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use of digoxigenin-labelled probes for detection and host-range studies of tomato yellow leaf curl geminivirus.we studied the host range of tomato yellow leaf curl virus (tylcv) in some agronomically important tomato species. transmission tests with the natural vector bemisia tabaci from tomato to sweet pepper, eggplant, cucumber, melon, zucchini and spinach showed that these species did not develop symptoms and did not support viral replication. these species therefore do not constitutive a reservoir of the virus and can be cultivated as alternatives to tomato in the most affected areas. for host-range ...19911796214
tomato yellow leaf curl virus from sardinia is a whitefly-transmitted monopartite geminivirus.the genome of an isolate of tomato yellow leaf curl virus from sardinia, italy (tylcv-s), a geminivirus transmitted by the whitefly bemisia tabaci, has been cloned and sequenced. the single circular dna molecule comprises 2770 nucleotides. genome organisation closely resembles that of the dna a component of the whitefly-transmitted geminiviruses with a bipartite genome. a 1.8 mer of the tylcv-s genome in a binary vector of agrobacterium tumefaciens is infectious upon agroinoculation of tomato pl ...19911840676
systemic movement and symptom production following agroinoculation with a single dna of tomato yellow leaf curl geminivirus (thailand).two different dna species were cloned from purified tomato yellow leaf curl geminivirus particles after annealing a specific primer to virus dna and generating a second strand; both were approximately 2.8 kbp in length. one clone contains sequences which hybridize to the coat protein gene of tomato golden mosaic virus and most likely represents the a dna of tomato yellow leaf curl virus (thailand). the other clone may represent the b dna of this geminivirus. both clones contain short sequences w ...19902219706
periodic occurrence of an anti-tmv factor in the body of whiteflies carrying tomato yellow leaf curl virus. 19705440444
the occurrence in the body of bemisia tabaci of a factor apparently related to the phenomenon of "periodic acquisition" of tomato yellow leaf curl virus. 19676017403
nucleotide sequences from tomato leaf curl viruses from different countries: evidence for three geographically separate branches in evolution of the coat protein of whitefly-transmitted geminiviruses.the coat protein (cp) gene-containing circular dna molecule of an isolate of tomato leaf curl geminivirus (itmlcv; 2749 nt) obtained from southern india, and the cp genes of tomato yellow leaf curl geminivirus isolates from nigeria and two regions of saudia arabia were sequenced. itmlcv dna had the same arrangement of orfs, and the same pattern of repeats in the large intergenic region as is found in in dna-a of other whitefly-transmitted geminivirus (wtgs) from the old world. however, the seque ...19957636485
in vitro cleavage and joining at the viral origin of replication by the replication initiator protein of tomato yellow leaf curl virus.replication of the single-stranded dna genome of geminiviruses occurs via a double-stranded intermediate that is subsequently used as a template for rolling-circle replication of the viral strand. only one of the proteins encoded by the virus, here referred to as replication initiator protein (rep protein), is indispensable for replication. we show that the rep protein of tomato yellow leaf curl virus initiates viral-strand dna synthesis by introducing a nick in the plus strand within the nonanu ...19957732000
transgenic tomato plants expressing the tomato yellow leaf curl virus capsid protein are resistant to the virus.the tomato yellow leaf curl virus (tylcv) gene that encodes the capsid protein (v1) was placed under transcriptional control of the cauliflower mosaic virus 35s promoter and cloned into an agrobacterium ti-derived plasmid and used to transform plants from an interspecific tomato hybrid, lycopersicon esculentum x l. pennellii (f1), sensitive to the tylcv disease. when transgenic f1 plants, expressing the v1 gene, were inoculated with tylcv using whiteflies fed on tylcv-infected plants, they respo ...19947764709
rep protein of tomato yellow leaf curl geminivirus has an atpase activity required for viral dna replication.the rep protein of geminiviruses is the sole viral protein required for their dna replication. the amino acid sequence of rep protein contains an ntp binding consensus motif (p-loop). here we show that purified rep protein of tomato yellow leaf curl virus expressed in escherichia coli exhibits an atpase activity in vitro. amino acid exchanges in the p-loop sequence of rep causes a substantial decrease or loss of the atpase activity. in vivo, mutant viruses carrying these rep mutations do not rep ...19957777563
advances in diagnosing tomato yellow leaf curl geminivirus infection.as a result of the spread of tylcv on tomato crops, reliable and rapid diagnostic tools to identify and isolate new sources of infection are necessary. we tested several methods, based both on antibodies and on nonradioactive dna probes. indirect plate-trapping elisa was only effective in detecting the virus in purified preparations, but not in crude extracts. dot-elisa with chemiluminescence detection gave satisfactory results when young stems were directly squashed on membranes. a digoxigenin- ...19947866878
acquisition and transmission of agrobacterium by the whitefly bemisia tabaci.whiteflies transmit many different plant pathogens. we show here that the whitefly bemisia tabaci can also acquire agrobacterium tumefaciens from liquid cultures and from crown galls, and transmit it to plants. cloned tomato yellow leaf curl virus (tylcv) dna and a. tumefaciens tumor-inducing functions were used as reporter genes. whiteflies were fed through membranes on cultures of agrobacterium at::pty4 containing a dimeric copy of an infectious tylcv genomic clone between the t-dna borders of ...19947873782
movement of tomato yellow leaf curl geminivirus (tylcv): involvement of the protein encoded by orf c4.tomato yellow leaf curl virus (tylcv) is a whitefly-transmitted geminivirus with a monopartite genome. we have investigated the ability of a tylcv dna mutant containing a disrupted orf c4 to infect nicotiana benthamiana and tomato plants. the mutant retained the capability of autonomous replication in protoplast-derived cells of tomato and was able to infect n. benthamiana plants systemically although dna levels were reduced and symptom development was attenuated. however, when tomato plants wer ...19948091687
complete nucleotide sequence of the geminivirus tomato yellow leaf curl virus, thailand isolate.the complete genome of a thailand isolate of the geminivirus tomato yellow leaf curl virus (tylcv-th) has been cloned and the nucleotide sequence determined. the genome consists of two dnas each slightly greater than 2700 nucleotides in length and designated a-dna and b-dna. the a-dna contains six open reading frames (orfs) capable of encoding proteins with m(r)s greater than 10k; two orfs were located on the b-dna. the predicted orfs were found at positions on the genome similar to those identi ...19948126446
high similarity among the tomato yellow leaf curl virus isolates from the west mediterranean basin: the nucleotide sequence of an infectious clone from spain.an isolate of tomato yellow leaf curl geminivirus, from the first epidemic outbreaks that occurred in murcia, spain (tylcv-m) in 1992, was cloned and its nucleotide sequence was determined. the circular single stranded dna consisted of 2777 nucleotides. the genome organization resembled that of other tylcv sequenced so far; regulatory signal sequences for bidirectional transcription and for polyadenylation of the transcripts were localized in the sequence. infectivity of the cloned dna was demon ...19948198442
