[Genomic characterization of tomato yellow leaf curl China virus and its associated satellite DNA infecting tobacco in Guangxi].

The virus isolates G102 and G103 were collected from tobacco showing leaf curl symptoms in Jingxi, Guangxi Province. A 0.5kb fragment was obtained by PCR using primers specific to geminivirus genome. The nucleotide sequence identity of the partial DNA-A sequence between the two isolates was over 99%. The complete DNA-A sequence of G102 was determined to be 2728 nucleotides. Comparisons showed that the DNA-A of G102 had the highest sequence identity (96.5%) with that of Tomato yellow leaf curl China virus (TYLCCNV). Further studies showed that both G102 and G103 were associated with satellite DNA molecules (DNAbeta). Sequence analysis revealed that DNAbeta of G102 and G103 contained 1342nt and they shared the highest sequence identities (92.9% and 93.4%, respectively) with that of TYLCCNV. This is the first report that TYLCCNV isolates in Guangxi were also associated with satellite DNA molecules. The previously results demonstrated that all 25 TYLCCNV isolates collected in Yunnan province were associated with DNA beta molecules. The finding that TYLCCNV isolates collected in Guangxi province were also associated with DNA beta molecules gives further evidence that TYLCCNV isolates are associated with DNA beta molecules in nature.