The whitefly Bemisia tabaci species complex and the begomoviruses they transmit are devastating agricultural pests worldwide.With the rapid and further inva-sions by some members of the whitefly species complex into n...The whitefly Bemisia tabaci species complex and the begomoviruses they transmit are devastating agricultural pests worldwide.With the rapid and further inva-sions by some members of the whitefly species complex into new regions,their impacts on human society are likely to increase in the years to come.展开更多
Begomoviruses and whiteflies have interacted for geological times.An assumed long-lasting virus-vector intimate relationship of this magnitude implies that the partners have developed co-evolutionary mechanisms that i...Begomoviruses and whiteflies have interacted for geological times.An assumed long-lasting virus-vector intimate relationship of this magnitude implies that the partners have developed co-evolutionary mechanisms that insure on one hand the survival and the efficient transmission of the virus,and on the other hand the safeguard of the insect host from possible deleterious effects of the virus.Several studies have indicated that viruses belonging to the Tomato yellow leaf curl virus（TYLCVs）family from China,Israel and Italy are reminiscent of insect pathogens.TYLCVs like all begomoviruses are transmitted in a circulative manner by the whitefly Bemisia tabaci.The survival of the virus in the haemolymph of B.tabaci is ensured by a GroEL homologue produced by a whitefly secondary endosymbiont.Following acquisition and transfer to non-host plants,the virus may remain associated with the insect for its entire 4-5 wk-long adult life.During this period,the ability of the insects to inoculate plants steadily decreased,but did not disappear.The long-term presence of TYLCVs in B.tabaci was associated with a decrease in the insect longevity and fertility.Viral DNA was transmitted to progeny,but seldom infectivity.TYLCV transcripts were found associated with the insects,raising the possibility of replication and expression in the vector.TYLCVs may spread amidst whiteflies during copulation.Functional genomics tools such as microarrays,deep sequencing,quantitative PCR and gene silencing allow revisiting the proposition that TYLCVs have retained,or acquired,some characteristics of an insect pathogen.展开更多
Cassava mosaic disease (CMD) caused by Cassava Mosaic Begomoviruses (CMBs) is one of the most devastating crop diseases and a major constraint for cassava production. In order to ensure surveillance for epidemic preve...Cassava mosaic disease (CMD) caused by Cassava Mosaic Begomoviruses (CMBs) is one of the most devastating crop diseases and a major constraint for cassava production. In order to ensure surveillance for epidemic prevention, low-cost diagnostic tools are appropriate for large-scale testing of cassava viruses. Multiplex PCR diagnosis is one approach that can reduce diagnostic costs and delays. A multiplex PCR approach was developed for simultaneous detection of African cassava mosaic virus (ACMV), East African Cassava Mosaic Virus and East African cassava mosaic Cameroon virus (EACMV/CM) in Togo CMD-infected cassava leaves. Three primers pairs were used to target their respective viruses in a single tube PCR. Multiplex PCR detected ACMV, EACMV and EACMV/CM in plant DNA extracts prepared from cassava leaves infected with CMB. The primers amplified 783 bp specific to ACMV, 650 bp specific to EACMV and 560 bp specific to EACMCV/CM in both uniplex and multiplex formats. Multiplex PCR is an excellent tool for the effective control of cassava diseases. .展开更多
Malvastrum coromandelianum is a common weed plant frequently found around agricultural fields.Three virus isolates(Y249,Y278 and Y281)were obtained from M.coromandelianum with yellow vein symptoms in Honghe and Baosha...Malvastrum coromandelianum is a common weed plant frequently found around agricultural fields.Three virus isolates(Y249,Y278 and Y281)were obtained from M.coromandelianum with yellow vein symptoms in Honghe and Baoshan,Yunnan Province,China.Specific 500 bp products were amplified from total DNA extracts using universal primers for members of the genus Begomovirus.The complete viral genome sequences of both Y278 and Y281 were determined to be 2743 nucleotides,and that of Y249 was determined to be 2740 nucleotides.Sequence alignments and phylogenetic analyses support the proposal of creating new species in the genus Begomovirus,for which the name malvastrum yellow vein Baoshan virus(MaYVBsV)is proposed for Y278 and Y281,and malvastrum yellow vein Honghe virus(MaYVHhV)is proposed for Y249.展开更多
The bipartite begomoviruses (Geminiviridae family), which are DNA viruses that replicate in the nucleus of infected cells, encode the nuclear shuttle protein (NSP) to facilitate the translocation of viral DNA from the...The bipartite begomoviruses (Geminiviridae family), which are DNA viruses that replicate in the nucleus of infected cells, encode the nuclear shuttle protein (NSP) to facilitate the translocation of viral DNA from the nucleus to the cytoplasm via nuclear pores. This intracellular trafficking of NSP-DNA complexes is accessorized by the NSP-interacting guanosine triphosphatase (NIG) at the cytosolic side. Here, we report the nuclear redistribution of NIG by AtWWPI, a WW domain-containing protein that forms immune nuclear bodies (NBs) against begomoviruses. We demonstrated that AtWWPI relocates NIG from the cytoplasm to the nucleus where it is confined to AtWWP1-NBs, suggesting that the NIG-AtWWP1 interaction may interfere with the NIG pro-viral function associated with its cytosolic localization. Consistent with this assumpti on joss AtWWPI functi on cuased plants more susceptible to begomovirus infection, whereas overexpression of AWWP1 enhaneed plant resistance to begomovirus. Furthermore, we found that a mutant versi on of AtWWPI defective for NB formatio n was noIonger capable of interacti ng with and relocating NIG to the nucleus and lost its immune function against begomovirus. The antiviral function of AtWWP1-NBs, however, could be antagonized by viral infection that induced either the disruption or a decrease in the number of AtWWP1-NBs. Collectively, these results led us to propose that AtWWPI organizes nuclear structures into nuclear foci, which provide intrinsic immunity against begomovirus infection.展开更多
