Genetic diversity of sweet potato feathery mottle vims from sweet potatoes in Korea

Sweet potato feathery mottle virus (SPFMV) is one of the most prevalent viruses infecting sweet potatoes and occurs widely in sweet potato cultivating areas in Korea. To assess their genetic variation, a total of 28 samples infected with SPFMV were subjected to restriction fragment length polymorphism (RFLP) analysis using DNAs amplified by RT-PCR with specific primer sets corresponding to the coat protein (CP) region of the virus. The similarity matrix by UPGMA procedure indicated that 28 samples infected with SPFMV were classified into three groups based on the number and size of DNA fragments by digestion of CP-encoding regions with 7 enzymes including Sail, Alul, EcoRI, HindOl, FokI, Sau3Al, and Dral bands. Four primer combinations out of 5 designed sets were able to differentiate SPFMV and sweet potato virus G infection, suggesting that these specific primers could be used to differentiate inter-groups of SPFMV. Sequence analysis of the CP genes of 17 SPFMV samples were 97-99% and 91-93% identical at the intra-group and intergroups of SPFMV, respectively. The N-terminal region of the CP is highly variable and examination of the multiple alignments of amino acid sequences revealed two residues (residues 31 and 32) that were consistently different between SPFMV-O and SPFMV-RC.