Identification and Characterization of New Sources of Genetic Resistance to Wheat Stem Sawfly in Wild Wheat Species

Project Summary:

Wheat stem sawfly (WSS, Cephus cinctus) has long been considered the most important pest of wheat in the northern Great Plains of North America. In recent years, damage from WSS has expanded to areas of Nebraska, Wyoming, and Colorado that had not previously been affected. Solid stem varieties of wheat have been shown to be effective in impeding larval development and movement, thus reducing larval survival. However, the solid-stemmed cultivars are not preferred by growers because of low yield (10-15% reduction) compared to hollow-stemmed cultivars and inconsistent solidness expression. Given the limited sources of resistance to WSS in the current elite germplasm, there is a need to evaluate diverse wheat genetic resources for additional alleles that can enhance development of WSS-resistant varieties.

As part of our previously funded grant, we screened 60 wheat lines from six species of wild wheat using a novel screening approach where plants were grown in cone-tainers in the greenhouse and placed in previous WSS-infested wheat field during peak WSS flight. We found Aegilops tauschii and Triticum urartu consistently had fewer eggs, smaller larvae, and less infested stems. These species contain potentially novel WSS resistance alleles that has never been accessed before and can be leveraged to combat WSS. The cone-tainer approach was complimented by field screening of hexaploidy wheat lines as well.

Moving forward, we propose to expand our screening to additional panels of wild wheat species using the container method and field screening. We also plan to develop a high-throughput phenotyping approach to aid in WSS resistance screening. In the long-term, the research we propose will lead to the identification of new sources of WSS resistance that can be bred into desired wheat varieties and identify a reliable and feasible high throughput phenotyping approach for WSS.