Characterization of the coat protein mRNA of southern bean mosaic virus and its relationship to the genomic RNA.

RNA isolated from southern bean mosaic virions contains, in small amount, a subgenomic RNA (molecular weight, 0.38 x 10(6)) that serves in vitro as an mRNA for southern bean mosaic virus coat protein. The RNA has a 5'-linked protein indistinguishable from the protein linked to the 5' end of full-length genomic RNA. Its base sequence, determined to 91 bases from the 3' end, is identical to the 3'-terminal sequence of the genomic RNA. The results suggest that the coat protein messenger sequence exists as a "silent" cistron near the 3' end of the genomic RNA.