Molecular characterization of viruses infecting canna in Russia

Canna yellow streak virus (CaYSV), Canna yellow mottle virus (CaYMV), Bean yellow mosaic virus (BYMV), and Cucumber mosaic virus (CMV) were detected by reverse transcription-polymerase chain reaction in 16 local and introduced canna cultivars grown in the collection of the Nikita Botanical Gardens, Crimea. CaYSV was detected in all the cultivars tested, and most of the cultivars had mixed infection with two or three viruses. Analysis of the 3′-terminal genomic sequences revealed a high degree of diversity among isolates of CaYSV and BYMV suggesting their multiple introductions in the Gardens. Phylogenetic analysis of the coat protein (CP) gene showed that all the Crimean BYMV isolates together with the Chinese and the Indian ones from canna formed a separate cluster of canna-adapted isolates. Unique amino acid substitutions at positions 58, 70, 106, 168 and 215 of the CP were found in all isolates from canna that may be relevant to the adaptation of BYMV to this host. The sequences of the CaYMV isolates were highly conserved. The sequence identities of their ORF3 genomic segment ranged from 98.7–100% and from 97.7–100% at the nucleotide and amino acid levels, respectively. The CMV isolate was most closely related to the isolate Fny (D10538) from muskmelon. This is the first report of CaYSV, CaYMV, BYMV and CMV on canna in Russia confirming their worldwide distribution on this culture.