Geographic Distribution Of Geminiviruses In Yunnan And Its Effect On The Disease Occurrence And Damage

Whitefly-Transmitted Geminiviruses (WTGs), which are belong to the family Geminiviridae that they are single-stranded circular DNA viruses causing economically significant diseases in a wide range of plant worldwide especially in tropic and subtropics area. The populations of WTGs have obvious character of geographic distribution, that is to say, different population distribution in different regions. The distribution of WTGs is intermittent rather than continuity, because of the segregation of high mountain and clough in Yunnan, a high-risk region. This paper is on the distribute character of the population of WTGs in different regions, which influence on the occurrence and prevalence of WTGs and its mechanism, and on the genetic diversity of the inter-specific and intraspecific of WTGs analysis.On the base of system survey and sampling at 4 different distribution areas of WTGs in Yunnan, the complete genome sequences of 42 WTGs isolates were amplified, cloned, and sequenced. Sequence analysis showed these 42 WTGs isolates were belonged to 13 species of the genus Begomovirus.They were Tomato yellow leaf curl China virus (TYLCCNV), Pepper leaf curl Yunnan virus(PeLCYnV),Crassocephalum yellow vein virus(CYVV),Tobacco leaf curl Yunnan virus(TbLCYnV),Tobacco curly shoot virus(TbCSV), Alternanthera yellow vein virus(AlYVV), Malvastrum yellow vein virus(MYVV), Malvastrum yellow vein Yunnan virus(MYVYnV), Squash leaf curl China virus(SLCCNV), Sweet potato leaf curl vzrus(SPLCV), Ageratum yellow vein China virus(AYVCNV), Ageratum yellow vein virus(AYVV), Tomato yellow leaf curl Thailand virus(TYLCTHV). It was first reported a new begomovirus species, Pepper leaf curl Yunnan virus, and a new record species of Crassocephalum yellow vein virus in China.There are four regions with obvious character of WTGs specifics in Yunnan.Ⅰ:Tomato yellow leaf curl China virus (TYLCCNV) is the dominant species in north area that is hot and dry, and there were 4 specieses in this area.Ⅱ:TYLCCNV is also the dominant species in south-central Yuanjiang—Honghe watershed, and Pepper leaf curl Yunnan virus (PeLCYnV) is the secondly dominant species,and there were 4 specieses in this area.Ⅲ:There were 4 species identified and obtained DNA-A complete gene sequence in west area that hot and damp. Sweet potato leaf curl virus(SPLCV) is the dominant species. IV:Tobacco leaf curl Yunnan virus(TbLCYnV) and Tobacco curly shoot virus(TbCSV) are dominant species in south Lancangjiang watershed., and there were 4 specieses in this area.The distinct species full-length DNA-A of Begomoviruses in Yunnan were very different. They were only shared 21% identities and were characterized by geographical areas.The complete nucleotide sequences of TYLCCNV in Yunnan shared 83.2%-99.9% identities, and 95.6% nucleotide sequence identity with TYLCCNV-[Guangxi]. Phylogenetic analysis indicated that TYLCCNV isolates from different region had heavily geographical difference. The isolates in different locations were separated the different branches, the closer adjacency, the higer similarity, for example, Dali and Lijiang.Species and population structure of WTGs have obvious characters of geographic distribution in four different regions.The dominant species, TYLCCNV, had minor variations in north area. They harmed mainly tomato crops, while TYLCCNV has obvious nucleotide polymorphism in south central area. They could infect several crops, such as tomatos, pepperes, tobacco and so on. The WTGs virus specieses are abundant diversity in west damp heat climate type and south Lancangjiang watershed, for these areas have suitable climate and rich virus specieses, and is near south Asia and Southeast Asia, the high-risk regions. And these conditions may generate virus species with high pathogenicity and widely host range. On the basis of study, the occurrence of WTGs diseases devoloped a more serious condition in four different distribution areas of Yunnan. The Species and population structures have changed in different annual. These areas are key point and difficulty monitor areas of the WTGs, and to enhance the monitoring and prevention of WTGs is needed.