellulose synthase genes (cesa) were inserted into potato virus x vectors for functional analysis in nicotiana benthamiana by using virus-induced gene silencing. plants infected with one group of cdnas had much shorter internode lengths, small leaves, and a "dwarf" phenotype. consistent with a loss of cell wall cellulose, abnormally large and in many cases spherical cells ballooned from the undersurfaces of leaves, particularly in regions adjacen ...	2000	10810144
rapid production of the major birch pollen allergen bet v 1 in nicotiana benthamiana plants and its immunological in vitro and in vivo characterization.	type i allergies are immunological disorders that afflict a quarter of the world's population. improved diagnosis of allergic diseases and the formulation of new therapeutic approaches are based on the use of recombinant allergens. we describe here for the first time the application of a rapid plant-based expression system for a plant-derived allergen and its immunological characterization. we expressed our model allergen bet v 1, the major birch pollen allergen, in the tobacco-related species n ...	2000	10877820
a single chimeric transgene derived from two distinct viruses confers multi-virus resistance in transgenic plants through homology-dependent gene silencing.	we showed previously that 218 and 110 bp n gene segments of tomato spotted wilt virus (tswv) that were fused to the non-target green fluorescent protein (gfp) gene were able to confer resistance to tswv via post-transcriptional gene silencing (ptgs). n gene segments expressed alone did not confer resistance. apparently, the gfp dna induced ptgs that targetted n gene segments and the incoming homologous tswv for degradation, resulting in a resistant phenotype. these observations suggested that mu ...	2000	10900050
transgenic or plant expression vector-mediated recombination of plum pox virus.	different mutants of an infectious full-length clone (p35ppv-nat) of plum pox virus (ppv) were constructed: three mutants with mutations of the assembly motifs rq and df in the coat protein gene (cp) and two cp chimeras with exchanges in the cp core region of zucchini yellow mosaic virus and potato virus y. the assembly mutants were restricted to single infected cells, whereas the ppv chimeras were able to produce systemic infections in nicotiana benthamiana plants. after passages in different t ...	2000	10906199
tobacco mosaic virus replicase-mediated cross-protection: contributions of rna and protein-derived mechanisms.	specific sequences of the tobacco mosaic virus (tmv) rna-dependent rna-polymerase (rdrp) gene were investigated for their ability to confer cross-protection. nine overlapping segments ranging from 713 to 1070 nucleotides in length and covering the methyltransferase, helicase, and polymerase (pol) domains of the tmv rdrp open reading frame were systemically expressed in nicotiana benthamiana using a potato x virus (pvx) vector [chapman, s., kavanagh, t., and baulcombe, d. c. (1992). plant j., 1, ...	2000	10915597
vascular invasion routes and systemic accumulation patterns of tobacco mosaic virus in nicotiana benthamiana.	plant viruses must enter the host vascular system in order to invade the young growing parts of the plant rapidly. functional entry sites into the leaf vascular system for rapid systemic infection have not been determined for any plant/virus system. tobacco mosaic virus (tmv) entry into minor, major and transport veins from non-vascular cells of nicotiana benthamiana in source tissue and its exit from veins in sink tissue was studied using a modified virus expressing green fluorescent protein (g ...	2000	10929128
delayed activation of post-transcriptional gene silencing and de novo transgene methylation in plants with the coat protein gene of sweet potato feathery mottle potyvirus.	the relationship between post-transcriptional gene silencing (ptgs) and dna methylation was examined using nicotiana benthamiana transformed with the coat protein gene including the 3' non-translated region of sweet potato feathery mottle potyvirus. line 4.28 showed a delayed activation of the transgene silencing in comparison with the other silenced lines, and showed complete resistance against the recombinant potato virus x engineered to contain the sequence homologous to the transgene when th ...	2000	10936519
analysis of transgenic grapevine (vitis rupestris) and nicotiana benthamiana plants expressing an arabis mosaic virus coat protein gene.	a disarmed lba4404 strain of agrobacterium tumefaciens harboring a binary vector which contained chimeric genes encoding the neomycin phosphotransferase (npt ii) and the coat protein (cp) of arabis mosaic nepovirus (armv) was used in co-cultivation experiments with leaf discs of nicotiana benthamiana and somatic embryos of the grapevine rootstock cultivar vitis rupestris. transgenic n. benthamiana expressing the armv cp gene were regenerated and six independent lines were characterized. enzyme-l ...	2000	10936531
