WHEAT STREAK MOSAIC VIRUS INTERACTIONS WITH HOST AND VECTOR
Location: Grain, Forage & Bioenergy Research
Title: Triticum Mosaic Virus: A Distinct Member of the Family Potyviridae with an Unusually Long Leader Sequence
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 2009
Publication Date: July 13, 2009
Citation: Tatineni, S., Ziems, A.D., Wegulo, S.N., French, R.C. 2009. Triticum Mosaic Virus: A Distinct Member of the Family Potyviridae with an Unusually Long Leader Sequence. Phytopathology. 99:943-950.
Interpretive Summary: Triticum mosaic virus (TriMV) was first reported from Kansas in 2006, followed by Nebraska in 2008. During the 2008 growing season, ~30% of wheat samples submitted to the University of Nebraska-Lincoln Plant and Pest Diagnostic Clinic tested positive for TriMV. TriMV was transmitted by the wheat curl mites, similar to Wheat streak mosaic virus (WSMV). In this study, we determined the complete genome sequence of TriMV and found that TriMV is a distinct potyvirus infecting wheat in the Great Plains. Our analyses suggest that TriMV is different from WSMV, another economically important virus infecting wheat in the Great Plains. The availability of TriMV sequence will allow further studies on the development of diagnostic methods, study the life cycle of TriMV, interaction between TriMV and WSMV, and the development of strategies for the effective management of TriMV.
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 polyadenylated tail at the 3’ end. 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’-leader sequence of 739 nts with 12 translation initiation codons, which resemble those of the internal ribosome entry site containing 5’-leader sequences of the members of Picornaviridae. Pair-wise comparison of 10 putative mature proteins of TriMV with those of representative members of genera in the family Potyviridae revealed 33-44% amino acid identity with the highly conserved NIb protein sequence, and 15-29% amino acid identity with the least conserved P1 protein, suggesting that TriMV is a distinct member in the family Potyviridae. In contrast, TriMV displayed 47-65% amino acid sequence identity with known 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 CP sequences of representative species of six genera and unassigned members of the Potyviridae suggested TriMV and SCSMV are sister taxa and share the most recent common ancestors with tritimoviruses or ipomoviruses. These results suggest that TriMV and SCSMV should be classified in a new genus, and we propose the genus Trimovirus (Triticum mosaic virus) in the family Potyviridae with TriMV as the type member.