Protection against cucumber mosaic virus (CMV) strains O and Y and chrysanthemum mild mottle virus in transgenic tobacco plants expressing CMV-O coat protein.

Transgenic tobacco expressing the coat protein (CP) of cucumber mosaic virus strain O (CMV-O) showed a significant level of protection against CMV strains O and Y. When inoculum concentrations were increased, the transformants showed a stronger level of protection against CMV-O than against CMV-Y. The substitution of an amino acid residue between CMV-O and CMV-Y, which is presumed to change the conformation of CP, may reflect the difference in susceptibility to these viruses. Furthermore the transgenic tobacco plants showed a significant level of protection against chrysanthemum mild mottle virus, a member of the cucumovirus group but with no serological relationship to CMV.