evidence for a role of the n terminus and leucine-rich repeat region of the mi gene product in regulation of localized cell death.	the tomato mi gene confers resistance against root-knot nematodes and potato aphids. chimeric constructs of the functional gene, mi-1. 2, with a homolog, mi-1.1, were produced, and their phenotypes were examined in agrobacterium rhizogenes-transformed roots. exchange of the leucine-rich repeat (lrr) region of mi-1.1 into mi-1.2 resulted in the loss of ability to confer nematode resistance, as did substitution of a 6-amino acid sequence from the mi-1.1 lrr into mi-1.2. introduction of the mi-1.2 ...	2000	10948252
native electrophoresis and western blot analysis (neweb): a method for characterization of different forms of potyvirus particles and similar nucleoprotein complexes in extracts of infected plant tissues.	a combination of native electrophoresis and immunodetection (western blot) was used for the characterization of nucleoprotein particles of the potyvirus plum pox virus (ppv). virus particles were electrophoresed directly from plant extracts in agarose or mixed acrylamide-agarose gels under native conditions, blotted on nitrocellulose membranes, and characterized with the aid of a coat protein-specific antibody. using this combined methodology, called neweb (native electrophoresis and western blo ...	2000	10950988
the valine anticodon and valylatability of peanut clump virus rnas are not essential but provide a modest competitive advantage in plants.	the role of valine aminoacylation of the two genomic rnas of peanut clump virus (pcv) was studied by comparing the amplification in vivo of rnas with gac, gdeltac, or cca anticodons in the trna-like structure (tls) present at the 3' end of each viral rna. the pcv rna1 tls of isolate pcv2 possesses a gac anticodon and is capable of highly efficient valylation, whereas the rna2 tls has a gdeltac anticodon that does not support valylation. the presence in rna1 of gdeltac or cca anticodons that conf ...	2000	10954573
the p20 gene product of citrus tristeza virus accumulates in the amorphous inclusion bodies.	citrus tristeza virus (ctv) has 10 3' open reading frames (orfs) of unknown function except for the two coat proteins. the highest produced subgenomic rnas are those of the major coat protein gene (p25) and the 3' most genes, p20 and p23. the proteins from three orfs, p25, p27, and p20, were examined in the yeast two-hybrid assay for the interactions between themselves and to one another. the p20 protein exhibited a high affinity for itself, suggesting that it might aggregate in infected cells. ...	2000	10964768
regulation of plasmodesmal transport by phosphorylation of tobacco mosaic virus cell-to-cell movement protein.	cell-to-cell spread of tobacco mosaic virus (tmv) through plant intercellular connections, the plasmodesmata, is mediated by a specialized viral movement protein (mp). in vivo studies using transgenic tobacco plants showed that mp is phosphorylated at its c-terminus at amino acid residues ser258, thr261 and ser265. when mp phosphorylation was mimicked by negatively charged amino acid substitutions, mp lost its ability to gate plasmodesmata. this effect on mp-plasmodesmata interactions was specif ...	2000	10990451
soluble, template-dependent extracts from nicotiana benthamiana plants infected with potato virus x transcribe both plus- and minus-strand rna templates.	we have developed a method to convert membrane-bound replication complexes isolated from nicotiana benthamiana plants infected with potato virus x (pvx) to a soluble, template-dependent system for analysis of rna synthesis. analysis of rna-dependent rna polymerase activity in the membrane-bound, endogenous template extracts indicated three major products, which corresponded to double-stranded versions of pvx genomic rna and the two predominant subgenomic rnas. the endogenous templates were remov ...	2000	10998342
mechanical transmission of potato leafroll virus.	like typical luteoviruses, potato leafroll virus (plrv) cannot be transmitted mechanically by rubbing plants with solutions containing virus particles. however, plrv was found to be mechanically transmissible from extracts of plants that had been inoculated by viruliferous aphids and then post-inoculated with pea enation mosaic virus-2 (pemv-2). unlike the asymptomatic infections induced by either virus alone, double infections in nicotiana benthamiana induced necrotic symptoms with some line pa ...	2000	11038393
partial purification and characterization of cucumber necrosis virus and tomato bushy stunt virus rna-dependent rna polymerases: similarities and differences in template usage between tombusvirus and carmovirus rna-dependent rna polymerases.	tombusviruses are small, plus-sense, single-stranded rna viruses of plants. rna-dependent rna polymerases (rdrp) of two tombusviruses, tomato bushy stunt virus (tbsv) and cucumber necrosis virus (cnv), have been partially purified from infected nicotiana benthamiana plants. the obtained rdrp complexes are capable of de novo initiation of complementary rna synthesis using either plus- or minus-strand templates derived from tombusvirus defective interfering (di) rnas. in addition to template-sized ...	2000	11040120
