RNA Secondary Structure and Sequence Variability of Apple Stem Pitting Virus

Nucleotide sequences of coat protein (CP) gene from 6 isolates of Apple stem pitting virus (ASPV) were obtained. Sequence analysis of CP gene showed nucleotide identities ranged from 68.7 to 99.7%. Phylogenetic analysis showed that all ASPV isolates fell into three groups. To a certain extent, the groups were related to the host origins of virus. The hypervariable and conserved region could be found in the CP gene. The variations of nucleotide sequence and predicted RNA secondary structure were analyzed for the CP gene, and the characteristic of RNA secondary structure of ASPV 5´ and 3´ untranslated region (UTR) were also studied. The result indicated that predicted RNA secondary structures could play an important role in studying the molecular variation of virus. The 3´ UTR of ASPV RNA was predicted to contain four stem-loop structures, and it was likely to imply that the variation of RNA secondary structure was related to groups of phylogenetic analysis.