nucleotide sequence evidence for the occurrence of three distinct whitefly-transmitted geminiviruses in cassava.the complete nucleotide sequence of the dna of indian cassava mosaic virus (icmv) and a key part of that of a group b isolate of african cassava mosaic virus from malawi (acmv-m) were determined and compared at the nucleotide and encoded amino acid levels with the published sequences of an acmv group a isolate (acmv-k) and other whitefly-transmitted gemini-viruses (wtgs). the dna of icmv consists of two circular single-stranded molecules, dna-a [2815 nucleotides (nt)] and dna-b (2645 nt), which ...19938245859
replication of tomato yellow leaf curl virus (tylcv) dna in agroinoculated leaf discs from selected tomato genotypes.the leaf disc agroinoculation system was applied to study tomato yellow leaf curl virus (tylcv) replication in explants from susceptible and resistant tomato genotypes. this system was also evaluated as a potential selection tool in breeding programmes for tylcv resistance. leaf discs were incubated with a head-to-tail dimer of the tylcv genome cloned into the ti plasmid of agrobacterium tumefaciens. in leaf discs from susceptible cultivars (lycopersicon esculentum) tylcv single-stranded genomic ...19938400142
complete nucleotide sequence of pepper huasteco virus: analysis and comparison with bipartite geminiviruses.the complete nucleotide sequence of pepper huasteco geminivirus (phv) isolated in northern mexico was determined. the phv genome consists of two circular ssdna molecules of 2631 bases (phv a) and 2589 bases (phv b). phv has a genome organization typical of a bipartite geminivirus with four open reading frames (orfs) (ar1, al1, al2 and al3) in component a and two (br1 and bl1) in component b. an unexpected orf was found in the complementary sense strand of phv a. this orf, termed al5, is found en ...19938409944
identification of the nicking tyrosine of geminivirus rep protein.the replication initiator (rep) proteins of geminiviruses perform a dna cleavage and strand transfer reaction at the viral origin of replication. as a reaction intermediate, rep proteins become covalently linked to the 5' end of the cleaved dna. we have used tomato yellow leaf curl virus rep protein for in vivo and in vitro analyses. isolating a covalent peptide-nucleotide complex, we have identified the amino acid of rep which mediates cleavage and links the protein to dna. we show that tyrosin ...19958543063
dna-binding activity of the c2 protein of tomato yellow leaf curl geminivirus.the in vitro dna-binding activity of the c2 protein of tomato yellow leaf curl geminivirus (tylcv) was studied following its expression in escherichia coli as a fusion protein with an his tag n-terminal extension (his-c2). southwestern blotting experiments demonstrated that the c2 protein is able to bind both single-stranded and double-stranded dna probes. in electrophoretic mobility shift assays performed using purified protein and single-stranded dna probes several shifted complexes were forme ...19968610454
resistance to tomato yellow leaf curl geminivirus in nicotiana benthamiana plants transformed with a truncated viral c1 gene.the c1 gene of tomato yellow leaf curl geminivirus (tylcv) encodes a multifunctional protein (rep) involved in replication. a truncated form of this gene, capable of expressing the n-terminal 210 amino acids (aa) of the rep protein, was cloned under the control of the camv 35s promoter and introduced into nicotiana benthamiana using agrobacterium tumefaciens. the same sequence was also cloned in antisense orientation. when self-pollinated progeny of 19 primary transformants were tested for resis ...19968862407
quantitative determination of tomato yellow leaf curl geminivirus dna by chemiluminescent assay using digoxigenin-labeled probes.a quantitative dot-blot hybridisation assay was developed for tomato yellow leaf curl geminivirus (tylcv). the assay is based on chemiluminescent detection of viral and plasmid dna using digoxigenin-labeled probes on nylon membranes. the response-error relationship was studied and a square root transformation was found to stabilise the variance of the response. an asymmetric sigmoid (gompertz) curve was used to describe the dose-response relationship. the detection limits and the precision profi ...19968919821
genetic analysis of the monopartite tomato yellow leaf curl geminivirus: roles of v1, v2, and c2 orfs in viral pathogenesis.tomato yellow leaf curl virus (tylcv) is a whitefly-transmitted geminivirus with a monopartite genome. we have investigated the functions of the v1, v2, and c2 orfs by mutational analysis. we analyzed the ability of tylcv mutants containing disrupted orfs v1, v2, or c2 to replicate, spread, and cause symptoms in nicotiana benthamiana and tomato plants. all the mutants retained the capability of autonomous replication in protoplast-derived cells of tomato and leaf discs of n. benthamiana, althoug ...19979123819
a novel subviral agent associated with a geminivirus: the first report of a dna satellite.numerous plant rna viruses have associated with them satellite (sat) rnas that have little or no nucleotide sequence similarity to either the viral or host genomes but are completely dependent on the helper virus for replication. we report here on the discovery of a 682-nt circular dna satellite associated with tomato leaf curl geminivirus (tlcv) infection in northern australia. this is the first demonstration that satellite molecules are not limited to rna viral systems. the dna satellite (tlcv ...19979192696
a worldwide survey of tomato yellow leaf curl viruses.the name tomato yellow leaf curl virus (tylcv) has been given to several whitefly-transmitted geminiviruses affecting tomato cultures in many tropical and subtropical regions. hybridization tests with two dna probes derived from a cloned isolate of tylcv from israel (tylcv-isr) were used to assess the affinities of viruses in naturally infected tomato plants with yellow leaf curl or leaf curl symptoms from 25 countries. probe a which included most of the intergenic region was expected to detect ...19979267451
long-term association of tomato yellow leaf curl virus with its whitefly vector bemisia tabaci: effect on the insect transmission capacity, longevity and fecundity.the association between tomato yellow leaf curl geminivirus (tylcv, israeli isolate) and its insect vector, the whitefly bemisia tabaci, was investigated. insects that emerged during a 24 h period were caged with tylcv-infected plants for a 48 h acquisition access period, then with egg-plants--a tylcv non-host--for the rest of their lives. while tylcv dna was associated with the whiteflies during their entire adult life, the amount of capsid protein rapidly decreased and was not detectable in th ...19979349491
evidence for transovarial transmission of tomato yellow leaf curl virus by its vector, the whitefly bemisia tabaci.the whitefly bemisia tabaci is the only vector of the tomato yellow leaf curl geminivirus (tylcv). the insect transmits the virus in a persistent-circulative manner. tylcv dna was detected by polymerase chain reaction and by southern blot hybridization in progeny (eggs, first and second instars, adults) of single viruliferous whiteflies that developed on eggplant or on cotton (two tylcv nonhost plants). furthermore, tylcv dna was present in the progeny of insects that had acquired the virus thro ...19989454703
