[Molecular characteristics of DNA-A of tomato leaf curl Guangdong virus isolate G2]

Virus isolate G2 was isolated from tomato plants showing leaf curl symptoms in Guangdong. The complete nucleotide sequence of G2 DNA-A was determined to be 2744 nucleotides encoding six potential ORFs, with two (AV1 and AV2) in virus sense and four (AC1, AC2, AC3 and AC4) in complementary sense. G2 DNA-A has a typical characteristics of Begomovirus genome organization. BLAST results showed that G2 DNA-A belonged to the Begomovirus of Geminiviridae. Pairwise comparisons of G2 DNA-A with those of other 41 begomoviruses indicated that G2 DNA-A was most closely related to that of Papaya leaf curl China virus isolate G10 (PaLCuCNV-[G10]) (82.8% sequence identity). The intergenic region (IR) of G2 differed to great extent with other begomoviruses (30.9%-81.8% nucleotide sequence identity); when individual encoded proteins were compared, the CP of G2 had relatively high amino acid sequence identity (77.6%-99.2%) with other begomoviruses whereas the AC4 of G2 had less amino acid sequence identity (43.5%-78.8%). Phylogenetic analysis based on the DNA-A sequences also showed that G2 was less related to the reported begomoviruses. These results revealed that G2 infecting Guangdong tomato might be a previously unreported species of Begomovirus, for which the name Tomato leaf curl Guangdong Virus (ToLCGDV) is proposed.