Biological and Molecular Characterization of Cucumber mosaic virus Isolate Causing Shoestring Disease of Tomato in India which has Closer Affinity to European or East Asian Isolates of CMV

An isolate of Cucumber mosaic virus (CMV) retrieved from tomato in India was characterized based on its transmission by sap inoculations, Western blot immuno-assay and sequence analysis of RNA3 and 2b genome. The RNA3 genome was of 2,220 nucleotides (nt) which contained two ORFs: movement protein of 852 nt translating 283 amino acids and coat protein of 657 nt translating 218 amino acids. The complete sequence of RNA3 geneome (Acc. EF153734) shared highest 98–99% identities with P1-1, Tfn, and Nt9 strains of CMV infecting tomato reported from abroad. The 333 nucleotides long RNA2b gene (Acc. EF710773) also showed highest 98% identities with P1-1 and 97% with Tfn and NT9 strains of CMV but only 83–84% identities with Indian strains of CMV. Therefore, the isolate under study was identified as a new isolate of CMV of subgroup IB based on highest sequence similarities and closer affinity to European or East Asian isolates of CMV.