recombination between a 3-kilobase tobacco mosaic virus transgene and a homologous viral construct in the restoration of viral and nonviral genes.	transgenic plants harboring various plant virus sequences have shown resistance to viral infections. an environmental risk associated with the use of these plants is the possibility of forming a novel virus by recombination between challenging viruses and transgenic viral mrna. two experiments were designed using tobacco mosaic virus (tmv) vectors and transgenic nicotiana benthamiana to determine if recombinant viral rna would be detectable. n. benthamiana was transformed with a nontranslatable ...	2000	11043947
generation of subgenomic rna directed by a satellite rna associated with bamboo mosaic potexvirus: analyses of potexvirus subgenomic rna promoter.	satellite rna of bamboo mosaic potexvirus (satbamv), a single-stranded positive-sense rna encoding a nonstructural protein of 20 kda (p20), depends on bamboo mosaic potexvirus (bamv) for replication and encapsidation. a full-length cdna clone of satbamv was used to examine the sequences required for the synthesis of potexvirus subgenomic rnas (sgrnas). subgenomic promoter-like sequences (sgps), 107 nucleotides (nt) upstream from the capsid protein (cp) gene of bamv-v, were inserted upstream of t ...	2000	11044078
a viral movement protein prevents spread of the gene silencing signal in nicotiana benthamiana.	in plants, viruses induce an rna-mediated defense that is similar to posttranscriptional gene silencing (ptgs) of transgenes. here we demonstrate with potato virus x (pvx) that ptgs operates as a systemic, sequence-specific defense system. however, in grafting experiments or with movement defective forms of pvx, we could not detect systemic silencing unless the 25 kda viral movement protein (p25) was made nonfunctional. investigation of p25 revealed two branches to the ptgs pathway that converge ...	2000	11051555
bromovirus movement protein conditions for the host specificity of virus movement through the vascular system and affects pathogenicity in cowpea.	previously, we reported that ccmv(b3a), a hybrid of bromovirus cowpea chlorotic mottle virus (ccmv) with the 3a cell-to-cell movement protein (mp) gene replaced by that of cowpea-nonadapted bromovirus brome mosaic virus (bmv), can form small infection foci in inoculated cowpea leaves, but that expansion of the foci stops between 1 and 2 days postinoculation. to determine whether the lack of systemic movement of ccmv(b3a) is due to restriction of local spread at specific leaf tissue interfaces, w ...	2000	11059486
the orf1 products of tombusviruses play a crucial role in lethal necrosis of virus-infected plants.	hybrids of cymbidium ringspot (cymrsv) and carnation italian ringspot (cirv) tombusviruses were used to identify viral symptom determinants responsible for the generalized necrosis in tombusvirus-infected plants. surprisingly, symptoms of nicotiana benthamiana infected with cymrsv/cirv hybrids were distinctly different. it was demonstrated that not all chimeras expressing wild-type (wt) levels of p19 protein caused systemic necrosis as both parents cymrsv and cirv did. we showed here that hybrid ...	2000	11069981
bipartite geminivirus host adaptation determined cooperatively by coding and noncoding sequences of the genome.	bipartite geminiviruses are small, plant-infecting viruses with genomes composed of circular, single-stranded dna molecules, designated a and b. although they are closely related genetically, individual bipartite geminiviruses frequently exhibit host-specific adaptation. two such viruses are bean golden mosaic virus (bgmv) and tomato golden mosaic virus (tgmv), which are well adapted to common bean (phaseolus vulgaris) and nicotiana benthamiana, respectively. in previous studies, partial host ad ...	2000	11080490
activities associated with the putative replication initiation protein of coconut foliar decay virus, a tentative member of the genus nanovirus.	the putative replication initiation protein (rep) of coconut foliar decay virus (cfdv) was expressed as a 6x his recombinant protein in e. coli and in recombinant baculovirus. purified 6x his-rep protein was demonstrated to possess sequence non-specific rna- and ssdna-binding activities as well as magnesium-dependent atpase/gtpase activity. the yeast two-hybrid system revealed that cfdv rep could interact with itself. subcellular distribution of the cfdv rep was studied by fractionation of insec ...	2000	11086141
tissue specificity of geminivirus infection is genetically determined.	the types of cells and tissues infected by a virus define its tissue tropism. determinants of tissue tropism in animal-infecting viruses have been extensively investigated, but little is known about plant viruses in this regard. some geminiviruses in the genus begomovirus exhibit phloem limitation and are restricted to cells of the vascular system, whereas others can invade mesophyll tissue. to identify viral genetic determinants of tissue tropism, we established a model system using two begomov ...	2000	11090223
closterovirus encoded hsp70 homolog and p61 in addition to both coat proteins function in efficient virion assembly.	assembly of the viral genome into virions is a critical process of the virus life cycle often defining the ability of the virus to move within the plant and to be transmitted horizontally to other plants. closteroviridae virions are polar helical rods assembled primarily by a major coat protein, but with a related minor coat protein at one end. the closteroviridae is the only virus family that encodes a protein with similarity to cellular chaperones, a 70-kda heat-shock protein homolog (hsp70h). ...	2000	11112500
