Biotype 2 Russian Wheat Aphid Resistance among Wheat Germplasm Accessions

Abstract

The Russian wheat aphid [Diuraphis noxia (Mordvilko), RWA] is an important pest of wheat (Triticum aestivum L.) in the western Great Plains region of the United States. The recent identification of a RWA biotype (provisionally denoted as Biotype 2) that is virulent on currently deployed RWA‐resistant cultivars necessitates the rapid identification of resistance to the new biotype. The objective of this study was to identify Biotype 2 RWA resistance among a collection of germplasm accessions previously determined to be resistant to the original North American biotype of RWA (provisionally denoted as Biotype 1). A collection of 761 germplasm accessions was evaluated in standard seedling screening tests with Biotype 2 RWA. ‘TAM 107’ (carries no RWA resistance genes) and ‘Halt’ (Dn4 resistance gene) were used as susceptible checks while the germplasm line 94M370 (Dn7 resistance gene) was used as a resistant check. Evaluation of accessions showing at least a moderate level of resistance in unreplicated tests was repeated with three replications in a randomized complete block design. Forty‐four germplasm accessions were identified as having high to moderate levels of resistance to Biotype 2 RWA. Most of these accessions originated from areas of the world where RWA is endemic or were derived from germplasm accessions that originated from these areas. Ten accessions showed a level of resistance comparable with the 94M370 check. These accessions should prove useful in future genetic studies and for breeding for resistance to Biotype 2 RWA.