Complete nucleotide sequence of Oat necrotic mottle virus: a distinct Tritimovirus species (family Potyviridae) most closely related to Wheat streak mosaic virus.

The RNA genome (9346 nucleotides) of Oat necrotic mottle virus (ONMV) was cloned and sequenced. Complete genome comparisons indicated that ONMV, currently classified as a rymovirus, was most closely related ( approximately 73% nucleotide, approximately 79% amino acid identity) to the tritimovirus Wheat streak mosaic virus (WSMV). ONMV encoded a single polyprotein, with proteinase cleavage sites very similar to those of WSMV. Pairwise comparison of ONMV and WSMV cistrons revealed that P3 was most conserved ( approximately 79% nucleotide, approximately 86% amino acid), whereas HC-Pro was most divergent ( approximately 67% nucleotide, approximately 69% amino acid). In contrast, the ONMV sequence was distantly related ( approximately 40% nt, approximately 26% amino acid identity) to that of the rymoviru s Ryegrass mosaic virus, with highest sequence conservation noted within the NIb cistron ( approximately 47% nucleotide, approximately 41% amino acid identity). These results firmly establish that ONMV is not a rymovirus but is instead a distinct species of the genus Tritimovirus.