role of satellite rna of an indian isolate of cucumber mosaic virus in inducing lethal necrosis of tobacco plants.	lethal necrosis or systemic stem necrosis followed by death of nicotiana benthamiana, severe leaf deformations of n. tabacum cv. white burley and blister formations on n. tabacum cv. samsun nn symptoms were induced by experimental inoculations of cmv rna preparations containing satellite rna (sat-rna). inoculations of rna preparations without sat-rna did not induce that severe symptoms on these plants, only late mild mosaic was observed. it is suggested that sat-rna of cmv isolate has a certain ...	2000	11116536
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
complete nucleotide sequence and host range of south african cassava mosaic virus: further evidence for recombination amongst begomoviruses.	complete nucleotide sequences of the dna-a (2800 nt) and dna-b (2760 nt) components of a novel cassava-infecting begomovirus, south african cassava mosaic virus (sacmv), were determined and compared with various new world and old world begomoviruses. sacmv is most closely related to east african cassava mosaic virus (eacmv) in both its dna-a (85% with eacmv-mh and -mk) and -b (90% with eacmv-ug2-mld and eacmv-ug3-svr) components; however, percentage sequence similarities of less than 90% in the ...	2001	11125158
the use of transgenic fruit trees as a resistance strategy for virus epidemics: the plum pox (sharka) model.	sharka or plum pox, caused by plum pox virus (ppv: genus potyvirus; family potyviridae), is the most serious disease of prunus. most cultivated prunus species are highly susceptible and conventional breeding has not produced highly resistant and commercially acceptable varieties. success in developing virus-resistant herbaceous crops through genetic engineering led us to investigate this approach for resistance to ppv. our programme aims to develop a biotechnological approach to ppv control that ...	2000	11137162
cellular basis of potato spindle tuber viroid systemic movement.	viroids are small, nontranslatable pathogenic rnas that replicate autonomously and traffic systemically in their host plants. we have used in situ hybridization to analyze the trafficking pattern of potato spindle tuber viroid (pstvd) in tomato and nicotiana benthamiana. when pstvd was inoculated onto the stem of a plant, it replicated and trafficked to sink, but not source, leaves. pstvd was absent from shoot apical meristems. in the flowers of infected plants, pstvd was present in the sepals, ...	2001	11145890
a novel strategy for the expression of foreign genes from plant virus vectors.	potato virus x (pvx)-based vector constructs were generated to investigate the use of an internal ribosome entry site (ires) sequence to direct translation of a viral gene. the 148-nucleotide irescp sequence from a crucifer-infecting strain of tobacco mosaic virus was used to direct expression of the pvx coat protein (cp). the ires was inserted downstream of the gene encoding green fluorescent protein (gfp) and upstream of the pvx cp, in either sense or antisense orientation, such that cp expres ...	2001	11165252
ancient origin of pathogen recognition specificity conferred by the tomato disease resistance gene pto.	we have investigated the origin of the pto disease resistance (r) gene that was previously identified in the wild tomato species lycopersicon pimpinellifolium and isolated by map-based cloning. pto encodes a serine-threonine protein kinase that specifically recognizes strains of pseudomonas syringae pv. tomato (pst) that express the avirulence gene avrpto. we examined an accession of the distantly related wild species lycopersicon hirsutum var. glabratum that exhibits avrpto-specific resistance ...	2001	11172075
functional equivalence of late gene promoters in bean golden mosaic virus with those in tomato golden mosaic virus.	in the bipartite geminivirus tomato golden mosaic virus (tgmv), the activity of late gene promoters is up-regulated by the multifunctional viral protein al2. cis-acting sequences required for al2-mediated promoter responses have not been well characterized. however, nucleotide sequence analysis has implicated a motif termed the conserved late element (cle). the cle is present in tgmv and many other begomoviruses, although it is not ubiquitous. here we analysed the regulation of late gene express ...	2001	11172109
the size of encapsidated single-stranded dna determines the multiplicity of african cassava mosaic virus particles.	transgenic nicotiana benthamiana plants harbouring a defective interfering (di) dna of african cassava mosaic virus (acmv) and control plants were inoculated with acmv. virus particles were purified from infected plants, separated in sucrose gradients and fractions were analysed by southern blotting. transgenic plant-derived virus particles taken from the top fractions of sucrose gradients contained di dna, middle fractions contained a mixture of genomic and di dna and bottom fractions contained ...	2001	11172110
