Evaluation and Reselection of Wheat Resistance to Russian Wheat Aphid Biotype 2

Abstract

ABSTRACTRussian wheat aphid (RWA, Diuraphis noxia, Mordvilko) biotype 2 (RWA2) is virulent to most known RWA resistance genes and severely threatens wheat (Triticum aestivum L.) production in the hard winter wheat area of the U.S. western Great Plains. We determined RWA2 reactions of 386 cultivars from China, 227 advanced breeding lines and recently released cultivars from the United States, 505 landraces from countries where RWA is endemic, and 31 genetic stocks developed in the United States, Australia, Canada, and Russia. The majority of wheat accessions from China and the United States were highly susceptible to RWA2. Only nine landrace accessions produced a homogeneous resistant reaction. In addition, highly resistant plants were identified in 28 heterogeneous landraces. Thus, reselection was conducted to purify some potential resistance sources, and the single‐plant progenies of 220 selected plants were evaluated. Homogeneous resistant or highly resistant lines were identified from seven previously heterogeneous landraces. Reselection line PI 626759‐20‐32 offered a high level of resistance similar to lines carrying Dn7, the rye (Secale cereale L.)‐derived resistance gene associated with undesirable bread‐making quality. PI 626759‐20‐32 has the potential to supplement or replace Dn7 as a new RWA2 resistance source in wheat breeding.