Taxonomy of cucurbit-infecting tobamoviruses as determined by serological and molecular hybridization analyses.

A number of cucurbit-infecting tobamoviruses have been reported in the past but there is confusion about their identity and relationships. Cucumber viruses 3 (CV3) and 4 (CV4) were originally described in the United Kingdom whereas the watermelon (W) and cucumber (C) 'isolates' of cucumber green mottle mosaic virus (CGMMV) came from Japan. The results of serological studies and RNA-cDNA analyses have shown that CV3, CV4 and CGMMV-W are very closely related, whereas CGMMV-C is quite different. It is concluded that there are two distinct tobamoviruses that infect cucurbits; they are only very remotely related to each other and to a number of other tobamoviruses. It is suggested that the name CGMMV be retained to include the isolates or strains CV3, CV4 and CGMMV-W, and that a new name, kyuri green mottle mosaic virus (KGMMV), be given to CGMMV-C.