Publications

use of posttranscription gene silencing in squash to induce resistance against the egyptian isolate of the squash leaf curl virus.	squash leaf curl virus (sqlcv) is a bipartite begomovirus affecting squash plants. it is transmitted by whitefly bemisia tabaci biotype b causing severe leaf curling, vein banding, and molting ending by stunting. in this study full-length genomic clone of sqlcv egyptian isolated and posttranscriptional gene silencing (ptgs) has been induced to develop virus resistance. the noubaria sqlcv has more than 95% homology with jordon, israel, lebanon, palestine, and cairo isolates. two genes fragment fr ...	2016	27034922
frequent migration of introduced cucurbit-infecting begomoviruses among middle eastern countries.	in the early 2000s, two cucurbit-infecting begomoviruses were introduced into the eastern mediterranean basin: the old world squash leaf curl virus (slcv) and the new world watermelon chlorotic stunt virus (wmcsv). these viruses have been emerging in parallel over the last decade in egypt, israel, jordan, lebanon and palestine.	2014	25300752
squash leaf curl virus (slcv): a serious disease threatening cucurbits production in palestine.	the incidence of squash leaf curl disease and molecular characterization of the palestinian isolate of squash leaf curl virus [slcv-(pal)] are described in this study. symptomatic leaf samples obtained from squash (cucurbita pepo), watermelon [citrullus lanatus (thunb.)], and cucumber (cucumis sativus l.) plants were tested for slcv-[pal] infection by pcr and rca. slcv was also found to occur naturally in chenopodium murale, convolvulus sp, and prosporis farcta which showed yellowing. the diseas ...	2014	24258392
detection and quantitation of the new world squash leaf curl virus by taqman real-time pcr.	squash leaf curl diseases are caused by distinct virus species that are separated into two major phylogenetic groups, western and eastern hemisphere groups. the western group includes the new world squash leaf curl virus (slcv) which causes major losses to cucurbit production and induces severe stunting and leaf curl in squash plants. a taqman-based real time polymerase chain reaction (qpcr) assay has been developed for detection and quantitation of slcv. designed primers and probe targeted the ...	2013	23583490
implication of bemisia tabaci heat shock protein 70 in begomovirus-whitefly interactions.	the whitefly bemisia tabaci (gennadius) is a major cosmopolitan pest capable of feeding on hundreds of plant species and transmits several major plant viruses. the most important and widespread viruses vectored by b. tabaci are in the genus begomovirus, an unusual group of plant viruses owing to their small, single-stranded dna genome and geminate particle morphology. b. tabaci transmits begomoviruses in a persistent circulative nonpropagative manner. evidence suggests that the whitefly vector e ...	2012	23015709
phylogenetic analysis of melon chlorotic leaf curl virus from guatemala: another emergent species in the squash leaf curl virus clade.	the genome of a new bipartite begomovirus melon chlorotic leaf curl virus from guatemala (mclcuv-gt) was cloned and the genome sequence was determined. the virus causes distinct symptoms on melons that were not previously observed in melon crops in guatemala or elsewhere. phylogenetic analysis of mclcuv-gt and begomoviruses infecting cucurbits and other host plant species indicated that its closest relative was mclcuv from costa rica (mclcuv-cr). the dna-a components of two isolates shared 88.8% ...	2011	21420452
TaqMan real-time PCR for detection and quantitation of squash leaf curl virus in cucurbits.	A real-time PCR assay based on the TaqMan chemistry was developed for reliable detection and quantitation of the squash leaf curl virus (SLCV) in melon and squash plants. This method was highly specific to SLCV and it was about one thousand times more sensitive than the conventional PCR method. The protocol of the real-time PCR established in this study enabled detection of as little as 10(2) copies of SLCV DNA with CP gene as the target. This TaqMan real-time PCR assay for detection and quantit ...	2011	22172970
molecular characterization of a new begomovirus that infects euphorbia heterophylla and solanum lycopersicum in venezuela.	we report the complete nucleotide sequence of a begomovirus isolate infecting euphorbia heterophylla and tomato (solanum lycopersicum) in central venezuela. based on the current taxonomic criteria for the genus begomovirus, the isolate was shown to represent a novel species, tentatively named euphorbia mosaic venezuela virus (eumvv). its dna-a is most closely related to those of euphorbia-infecting begomoviruses from the caribbean and central america. the dna b component forms a phylogenetic clu ...	2011	22052541