Bemisia tabaci adults from various host-plant species were collected from 31 regions across India.266 B.tabaci samples were first screened by RAPD-PCR to examine molecular variability and to select individuals with di...Bemisia tabaci adults from various host-plant species were collected from 31 regions across India.266 B.tabaci samples were first screened by RAPD-PCR to examine molecular variability and to select individuals with different fingerprints.Host-plant and region of collection were then used to select 25 individuals for PCR amplification and sequencing of their partial mitochondrial cytochrome oxidase subunit one（mtCOI）genes.Pairwise comparisons with mtCOI consensus sequences showed that the majority of these samples had 〈3.5% sequence divergence from groups currently termed Asia I,Asia II-5,Asia II-7,and Asia II-8.The biotype-B B.tabaci from India clustered into the Middle East-Asia Minor 1 group.A new group of B.tabaci from Coimbatore,collected from pumpkin,was related most closely to the Asia I group（6.2% sequence divergence from the consensus Asia I sequence）.To increase our understanding of the epidemiology of tomato leaf curl disease（ToLCD）and the key B.tabaci genetic groups involved in virus spread,the indigenous Asia I and the exotic biotype-B population from South India were used to carry out transmission experiments using Tomato leaf curl Bangalore virus（ToLCBV）.The acquisition access periods（AAP）,inoculation access periods（IAP）,latent periods（LP）,and ToLCBV transmission efficiencies of the two populations were compared and the biotype-B had the more efficient transmission characteristics.These results are discussed in relation to recent changes in the epidemiology of tomato leaf curl disease in South India.展开更多
Geminiviruses, in particular the members of the genus Begomovirus , are considered to be a major phytosanitary problem for tomato crops production in the world. They are responsible for yield losses of up to 20% to 10...Geminiviruses, in particular the members of the genus Begomovirus , are considered to be a major phytosanitary problem for tomato crops production in the world. They are responsible for yield losses of up to 20% to 100%. Regrettably, Togo is not spared from this situation. This work aims to show the genetic diversity of the begomoviruses affecting tomato crops production in Togo and their relationship with other begomoviruses. To achieve these objectives, 307 samples of tomato leaves and wild plant species with typical virus symptoms were collected in the Maritime, Plateaus, Central, Kara and Savannah regions and submitted to PCR analysis. The results revealed the presence of begomovirus in 25.40% of the analyzed samples. The PCR products obtained were submitted to direct sequencing. Phylogenetic analysis of sequences of DNA-A different regions of begomovirus identified in this work with that of other begomoviruses showed a nucleotide identity of 96% respectively for Tomato leaf curl Togo virus-Fontem, Tomato Leaf Curl Togo Virus , Ageratum leaf curl Cameroon Alphasatellite;98% respectively to Tomato leaf curl Nigeria virus , Ageratum leaf curl Cameroon virus , Tomato leaf curl Cameroon virus-Fontem, Ageratum leaf curl Cameroon virus and 99% respectively to Tomato leaf curl Kumasi virus , Pepper yellow vein Mali virus Bazegahot and Pepper yellow vein Mali virus-Ouaga. These results suggest a high degree of genetic diversity of tomato begomoviruses identified in Togo.展开更多
The ecological effects of plant-virus-vector interactions on invasion of alien plant viral vectors have been rarely investigated. We examined the transmission of Tomato yellow leaf cur/China virus （TYLCCNV） by the i...The ecological effects of plant-virus-vector interactions on invasion of alien plant viral vectors have been rarely investigated. We examined the transmission of Tomato yellow leaf cur/China virus （TYLCCNV） by the invasive Q biotype and the indigenous ZHJ2 biotype of the whitefly Bemisia tabaci, a plant viral vector, as well as the influence of TYLCCNV-infection of plants on the performance of the two whitefly biotypes. Both whitefly biotypes were able to acquire viruses from infected plants and retained them in their bodies, but were unable to transmit them to either tobacco or tomato plants. However, when the Q biotype fed on tobacco plants infected with TYLCCNV, its fecundity and longevity were increased by 7- and 1-fold, respectively, compared to those of the Q biotype fed on uninfected tobacco plants. When the ZHJ2 biotype fed on virus-infected plants, its fecundity and longevity were increased by only 2- and 0.5-fold, respectively. These data show that the Q biotype acquired higher beneficial effects from TYLCCNV-infection of tobacco plants than the ZHJ2 biotype. Thus, the Q biotype whitefly may have advantages in its invasion and displacement of the indigenous ZHJ2 biotype.展开更多