production of antimicrobial defensin in nicotiana benthamiana with a potato virus x vector.	a recombinant plasmid, ptxs.th, was constructed to express the gene-encoding wasabi (wasabia japonica) defensin with the potato virus x (pvx) vector. ptxs.th allows the expression of defensin in the host nicotiana benthamiana, and the defensin protein wt1 can be purified from virus-infected leaves by heat treatment and affinity chromatography. wt1 exhibits strong antifungal activity toward the phytopathogenic fungi magnaporthe grisea (50% inhibitory concentration [ic50] = 5 microg/ml) and botryt ...	2001	11204773
replicase-derived resistance against pea early browning virus in nicotiana benthamiana is an unstable resistance based upon posttranscriptional gene silencing.	virus resistance in nicotiana benthamiana plants containing a translatable pea early browning virus (pebv) 54k sequence from the 201k replicase gene has been reported previously. resistant plants contain multiple transgene copies divided between two loci. analysis of a genetic series containing the two loci in separate homozygous or heterozygous condition suggest that only one of the loci is necessary to induce the resistance. the resistance observed in r2 and r3 generations of lines containing ...	2001	11204783
development and evaluation of a complementation-dependent gene delivery system based on cucumber mosaic virus.	to engineer cucumber mosaic virus (cmv-ix) into a gene vector, genome component rna 3 of the virus was modified and split into two sub-components, rna 3a and rna 3b. in rna 3a, the open reading frame of the movement protein (mp) was replaced by a reporter gene encoding the green fluorescent protein (gfp), to monitor virus replication and movement. in rna 3b, the coat protein (cp) gene was eliminated and a multiple cloning site (mcs) was created for foreign gene insertion. each sub-component alon ...	2000	11205118
size constraints for targeting post-transcriptional gene silencing and for rna-directed methylation in nicotiana benthamiana using a potato virus x vector.	using a recombinant potato virus x (pvx) vector, we investigated the relationship between the length of rna sequence identity with a transgene and the ability to promote post-transcriptional gene silencing (ptgs) and transgene methylation. the lower size limit required for targeting reporter transgene mrna de novo using ptgs was 23 nucleotides (nt) of complete identity, a size corresponding to that of small rnas associated with ptgs in plants and rna interference (rnai) in animals. the size and ...	2001	11260498
systemic spread of an rna insect virus in plants expressing plant viral movement protein genes.	flock house virus (fhv), a single-stranded rna insect virus, has previously been reported to cross the kingdom barrier and replicate in barley protoplasts and in inoculated leaves of several plant species [selling, b. h., allison, r. f. & kaesberg, p. (1990) proc. natl. acad. sci. usa 87, 434-438]. there was no systemic movement of fhv in plants. we tested the ability of movement proteins (mps) of plant viruses to provide movement functions and cause systemic spread of fhv in plants. we compared ...	2001	11296259
rapid production of recombinant allergens in nicotiana benthamiana and their impact on diagnosis and therapy.	type i allergies are immunological disorders that afflict a quarter of the world's population. recombinant allergens have improved the diagnosis of allergic diseases and allow the formulation of new therapeutic approaches. over 50% of all allergens are of plant origin.	2001	11306923
the c terminus of brome mosaic virus coat protein controls viral cell-to-cell and long-distance movement.	to investigate the functional domains of the coat protein (cp; 189 amino acids) of brome mosaic virus, a plant rna virus, 19 alanine-scanning mutants were constructed and tested for their infectivity in barley and nicotiana benthamiana. despite its apparent normal replicative competence and cp production, the c-terminal mutant f184a produced no virions. furthermore, virion-forming c-terminal mutants p178a and d182a failed to move from cell to cell in both plant species, and mutants d181a and v18 ...	2001	11333922
potyviral helper-component proteinase expressed in transgenic plants enhances titers of potato leaf roll virus but does not alleviate its phloem limitation.	coinfection of nicotiana benthamiana with potato virus a (pva, a potyvirus) and potato leaf-roll virus (plrv, a luteovirus) induces a synergistic interaction manifested by enhanced titers of plrv. the helper component proteinase (hc-pro) of potyviruses is involved in viral vascular movement and suppression of an antiviral defense mechanism in plants. data of our study showed that accumulation of plrv in transgenic n. benthamiana expressing the pva hc-pro was enhanced on average by 4.5-fold, as c ...	2001	11336553