nuclear import of the capsid protein of tomato yellow leaf curl virus (tylcv) in plant and insect cells.the tomato yellow leaf curl virus (tylcv) found in israel is a whitefly-transmitted monopartite geminivirus. although geminiviruses have been found in the nuclei of phloem-associated cells, the mechanism of viral invasion is poorly understood. the possible role of the tylcv capsid protein (cp), the only known component of the viral coat, in virus transport into the host cell nucleus was investigated by monitoring its specific nuclear accumulation in plant and insect cells. cp was fused to the be ...19989680988
amino acids in the capsid protein of tomato yellow leaf curl virus that are crucial for systemic infection, particle formation, and insect transmission.a functional capsid protein (cp) is essential for host plant infection and insect transmission in monopartite geminiviruses. we studied two defective genomic dnas of tomato yellow leaf curl virus (tylcv), sic and sicrcv. sic, cloned from a field-infected tomato, was not infectious, whereas sicrcv, which spontaneously originated from sic, was infectious but not whitefly transmissible. a single amino acid change in the cp was found to be responsible for restoring infectivity. when the amino acid s ...19989811744
the capsid protein of tomato yellow leaf curl virus binds cooperatively to single-stranded dna.the capsid protein (cp) of tomato yellow leaf curl virus (tylcv) is the only known component of the virus coat. here, we identify tylcv cp as a single-stranded (ss) dna binding protein. purified tylcv cp bound ssdna in a highly cooperative and sequence-nonspecific fashion. tylcv cp-ssdna complexes were resistant to nucleolytic digestion and remained stable at relatively high salt concentrations. because tylcv cp is known to contain an active nuclear targeting signal, we propose that its associat ...19989820160
types of variation in dna-a among isolates of east african cassava mosaic virus from kenya, malawi and tanzania.complete nucleotide sequences of the dna-a-like molecules of three east african cassava mosaic virus (eacmv) isolates from kenya (-k, 2801 nt) and malawi (-mh and -mk, both 2804 nt) were determined. these sequences were compared with that published for a tanzanian isolate (-t, 2801 nt) and the partial sequence of a third malawian isolate. intergenic region sequences of all isolates, and deduced amino acid sequences of their ac1 (rep) proteins, each formed a tightly related cluster that was disti ...19989820161
using non-radioactive probes on plants: a few examples.due to costs in using and disposing of radiochemicals and to health considerations, we have been developing applications which include non-isotopic detection of dna and proteins using chemiluminescence. our major interests are in the detection of viral nucleic acids and in the analysis of transgenic plants. generally, probes were labelled with digoxigenin, either by the random priming method or by pcr, and then detected with cspd or cdp-star. we routinely use a tissue blotting protocol for diagn ...19989839194
improvement of the print-capture polymerase chain reaction procedure for efficient amplification of dna virus genomes from plants and insect vectors.a rapid and simple procedure is described to amplify efficiently geminivirus dna genomes by improving the print-capture polymerase chain reaction (pcr) procedure reported recently for rna viruses. this method, termed print-pcr (p-pcr), allows direct amplification of dna from infected plant or whitefly tissues printed directly on whatman 3mm paper, without the need of any grinding, incubation, or washing steps previous to the amplification reaction. p-pcr reduces sample manipulation and avoids pr ...19989870594
a groel homologue from endosymbiotic bacteria of the whitefly bemisia tabaci is implicated in the circulative transmission of tomato yellow leaf curl virus.evidence for the involvement of a bemisia tabaci groel homologue in the transmission of tomato yellow leaf curl geminivirus (tylcv) is presented. a approximately 63-kda protein was identified in b. tabaci whole-body extracts using an antiserum raised against aphid buchnera groel. the groel homologue was immunolocalized to a coccoid-shaped whitefly endosymbiont. the 30 n-terminal amino acids of the whitefly groel homologue showed 80% homology with that from different aphid species and groel from ...199910087228
tomato yellow leaf curl geminivirus (tylcv-is) is transmitted among whiteflies (bemisia tabaci) in a sex-related manner.tomato yellow leaf curl virus (tylcv) is the name given to a complex of geminiviruses infecting tomato cultures worldwide. tylcv is transmitted by a single insect species, the whitefly bemisia tabaci. herein we show that a tylcv isolate from israel (tylcv-is) can be transmitted among whiteflies in a sex-dependent manner, in the absence of any other source of virus. tylcv was transmitted from viruliferous males to females and from viruliferous females to males but not among insects of the same se ...200010775612
natural recombination between tomato yellow leaf curl virus-is and tomato leaf curl virus.the complete genome sequences (2791 and 2793 nt) of isolates of tomato yellow leaf curl virus-is (tylcv-is) from spain (sp72/97) and portugal (port2/95) were determined. these isolates are closely related to tylcv-is isolates reported in japan (japan-a and japan-s) and israel (israel/mild). comparison of all sequenced isolates of tylcv-is showed that part of the genome comprising the intergenic region and the 5'-end of the rep gene of the iran and israel isolates was not closely related to that ...200011038394
the groel protein of the whitefly bemisia tabaci interacts with the coat protein of transmissible and nontransmissible begomoviruses in the yeast two-hybrid system.we have previously suggested that a groel homolog produced by the whitefly bemisia tabaci endosymbiotic bacteria interacts in the insect hemolymph with particles of tomato yellow leaf curl virus from israel (tylcv-is), ensuring the safe circulative transmission of the virus. we have now addressed the question of whether the nontransmissibility of abutilon mosaic virus from israel (abmv-is) is related to a lack of association between groel and the virus coat protein (cp). translocation analysis h ...200011040131
tomato yellow leaf curl virus, an emerging virus complex causing epidemics worldwide.tomato yellow leaf curl (tylc) is one of the most devastating viral diseases of cultivated tomato (lycopersicon esculentum) in tropical and subtropical regions worldwide, and losses of up to 100% are frequent. in many regions, tylc is the main limiting factor in tomato production. the causal agents are a group of geminivirus species belonging to the genus begomovirus of the family geminiviridae, all of them named tomato yellow leaf curl virus (tylcv) (sensu lato). there has been almost 40 years ...200011137167
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 ...200111551077
tomato yellow leaf curl virus (tylcv) capsid protein (cp) subunit interactions: implications for viral assembly.tomato yellow leaf curl virus (tylcv) capsid protein (cp) forms the capsule that encapsidates the viral genomic ssdna. we have analyzed the homotypic interaction capacity of full-length and mutated cp. we found that full-length cp interacts with itself. truncation of the protein from the c-terminal led to diminution of the self-interaction process. also, the n-terminal region of the cp seemed to be necessary for the interaction. as the two deletion mutants interacted successfully with the wildty ...200111699961
