Genetic variability and population structure of Grapevine virus A in China based on the analysis of its coat protein gene

摘要

In this study, reverse transcription PCR (RT-PCR) detection revealed a high infection rate of Grapevine virus A (GVA) in grapevine plants cultivated in China. Population structures of 14 GVA isolates from Chinese grapevines were studied by single-stranded conformation polymorphism (SSCP) of the coat protein (CP) gene. Results showed that while most isolates contained a population of sequence variants, with one being predominant, one isolate (AF) had three major variants, and two isolates (BSSL and BSBD) consisted of a number of sequence variants with almost the same detection frequencies. The estimation of genetic diversity intra isolates by sequence alignment analysis indicated a high variability in the CP gene and the occurrence of mixed infections in some grapevines by divergent sequence variants. RT-PCR analysis using variant-specific primers (H587/C995, GVA6591F/GVA6906R) and phylogenetic analyses of CP gene sequences suggested that all sequence variants from Chinese isolates were separated into two subgroups IA and IB in the group I.