Project Number: 5440-22000-024-00
Project Type: Appropriated

Start Date: Mar 14, 2012
End Date: Mar 13, 2017

Objective:
Objective 1: Elucidate the underlying mechanism of virus resistance in the resistant wheat variety Mace, its derivatives, and other sources to identify new disease-resistant lines with increased yield potential. Objective 2: Develop and evaluate transgenic wheat for disease resistance by expression of viral genome sequences in various forms. Objective 3: Define the role of Triticum mosaic virus proteins in semi-persistent transmission by the wheat curl mite, vector of both Wheat streak mosaic virus and Triticum mosaic virus. Objective 4: Identify and characterize Triticum mosaic virus gene functions, host interactions and rate of evolution, and strain differentiation during horizontal transmission.

Approach:
Wheat streak mosaic virus (WSMV) is common throughout the American Great Plains and is responsible for significant and recurring economic losses in wheat (losses over the past five years are estimated to average $460 million annually). Triticum mosaic virus (TriMV) is a recently emerged virus in the same geographic region and likely poses the same risks as WSMV. Wheat varieties with temperature-dependent genetic resistance to WSMV recently have become available. One wheat variety, Mace, is resistant to both WSMV and TriMV but the mechanism(s) of virus resistance is unknown. Knowledge of resistance mechanisms can suggest techniques for rapidly screening wheat lines for WSMV and TriMV resistance. New screening methods will be essential to track the Wsm1 resistance gene in wheat lines that have lost closely linked PCR markers. In addition, other sources of resistance to WSMV and TriMV to augment natural resistance and mitigate against the evolution of resistance-breaking strains of these viruses is desirable. Virtually nothing is known about the molecular biology of TriMV and the roles of viral proteins in replication, vector transmission, and virus-plant host interactions. Improved understanding of the genetic basis of these basic viral functions will facilitate efforts to ameliorate the effects of viral infection in wheat and other cereal crops. The objectives here are designed to fill these knowledge gaps with WSMV and TriMV resistance, TriMV molecular biology and vector transmission. In addition, we will develop transgenic wheat with resistance likely to be effective against a broad spectrum of WSMV and TriMV strains.