Sequence analysis and genetic diversity of five new Indian isolates of cucumber mosaic virus

Cucumber mosaic virus (CMV) is an important virus since it causes severe losses to many economically important crops worldwide. Five new isolates of CMV were isolated from naturally infected Hippeastrum hybridum, Dahlia pinnata, Hemerocallis fulva, Acorus calamus and Typhonium trilobatum plants, all exhibiting severe leaf mosaic symptoms. For molecular identification and sequence analyses, the complete coat protein (CP) gene of these isolates was amplified by RT-PCR. The resulting amplicons were cloned and sequenced and isolates were designated as HH (KP698590), DP (JF682239), HF (KP698589), AC (KP698588) and TT (JX570732). For study of genetic diversity among these isolates, the sequence data were analysed by BLASTn, multiple alignment and generating phylogenetic trees along with the respective sequences of other CMV isolates available in GenBank Database were done. The isolates under study showed 82-99% sequence diversity among them at nucleotide and amino acid levels; however they showed close relationships with CMV isolates of subgroup IB. In alignment analysis of amino acid sequences of HH and AC isolates, we have found fifteen and twelve unique substitutions, compared to HF, DP and TT isolates, suggesting the cause of high genetic diversity.