functional analysis of proteins involved in movement of the monopartite begomovirus, tomato yellow leaf curl virus.the functional properties of proteins [capsid protein (cp), v1, and c4] potentially involved with movement of the monopartite begomovirus, tomato yellow leaf curl virus (tylcv), were investigated using microinjection of escherichia coli expressed proteins and transient expression of gfp fusion proteins. the tylcv cp localized to the nucleus and nucleolus and acted as a nuclear shuttle, facilitating import and export of dna. thus, the cp serves as the functional homolog of the bipartite begomovir ...200111878881
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 ...200211952122
the structure of a replication initiator unites diverse aspects of nucleic acid metabolism.rolling circle replication is a mechanism for copying single-stranded genomes by means of double-stranded intermediates. a multifunctional replication initiator protein (rep) is indispensable for the precise initiation and termination of this process. despite the ubiquitous presence and fundamental importance of rolling circle replication elements, structural information on their respective replication initiators is still missing. here we present the solution nmr structure of the catalytic domai ...200212130667
contribution of the zinc finger to zinc and dna binding by a suppressor of posttranscriptional gene silencing.the zinc finger c(36)-x1-c(38)-x7-c(46)-x6-h(53) of the nuclearly localized c2 protein of tomato yellow leaf curl virus china is involved in pathogenicity and suppression of posttranscriptional gene silencing (ptgs). here, we demonstrate that the zinc finger is indispensable for the c2 protein to bind zinc and dna. mutation of cysteine residue c(36), c(38), or c(46) reduced the zinc and dna binding capacity of c2 protein. when expressed from potato virus x, all three mutants, c2-c(36)r, c2-c(38) ...200312477872
a natural recombinant between the geminiviruses tomato yellow leaf curl sardinia virus and tomato yellow leaf curl virus exhibits a novel pathogenic phenotype and is becoming prevalent in spanish populations.this work provides evidence of the significant contribution of recombination to the genetic diversification of emerging begomovirus populations. in southern spain, tomato yellow leaf curl sardinia virus (tylcsv) and tomato yellow leaf curl virus (tylcv) are distinct geminivirus species that coexist in the field and contribute to the tomato yellow leaf curl disease epidemic. a natural recombinant between tylcsv and tylcv has been detected and an infectious clone of a recombinant isolate (es421/99 ...200212490393
multitasking in replication is common among geminiviruses.geminiviruses package single-stranded circular dna and replicate via double-stranded dna intermediates. during the past decade, increasing evidence has led to the general acceptance that their replication follows a rolling-circle replication mechanism like bacteriophages with single-stranded dna. in a recent study, we showed that this is also true for abutilon mosaic geminivirus (abmv), but that this particular virus may also use a recombination-dependent replication (rdr) route in analogy to t4 ...200312584322
functional characterization of the nuclear localization signal for a suppressor of posttranscriptional gene silencing.the nucleus-localized c2 protein of tomato yellow leaf curl virus-china (tylcv-c) is an active suppressor of posttranscriptional gene silencing (ptgs). consistently, infection with tylcv-c resulted in ptgs arrest in plants. the c2 protein possesses a functional, arginine-rich nuclear localization signal within the basic amino acid-rich region (17)kvqhriakkttrrrr(31). when expressed from potato virus x, c2-rrrr(31)dvgg (in which the four consecutive arginine residues (28)rrrr(31) were replaced wi ...200312768021
tomato mottle taino virus pseudorecombines with pymv but not with tomov: implications for the delimitation of cis- and trans-acting replication specificity determinants.over the last decade, the tomato production in cuba has been affected by new whitefly-associated diseases. in addition to the well-documented presence of tomato yellow leaf curl virus (tylcv) along the island, the occurrence of bipartite begomoviruses has also been reported. one of them, tentatively named tomato mottle taino virus (tomotv), has now been cloned and characterized at the molecular level. its genomic organization is similar to other bipartite geminiviruses. phylogenetic analyses pla ...200314505083
a novel motif in geminivirus replication proteins interacts with the plant retinoblastoma-related protein.the geminivirus replication factor al1 interacts with the plant retinoblastoma-related protein (prbr) to modulate host gene expression. the al1 protein of tomato golden mosaic virus (tgmv) binds to prbr through an 80-amino-acid region that contains two highly predicted alpha-helices designated 3 and 4. earlier studies suggested that the helix 4 motif, whose amino acid sequence is strongly conserved across geminivirus replication proteins, plays a role in prbr binding. we generated a series of al ...200415078963
tylcsv dna, but not infectivity, can be transovarially inherited by the progeny of the whitefly vector bemisia tabaci (gennadius).the transovarial transmission of two species of begomovirus, tomato yellow leaf curl virus (tylcv) and tomato yellow leaf curl sardinia virus (tylcsv), through generations of bemisia tabaci of the b and q biotypes has been investigated. different life stages of the progeny of viruliferous female whiteflies have been analysed by pcr detection of viral dna and infectivity tests. our results indicate that tylcsv dna can be detected in eggs and nymphs, and to a lesser extent adults, of the first-gen ...200415193923
complete nucleotide sequence of iranian tomato yellow leaf curl virus isolate: further evidence for natural recombination amongst begomoviruses. brief report.complete nucleotide sequence of the iranian strain of tomato yellow leaf curl virus (tylcv-ir) was determined and compared with some begomoviruses. the complete sequence of tylcv-ir clustered together with tylcv and tylcv-mid from israel. a similar relationship holds when the deduced amino acid sequences of v1, v2, c2 and c3 and nucleotide sequences of ir, and rir were compared. in contrast, phylogenetic analyses of amino acid sequences of c4, c1, and nucleotide sequences of lir revealed that ty ...200415221543
trapping of tomato yellow leaf curl virus (tylcv) and other plant viruses with a groel homologue from the whitefly bemisia tabaci.to avoid destruction in the haemolymph of their vector, many plant circulative viruses interact with groel homologues produced by insect endosymbiotic bacteria. we have exploited this phenomenon to devise tools allowing trapping of plant viruses by either groel purified from the whitefly bemisia tabaci or by whitefly groel over-expressed in e. coli. pcr tubes or 96-well plates coated with a groel preparation were incubated with cleared sap of virus infected plant leaves or insect vectors. groel- ...200415290375
tête à tête of tomato yellow leaf curl virus and tomato yellow leaf curl sardinia virus in single nuclei.since 1997 two distinct geminivirus species, tomato yellow leaf curl sardinia virus (tylcsv) and tomato yellow leaf curl virus (tylcv), have caused a similar yellow leaf curl disease in tomato, coexisted in the fields of southern spain, and very frequently doubly infected single plants. tomatoes as well as experimental test plants (e.g., nicotiana benthamiana) showed enhanced symptoms upon mixed infections under greenhouse conditions. viral dna accumulated to a similar extent in singly and doubl ...200415367638
