Identification of genes for resistance to Puccinia striiformis f. sp. hordei in 18 barley genotypes

Barley genotypes Hor 1428, Hor 2926, Hor 3209, BBA 2890, Abyssinian 14, Grannelose Zweizeilige, and Stauffers Obersulzer are resistant to all races of Puccinia striiformis f. sp. hordei so far detected in the U.S.A. Heils Franken, Cambrinus, Astrix, Emir, Hiproly, Varunda, Trumpf, Mazurka, Bigo, BBA 2890, and I 5 are resistant to some races and susceptible to others. Previous studies showed that Hor 1428, Hor 2926, Hor 3209, Abyssinian 14, Stauffers Obersulzer, I 5, Heils Franken, Emir, Astrix, Hiproly, Varunda, and Trumpf each have two genes, and BBA 2890, Grannelose Zweizeilige, Cambrinus, Mazurka, Bigo, and BBA 809 each have a single gene for resistance. To determine the genes in specific genotypes and their relationships, all possible crosses were made among the 18 genotypes. Seedlings of parents and F2 progeny were tested under controlled conditions for resistance to selected races that were avirulent on both parents. Based on segregation within the individual crosses to selected races, at least 26 of 30 genes detected in the 18 genotypes were different. Allelic and linkage relationships of some of the genes were determined. The genetic information should be useful for understanding the host-pathogen interactions and for control of stripe rust using resistance.