Avirulence factors corresponding to barley genes Pa3 and Pa7 which confer resistance against Puccinia hordei in rust fungi other than P. hordei

Abstract

The interactions between near-isogenic lines of barley line L94 containing the resistance genes Pa3 or Pa7 and one isolate each of Puccinia hordei, Uromyces viennot-bourginii, P. hordei-murini, P. recondita f.sp. agropyrina and two isolates of P. recondita f.sp. tritici were examined. The infection types and the development of the rust fungi suggested that the avirulence genes Avr3 and Avr7 corresponding to the two resistance genes were absent from the isolate of U. viennot-bourginii but present in the P. hordei-murini isolate. In both near-isogenic lines the development of the P. recondita f.sp. tritici isolates appeared to be affected quantitatively. The apparent presence of Avr3 and Avr7 in P. hordei-murini supports other reports that a pathogen biotype may possess avirulence genes that correspond with resistance genes in non-host plant species.