Molecular Identification Of Double Virus On Tomato In Henan Province

Geminiviruses, encapsidated in twinned ieosahedral particles, are plant virusescharacterized by having small circular single-stranded DNA genomes. Several kinds ofgeminiviruses have been detected in many crops such as tomato, tobacco and poinsettiain Yunnan, Guangxi and Guangdong provinces. Geminiviruses have a wide host rangeand their genomes evolve very fast. In order to provide a better understanding of thediversity, evolution and spread of geminiviruses,59samples showing typiclegeminivirus symptoms were collected from tomato in12places (Luoyang, Kaifeng,Xinxiang, Anyang, Nanyang, Xinyang, Zhumadian, shangqiu, Xuchang, Changge andSanmenxia) in Henan provinces during2012-2013. Geminiviruses in these sampleswere detected and identified with molecular technique. The main results are as follows:(1) Using universal primer pair PA/PB for the genus Begomovirus,36samplesconfirmed to be infected by geminiviruses with PCR detection in the59samplescollected. The total detectable rate was61%. That is to say, the36samples wereinfected by whitefly-transmitted geminiviruses. The partial DNA-A sequences sharedmore than99%homology with the isolates of TYLCV which were recorded in NCBI. Itcan be speculated that the geminiviruse infected in tomato plants in Henan province isTYLCV.(2) Nine isolates were then randomly chosen for complete DNA-A sequencesanalysis. The complete sequences of these isolates were determined to be2781nucleotides, have a typical genetic organization of a begomovirus. They shared morethan98.6%nucleotide sequence identity amony themselves. At the same time, theisolates shared more than98.7%nucleotide sequence identity with the isolate ofTYLCV-Israel Australia.(3) Phylogenetic analysis based on the complete DNA-A sequences showed that7isolates had close relationship with the virus of neighboring provinces. Thesegeminiviruses may be transmitted by the vector of whitefly. However, two isolates ofHNXC2and HNXY1had close relationship with the isolate of Xinjiang(TYLCV-KSCT016). Then, the two provinces are far apart in location, it can bespeculated that these geminiviruses were transmitted by the vegetables and seedlingswhich were infected by geminiviruses.(4)1.3kb fragments named DNAβ were amplified from the two samples ofChangge. The satellite DNAβ associated with HNCG consist of1347nts and share 90.0%nucleotide sequence identity of HNCG DNAβ associated with TYLCVV-DX2isolated from tomato plants in Vietnam. It’s the first time to find that the satellite DNAβmolecule associated with TYLCV.