cDNA cloning and sequence analysis of the 3′-terminal region of zucchini yellow mosaic virus RNA

The 3′ half of the RNA of the cucurbit potyvirus zucchini yellow mosaic virus (ZYMV) was genetically cloned and the cDNA sequence of a portion of the putative RNA polymerase gene, the complete coat protein gene and the 3′ untranslated region was determined. The coat protein and putative polymerase genes are both part of a continuous open reading frame as is the case for other potyviruses whose genomes are expressed as polyproteins. The Q/S protease cleavage site for the N terminus of the coat protein was deduced by alignment of the coat protein and polymerase genes with other potyviral sequences. The resulting protein has 279 amino acids and a calculated M r of 31 214. The predicted amino acid sequence indicates a ZYMV-unique N-terminal region and potyvirus-characteristic central and C-terminal regions. These data also verify that ZYMV is distinct from the cucurbit potyvirus watermelon mosaic virus 2.