The coat protein of Tomato mosaic virus L11Y is associated with virus-induced chlorosis on infected tobacco plants

The L11Y strain of Tomato mosaic virus (ToMV) causes severe chlorosis on infected tobacco leaves. Sequencing analysis for the genome showed that L11Y contained multiple nucleotide changes and that some led to amino acid substitutions, when compared with that of the common L strain of ToMV. The chimeric virus, which has the CP of L11Y in the context of the L strain RNA genome, caused severe chlorosis on infected tobacco plants, suggesting that the CP of L11Y containing three amino acid changes (E33S, A86T and E97K) was the determinant of the chlorosis. Two of these amino acid changes (A86T and E97K) were associated with the induction of chlorosis when present together in the CP. Severe destruction and deformation of chloroplasts and the formation of discrete dark-staining materials adjacent to chloroplasts were observed with electron microscopy in L11Y-infected plants. Fewer virus particles accumulated in the cytoplasm of L11Y-infected plant cells. The level of accumulation of CP subgenomic RNA and CP in the infected protoplasts was similar between L and L11Y. Fewer virus particles accumulated in L11Y-infected protoplasts, and many of them were shorter-than-full-length.