watermelon chlorotic stunt virus (wmcsv): a serious disease threatening watermelon production in jordan.	the incidence of watermelon chlorotic stunt disease and the molecular characterization of the jordanian isolate of watermelon chlorotic stunt virus (wmcsv-[jo]) are described in this study. symptomatic leaf samples obtained from watermelon (citrullus lanatus thunb.), melon (cucumis melo l.), squash (cucurbita pepo), cucumber (cucumis sativus l.), and bottle gourd (lagenaria siceraria) plants were tested for wmcsv-[jo] infection by pcr. the virus could be detected in 8 melon and 87 watermelon sam ...	2011	21399920
characterization of a synergistic interaction between two cucurbit-infecting begomoviruses: squash leaf curl virus and watermelon chlorotic stunt virus.	squash leaf curl virus (slcv) and watermelon chlorotic stunt virus (wmcsv) are cucurbit-infecting bipartite begomoviruses. both viruses are found in the eastern mediterranean basin but the effects of dual infection of both viruses on melon (cucumis melo l.) have not been described. 'arava' melon plants were inoculated in the greenhouse, using whiteflies, with either slcv, wmcsv, or both. control plants were exposed to nonviruliferous whiteflies or not exposed at all. following inoculation, plant ...	2011	21219130
rapid detection of squash leaf curl virus by loop-mediated isothermal amplification.	a loop-mediated isothermal amplification (lamp) assay was employed to develop a simple and efficient system for the detection of squash leaf curl virus (slcv) in diseased plants of squash (cucurbita pepo) and melon (cucumis melo). completion of lamp assay required 30-60 min under isothermal conditions at 65 degrees c by employing a set of four primers targeting slcv. although the sensitivity of the lamp assay and the polymerase chain reaction (pcr) assay was comparable at high virus concentratio ...	2010	20603151
characterization of rhynchosia yellow mosaic yucatan virus, a new recombinant begomovirus associated with two fabaceous weeds in yucatan, mexico.	rhynchosia minima (l.) dc. (fabaceae) plants exhibiting bright golden mosaic symptoms were previously associated with begomovirus infection in yucatan, méxico [1]. to characterize the begomovirus infecting these plants, the complete bipartite genome was cloned and sequenced. sequence comparisons indicated that the virus was distinct from all other begomoviruses known to date, including those previously identified from symptomatic r. minima, and the name rhynchosia yellow mosaic yucatan virus (rh ...	2010	20574644
inoculation of plants with begomoviruses by particle bombardment without cloning: using rolling circle amplification of total dna from infected plants and whiteflies.	a new system for inoculation of plants with begomoviral dna without cloning or the use insect vectors is described. total dna extracted from begomovirus-infected plants was amplified by rolling circle amplification (rca) using the bacteriophage phi29 dna polymerase, and inoculated to plants by particle bombardment. infection rates of up to 100% were obtained using this technique. this technique successfully inoculated all the begomoviruses evaluated: five bipartite (bean golden yellow mosaic vir ...	2010	20447420
melon chlorotic leaf curl virus: characterization and differential reassortment with closest relatives reveal adaptive virulence in the squash leaf curl virus clade and host shifting by the host-restricted bean calico mosaic virus.	the genome components of the melon chlorotic leaf curl virus (mclcuv) were cloned from symptomatic cantaloupe leaves collected in guatemala during 2002. the mclcuv dna-a and dna-b components shared their closest nucleotide identities among begomoviruses, at approximately 90 and 81%, respectively, with a papaya isolate of mclcuv from costa rica. the closest relatives at the species level were other members of the squash leaf curl virus (slcv) clade, which is endemic in the southwestern united sta ...	2008	18057231
a simplified method of constructing infectious clones of begomovirus employing limited restriction enzyme digestion of products of rolling circle amplification.	most infectious clones of geminiviruses consist of (partial) tandem repeats of viral genomes in the vectors, which usually involve tedious, multi-step assemblies of genomic fragments in the construction process. a simplified procedure was devised to circumvent these problems, which employs limited restriction digestion of multimeric viral genomes produced by rolling circle amplification (rca), followed by direct cloning into appropriate vectors. the efficiency of the procedure, and infectivity o ...	2008	18031835