evidence for interspecific-recombination for three monopartite begomoviral genomes associated with the tomato leaf curl disease from central sudan.two distinct viral genotypes were identified in the same tomato plant collected from gezira, sudan and are provisionally designated tomato leaf curl sudan virus (tolcsdv-gez) and tomato yellow leaf curl virus-sudan (tylcv-sd). a third genotype was identified in tomato samples collected in shambat, sudan (tolcsdv-sha). the tolcsdv-gez and tolcsdv-sha isolates were approximately 90% identical, tylcv-sd from gezira shared approximately 93% identity with tylcv-mld. recombination analyses identified ...200515703848
a new silverleaf-inducing biotype ms of bemisia tabaci (hemiptera: aleyrodidae) indigenous to the islands of the south-west indian ocean.following the first detection of tomato yellow leaf curl virus (tylcv) from reunion (700 km east of madagascar) in 1997 and the upsurge of bemisia tabaci (gennadius) on vegetable crops, two genetic types of b. tabaci were distinguished using rapd-pcr and cytochrome oxidase i (coi) gene sequence comparisons. one type was assigned to biotype b and the other was genetically dissimilar to the populations described elsewhere and was named ms, after the mascarenes archipelago. this new genetic type fo ...200515705212
severe outbreaks of tomato yellow leaf curl sardinia virus in calabria, southern italy.during the winter 2003--2004 a serious disease was observed in protected tomato crops in castrovillari, reggio calabria province, southern italy. symptoms consisted in marginal leaf yellowing, leaf curling, plant stunting, flower abortion. the disease was detected in a group of greenhouses (about 10ha) where several tomato cultivars were grown hydroponically. the highest incidence of infection (60-100%) was observed in tomatoes grafted on beaufort drs tomato rootstock. since the symptoms were si ...200415756842
molecular characterization of tomato-infecting begomoviruses in thailand.bipartite geminiviruses infecting tomatoes in thailand were detected by polymerase chain reaction (pcr) using cpa5/cpa2 primers. products derived from pcr-amplified full-length dna-a and dna-b of tylcv collected from chiang mai, nong khai, and sakon nakhon were cloned and sequenced. dna-a from chiang mai was 2747 nts long; nong khai, 2744 nts; and sakon nakhon, 2747 nts, and those of dna-b from chiang mai were 2750 nts long; nong khai, 2749 nts; and sakon nakhon, 2749 nts. the genomes of these v ...200415826907
differential transcriptional activity of plant-pathogenic begomoviruses in their whitefly vector (bemisia tabaci, gennadius: hemiptera aleyrodidae).plant-pathogenic begomoviruses have a complex association with their whitefly vector and aspects concerning virus genetic activity (genome replication and gene transcription) within the insect remain highly controversial. virus transcript abundance was assessed by quantifying selected gene transcripts of tomato mottle virus (tomov, a new world bipartite begomovirus) and tomato yellow leaf curl virus (tylcv, an old world monopartite begomovirus) in whiteflies (bemisia tabaci biotype b) after feed ...200515831966
south west indian ocean islands tomato begomovirus populations represent a new major monopartite begomovirus group.biological and molecular properties of tomato leaf curl madagascar virus isolates from morondova and toliary (tolcmgv-[tol], -[mor]), tomato leaf curl mayotte virus isolates from dembeni and kahani (tolcytv-[dem], -[kah]) and a tomato yellow leaf curl virus isolate from reunion (tylcv-mld[re]) were determined. full-length dna components of the five isolates from madagascar, mayotte and reunion were cloned and sequenced and, with the exception of tolcmgv-[tol], were shown to be both infectious in ...200515831967
geminivirus c3 protein: replication enhancement and protein interactions.most dicot-infecting geminiviruses encode a replication enhancer protein (c3, al3, or ren) that is required for optimal replication of their small, single-stranded dna genomes. c3 interacts with c1, the essential viral replication protein that initiates rolling circle replication. c3 also homo-oligomerizes and interacts with at least two host-encoded proteins, proliferating cell nuclear antigen (pcna) and the retinoblastoma-related protein (prbr). it has been proposed that protein interactions c ...200516014949
begomovirus genetic diversity in the native plant reservoir solanum nigrum: evidence for the presence of a new virus species of recombinant nature.we examined the native plant host solanum nigrum as reservoir of genetic diversity of begomoviruses that cause the tomato yellow leaf curl disease (tylcd) emerging in southern spain. presence of isolates of all the species and strains found associated with tylcd in this area was demonstrated. mixed infections were common, which is a prerequisite for recombination to occur. in fact, presence of a novel recombinant begomovirus was demonstrated. analysis of an infectious clone showed that it result ...200616580040
intron-hairpin rna derived from replication associated protein c1 gene confers immunity to tomato yellow leaf curl virus infection in transgenic tomato plants.the whitefly-transmitted tomato yellow leaf curl virus (tylcv) is the major pathogen of tomato crop in cuba and one of the most outstanding viral diseases of plants worldwide. in this work, we have developed transgenic tomato plants, transformed with an intron-hairpin genetic construction to induce post- transcriptional gene silencing against the early tylcv replication associated protein gene (c1). the intron-hairpin rna produced involves 726 nts of the 3' end of the tylcv c1 gene as the arms o ...200616779645
permeabilized mammalian cells as an experimental system for nuclear import of geminiviral karyophilic proteins and of synthetic peptides derived from their nuclear localization signal regions.the plant-infecting geminiviruses deliver their genome and viral proteins into the host cell nucleus. members of the family geminiviridae possess either a bipartite genome composed of two approximately 2.6 kb dnas or a monopartite genome of approximately 3.0 kb dna. the bipartite genome of bean dwarf mosaic virus (bdmv) encodes several karyophilic proteins, among them the capsid protein (cp) and bv1 (nuclear shuttle protein). a cp is also encoded by the monopartite genome of tomato yellow leaf c ...200616894212
dna helicase activity is associated with the replication initiator protein rep of tomato yellow leaf curl geminivirus.the rep protein of tomato yellow leaf curl sardinia virus (tylcsv), a single-stranded dna virus of plants, is the replication initiator essential for virus replication. tylcsv rep has been classified among atpases associated with various cellular activities (aaa+ atpases), in superfamily 3 of small dna and rna virus replication initiators whose paradigmatic member is simian virus 40 large t antigen. members of this family are dna- or rna-dependent atpases with helicase activity necessary for vir ...200616943286
