Amino acid changes in the coat protein of cucumber mosaic virus differentially affect transmission by the aphids Myzus persicae and Aphis gossypii.

Cucumber mosaic virus (CMV) transmission by two aphid species was investigated using strains of the virus with modified coat proteins. Chimeric viral RNA 3 cDNA constructs were designed with coat protein-encoding sequences from the efficiently aphid-transmitted Fny-CMV and the very poorly aphid-transmitted M-CMV. Different regions of the viral coat protein variably influenced transmission; the magnitude of effects depended on the aphid species used as vector. Five amino acid changes in the coat protein of M-CMV (positions 25, 129, 162, 168, and 214) were required to restore efficient transmission by Myzus persicae. This contrasts with previously demonstrated, more limited changes required for restoration of transmission by Aphis gossypii. A construct with modified amino acids 129, 162, and 168 was efficiently transmitted by A. gossypii, while remaining poorly transmissible by M. persicae. Transmission of Fny-CMV by single aphids of A. gossypii and M. persicae was 54.0% and 27.9%, respectively. Single coat protein amino acid changes in Fny-CMV dramatically reduced transmission by M. persicae, while showing little effect on transmission by A. gossypii.