cotton leaf crumple virus is a distinct western hemisphere begomovirus species with complex evolutionary relationships indicative of recombination and reassortment.	abstract the bipartite dna genome of cotton leaf crumple virus (clcrv), a whitefly-transmitted begomovirus from the sonoran desert, was cloned and completely sequenced. the cloned clcrv genome was infectious when biolistically delivered to cotton or bean seedlings and progeny virus was whitefly-transmissible. koch's postulates were completed by the reproduction of characteristic leaf crumple symptoms in cotton seedlings infected with cloned clcrv dna, thereby verifying the etiology of leaf crump ...	2004	18943795
identification of a nuclear localization signal and nuclear export signal of the umbraviral long-distance rna movement protein.	the 27 kda protein encoded by orf3 of groundnut rosette virus (grv) is required for viral rna protection and movement of viral rna through the phloem. localization studies have revealed that this protein is located in nuclei, preferentially targeting nucleoli. we have demonstrated that amino acids (aa) 108-122 of the grv orf3 protein contain an arginine-rich nuclear localization signal. arginine-to-asparagine substitutions in this region decreased the level of the orf3 protein accumulation in nu ...	2004	15105550
the complete nucleotide sequence of two distinct geminiviruses infecting cucurbits in vietnam.	we have characterised two distinct geminiviruses that infect cucurbit cultivars in vietnam. the genomes of both viruses consisted of two circular ssdna components (dna-a and dna-b), with a genome arrangement and coding sequence typical of viruses in the begomovirus genus in the family geminiviridae. the sequence of dna-a of one of the viruses was approximately 97% similar to squash leaf curl virus-china (slcv-ch), for which a dna-b has yet to be identified. we have named this virus squash leaf c ...	2003	12898329
emergence of a new cucurbit-infecting begomovirus species capable of forming viable reassortants with related viruses in the squash leaf curl virus cluster.	abstract cucurbit leaf curl virus (culcv), a whitefly-transmitted geminivirus previously partially characterized from the southwestern united states and northern mexico, was identified as a distinct bipartite begomovirus species. this virus has near sequence identity with the previously partially characterized cucurbit leaf crumple virus from california. experimental and natural host range studies indicated that culcv has a relatively broad host range within the family cucurbitaceae and also inf ...	2002	18943269
[cloning and sequencing of chinese squash leaf curl virus].	sequence analysis of virus isolation dna of squash leaf curl disease shows that squash leaf curl virus (slch-chi) contains 2741nt, which encode six open reading frames (orfs). two of them are on virus sense strand: av1 (256aa) and av2 (140aa). av1 encode coat protein. the other of orfs are on complementary sense strand: ac1 (replicase gene, 243aa), ac2 (transactivtor, 134aa), ac3 (136aa) and ac4 (172aa). the virus belongs to one number of begomoviruses from old world.	2001	12549185
nuclear export in plants. use of geminivirus movement proteins for a cell-based export assay.	the nuclear export of proteins and rnas has been studied in heterokaryons or by microinjecting test substrates into nuclei of hela cells or xenopus oocytes. we have previously shown that the two movement proteins br1 and bl1 encoded by the plant pathogenic squash leaf curl virus act in a coordinated manner to facilitate virus cell-to-cell movement and that one of these (br1) is a nuclear shuttle protein. by using a novel in vivo cell-based assay for nuclear export in which nuclear-localized br1 ...	1999	10402428
tracing the geminivirus-whitefly transmission pathway by polymerase chain reaction in whitefly extracts, saliva, hemolymph, and honeydew.	abstract a membrane feeding system and polymerase chain reaction (pcr) were used to track squash leaf curl virus (slcv) dna in whole whitefly body extracts and in saliva, honeydew, and hemolymph of its whitefly vector, bemisia tabaci, and a whitefly nonvector, trialeurodes vaporariorum. slcv ingestion was monitored by pcr in whiteflies that were given acquisition access periods (aaps) ranging from 0.5 to 96 h on virus-infected plants. slcv detection by pcr in whole body extracts was considered r ...	1999	18944765