5'-coterminal subgenomic rnas in citrus tristeza virus-infected cells.	three unusual 5' coterminal positive-stranded subgenomic (sg) rnas, two of about 0.8 kb and one of 10 kb (designated lmt1, lmt2, and lamt, respectively), from citrus spp. plants and nicotiana benthamiana protoplasts infected with citrus tristeza virus (ctv) were characterized. the 5' termini of the lmt rnas were mapped by runoff reverse transcription and found to correspond with the 5' terminus of the genomic rna. the lmt 5'-coterminal sgrnas consisted of two modal lengths of 744--746 and 842--8 ...	2001	11336562
expression of the oligomerization domain of the replication-associated protein (rep) of tomato leaf curl new delhi virus interferes with dna accumulation of heterologous geminiviruses.	the minimal dna binding domain of the replication-associated protein (rep) of tomato leaf curl new delhi virus was determined by electrophoretic mobility gel shift analysis and co-purification assays. dna binding activity maps to amino acids 1-160 (rep-(1-160)) of the rep protein and overlaps with the protein oligomerization domain. transient expression of rep protein (rep-(1-160)) was found to inhibit homologous viral dna accumulation by 70-86% in tobacco protoplasts and in nicotiana benthamian ...	2001	11342533
use of a vector based on potato virus x in a whole plant assay to demonstrate nuclear targeting of potato spindle tuber viroid.	potato spindle tuber viroid (pstvd) is a covalently closed circular rna molecule of 359 nucleotides that replicates within the nucleus of host cells. to determine how this small, highly structured rna enters the nucleus, we have developed a virus-based, whole plant in vivo assay that uses green fluorescent protein (gfp) as the reporter molecule. the coding region of gfp was interrupted by insertion of an intron derived from the intervening sequence 2 of the potato st-ls1 gene. a cdna copy of the ...	2001	11369895
the suppressor of transgene rna silencing encoded by cucumber mosaic virus interferes with salicylic acid-mediated virus resistance.	the cucumber mosaic virus (cmv)-encoded 2b protein (cmv2b) is a nuclear protein that suppresses transgene rna silencing in nicotiana benthamiana. cmv2b is an important virulence determinant but nonessential for systemic spread in n. glutinosa, in contrast to its indispensable role for systemic infections in cucumber. here, we report that cmv2b became essential for systemic infections in older n. glutinosa plants or in young seedlings pretreated with salicylic acid (sa). expression of cmv2b from ...	2001	11386367
the expression of a single-chain fv antibody fragment in different plant hosts and tissues by using potato virus x as a vector.	some aspects of the expression of a single-chain fv antibody fragment (scfv) driven by the plant viral vector potato virus x (pvx) have been studied by quantitative elisa. after inoculation of the infectious transcript, the vector was stable only for a few passages of sap transmission in the inoculated leaves of nicotiana benthamiana and the reversal to wild type was more pronounced in the systemically invaded leaves. the amount of synthesized scfv varied when different solanaceous hosts were te ...	2001	11388801
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
role of the 3'-untranslated regions of alfalfa mosaic virus rnas in the formation of a transiently expressed replicase in plants and in the assembly of virions.	alfalfa mosaic virus (amv) rnas 1 and 2 encode the replicase proteins p1 and p2, respectively, whereas rna 3 encodes the movement protein and the coat protein (cp). when rnas 1 and 2 were transiently expressed from a t-dna vector (r12 construct) by agroinfiltration of nicotiana benthamiana, the infiltrated leaves accumulated minus-strand rnas 1 and 2 and relatively small amounts of plus-strand rnas. in addition, rna-dependent rna polymerase (rdrp) activity could be detected in extracts of the in ...	2001	11413311
plants expressing tomato golden mosaic virus al2 or beet curly top virus l2 transgenes show enhanced susceptibility to infection by dna and rna viruses.	the al2 gene of the geminivirus tomato golden mosaic virus (tgmv) encodes a transcriptional activator protein (trap) that is required for efficient expression of the viral coat protein (cp) and br1 gene promoters. in contrast, l2, the positional homolog of al2 in the related beet curly top virus (bctv), is not required for cp expression, raising questions about the functional relationship between the al2 and l2 gene products. in this study, transgenic nicotiana benthamiana and n. tabacum var. sa ...	2001	11414806
inducible high-level mrna amplification system by viral replicase in transgenic plants.	we have constructed a new system for inducible high-level expression of mrna for foreign genes in transgenic plants by introducing a glucocorticoid-inducible transcription system into the previously developed "mrna amplification system" where target mrna can be amplified as a subgenomic rna by the replicase of a plant tripartite rna virus, brome mosaic virus (bmv). in the new amplification system, the amplification of mrna is tightly regulated by the expression of a subunit of the bmv replicase. ...	2001	11489185
