Molecular characterization of resistance to Russian wheat aphid (Diuraphis noxia Kurdjumov) in bread wheat (Triticum aestivum L.) line KRWA9

Abstract

The Russian wheat aphid (RWA), Diuraphis noxia (Kurdjumov) causes extensive economic damage to wheat (Triticum aestivum L.) in most wheat growing regions of the world. Control of RWA using systemic insecticides is expensive and pollutes the environment therefore the most effective method of RWA control is the development of RWA resistant cultivars. This study was initiated to determine inheritance of RWA resistance in a wheat resistance source KRWA9, and identify the chromosome location of the resistance gene. Inheritance was studied in parent materials, F1 populations, F2 populations and F2:3 families of a cross between resistant line KRWA9 and a susceptible variety NjoroBW2. Seedlings were infested with RWA then scored for damage on a visual scale of 1 to 9 after 21 days of infestation. The segregation data from NjoroBW2 × KRWA9 population depicted monogenic dominant inheritance of the resistance gene with phenotypic ratios of 3:1 in F2 populations and 1:2:1 in F2:3 families. Bulk segregant analysis approach was used for the mapping of resistance. Nine simple sequence repeat (SSR) primers were tested between parental lines and bulks, and only chromosome 7DS SSR marker Xgwm111 produced clear polymorphism between the parental lines and the resistant and susceptible bulks. Detailed analysis of this marker with the full population revealed very close linkage to resistance with a coefficient of determination (R2) value of 85%. This marker provides good opportunities for the marker-assisted breeding towards improving Russian wheat aphid resistance. Key words: Russian wheat aphid, resistance, susceptibility, simple sequence repeat (SSR) markers.