biotic, molecular, and phylogenetic characterization of bean calico mosaic virus, a distinct begomovirus species with affiliation in the squash leaf curl virus cluster.	abstract bean calico mosaic virus (bcmov), a whitefly-transmitted geminivirus from sonora, mexico, was purified, and the genome components were cloned and sequenced. purified viral fractions and cloned genome components were infectious by biolistic inoculation to bean, completing koch's postulates for both. the b biotype of the whitefly bemisia tabaci efficiently transmitted both native virus and progeny virus derived from cloned dna inoculum. host ranges of native virus and of progeny virus der ...	1999	18944770
asymmetric infectivity of pseudorecombinants of cabbage leaf curl virus and squash leaf curl virus: implications for bipartite geminivirus evolution and movement.	the bipartite geminiviruses squash leaf curl virus (sqlcv) and cabbage leaf curl virus (clcv) have distinct host ranges. sqlcv infects a broad range of plants within the cucurbitaceae, including pumpkin and squash, and clcv has a broad host range within brassicaceae that includes cabbage and arabidopsis thaliana. despite this, the genomic a components of these viruses share a high degree of sequence identity, particularly in the gene encoding the replication protein al1, and their common regions ...	1998	9792839
the bipartite geminivirus coat protein aids br1 function in viral movement by affecting the accumulation of viral single-stranded dna.	the movement of bipartite geminiviruses such as squash leaf curl virus (sqlcv) requires the cooperative interaction of two essential virus-encoded movement proteins, br1 and bl1. while the viral coat protein ar1 is not essential for systemic infection, genetic studies demonstrate that its presence masks the defective phenotype of certain br1 missense mutants, thus suggesting that coat protein does interact with the viral movement pathway. to further examine the mechanism of this interaction, we ...	1998	9765472
the geminivirus bl1 movement protein is associated with endoplasmic reticulum-derived tubules in developing phloem cells.	plant viruses encode movement proteins that are essential for systemic infection of their host but dispensable for replication and encapsidation. bl1, one of the two movement proteins encoded by the bipartite geminivirus squash leaf curl virus, was immunolocalized to unique approximately 40-nm tubules that extended up to and across the walls of procambial cells in systemically infected pumpkin leaves. these tubules were not found in procambial cells from pumpkin seedlings inoculated with bl1 mut ...	1997	9094647
horseradish curly top virus is a distinct subgroup ii geminivirus species with rep and c4 genes derived from a subgroup iii ancestor.	the complete nucleotide sequence (3080 nt) of an infectious dna clone derived from the geminivirus horseradish curly top virus (hrctv) has been determined. the relationship of hrctv to other geminiviruses was examined using dot matrix plots of nucleotide sequence similarities, and by phylogeny of predicted amino acid sequences of individual orfs based upon parsimony or neighbour-joining methods. these analyses indicate that the v1 and v2 virion sense orfs of hrctv are most closely related to, ye ...	1996	8757976
a viral movement protein as a nuclear shuttle. the geminivirus br1 movement protein contains domains essential for interaction with bl1 and nuclear localization.	for the nuclear replicating bipartite geminiviruses such as squash leaf curl to systemically infect the host requires the active participation of two virus-encoded movement proteins, br1 and bl1. these act in a cooperative manner to transport the viral single-stranded dna genome from its site of replication in the nucleus to the cell periphery (a.a. sanderfoot, s.g. lazarowitz [1995] plant cell 7: 1185-1194). we have proposed that br1 functions as a nuclear shuttle protein, transporting the vira ...	1996	8587985
getting it together in plant virus movement: cooperative interactions between bipartite geminivirus movement proteins.	to move cell-to-cell and systemically infect the host, plant viruses must cross the barrier posed by the plant cell wall. plant viruses accomplish this through strategies that alter the architecture of the infected cell, eliminating this barrier through the action of viral-encoded 'movement proteins'. detailed studies of a number of cytoplasmically replicating viruses suggest that movement proteins interact with components of the cytoskeleton and transport systems of the plant cell to allow pass ...	1996	15157433
