A combined source of resistance against corn leaf aphid and yellow rust in barley

Abstract

Barley has assumed the status of an industrial crop in India over recent years. Once grown as a rain-fed crop with minimum input, presently it is grown under optimum input to produce plump and mealy grains required for malting. The increased use of nitrogenous fertilizer and irrigation is likely to increase the incidence of biotic stresses. Aphids are the most widely distributed and serious threat to this crop under favourable conditions. Among the various diseases infecting barley, yellow rust is the most important in India. Germplasm lines maintained at the Directorate of Wheat Research, Karnal (India) were evaluated both against corn leaf aphid (Rhopalosiphum maidis) and yellow rust (Puccinia striiformis). Resistant lines were tested over 3 years under field conditions and thereafter under polyhouse conditions to confirm their resistance. One of the lines (BCU 284) was found to be resistant against both corn leaf aphid and yellow rust and is, therefore, potentially of great value to barley breeders. BCU 284 was crossed with highly aphid-susceptible BCU 274 and aphid-resistant EB 921. A single gene in BCU 284 was found to control the resistance against corn leaf aphid, which was different from that in EB 921.