Plant viruses in the families Luteoviridae and Geminiviridae are phloem restricted and are transmitted in a persistent,circulative manner by homopteran insects.Using fluorescence 2-D difference gel electrophoresis to ...Plant viruses in the families Luteoviridae and Geminiviridae are phloem restricted and are transmitted in a persistent,circulative manner by homopteran insects.Using fluorescence 2-D difference gel electrophoresis to compare the proteomes of F2 genotypes of Schizaphis graminum segregating for virus transmission ability,we recently discovered a panel of protein biomarkers that predict vector competency.Here we used aphid and whitefly nucleotide and expressed sequence tag database mining to test whether these biomarkers are conserved in other homopteran insects.S.graminum gene homologs that shared a high degree of predicted amino acid identity were discovered in two other aphid species and in the whitefly Bemisia tabaci.Selected reaction monitoring mass spectrometry was used to validate the expression of these biomarkers proteins in multiple aphid vector species.The conservation of these proteins in multiple insect taxa that transmit plant viruses along the circulative transmission pathway creates the opportunity to use these biomarkers to rapidly identify insect populations that are the most efficient vectors and allow them to be targeted for control prior to the spread of virus within a crop.展开更多
Research carried out to assess the impact of open-pollinated Tomato leaf curl virus（ToLCV）-resistant tomatoes and hybrids on the livelihoods of resource-poor farmers in Southern India is described and discussed.Thre...Research carried out to assess the impact of open-pollinated Tomato leaf curl virus（ToLCV）-resistant tomatoes and hybrids on the livelihoods of resource-poor farmers in Southern India is described and discussed.Three high-yielding ToLCV-resistant tomato varieties were developed initially using conventional breeding and screening techniques involving inoculation by ToLCV-viruliferous whitefly,Bemisia tabaci.In 2003 and 2004,respectively,these varieties were released officially by the Karnataka State Seed Committee and the Indian Ministry of Agriculture through notification in the Gazette of India.From 2003 to 2005,eleven seed companies bought breeder seed of the ToLCV-resistant varieties and used them to begin breeding F1 hybrids from them.Socio-economic studies carried out to assess the benefits obtained from growing the ToLCV-resistant varieties found that farmers could gain up to 10 times the profit by growing the ToLCV-resistant varieties compared to the pre-existing ToLCV-susceptible varieties.Adoption of ToLCV-resistant tomatoes was also associated with reduced pesticide use.Extra income from tomato sales was prioritised by farmers to pay for children＇s education,better nutrition and medicines.In a joint effort with the commercial seed sector in India,a promotional field day was organised in 2007.As well as the three ToLCV-resistant varieties,62 ToLCV-resistant hybrid tomatoes were exhibited during a farmer-field day by 17 commercial seed companies and several public institutes.Tomatoes with ToLCV-resistance are now grown widely in South India and seeds of the three open-pollinated varieties have been distributed to more than 12 countries.In 2007,a conservative estimate of the financial-benefit to cost of the research ratio was already more than 837：1.展开更多
Bemisia tabaci is a cryptic species complex, causing signiifcant loss on many agricultural y important crops worldwide. Knowledge on species composition and diversity within B. tabaci complex is critical for evolving ...Bemisia tabaci is a cryptic species complex, causing signiifcant loss on many agricultural y important crops worldwide. Knowledge on species composition and diversity within B. tabaci complex is critical for evolving sustainable pest management strategies. Here we investigate the whitelfy species complex in soybean in major soybean growing states of India. The mitochondrial cytochrome oxidase gene subunit-1 (mtCOI) based phylogenetic relationships established using Bayesian methods indicated the existence of three cryptic species namely Asia I, Asia II 1, and Asia II 7. Al the haplotypes detected in the study could be assigned to these three cryptic species fol owing the species demarcation criteria of 3.5%divergence threshold. Of these, Asia II 1 was found to be predominant with wide spread distribution across the surveyed regions from cool temperate zones to hot and humid tropical plains. On the contrary, cryptic species Asia II 7 showed localized distribu-tion. The Asia II 1 exhibited the highest haplotype diversity and Asia I showed high level of nucleotide diversity. There was a signiifcantly high genetic differentiation among these three cryptic species. The MEAM 1, a dreadful invasive species was not detected in the specimens tested in the current study. The diversity and distribution of three cryptic species is discussed in the light of current knowledge on distribution of whitelfy species in India and yel ow mosaic disease observed during sampling survey.展开更多
Okra is one of the most widespread vegetable crops in the world, particularly in West Africa. However, several factors influence okra crops as biotic and abiotic factors. Among the diseases affecting its culture, okra...Okra is one of the most widespread vegetable crops in the world, particularly in West Africa. However, several factors influence okra crops as biotic and abiotic factors. Among the diseases affecting its culture, okra leaf curl disease is a major threat. This study aims to assess begomoviruses from okra plants with symptoms like leaves curl by molecular approach. A total of thirteen serologically positive samples were tested by PCR assay, and one sample was sequenced among them. The begomovirus was found in six isolates, Bhendi yellow vein mosaic virus (BYVMV) in three isolates, and Okra enation leaf curl virus (OELCuV) in three isolates, respectively. The begomovirus isolate sequences shared 90% identity with the Cotton leaf curl Gezira virus. Mixed infections between these viruses were found. Thus, these results highlight the need to monitor the spread of these disease-causing viruses for okra crops in Mali. In addition, they can also lead to a considerable loss in okra fields in Koulikoro, which is an agricultural region by excellence.展开更多
