Nucleotide Sequence of the Coat Protein Gene and 3'-noncoding Region of a Japanese Isolate of WMV 2.

Potyvirus is a large and economically important group of plant viruses. Watermelon mosaic virus 2 (WMV 2), which belongs to the genus Potyvirus, is one of the serious pathogens in Cucurbitaceae. The genome of WMV 2 consists of a single-stranded, plus-sense RNA, and has a poly (A) tail at the 3•Œ end. We determined the nucleotide sequence of the 3•Œ-terminal region containing the complete coding region of the coat protein gene of a Japanese isolate of WMV 2. The Japanese isolate of WMV 2 (WMV 2-80) used in this work was described by Yamamoto et al.8) The virus was propagated in cucumber and purified according to the procedure previously described5). Viral RNA was extracted by the method described by Quemada et al.4) cDNAs were synthesized according to the method of Gubler and Hoffman3) using oligo dT primers and ligated into the PstI site of pBR 322. These cDNAs were subcloned into the PstI site of pBluescript II SK+ and different-sized cDNA clones were obtained. Among them, cDNA clones W17 and W46, both of which had inserts of approximately 1.7kb, were used for determination of nucleotide sequence. Nucleotide sequences of deletion clones obtained from the two cDNAs were determined by the dideoxy-chain termination method6) using the M13, M4 and RV primers with a DNA sequencer model 373A (Applied Bio Systems Co., Ltd.). Com-