suppressor of rna silencing encoded by tomato yellow leaf curl virus-israel.the israeli isolate of tomato yellow leaf curl geminivirus (tylcv-is) is a major tomato pathogen, causing extensive crop losses both in the new and old world. surprisingly, however, little is known about the molecular mechanisms of tylcv-is interactions with tomato cells. here, we have identified a tylcv-is protein, v2, which acts as a suppressor of rna silencing and which is unrelated to presently known viral suppressors. specifically, v2, but not other proteins of tylcv-is, inhibited rna silen ...200716979684
founder effect, plant host, and recombination shape the emergent population of begomoviruses that cause the tomato yellow leaf curl disease in the mediterranean basin.tomato yellow leaf curl disease (tylcd)-associated viruses present a highly structured population in the western mediterranean basin, depending on host, geographical region and time. about 1,900 tomato and common bean samples were analyzed from which 111 isolates were characterized genetically based on a genome sequence that comprises coding and non-coding regions. isolates of three distinct begomoviruses previously described were found (tomato yellow leaf curl virus, tylcv, tomato yellow leaf c ...200717070885
production of sirna targeted against tylcv coat protein transcripts leads to silencing of its expression and resistance to the virus.the coat protein (cp) of tomato yellow leaf curl virus (tylcv), encoded by the v1 gene, is the only known component of the viral capsid. in addition, the cp plays a role in the virus transport into the host cell nucleus where viral genes are replicated and transcribed. in this study, we analyzed the effect of small interfering double-stranded rnas (sirnas), derived from an intron-hairpin rna (ihprna) construct and targeting the v1 gene product, on cp accumulation. transient assays involving agro ...200717103242
making a friend from a foe: expressing a groel gene from the whitefly bemisia tabaci in the phloem of tomato plants confers resistance to tomato yellow leaf curl virus.some (perhaps all) plant viruses transmitted in a circulative manner by their insect vectors avoid destruction in the haemolymph by interacting with groel homologues, ensuring transmission. we have previously shown that the phloem-limited begomovirus tomato yellow leaf curl virus (tylcv) interacts in vivo and in vitro with groel produced by the whitefly vector bemisia tabaci. in this study, we have exploited this phenomenon to generate transgenic tomato plants expressing the whitefly groel in th ...200717334947
typing of tomato yellow leaf curl viruses and their vector in italy.a molecular survey of tylcv/tylcsv and their associated vector bemisia tabaci, was performed during 2004-2005 in five regions of southern italy: i.e. sardinia (one locations), sicily (one location), calabria (three locations), campania (two locations) and basilicata (one location). a total of 71 tomato samples were checked for virus infection and for the presence of the vector. degenerate primers allowing the amplification of the coat protein gene of both tylcsv and tylcv isolates were designed. ...200617390884
integrated management of tylcv/tylcsv on greenhouse hydroponic tomatoes in southern italy.tomato yellow leaf curl (tylc) caused by tomato yellow leaf curl virus (tylcv) and tomato yellow leaf curl sardinia virus (tylcsv), vectored by the whitefly bemisia tabaci, is a major disease of tomato in sardinia and sicily, and is becoming a serious threat in southern italy too. tylcsv was first reported in calabria region in 1991, but apparently it was an occasional outbreak, and b. tabaci was not detected. later, during the 2003-2004 winter, a serious epidemic was observed in protected tomat ...200617390886
frequent occurrence of recombinants in mixed infections of tomato yellow leaf curl disease-associated begomoviruses.begomoviruses are plant dna viruses for which recombination plays a key role in driving evolution. however, little is known about how frequently begomovirus recombinants arise in mixed infected plants. to tackle this issue, co-infections of tomato with monopartite begomoviruses associated with the tomato yellow leaf curl disease, tomato yellow leaf curl sardinia virus and tomato yellow leaf curl virus, have been studied as a model system. the frequency of recombinant genotypes in the progeny pop ...200717467025
a multiplex pcr method discriminating between the tylcv and tylcv-mld clades of tomato yellow leaf curl virus.tomato yellow leaf curl virus (tylcv) is one of the causal agents of tomato yellow leaf curl disease (tylcd) and can cause up to 100% yield losses in tomato fields. as tylcv continues to spread, many isolates have been described in different parts of the world. recently two closely related but distinct tylcv clades, called tylcv and tylcv-mld, have been identified. isolates from those two clades differ mainly in the nucleotide sequences of their replication associated protein genes but do not di ...200717485124
genetic structure and evolution of natural populations of viruses causing the tomato yellow leaf curl disease in spain.the population structure and genetic variation of two begomoviruses: tomato yellow leaf curl sardinia virus (tylcsv) and tomato yellow leaf curl virus (tylcv) in tomato crops of spain were studied from 1997 until 2001. restriction digestion of a genomic region comprised of the cp coat protein gene (cpr) of 358 tylc virus isolates enabled us to classify them into 14 haplotypes. nucleotide sequences of two genomic regions: cpr, and the surrounding intergenic region (sir) were determined for at lea ...200717524509
biolistic inoculation of plants with tomato yellow leaf curl virus dna.tomato yellow leaf curl virus (tylcv) full-length dna was amplified by pcr and cloned into a bacterial plasmid. the cloned tylcv dna was excised from the plasmid, ligated and the resulting monomeric circular double-stranded tylcv dna was used to inoculate tomato (solanum lycopersicom) and datura (datura stramonium) plants by particle bombardment. the bombarded plants produced typical disease symptoms, similar to those produced following whitefly-mediated inoculation, albeit 5-7 days later than w ...200717573131
evidence for a founder effect after introduction of tomato yellow leaf curl virus-mild in an insular environment.evolution of tomato yellow leaf curl virus-mild (tylcv-mld[re]) (family geminiviridae, genus begomovirus) was monitored in la réunion island from its first upsurge in 1997 until 2004. two genome fragments, one comprising partial c4 and c1 open reading frames (orfs), and the other comprising part of the v1 and v2 orfs and part of the intergenic region were sequenced in 111 isolates. the very low initial diversity of tylcv-mld[re] in la réunion was followed by a quasi-linear increase in genetic di ...200717609843
multiple introductions of the old world begomovirus tomato yellow leaf curl virus into the new world.a phylogenetic analysis of three genomic regions revealed that tomato yellow leaf curl virus (tylcv) from western north america is distinct from tylcv isolated in eastern north america and the caribbean. this analysis supports a second introduction of this old world begomovirus into the new world, most likely from asia.200717827315
a single-tube pcr assay for detecting viruses and their recombinants that cause tomato yellow leaf curl disease in the mediterranean basin.tomato yellow leaf curl disease (tylcd) is well known in mediterranean countries, where it has been causing severe losses in tomato crops for decades. until recently, two viruses (with several isolates) in the genus begomovirus, family geminiviridae, have been associated with the epidemics: tomato yellow leaf curl virus (tylcv) and tomato yellow leaf curl sardinia virus (tylcsv). however, recombinants between these, such as tomato yellow leaf curl malaga virus (tylcmalv), are spreading, and new ...200817868911