Cassava mosaic disease (CMD) caused by the whitefly-transmitted Begomoviruses (family Geminiviridae) is a major threat to production of cassava (Manihot esculenta Crantz) in Togo. Survey was conducted in 2020 in the 5...Cassava mosaic disease (CMD) caused by the whitefly-transmitted Begomoviruses (family Geminiviridae) is a major threat to production of cassava (Manihot esculenta Crantz) in Togo. Survey was conducted in 2020 in the 5 agroecological zones of Togo to assess the status of East African cassava mosaic virus (EACMV), East African cassava mosaic Cameroon virus (EACMCMV) and its distribution. Polymerase chain reaction (PCR) and Sanger sequencing were used for the detection of cassava mosaic Begomoviruses (CMBs) in the sampled leaves. The incidence of EACMV was 47.93% (278/580) and varied between 41.30% (Zone V) and 62.29% (Zone IV) across the agroecological zone but no significant difference was observed. The EACMCMV incidence was 13.67% (38/278) and varied significantly (p ≤ 0.001) through the agroecological zone. Phylogenetic analysis of the viral isolates showed that they are closely related to those from Nigeria, Ghana, and Ivory coast. Nucleotide sequence analysis of CP revealed an overall genetic diversity (π) of around 3.4%. These results showed that EACMV was the predominant virus and that EACMCMV incidence could be more widespread in Togo.展开更多
Cassava mosaic disease caused by the whitefly-transmitted begomoviruses (family Geminiviridae) is a major threat to cassava (Manihot esculenta Crantz) production, which can be intercropped with other plants such as pe...Cassava mosaic disease caused by the whitefly-transmitted begomoviruses (family Geminiviridae) is a major threat to cassava (Manihot esculenta Crantz) production, which can be intercropped with other plants such as pepper (Capsicum annuum L.). The aim of this study is to identify cassava begomoviruses on other crops in cassava intercropping systems. Thus, foliar samples showing typical symptoms of virus diseases in cassava intercropping systems were collected from pepper and submitted to PCR analysis and direct sequencing. Three begomovirus species ACMV, EACMV and ALCCMV were identified and characterized in samples. Isolates of these species shared respectively 90% - 93%, 74% and 80% nucleotide identities with begomoviruses. These findings show that cassava begomoviruses can infect other crops and will help in understanding the epidemiology related to whitefly-transmitted begomoviruses in cassava intercropping systems.展开更多
The simplicity of Tomato yellow leaf curl virus(TYLCV)genome,encoding six proteins only,contrasts with the complexity of its impact on tomato plants.In this review,we discuss our understanding of how TYLCV proteins es...The simplicity of Tomato yellow leaf curl virus(TYLCV)genome,encoding six proteins only,contrasts with the complexity of its impact on tomato plants.In this review,we discuss our understanding of how TYLCV proteins establish infection,and how the virus suppresses the effects of several abiotic stresses.TYLCV counteracts cell death induced by other factors,such as inactivation of HSP90 functions.Suppression of plant death is associated with the inhibition of the ubiquitin 26S proteasome degradation and with a deactivation of the heat shock transcription factor HSFA2 pathways.In order to ensure its own life cycle and spread,TYLCV protects the infected host from various unfriendly stresses,and this property can be exploited to protect crops from environmental stresses.展开更多
A novel monopartite begomovirus was found in naturally infected Conyza canadensis plants exhibiting typical begomovirus-induced yellow vein symptoms in Yunnan Province of China.Analysis of two obtained full-length vir...A novel monopartite begomovirus was found in naturally infected Conyza canadensis plants exhibiting typical begomovirus-induced yellow vein symptoms in Yunnan Province of China.Analysis of two obtained full-length viral genome sequences showed that they shared 99.8%nucleotide(nt)sequence similarity,and both consisted of 2733 nts(GenBank accession no.OK120264 and OK120266,respectively).Further analysis showed that these two sequences shared the highest nt sequence similarity(78.9%)with tomato yellow leaf curl Vietnam virus(TYLCVV)(EU189150).In the assayed C.canadensis plants,a betasatellite of 1,341 nts(Accession no.OK120265 and OK120267,respectively)was also found,and it shared 98.1%sequence similarity with malvastrum yellow vein betasatellite(MaYVB)(JX679254).Based on the current classification criteria for begomoviruses,we consider that the two obtained viral isolates are a novel begomovirus,and named it as conyza yellow vein virus(CoYVV).Our further analysis result showed that CoYVV is likely originated from a recombination event between tomato yellow leaf curl Yunnan virus(TYLCYnV)and tomato yellow leaf curl China virus(TYLCCNV).To investigate the effect of CoYVV infection in plant,we constructed two infectious clones(i.e.,pCoYVV and pMaYVB),and inoculated them individually or together to Nicotiana benthamiana plants through agro-infiltration.The result showed that the plants co-inoculated with CoYVV and MaYVB developed yellow vein and downward leaf-curling symptoms,whereas the plants inoculated with CoYVV alone showed no clear virus-like symptoms.Virus infection in the inoculated N.benthamiana plants was confirmed through polymerase chain reaction(PCR).The result of quantitative PCR(qPCR)showed that in the presence of MaYVB,the accumulation level of CoYVV DNA was significantly increased compared to that in the plants infected with CoYVV alone.展开更多
基金the National Natural Science Foundation of China(projects30730061 and 31021003)the National Basic Research Programme of China(2009CB119203)for support to the International Symposium on Future Directions in Bemisia Research held in Hangzhou and thepublication of this special issue
文摘The whitefly Bemisia tabaci species complex and the begomoviruses they transmit are devastating agricultural pests worldwide.With the rapid and further inva-sions by some members of the whitefly species complex into new regions,their impacts on human society are likely to increase in the years to come.
