Molecular analysis of Genetic Diversity Associated with Resistance to Russian Wheat Aphid

Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), causes hundreds of millions of dollars in wheat production losses in the U.S. So far, host plant resistance has been used to manage this damaging pest, and has proved to be effective, economical and environment-friendly. Genetic diversity and durability are two of the most important features of host plant resistance to Russian wheat aphid for various wheat improvement programs. In this study, a collection of RWA resistant germplasm lines and varieties of wheat were evaluated for their genetic diversity using the amplified fragment length polymorphism (AFLP) technique. Fifteen AFLP selective primer combinations were used to genotype these accessions, resulting in 893 amplicons. Of these, 274 (30.6%) informative polymorphic bands were used for genetic diversity analysis. Genetic similarity coefficients ranged from 0.47 to 0.87 among the resistant accessions, indicating high genetic diversity among them. Cluster analysis grouped the 38 accessions into two major clusters. These results indicated that the germplasm accessions in this study which confer RWA1 or RWA2 resistance comprise diversified resistance sources to support introgression efforts and have the potential to increase resistance levels further through pyramiding different resistance genes for broadening the resistance bases and tailoring of cultivars for enhanced RWA resistance in wheat. Also, the improved understanding of the genetic basis of such resistance could aid the direct transfer of resistance as well as the search for additional genes that will contribute to new durable resistance gene combinations.