secretion of biologically active glycoforms of bovine follicle stimulating hormone in plants.	we chose the follicle stimulating hormone (fsh), a pituitary heterodimeric glycoprotein hormone, as a model to assess the ability of the plant cell to express a recombinant protein that requires extensive n-glycosylation for subunit folding and assembly, intracellular trafficking, signal transduction and circulatory stability. a tobacco mosaic virus (tmv) based transient expression system was used to express a single-chain (sc) version of bovine fsh in the tobacco related species nicotiana benth ...	2001	11502219
interactions of the tgb1 protein during cell-to-cell movement of barley stripe mosaic virus.	we have recently used a green fluorescent protein (gfp) fusion to the gammab protein of barley stripe mosaic virus (bsmv) to monitor cell-to-cell and systemic virus movement. the gammab protein is involved in expression of the triple gene block (tgb) proteins encoded by rnabeta but is not essential for cell-to-cell movement. the gfp fusion appears not to compromise replication or movement substantially, and mutagenesis experiments demonstrated that the three most abundant tgb-encoded proteins, b ...	2001	11507216
coat protein gene-mediated resistance to potato virus a in transgenic plants is suppressed following infection with another potyvirus.	high levels of resistance to potato virus a (pva, genus potyvirus), indicated by absence of detectable infection in inoculated leaves, were attained in nicotiana benthamiana transformed with a construct expressing the pva 5'-untranslated region fused with the coat protein (cp)-encoding sequence. low steady-state levels of the transgene transcripts were detected. resistance was pva-specific and did not protect the plants against infection with potato virus y (pvy, genus potyvirus). consequently, ...	2001	11514739
induction of a hypersensitive response by chimeric helicase sequences of tobamoviruses u1 and ob in n-carrying tobacco.	recently, the helicase domain of the tobacco mosaic virus (tmv)-u1 replicase proteins (designated morehel:u1) was identified as the elicitor of the n gene-mediated hypersensitive response (hr) in tobacco. in this study, we used agroinfiltration to express the equivalent morehel domain of the non-hr-inducing tobamovirus strain tmv-ob. it appeared that this morehel:ob sequence did not elicit a hr in n gene-carrying tobacco. both morehel sequences were divided into eight subdomains, and chimeras of ...	2001	11551073
gene c2 of the monopartite geminivirus tomato yellow leaf curl virus-china encodes a pathogenicity determinant that is localized in the nucleus.	expression of the tomato yellow leaf curl virus-china (tylcv-c) c2 protein and green fluorescent protein (gfp) fused to the c2 protein (c2-gfp) in nicotiana benthamiana from a potato virus x (pvx) vector induced necrotic ringspots on inoculated leaves as well as necrotic vein banding and severe necrosis on systemically infected leaves. the localization of gfp fluorescence in plant cells infected with pvx/c2-gfp and in insect cells transfected with baculovirus expressing c2-gfp indicates that the ...	2001	11551077
rna-binding properties of the 63 kda protein encoded by the triple gene block of poa semilatent hordeivirus.	the 63 kda '63k' movement protein encoded by the triple gene block of poa semilatent virus (pslv) comprises the c-terminal ntpase/helicase domain and the n-terminal extension domain, which contains two positively charged sequence motifs, a and b. in this study, the in vitro rna-binding properties of pslv 63k and its mutants were analysed. membrane-immobilized 63k and n-63k (isolated n-terminal extension domain) bound rna at high nacl concentrations. in contrast, c-63k (isolated ntpase/helicase d ...	2001	11562549
promoters for pregenomic rna of banana streak badnavirus are active for transgene expression in monocot and dicot plants.	two putative promoters from australian banana streak badnavirus (bsv) isolates were analysed for activity in different plant species. in transient expression systems the my (2105 bp) and cv (1322 bp) fragments were both shown to have promoter activity in a wide range of plant species including monocots (maize, barley, banana, millet, wheat, sorghum), dicots (tobacco, canola, sunflower, nicotiana benthamiana, tipu tree), gymnosperm (pinus radiata) and fern (nephrolepis cordifolia). evaluation of ...	2001	11587511
the partial purified rna-dependent rna polymerases from bamboo mosaic potexvirus and potato virus x infected plants containing the template-dependent activities.	rna-dependent rna polymerases (rdrp) isolated from bamboo mosaic potexvirus (bamv) and potato virus x infected nicotiana benthamiana plants and solubilized with the detergent np-40, generated a full-length genomic and two subgenomic double-stranded rnas of respective viruses in an in vitro rdrp assay containing endogenous rna templates. template-dependent and species-specific rdrp activity could be detected after the removal of endogenous rna templates. the 3' untranslated regions (utr) containi ...	2001	11597747
calcium-dependent protein kinases play an essential role in a plant defence response.	calcium-dependent protein kinases (cdpks) comprise a large family of serine/threonine kinases in plants and protozoans. we isolated two related cdpk cdnas (ntcdpk2 and ntcdpk3) from nicotiana tabacum. these cdpk transcripts are elevated after race-specific defence elicitation and hypo-osmotic stress. transiently expressed myc-epitope-tagged ntcdpk2 in nicotiana benthamiana and n.tabacum leaves showed a rapid transient interconversion to an activated form after elicitation and hypo-osmotic stress ...	2001	11597999