基金Supported by grant IS-4062-07 from the United States-Israel Binational Agricultural Research and Development Fund(BARD)to Czosnek H and Ghanim Mresearchgrant 887/07from the Israel Science Foundation(ISF)to C.H.and G.M.research grant 42-204.2/2006from theGerman-Israel Foundation(GIF) to C.H.and G.M
文摘Begomoviruses and whiteflies have interacted for geological times.An assumed long-lasting virus-vector intimate relationship of this magnitude implies that the partners have developed co-evolutionary mechanisms that insure on one hand the survival and the efficient transmission of the virus,and on the other hand the safeguard of the insect host from possible deleterious effects of the virus.Several studies have indicated that viruses belonging to the Tomato yellow leaf curl virus（TYLCVs）family from China,Israel and Italy are reminiscent of insect pathogens.TYLCVs like all begomoviruses are transmitted in a circulative manner by the whitefly Bemisia tabaci.The survival of the virus in the haemolymph of B.tabaci is ensured by a GroEL homologue produced by a whitefly secondary endosymbiont.Following acquisition and transfer to non-host plants,the virus may remain associated with the insect for its entire 4-5 wk-long adult life.During this period,the ability of the insects to inoculate plants steadily decreased,but did not disappear.The long-term presence of TYLCVs in B.tabaci was associated with a decrease in the insect longevity and fertility.Viral DNA was transmitted to progeny,but seldom infectivity.TYLCV transcripts were found associated with the insects,raising the possibility of replication and expression in the vector.TYLCVs may spread amidst whiteflies during copulation.Functional genomics tools such as microarrays,deep sequencing,quantitative PCR and gene silencing allow revisiting the proposition that TYLCVs have retained,or acquired,some characteristics of an insect pathogen.
文摘Cassava mosaic disease (CMD) caused by Cassava Mosaic Begomoviruses (CMBs) is one of the most devastating crop diseases and a major constraint for cassava production. In order to ensure surveillance for epidemic prevention, low-cost diagnostic tools are appropriate for large-scale testing of cassava viruses. Multiplex PCR diagnosis is one approach that can reduce diagnostic costs and delays. A multiplex PCR approach was developed for simultaneous detection of African cassava mosaic virus (ACMV), East African Cassava Mosaic Virus and East African cassava mosaic Cameroon virus (EACMV/CM) in Togo CMD-infected cassava leaves. Three primers pairs were used to target their respective viruses in a single tube PCR. Multiplex PCR detected ACMV, EACMV and EACMV/CM in plant DNA extracts prepared from cassava leaves infected with CMB. The primers amplified 783 bp specific to ACMV, 650 bp specific to EACMV and 560 bp specific to EACMCV/CM in both uniplex and multiplex formats. Multiplex PCR is an excellent tool for the effective control of cassava diseases. .
基金supported by a grant from the National Natural Science Foundation of China to Yaqin Wang(31972235).
文摘Malvastrum coromandelianum is a common weed plant frequently found around agricultural fields.Three virus isolates(Y249,Y278 and Y281)were obtained from M.coromandelianum with yellow vein symptoms in Honghe and Baoshan,Yunnan Province,China.Specific 500 bp products were amplified from total DNA extracts using universal primers for members of the genus Begomovirus.The complete viral genome sequences of both Y278 and Y281 were determined to be 2743 nucleotides,and that of Y249 was determined to be 2740 nucleotides.Sequence alignments and phylogenetic analyses support the proposal of creating new species in the genus Begomovirus,for which the name malvastrum yellow vein Baoshan virus(MaYVBsV)is proposed for Y278 and Y281,and malvastrum yellow vein Honghe virus(MaYVHhV)is proposed for Y249.