a universal expression/silencing vector in plants.a universal vector (il-60 and auxiliary constructs), expressing or silencing genes in every plant tested to date, is described. plants that have been successfully manipulated by the il-60 system include hard-to-manipulate species such as wheat (triticum duram), pepper (capsicum annuum), grapevine (vitis vinifera), citrus, and olive (olea europaea). expression or silencing develops within a few days in tomato (solanum lycopersicum), wheat, and most herbaceous plants and in up to 3 weeks in woody ...200717905866
a divergent isolate of tomato yellow leaf curl virus from oman with an associated dna beta satellite: an evolutionary link between asian and the middle eastern virus-satellite complexes.tomato is cultivated in the coastal region of al-batinah, in the sultanate of oman, during the winter season, to meet the high demand for fresh produce in the domestic market. in order to identify the causal agent of a widespread disease associated with infestations of the whitefly bemisia tabaci (genn.) leaves were collected from tomato plants showing symptoms characteristic of the disease in al-batinah during 2004 and 2005. total nucleic acids were isolated from the tomato leaves and used as t ...200817932737
expression of stress-response proteins upon whitefly-mediated inoculation of tomato yellow leaf curl virus in susceptible and resistant tomato plants.to better understand the nature of resistance of tomato to the whitefly (bemisia tabaci, b biotype)-transmitted tomato yellow leaf curl virus (tylcv), whiteflies and tylcv were considered as particular cases of biotic stresses and virus resistance as a particular case of successful response to these stresses. two inbred tomato lines issued from the same breeding program that used solanum habrochaites as a tylcv resistance source, one susceptible and the other resistant, were used to compare the ...200717977149
phylogenetic evidence for rapid rates of molecular evolution in the single-stranded dna begomovirus tomato yellow leaf curl virus.geminiviruses are devastating viruses of plants that possess single-stranded dna (ssdna) dna genomes. despite the importance of this class of phytopathogen, there have been no estimates of the rate of nucleotide substitution in the geminiviruses. we report here the evolutionary rate of the tomato yellow leaf curl disease-causing viruses, an intensively studied group of monopartite begomoviruses. sequences from genbank, isolated from diseased plants between 1988 and 2006, were analyzed using baye ...200817977971
effect of plant age at inoculation on expression of genetic resistance to tomato yellow leaf curl virus.to determine the effects of plant age on the expression of genetic resistance to tomato yellow leaf curl virus (tylcv), six tylcv-resistant and two susceptible tomato varieties were inoculated at 14, 28 or 45 days after sowing (das). inoculation at 14 and 28 das was performed in the greenhouse, and the plants were transplanted to the field at 30 das. inoculation at 45 das was performed in the field, by covering the target plants with polypropylene ("agril") sheets and releasing viruliferous whit ...200818000639
inhibition of tomato yellow leaf curl virus replication by artificial zinc-finger proteins.previously, we designed an artificial zinc-finger protein (azp) for blocking a replication protein (rep) of beet severe curly top virus (bsctv) from binding to its replication origin and demonstrated that transgenic arabidopsis plants expressing the azp are completely resistant to the virus infection. here we applied the azp technology to tomato yellow leaf curl virus (tylcv) infective to an important agricultural crop, tomato. we designed an azp binding to the direct repeat to block the tylcv r ...200718029770
interaction with host sgs3 is required for suppression of rna silencing by tomato yellow leaf curl virus v2 protein.the v2 protein of tomato yellow leaf curl geminivirus (tylcv) functions as an rna-silencing suppressor that counteracts the innate immune response of the host plant. the host-cell target of v2, however, remains unknown. here we show that v2 interacts directly with slsgs3, the tomato homolog of the arabidopsis sgs3 protein (atsgs3), which is known to be involved in the rna-silencing pathway. slsgs3 genetically complemented an atsgs3 mutation and restored rna silencing, indicating that slsgs3 is i ...200818165314
molecular identification and the complete nucleotide sequence of tylcv isolate from shanghai of china.tomato yellow leaf curl virus (tylcv) belongs to the genus begomovirus, family geminiviridae. it is transmitted by the whitefly bemisia tabaci. a pair of primers was designed according to the specific sequence of the tylcv gene and used in the pcr detection of the virus in the infected tissues of tomato grown in the shanghai area of china. dna was extracted from leaves, fruits, seeds, and roots of infected tomato plants separately. the results showed that the target fragment of about 570 bp coul ...200818373188
three years survey of tomato yellow leaf curl sardinia virus reservoir weed hosts in southern italy.during the period from august 2004 to june 2006 a serious tomato yellow leaf curl epidemic caused by both tomato yellow leaf curl sardinia virus (tylcsv) and tomato yellow leaf curl virus (tylcs) was observed in protected tomato crops in castrovillari, calabria region, in a group of greenhouses where tomato is grown hydroponically. a three years survey for reservoir weed hosts of these viruses was performed during summer period in order to identify where the viruses persist during the host-free ...200718396845
relationship between tomato yellow leaf curl viruses and the whitefly vector.tomato yellow leaf curl virus (tylcv) and tomato leaf curl virus (tolcv) are the currently known begomoviruses in uganda. the relationship with their whiteflies (bemisia tabaci) vector and its management were not known in uganda. a direct relationship was expected between these begomoviruses and whiteflies at buwama in mpigi district of uganda. farmer practices were expected to have limited efficacy. to investigate this, a completely randomised block design was used for all trials with six treat ...200718396846
functional analysis of bipartite begomovirus coat protein promoter sequences.we demonstrate that the al2 gene of cabbage leaf curl virus (calcuv) activates the cp promoter in mesophyll and acts to derepress the promoter in vascular tissue, similar to that observed for tomato golden mosaic virus (tgmv). binding studies indicate that sequences mediating repression and activation of the tgmv and calcuv cp promoter specifically bind different nuclear factors common to nicotiana benthamiana, spinach and tomato. however, chromatin immunoprecipitation demonstrates that tgmv al2 ...200818430450
chinese tomato yeliow ieaf curl virus- a new species of geminivirus.chine tomato yellow leaf curl virus (tylcv-chi) and other geminiviruses were analysed with 20 monoclonai antibodies. it was shown that tylcv-chi is serclogicaily close to chinese tabacco ieaf curl virus (tblcv-chi). the fragment of tylcv-chi dna including the common region (cr), n-terminal of coat protein gene and av1 gene was amplified by pcr and cloned, and its dna sequence was determined. these raults showed that tylcv-chi is different from other known geminiviruses in the world, and is a new ...199818726248
