Identification of wheat germplasm resistant to major Russian wheat aphid biotypes in the United States.

Russian wheat aphid (Diuraphis noxia Kurdjumov [RWA]) is one of the most invasive and detrimental pests, and host plant resistance is the most efficient approach to manage RWA. Wheat (Triticum aestivum L.) accessions resistant to RWA biotype 1 (RWA1) and biotype 2 (RWA2) were previously identified by screening wheat accessions available at the USDA‐ARS National Small Grains Collection. However, RWA biotypic variation necessitates a continuous search for sources of resistance to new RWA biotypes. The objective of this study was to identify wheat accessions resistant to all major RWA biotypes in the United States. A set of 172 RWA‐resistant wheat accessions, mainly Iranian landraces, were evaluated for responses to five predominant U.S. biotypes—RWA1, RWA2, RWA3, RWA6, and RWA8—in controlled environments. Of these, 137 accessions showed homogeneous or heterogeneous resistance to at least one biotype, and 14 of them were resistant or highly resistant to all five biotypes. Another set of 19 accessions were resistant or highly resistant to two to four biotypes. These RWA‐resistant accessions are valuable sources for RWA resistance improvement, and further purification of some accessions and characterization of the underlying RWA resistance genes are imperative for their utilization in wheat breeding. [ABSTRACT FROM AUTHOR]