文摘The bipartite begomoviruses (Geminiviridae family), which are DNA viruses that replicate in the nucleus of infected cells, encode the nuclear shuttle protein (NSP) to facilitate the translocation of viral DNA from the nucleus to the cytoplasm via nuclear pores. This intracellular trafficking of NSP-DNA complexes is accessorized by the NSP-interacting guanosine triphosphatase (NIG) at the cytosolic side. Here, we report the nuclear redistribution of NIG by AtWWPI, a WW domain-containing protein that forms immune nuclear bodies (NBs) against begomoviruses. We demonstrated that AtWWPI relocates NIG from the cytoplasm to the nucleus where it is confined to AtWWP1-NBs, suggesting that the NIG-AtWWP1 interaction may interfere with the NIG pro-viral function associated with its cytosolic localization. Consistent with this assumpti on joss AtWWPI functi on cuased plants more susceptible to begomovirus infection, whereas overexpression of AWWP1 enhaneed plant resistance to begomovirus. Furthermore, we found that a mutant versi on of AtWWPI defective for NB formatio n was noIonger capable of interacti ng with and relocating NIG to the nucleus and lost its immune function against begomovirus. The antiviral function of AtWWP1-NBs, however, could be antagonized by viral infection that induced either the disruption or a decrease in the number of AtWWP1-NBs. Collectively, these results led us to propose that AtWWPI organizes nuclear structures into nuclear foci, which provide intrinsic immunity against begomovirus infection.
基金R.V.Chowda-Reddy(HEFCE fellowship)and Kiran Kumar,from the research projects funded by the University of Greenwich,together with the Department for International Development,UK(DFID project code R8247,Crop Protection Programme)
文摘Bemisia tabaci adults from various host-plant species were collected from 31 regions across India.266 B.tabaci samples were first screened by RAPD-PCR to examine molecular variability and to select individuals with different fingerprints.Host-plant and region of collection were then used to select 25 individuals for PCR amplification and sequencing of their partial mitochondrial cytochrome oxidase subunit one（mtCOI）genes.Pairwise comparisons with mtCOI consensus sequences showed that the majority of these samples had 〈3.5% sequence divergence from groups currently termed Asia I,Asia II-5,Asia II-7,and Asia II-8.The biotype-B B.tabaci from India clustered into the Middle East-Asia Minor 1 group.A new group of B.tabaci from Coimbatore,collected from pumpkin,was related most closely to the Asia I group（6.2% sequence divergence from the consensus Asia I sequence）.To increase our understanding of the epidemiology of tomato leaf curl disease（ToLCD）and the key B.tabaci genetic groups involved in virus spread,the indigenous Asia I and the exotic biotype-B population from South India were used to carry out transmission experiments using Tomato leaf curl Bangalore virus（ToLCBV）.The acquisition access periods（AAP）,inoculation access periods（IAP）,latent periods（LP）,and ToLCBV transmission efficiencies of the two populations were compared and the biotype-B had the more efficient transmission characteristics.These results are discussed in relation to recent changes in the epidemiology of tomato leaf curl disease in South India.
基金the West African Agricultural Productivity Program(WAAPP/TOGO)and Bill and Melinda Gates Foundation(BMGF)for supporting this project.
文摘Geminiviruses, in particular the members of the genus Begomovirus , are considered to be a major phytosanitary problem for tomato crops production in the world. They are responsible for yield losses of up to 20% to 100%. Regrettably, Togo is not spared from this situation. This work aims to show the genetic diversity of the begomoviruses affecting tomato crops production in Togo and their relationship with other begomoviruses. To achieve these objectives, 307 samples of tomato leaves and wild plant species with typical virus symptoms were collected in the Maritime, Plateaus, Central, Kara and Savannah regions and submitted to PCR analysis. The results revealed the presence of begomovirus in 25.40% of the analyzed samples. The PCR products obtained were submitted to direct sequencing. Phylogenetic analysis of sequences of DNA-A different regions of begomovirus identified in this work with that of other begomoviruses showed a nucleotide identity of 96% respectively for Tomato leaf curl Togo virus-Fontem, Tomato Leaf Curl Togo Virus , Ageratum leaf curl Cameroon Alphasatellite;98% respectively to Tomato leaf curl Nigeria virus , Ageratum leaf curl Cameroon virus , Tomato leaf curl Cameroon virus-Fontem, Ageratum leaf curl Cameroon virus and 99% respectively to Tomato leaf curl Kumasi virus , Pepper yellow vein Mali virus Bazegahot and Pepper yellow vein Mali virus-Ouaga. These results suggest a high degree of genetic diversity of tomato begomoviruses identified in Togo.
基金supported by the National Natural Science Foundation of China (No.30730061)the National Basic Research Program (973) of China (No.2009CB119203)the Zhejiang Provincial Key Agricultural Project (No.2007C12045),China
文摘The ecological effects of plant-virus-vector interactions on invasion of alien plant viral vectors have been rarely investigated. We examined the transmission of Tomato yellow leaf cur/China virus （TYLCCNV） by the invasive Q biotype and the indigenous ZHJ2 biotype of the whitefly Bemisia tabaci, a plant viral vector, as well as the influence of TYLCCNV-infection of plants on the performance of the two whitefly biotypes. Both whitefly biotypes were able to acquire viruses from infected plants and retained them in their bodies, but were unable to transmit them to either tobacco or tomato plants. However, when the Q biotype fed on tobacco plants infected with TYLCCNV, its fecundity and longevity were increased by 7- and 1-fold, respectively, compared to those of the Q biotype fed on uninfected tobacco plants. When the ZHJ2 biotype fed on virus-infected plants, its fecundity and longevity were increased by only 2- and 0.5-fold, respectively. These data show that the Q biotype acquired higher beneficial effects from TYLCCNV-infection of tobacco plants than the ZHJ2 biotype. Thus, the Q biotype whitefly may have advantages in its invasion and displacement of the indigenous ZHJ2 biotype.