both bipartite geminivirus movement proteins define viral host range, but only bl1 determines viral pathogenicity.	bipartite geminiviruses such as squash leaf curl virus (sqlcv) encode two movement proteins (mps), br1 and bl1, that are essential for virus movement and systemic infection of host plants. br1 has been implicated in the host range properties of the virus, and bl1 in viral pathogenic properties. to more precisely examine the roles of each mp, we have introduced missense and deletion mutations into the coding sequence of both br1 and bl1, and examined the effects of these mutations on viral infect ...	1995	7871727
chinese squash leaf curl virus: a new whitefly-transmitted geminivirus.	coat protein (cp) gene of the chinese squash leaf curl virus (sqlcv-c) was amplified through pcr, cloned and completely sequenced. based on the comparisons at the levels of both cp gene nucleotide and cp-deduced amino acid sequences with other geminiviruses, sqlcv-c is confirmed to be distinct from the american squash leaf curl virus (sqlcv-e). it is a new geminivirus transmitted by whitefly bemisia tabaci, which infects dicotyledonous plants and is more closely related to the indian cassava mos ...	1995	7755872
cooperation in viral movement: the geminivirus bl1 movement protein interacts with br1 and redirects it from the nucleus to the cell periphery.	for plant viruses to systemically infect a host requires the active participation of viral-encoded movement proteins. it has been suggested that bl1 and br1, the two movement proteins encoded by the bipartite geminivirus squash leaf curl virus (sqlcv), act cooperatively to facilitate movement of the viral single-stranded dna genome from its site of replication in the nucleus to the cell periphery and across the cell wall to adjacent uninfected cells. to better understand the mechanism of sqlcv m ...	1995	12242403
the geminivirus br1 movement protein binds single-stranded dna and localizes to the cell nucleus.	plant viruses encode movement proteins that are essential for infection of the host but are not required for viral replication or encapsidation. squash leaf curl virus (sqlcv), a bipartite geminivirus with a single-stranded dna genome, encodes two movement proteins, br1 and bl1, that have been implicated in separate functions in viral movement. to further elucidate these functions, we have investigated the nucleic acid binding properties and cellular localization of br1 and bl1. in this study, w ...	1994	8069108
transgenic tobacco plants expressing the geminivirus bl1 protein exhibit symptoms of viral disease.	bipartite geminiviruses, such as squash leaf curl virus (sqlcv), encode two movement proteins (mps), br1 and bl1, that are essential for viral movement in and subsequent infection of the host plant. to elucidate the biochemical functions of these mps and define their respective contributions to viral infection, we have generated transgenic nicotiana benthamiana plants expressing sqlcv br1 and bl1. transgenic plants expressing br1 or a truncated bl1 were phenotypically indistinguishable from wild ...	1993	8364356
sequence-specific interaction with the viral al1 protein identifies a geminivirus dna replication origin.	the bipartite geminiviruses such as tomato golden mosaic virus (tgmv) and squash leaf curl virus (sqlcv) have two single-stranded circular genomic dnas, the a and b components, thought to be replicated from double-stranded circular dna intermediates. although it has been presumed that the origin sequences for viral replication are located in the highly conserved 200-nucleotide common region (cr) present in both genomic components and that the viral-encoded al1 protein interacts with these sequen ...	1992	1392596
infectivity and complete nucleotide sequence of the cloned genomic components of a bipartite squash leaf curl geminivirus with a broad host range phenotype.	through cloning and molecular analysis we have identified two highly homologous bipartite geminiviruses as causing squash leaf curl disease. mechanical and agrobacterium-mediated inoculation of plants with cloned viral dna components identified the two genomic components of sqlcv-e, a squash leaf curl virus with an unexpectedly broad host range for a whitefly-transmitted geminivirus. nucleotide sequence analysis of the genome of this virus showed it to have the same bipartite component organizat ...	1991	1984668