Distribution and genetic diversity of tomato-infecting begomoviruses in Guangxi, China

ObjectiveThe present study investigated virus species,distributions,and mixed-infections of tomato-infecting begomoviruses in Guangxi,in order to provide theoretical support for tomato breeding and rational distribution of tomato anti-virus variety.MethodSince 2011,the study have investigated and identified begomoviruses which caused tomato yellow leaf curl disease (TYLCD) in Guangxi,and collected 189 samples with typical symptoms of begomoviruses infection.Total DNA were extracted and all the samples were detected using degenerate primers of begomoviruses.PCR products of positive samples were selected,purified and sequenced after linking to clone vector.The sequences were compared to those in GenBank.Virus isolates from different places were selected,full-length amplification and detection of these isolates were conducted.The researchers also established phylogenetic trees to study their evolutionary relationships and genetic diversity.ResultAccording to PCR detection,there were 139 positive samples out of 189 tomato samples,positive rate being 73.54%.Typical tomato samples were selected and sequenced,four kinds of begomoviruses that caused TYLCD in Guangxi were found:Tomato leaf curl China virus,Papaya leaf curl China virus,Tomato yellow leaf curl China virus and Ageratum yellow vein China virus.Complicated mixed infections were detected in the samples and at least seven types of mixed infections were found.Forty-seven full DNA-A sequences of virus isolates were obtained.Phylogenetic tree analysis indicated that virus isolates from the same region belonged to the same sub-clade,and showed rich genetic evolutionary relationship.ConclusionAfter investigation and identification,four kinds of tomato-infecting begomoviruses are found existing in Guangxi.They are widely distributed in major tomato planting regions in Guangxi,and complicated mixed infections occur among them.Certain kinds of tomatoinfecting begomoviruses distribute in certain regions.