umbravirus-encoded proteins both stabilize heterologous viral rna and mediate its systemic movement in some plant species.	the proteins encoded by open reading frame 3 (orf3) of the umbraviruses pea enation mosaic virus-2 and tobacco mottle virus, like that of groundnut rosette virus, mediated the movement of viral rna through the phloem of infected nicotiana benthamiana or n. clevelandii plants when they were expressed from chimeric tobacco mosaic virus in place of the coat protein. however, these chimeras did not move systemically in n. tabacum. in lysates of n. benthamiana or n. tabacum protoplasts, the chimeric ...	2001	11601910
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
cell-to-cell movement of potato virus x: the role of p12 and p8 encoded by the second and third open reading frames of the triple gene block.	potato virus x (pvx) requires three proteins, p25, p12, and p8, encoded by the triple gene block plus the coat protein (cp) for cell-to-cell movement. when each of these proteins was co-expressed with a cytosolic green fluorescent protein (gfp) in the epidermal cells of nicotiana benthamiana by the microprojectile bombardment-mediated gene delivery method, only p12 enhanced diffusion of co-expressed gfp, indicating an ability to alter plasmodesmal permeability. p25, p12, and cp, expressed transi ...	2001	11605955
expression of functional replication protein from tomato golden mosaic virus in transgenic tobacco plants.	the a component of the bipartite genome of the geminivirus tomato golden mosaic virus (tgmv) encodes the viral protein (al1) that is required for viral dna replication. we have constructed transgenic nicotiana benthamiana plants in which the al1 open reading frame is transcribed under the control of the cauliflower mosaic virus 35s promoter. the transgenic plants, which were phenotypically normal, produced a single transcript from the 35s-al1 construct and a 40-kda protein that cross-reacted wit ...	1990	11607065
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
evidence for rna-mediated defence effects on the accumulation of potato leafroll virus.	in plants infected with potato leafroll virus (plrv), or other luteoviruses, infection is very largely confined to cells in the vascular system. even in tobacco plants transformed with plrv full-length cdna, in which all mesophyll cells should synthesize infectious plrv rna transcripts, only a minority of the mesophyll cells accumulate detectable amounts of virus. we have explored this phenomenon further by transforming a better plrv host, nicotiana benthamiana, with the same transgene, by super ...	2001	11714988
effects of inactivation of the coat protein and movement genes of tomato bushy stunt virus on early accumulation of genomic and subgenomic rnas.	accumulation of rna of tomato bushy stunt virus (tbsv) was examined within the first few hours after infection of nicotiana benthamiana protoplasts to determine the influence of the coat protein (cp), the movement-associated proteins p22 and p19 and rna sequences at very early stages of replication. the results showed that p19 had no effect on early rna replication, whereas the absence of cp and/or p22 expression delayed rna accumulation only marginally. removal of cp-coding sequences had no add ...	2001	11714989
completion of nucleotide sequence and generation of highly infectious transcripts to cucurbits from full-length cdna clone of kyuri green mottle mosaic virus.	the nucleotide sequence of the genome of the type strain of kyuri green mottle mosaic virus (kgmmv-c1) has been completely determined. the genome structure and sequence of the virus were compared to those of yodo strain of kgmmv (kgmmv-y). the genome of kgmmv-c1 is 6,514 nucleotides long consisting of 5' and 3' nontranslated regions (ntrs) and four open reading frames coding for 131 kda and 189 kda viral replicases, 28 kda movement protein and 17 kda coat protein. the nucleotide and amino acid s ...	2001	11765913
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
genetic analysis of bipartite geminivirus tissue tropism.	the bipartite geminiviruses bean golden mosaic virus (bgmv), cabbage leaf curl virus (cablcv), and tomato golden mosaic virus (tgmv) exhibit differential tissue tropism in nicotiana benthamiana. in systemically infected leaves, bgmv remains largely confined to vascular-associated cells (phloem-limited), whereas cablcv and tgmv can escape into the surrounding mesophyll. previous work established that tgmv bri, the noncoding region upstream from the br1 open reading frame (orf), is required for me ...	2001	11878900
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
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
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
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
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
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
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
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