Molecular characterization of a distinct begomovirus infecting tobacco in Yunnan, China.

Virus isolate Y3V, obtained from tobacco showing leaf curl symptoms in Yunnan, China, had particles with the size and morphology typical of geminiviruses. In reactions with a set of monoclonal antibodies raised against begomoviruses, Y3V was readily differentiated from two previously studied Chinese Begomovirus isolates. The complete nucleotide sequence of a DNA-A-like molecule of Y3V was determined; it comprises 2744 nucleotides and has a typical Begomovirus genome organization. When compared with the DNA-A sequences of other begomoviruses, the total DNA-A of Y3V was most closely related to that of Ageratum yellow vein virus (AYVV) (85% sequence identity), but the Y3V intergenic region differed greatly from those of the other sequences (maximum 70% identity). In contrast, the deduced coat protein of Y3V is most like that of Tomato yellow leaf curl Thailand virus-[1] (TYLCTHV-[1]) (92% amino acid sequence identity). The molecular data show that the Yunnan isolate of Tobacco leaf curl virus is a distinct Begomovirus species, for which the name Tobacco leaf curl Yunnan virus (TLCYnV) is proposed.