Nucleotide sequence and genome characterization of rice yellow mottle virus RNA.

The genome of rice yellow mottle virus (RYMV) is a single-stranded positive-sense RNA that is not polyadenylated, and has an M(r) of 1.4 x 10(6). We present here the 4550 nucleotide (nt) sequence of RYMV RNA, and its predicted genomic organization. The RYMV genomic RNA contains four open reading frames (ORFs). The first (nt 80 to 553) encodes a protein containing 157 amino acids with a predicted M(r) of 17.8K. No function has yet been attributed to this product. ORF2 (nt 608 to 3607) encodes a polyprotein of 999 amino acids, with a predicted M(r) of 110.7K. The first 134 amino acids of ORF2 are predicted to be the genome-linked protein, VPg, followed by the viral protease, the helicase and the RNA-dependent RNA polymerase. ORF3 is within the boundaries of ORF2 and is predicted to encode a polypeptide with 126 amino acids and an M(r) of 13.7K. No function has yet been attributed to this protein. ORF4 (nt 3447 to 4166), which overlaps the 3' terminus of ORF2, encodes a 26K protein. This polypeptide has been identified as the RYMV coat protein. The data presented here confirm that RYMV belongs to the sobemovirus group and thus is a member of the picorna-like family of plant viruses.