Triticum mosaic virus: a distinct member of the family potyviridae with an unusually long leader sequence.

The complete genome sequence of Triticum mosaic virus (TriMV), a member in the family Potyviridae, has been determined to be 10,266 nucleotides (nt) excluding the 3' polyadenylated tail. The genome encodes a large polyprotein of 3,112 amino acids with the "hall-mark proteins" of potyviruses, including a small overlapping gene, PIPO, in the P3 cistron. The genome of TriMV has an unusually long 5' nontranslated region of 739 nt with 12 translation initiation codons and three small open reading frames, which resemble those of the internal ribosome entry site containing 5' leader sequences of the members of Picornaviridae. Pairwise comparison of 10 putative mature proteins of TriMV with those of representative members of genera in the family Potyviridae revealed 33 to 44% amino acid identity within the highly conserved NIb protein sequence and 15 to 29% amino acid identity within the least conserved P1 protein, suggesting that TriMV is a distinct member in the family Potyviridae. In contrast, TriMV displayed 47 to 65% amino acid sequence identity with available sequences of mature proteins of Sugarcane streak mosaic virus (SCSMV), an unassigned member of the Potyviridae. Phylogenetic analyses of the complete polyprotein, NIa-Pro, NIb, and coat protein sequences of representative species of six genera and unassigned members of the family Potyviridae suggested that TriMV and SCSMV are sister taxa and share a most recent common ancestor with tritimoviruses or ipomoviruses. These results suggest that TriMV and SCSMV should be classified in a new genus, and we propose the genus Poacevirus in the family Potyviridae, with TriMV as the type member.

Response of Soybean Cultivars to Bean pod mottle virus Infection.

Bean pod mottle virus (BPMV) has become increasingly common in soybean throughout the north-central region of the United States. Yield loss assessments on southern soybean germplasm have reported reductions ranging from 3 to 52%. Currently, no soybean cultivars have been identified with resistance to BPMV. The objective of this study was to determine the impact of BPMV infection on soybean cultivars representing a broad range of northern soybean germ-plasm by comparing inoculated and noninoculated soybean plants in paired row studies. In all, 30 and 24 cultivars were evaluated in Nebraska (NE) in which soybean plants were inoculated at the V3 to V4 growth stage. Eleven cultivars from public and breeding lines were inoculated at the VC and R5 to R6 growth stages in Ohio (OH). Disease severity, yield, and percent seed coat mottling were assessed at both locations, whereas protein and oil content also were assessed at NE. Yield and percent seed coat mottling was significantly reduced following inoculation at the VC (OH) and V3 to V4 (NE) growth stages. In addition, seed oil and protein composition were impacted in 1 of the 2 years of the study. This study demonstrates that substantial yield losses can occur in soybean due to BPMV infection. In addition, protein and oil may be affected depending on the environment during the production season.