Triticum mosaic virus: An overview of biology, functional genomics, gene expression vector, and management strategies.

Triticum mosaic virus (TriMV; Poacevirus tritici) is the founding member of the genus Poacevirus within the family Potyviridae. TriMV is one of the components of the wheat streak mosaic disease (WSMD) complex, an economically significant wheat disease in the Great Plains region of the USA. TriMV contains a single-stranded positive-sense RNA genome of 10,266 nts with an unusually long 5'-nontranslated region of 739 nts. TriMV is transmitted only by the Type-2 genotype of wheat curl mites (Aceria tosichella Keifer) and is mostly found as a co-infection with another wheat curl mite-transmitted wheat streak mosaic virus (WSMV). TriMV and WSMV synergistically interact in co-infected wheat with exacerbated disease symptoms. The development of an infectious cDNA clone and GFP or RFP-tagged stable expression vectors has advanced the functional genomics of TriMV, including virus-virus and virus-host interactions. NIa-Pro and CP, and P1 and NIa-Pro cistrons of TriMV are identified as elicitors of superinfection exclusion and determinants of synergistic interaction with WSMV, respectively. TriMV stably maintained P1 (1083 nts) plus NIa (1305 nts) cistrons of WSMV for more than 28 days postinoculation, suggesting that TriMV can be used as a stable gene expression vector in wheat. Because of the synchrony of the mites and viruses in this disease complex, primary management efforts should focus on the timing and presence of vector hosts. Importantly, an enhanced understanding of TriMV biology and its interactions with plants, mites, and WSMV will facilitate the development of effective tools to improve the sustainable management of the wheat-mite-virus complex.