Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2009
Publication Date: February 3, 2010
Repository URL: http://hdl.handle.net/10113/41308
Citation: Tatineni, S., Graybosch, R.A., Hein, G.L., Wegulo, S.N., French, R.C. 2010. Wheat Cultivar-Specific Disease Synergism and Alteration of Virus Accumulation During Co-Infection with Wheat Streak Mosaic Virus and Triticum Mosaic Virus. Phytopathology, volume 100, pages 230-238. Interpretive Summary: Wheat streak mosaic virus (WSMV) is the most important virus negatively impacting wheat production in the Great Plains region. Recently, a new wheat virus, Triticum mosaic virus (TriMV), distinct from WSMV, reported from Kansas and Nebraska and is present in the most of the Great Plains region. Both viruses transmitted by a common vector, the wheat curl mite and co-transmission of both viruses may contribute to double infections in wheat. In this study, we examined the effects of WSMV and/or TriMV on two susceptible wheat cultivars, Arapahoe and Tomahawk and a resistant cultivar, Mace at two different temperatures (19ºC and 20-26ºC). At both temperatures, double infections in wheat cvs. Arapahoe and Tomahawk induced more severe symptoms than those of single infections. Double infections resulted in more virus particles of WSMV and TriMV in Arapahoe and Tomahawk than single infections, which may lead to be higher mite transmissions from doubly infected plants (more virus particles=more mite transmissions). In contrast, both viruses poorly replicated in Mace at 19ºC and double infections failed to induce disease synergism. However, WSMV and/or TriMV replicated moderately in Mace at 20-26ºC (~50% of Tomahawk and Arapahoe) and induced delayed, mild to moderate disease synergism in doubly infected plants. Our study implies that damage and yield loss caused by co-infection by both viruses is likely to be more severe in susceptible cultivars and cultivar selection will be an important management strategy for the WSMV/TriMV disease complex in wheat.
Technical Abstract: Triticum mosaic virus (TriMV), the type member of the newly proposed Poacevirus genus and Wheat streak mosaic virus (WSMV), the type member of Tritimovirus genus of the family Potyviridae, infect wheat naturally in the Great Plains and are transmitted by wheat curl mites. In this study, we examined the ability of these viruses to infect selected cereal hosts, and found several differential hosts between TriMV and WSMV. Additionally, we examined the interaction between WSMV and TriMV in three wheat cultivars at two temperature regimens (19ºC and 20-26ºC), and quantified the virus concentration in single and double infections by real-time RT-PCR. Double infections in wheat cultivars Arapahoe and Tomahawk at both temperature regimens induced disease synergism with severe leaf deformation, bleaching effect, and stunting with a 2.2 to 7.4-fold increase in accumulation of both viruses over single infections at 14 days postinoculation (dpi). However, at 28 dpi, in double infections at 20-26ºC, TriMV concentration was increased by 1.4 to 1.8-fold in Arapahoe and Tomahawk, but WSMV concentration was decreased by 0.5-fold. WSMV and/or TriMV replicated poorly in Mace at 19ºC with no synergistic interaction whereas both viruses accumulated at moderate levels at 20-26ºC and induced mild to moderate disease synergism in doubly infected Mace when compared to Arapahoe and Tomahawk. Co-infections in Mace at 20-26ºC caused increased TriMV accumulation at 14 dpi and 28 dpi by 2.6- and 1.4-fold, and WSMV accumulated at 0.5- and 1.6-fold over single infections, respectively. Our data suggest that WSMV and TriMV induced cultivar-specific disease synergism in Arapahoe, Tomahawk and Mace, and these findings could have several implications on management of wheat viruses in the Great Plains.