|Cruz, Luisa -|
|Shoup Rupp, Jessica -|
|Trick, Harold -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2014
Publication Date: August 7, 2014
Citation: Cruz, L.F., Shoup Rupp, J.L., Trick, H.N., Fellers, J.P. 2014. Stable Resistance to Wheat streak mosaic virus in wheat mediated by RNAi. Crop Science. doi: 10.1007/s11627-014-9634-0). Interpretive Summary: Wheat streak mosaic virus (WSMV) is a viral pathogen of wheat that causes significant yield losses each year in the Great Plains. Control measures include delayed planting and eliminating alternate sources of virus like volunteer wheat and other grasses. Plant breeding programs only have three resistance genes available for WSMV, however, each is sensitive to high temperatures and two of them have negative agronomic traits associated with the genes. This paper describes a new approach to obtaining virus resistance in wheat. The genetic sequence for a small fragment of the coat protein gene of WSMV was transformed into a spring wheat variety. This gene fragment triggers the virus defense responses of the plant and prevents the reproduction of the virus. Four resulting wheat lines were found to be resistant to WSMV infection and this resistance was stable over six generations. These new virus resistance genes are being transferred into adapted wheat varieties for further testing.
Technical Abstract: Wheat streak mosaic virus (WSMV) is one of the major wheat viruses in the Great Plains of the United States. Cultural practices are the primary method of disease management, though not fully effective. Genetic resistance is available but is temperature sensitive. Alternative approaches to viral resistance are needed. RNAi has been shown to play a role in viral defense response and has been successfully used as a biotechnological tool to preprogram viral resistance in transgenic plants. In this work, a hairpin construct of the coat protein of WSMV was transformed into wheat along with pAHC20-bar to elicit viral resistance. Eleven WSMV RNAi independent transgenic events were obtained. Thirteen T1 lines were resistant as evidenced by the lack of WSMV symptoms and the lack of viral RNA within the tissue. Beginning in the T2 generation, single plants of each generation were selected from the lineages 110B4, 110B8, 195A17 and 195A20, selfed, and evaluated for resistance and presence of the transgene until the T5 generation. At T5, plants were evaluated for presence of the transgene, presence of the selectable marker, and virus resistance. Each of the families in the T5 generation was resistant to the virus, however, thirteen of the families were still segregating for bar. Transgene expression can be lost due to silencing, however, generational selection has maintained expression of the transgene and resistance to WSMV.