基金supported by NSF BREAD IOS:1109989,USDA-NRI 2007-04567,NSFDBI-0606596USDA-ARS 764 CRIS projects1907-101-16,1907-21000-024/25-00DNIH/NCRR funded Yeast Resource Center P41RR01182
文摘Plant viruses in the families Luteoviridae and Geminiviridae are phloem restricted and are transmitted in a persistent,circulative manner by homopteran insects.Using fluorescence 2-D difference gel electrophoresis to compare the proteomes of F2 genotypes of Schizaphis graminum segregating for virus transmission ability,we recently discovered a panel of protein biomarkers that predict vector competency.Here we used aphid and whitefly nucleotide and expressed sequence tag database mining to test whether these biomarkers are conserved in other homopteran insects.S.graminum gene homologs that shared a high degree of predicted amino acid identity were discovered in two other aphid species and in the whitefly Bemisia tabaci.Selected reaction monitoring mass spectrometry was used to validate the expression of these biomarkers proteins in multiple aphid vector species.The conservation of these proteins in multiple insect taxa that transmit plant viruses along the circulative transmission pathway creates the opportunity to use these biomarkers to rapidly identify insect populations that are the most efficient vectors and allow them to be targeted for control prior to the spread of virus within a crop.
基金funded by the Department for Interna-tional Development,UK(DFID project codes R6627,R7460,R8247(Crop Protection Programme)and Phase Ⅲ of the International Whitefly Project)
文摘Research carried out to assess the impact of open-pollinated Tomato leaf curl virus（ToLCV）-resistant tomatoes and hybrids on the livelihoods of resource-poor farmers in Southern India is described and discussed.Three high-yielding ToLCV-resistant tomato varieties were developed initially using conventional breeding and screening techniques involving inoculation by ToLCV-viruliferous whitefly,Bemisia tabaci.In 2003 and 2004,respectively,these varieties were released officially by the Karnataka State Seed Committee and the Indian Ministry of Agriculture through notification in the Gazette of India.From 2003 to 2005,eleven seed companies bought breeder seed of the ToLCV-resistant varieties and used them to begin breeding F1 hybrids from them.Socio-economic studies carried out to assess the benefits obtained from growing the ToLCV-resistant varieties found that farmers could gain up to 10 times the profit by growing the ToLCV-resistant varieties compared to the pre-existing ToLCV-susceptible varieties.Adoption of ToLCV-resistant tomatoes was also associated with reduced pesticide use.Extra income from tomato sales was prioritised by farmers to pay for children＇s education,better nutrition and medicines.In a joint effort with the commercial seed sector in India,a promotional field day was organised in 2007.As well as the three ToLCV-resistant varieties,62 ToLCV-resistant hybrid tomatoes were exhibited during a farmer-field day by 17 commercial seed companies and several public institutes.Tomatoes with ToLCV-resistance are now grown widely in South India and seeds of the three open-pollinated varieties have been distributed to more than 12 countries.In 2007,a conservative estimate of the financial-benefit to cost of the research ratio was already more than 837：1.
基金Department of Biotechnology, Government of India for liberal funding (Functional Genomics of Yellow Mosaic Viruses of Soybean and Development of Transgenic Resistance in Soybean: BT/PR9631/AGR/02/468/2007)
文摘Bemisia tabaci is a cryptic species complex, causing signiifcant loss on many agricultural y important crops worldwide. Knowledge on species composition and diversity within B. tabaci complex is critical for evolving sustainable pest management strategies. Here we investigate the whitelfy species complex in soybean in major soybean growing states of India. The mitochondrial cytochrome oxidase gene subunit-1 (mtCOI) based phylogenetic relationships established using Bayesian methods indicated the existence of three cryptic species namely Asia I, Asia II 1, and Asia II 7. Al the haplotypes detected in the study could be assigned to these three cryptic species fol owing the species demarcation criteria of 3.5%divergence threshold. Of these, Asia II 1 was found to be predominant with wide spread distribution across the surveyed regions from cool temperate zones to hot and humid tropical plains. On the contrary, cryptic species Asia II 7 showed localized distribu-tion. The Asia II 1 exhibited the highest haplotype diversity and Asia I showed high level of nucleotide diversity. There was a signiifcantly high genetic differentiation among these three cryptic species. The MEAM 1, a dreadful invasive species was not detected in the specimens tested in the current study. The diversity and distribution of three cryptic species is discussed in the light of current knowledge on distribution of whitelfy species in India and yel ow mosaic disease observed during sampling survey.
文摘Okra is one of the most widespread vegetable crops in the world, particularly in West Africa. However, several factors influence okra crops as biotic and abiotic factors. Among the diseases affecting its culture, okra leaf curl disease is a major threat. This study aims to assess begomoviruses from okra plants with symptoms like leaves curl by molecular approach. A total of thirteen serologically positive samples were tested by PCR assay, and one sample was sequenced among them. The begomovirus was found in six isolates, Bhendi yellow vein mosaic virus (BYVMV) in three isolates, and Okra enation leaf curl virus (OELCuV) in three isolates, respectively. The begomovirus isolate sequences shared 90% identity with the Cotton leaf curl Gezira virus. Mixed infections between these viruses were found. Thus, these results highlight the need to monitor the spread of these disease-causing viruses for okra crops in Mali. In addition, they can also lead to a considerable loss in okra fields in Koulikoro, which is an agricultural region by excellence.
