Sequence Analysis of the Genomic RNA 3ʹ-terminal Region of a Potyvirus from Brachiaria spp. Related to Gulneagrass Mosaic Virus

The 3ʹ terminal region ofthe genomic RNA of a potyvirus isolated from Brachiaria spp. which is related to guinea grass mosaic virus (GGMV), was compared to that of members of the sugarcane mosaic stibgroup of poty viruses. Reverse transcription-polymerase chain reaction (RT-PCR) of total nucleic acid extracted from infected B, brizantha resulted in the amplification of a DNA product of c, 0.9 kb. This product was cloned and sequenced; it has an open reading frame of 149 amino acid residues, and a 3ʹ untranslated region (UTR) of 474 nucleotides. Optimal alignments of the 3ʹ UTRs of the Brachiaria potyvirus and members of the sugarcane mosaic stibgroup of potyvirtises showed that it has nucleotide sequence similarities of c. Al, 46, 46, and 46% to maize dwarf mosaic virtis strain A, sugarcane mosaic virus strains SC and MDB, and sorghum mosaic virus strain SCH, respectively. It had higher nucleotide sequence similarities of c. 88, 89, and 92% with Johnsongrass mosaic virus (JGMV) strains MDO, MDKSl and JG, respectively. Analyses of the deduced amino acid sequence of the Brachiaria potyvirus coat protein fragment revealed a 97.3% similarity to the JG strain of JGMV to which it is serologically related. We propose that the Brachiaria potyvirus now be considered a strain of JGMV (designated JGMV-Brac).