generation of plants resistant to tomato yellow leaf curl virus by using artificial zinc-finger proteins.previously, we designed an artificial zinc-finger protein (azp) for blocking a replication protein (rep) of beet severe curly top virus (bsctv) from binding to its replication origin and demonstrated that transgenic arabidopsis plants expressing the azp are completely resistant to the virus infection. here we applied the azp technology to tomato yellow leaf curl virus (tylcv) infective to an important agricultural crop, tomato. we designed and constructed an azp binding to the direct repeat to b ...200818776317
resistance to monopartite begomoviruses associated with the bean leaf crumple disease in phaseolus vulgaris controlled by a single dominant gene.abstract tomato yellow leaf curl virus (tylcv) and tomato yellow leaf curl málaga virus are monopartite begomoviruses (genus begomovirus, family geminiviridae) that infect common bean (phaseolus vulgaris), causing bean leaf crumple disease (blcd). this disease was found to be widespread in southern spain and causes stunted growth, flower abortion, and leaf and pod deformation in common bean plants. commercial yield losses of up to 100% occur. in the present study, we have identified and characte ...200518943015
tomato yellow leaf curl virus in the dominican republic: characterization of an infectious clone, virus monitoring in whiteflies, and identification of reservoir hosts.abstract epidemics of tomato yellow leaf curl disease (tylcd) in the dominican republic in the early to mid-1990s resulted in catastrophic losses to processing tomato production. as part of an integrated management approach to tylcd, the complete nucleotide sequence of a full-length infectious clone of an isolate of tomato yellow leaf curl virus (tylcv) from the dominican republic (tylcv-[do]) was determined. the tylcv-[do] genome was nearly identical in sequence (>97%) and genome organization t ...200218943022
phenotypic expression, stability, and inheritance of a recessive resistance to monopartite begomoviruses associated with tomato yellow leaf curl disease in tomato.tomato-infecting begomoviruses comprise a complex of monopartite and bipartite virus species that cause severe yield and quality losses worldwide. therefore, the availability of wide spectrum resistance for begomovirus control is desirable. however, limited sources of resistance are available. in this study, three tomato inbred lines with resistance to bipartite begomoviruses of brazil were tested for resistance to monopartite begomoviruses associated with the tomato yellow leaf curl disease (ty ...200818943231
pepper (capsicum annuum) is a dead-end host for tomato yellow leaf curl virus.abstract tomato yellow leaf curl (tylc) is one of the most devastating pathogens affecting tomato (lycopersicon esculentum) worldwide. the disease is caused by a complex of begomovirus species, two of which, tomato yellow leaf curl sardinia virus (tylcsv) and tomato yellow leaf curl virus (tylcv), are responsible for epidemics in southern spain. tylcv also has been reported to cause severe damage to common bean (phaseolus vulgaris) crops. pepper (capsicum annuum) plants collected from commercial ...200518943307
sequence analysis and classification of apparent recombinant begomoviruses infecting tomato in the nile and mediterranean basins.abstract numerous whitefly-transmitted viral diseases of tomato have emerged in countries around the nile and mediterranean basins the last 20 years. these diseases are caused by monopartite geminiviruses (family gemini viridae) belonging to the genus begomovirus that probably resulted from numerous recombination events. the molecular biodiversity of these viruses was investigated to better appreciate the role and importance of recombination and to better clarify the phylogenetic relationships a ...200518943321
effect of host plant resistance to tomato yellow leaf curl virus (tylcv) on virus acquisition and transmission by its whitefly vector.abstract the effect that tomato yellow leaf curl virus (tylcv)-infected resistant tomato plants may have on virus epidemiology was studied. four tomato genotypes that exhibit different levels of viral resistance, ranging from fully susceptible to highly resistant, served as tylcv-infected source plants. viral acquisition and transmission rates by white-flies following feeding on the different source plants were evaluated. tylcv transmission rate by whiteflies that had fed on infected source plan ...200118943336
development of a scale for evaluation of tomato yellow leaf curl virus resistance level in tomato plants.abstract we have developed a scale of differential hosts that enables the determination and comparison of level of resistance to tomato yellow leaf curl virus (tylcv) expressed by resistant tomato lines or by individual plants in a segregating population. the scale is composed of seven different homozygous tomato genotypes that exhibit different levels of tylcv resistance, ranging from fully susceptible to highly resistant. the differential hosts composing the scale were inoculated with tylcv un ...200618943674
use of tomato yellow leaf curl virus (tylcv) rep gene sequences to engineer tylcv resistance in tomato.abstract tomato yellow leaf curl virus (tylcv), a member of the genus begomovirus (family geminiviridae), causes severe losses in tomato production in the tropics and subtropics. in order to generate engineered resistance, eight different constructs of the tylcv replication-associated protein (rep) and c4 gene sequences were tested in transformed tomato inbred lines. transgenic plants were screened for resistance to tylcv using viruliferous whiteflies. no symptoms were observed and no tylcv geno ...200418943768
watermelon chlorotic stunt virus from the sudan and iran: sequence comparisons and identification of a whitefly-transmission determinant.abstract the genomes of two watermelon chlorotic stunt virus (wmcsv) isolates, one from the sudan and one from iran, were cloned and sequenced. sequence relationship with other geminiviruses characterizes wmcsv as a typical eastern hemisphere geminivirus with a bipartite genome. the two geographically distant wmcsv isolates from africa and the middle east share a very high overall sequence similarity: 98% between their dna-a and 96% between their dna-b components, and their respective capsid pro ...200018944543
displacement of tomato yellow leaf curl virus (tylcv)-sr by tylcv-is in tomato epidemics in spain.abstract a progressive displacement of tomato yellow leaf curl virus (tylcv)-sr by tylcv-is was observed in tomato epidemics in southern spain based on incidence data of both virus species obtained during surveys conducted between 1996 and 1998. ecological factors that might be involved in such a displacement, such as competition of tylcv-sr and tylcv-is in tomato, transmission by local biotypes (b and q) of bemisia tabaci, and presence in weeds and alternate crops, have been analyzed. no select ...199918944659
tomato breeding lines resistant and tolerant to tomato yellow leaf curl virus issued from lycopersicon hirsutum.abstract two tomato yellow leaf curl virus (tylcv)-resistant plants from accessions la1777 and la386 of the wild tomato species lycopersicon hirsutum have been crossed. the resulting resistant f1 plants were crossed with the domesticated tomato l. esculentum, and a series of selfing was performed. at each generation, individuals were selected for resistance (no symptoms and undetectable viral dna) and tolerance (no symptoms but with detectable viral dna) following controlled massive and repeated ...199818944868
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