文摘Cassava mosaic disease (CMD) caused by the whitefly-transmitted Begomoviruses (family Geminiviridae) is a major threat to production of cassava (Manihot esculenta Crantz) in Togo. Survey was conducted in 2020 in the 5 agroecological zones of Togo to assess the status of East African cassava mosaic virus (EACMV), East African cassava mosaic Cameroon virus (EACMCMV) and its distribution. Polymerase chain reaction (PCR) and Sanger sequencing were used for the detection of cassava mosaic Begomoviruses (CMBs) in the sampled leaves. The incidence of EACMV was 47.93% (278/580) and varied between 41.30% (Zone V) and 62.29% (Zone IV) across the agroecological zone but no significant difference was observed. The EACMCMV incidence was 13.67% (38/278) and varied significantly (p ≤ 0.001) through the agroecological zone. Phylogenetic analysis of the viral isolates showed that they are closely related to those from Nigeria, Ghana, and Ivory coast. Nucleotide sequence analysis of CP revealed an overall genetic diversity (π) of around 3.4%. These results showed that EACMV was the predominant virus and that EACMCMV incidence could be more widespread in Togo.
基金This work was supported by International Foundation of Science(IFS)research grant C/5596-1 to K.A.Dansou-Kodjoand by West African Virus Epidemiology for Togo(WAVE-UL)project.
文摘Cassava mosaic disease caused by the whitefly-transmitted begomoviruses (family Geminiviridae) is a major threat to cassava (Manihot esculenta Crantz) production, which can be intercropped with other plants such as pepper (Capsicum annuum L.). The aim of this study is to identify cassava begomoviruses on other crops in cassava intercropping systems. Thus, foliar samples showing typical symptoms of virus diseases in cassava intercropping systems were collected from pepper and submitted to PCR analysis and direct sequencing. Three begomovirus species ACMV, EACMV and ALCCMV were identified and characterized in samples. Isolates of these species shared respectively 90% - 93%, 74% and 80% nucleotide identities with begomoviruses. These findings show that cassava begomoviruses can infect other crops and will help in understanding the epidemiology related to whitefly-transmitted begomoviruses in cassava intercropping systems.
基金supported by a grant from the U.S.Agency for International Development,Middle East Research and Cooperation(MERC)program(M36–015).
文摘The simplicity of Tomato yellow leaf curl virus(TYLCV)genome,encoding six proteins only,contrasts with the complexity of its impact on tomato plants.In this review,we discuss our understanding of how TYLCV proteins establish infection,and how the virus suppresses the effects of several abiotic stresses.TYLCV counteracts cell death induced by other factors,such as inactivation of HSP90 functions.Suppression of plant death is associated with the inhibition of the ubiquitin 26S proteasome degradation and with a deactivation of the heat shock transcription factor HSFA2 pathways.In order to ensure its own life cycle and spread,TYLCV protects the infected host from various unfriendly stresses,and this property can be exploited to protect crops from environmental stresses.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.XDJK2017A006).
文摘A novel monopartite begomovirus was found in naturally infected Conyza canadensis plants exhibiting typical begomovirus-induced yellow vein symptoms in Yunnan Province of China.Analysis of two obtained full-length viral genome sequences showed that they shared 99.8%nucleotide(nt)sequence similarity,and both consisted of 2733 nts(GenBank accession no.OK120264 and OK120266,respectively).Further analysis showed that these two sequences shared the highest nt sequence similarity(78.9%)with tomato yellow leaf curl Vietnam virus(TYLCVV)(EU189150).In the assayed C.canadensis plants,a betasatellite of 1,341 nts(Accession no.OK120265 and OK120267,respectively)was also found,and it shared 98.1%sequence similarity with malvastrum yellow vein betasatellite(MaYVB)(JX679254).Based on the current classification criteria for begomoviruses,we consider that the two obtained viral isolates are a novel begomovirus,and named it as conyza yellow vein virus(CoYVV).Our further analysis result showed that CoYVV is likely originated from a recombination event between tomato yellow leaf curl Yunnan virus(TYLCYnV)and tomato yellow leaf curl China virus(TYLCCNV).To investigate the effect of CoYVV infection in plant,we constructed two infectious clones(i.e.,pCoYVV and pMaYVB),and inoculated them individually or together to Nicotiana benthamiana plants through agro-infiltration.The result showed that the plants co-inoculated with CoYVV and MaYVB developed yellow vein and downward leaf-curling symptoms,whereas the plants inoculated with CoYVV alone showed no clear virus-like symptoms.Virus infection in the inoculated N.benthamiana plants was confirmed through polymerase chain reaction(PCR).The result of quantitative PCR(qPCR)showed that in the presence of MaYVB,the accumulation level of CoYVV DNA was significantly increased compared to that in the plants infected with CoYVV alone.
