Molecular characterization of two isolates of sweet potato leaf curl virus infecting Ipomoea indica in China
Morning glory (Ipomoea indica) plants showing yellow mosaic and vein yellowing symptoms were collected from Jiangsu and Yunnan province of China. The amplified DNA-A components of two isolates named JS1 and Y338 were comprised of 2827 and 2801 nucleotides, respectively, in length with genome organization similar to that of begomoviruses. Complete nucleotide sequence revealed the presence of two ORFs (AV1 and AV2) in the virion sense and four ORFs (AC1, AC2, AC3 and AC4) in the complementary sense. Comparison analysis showed that DNA-A sequence of JS1 isolate was closely related to that of sweet potato leaf curl virus (SPLCV) from United States with nucleotide sequence identity of 97.0% and DNA-A of Y338 showed highest sequence identity at 97.8% with an isolate of SPLCV from China. Phylogenetic analysis showed that JS1 clustered together with SPLCV-US and Y338 showed close relationship with SPLCV-CN. Sequence analysis indicated that isolates JS1 and Y338 were strains of SPLCV.
Key words: Sweet potato leaf curl virus, begomoviruses, Ipomoea indica, sequence comparison.