Stripe rust of barley, caused by Puccinia striiformis f. sp. hordei, was first observed in the United States in 1991 at Uvalde, Texas. Within five years, the disease spread throughout the western United States. The disease is firmly established in the United States and has a high potential for causing major losses if not controlled.
The use of resistant cultivars has been the most economical method of controlling rusts on cereals. To study the genetics of barley stripe rust resistance, 18 resistant genotypes were crossed with the susceptible barley cultivars Topper and Steptoe. Also, diallel crosses among the 18 genotypes were made to determine the relationships among the resistance genes. Seedlings of parents and F1, F2, and F3 progenies were inoculated with different races under controlled conditions in the greenhouse. Infection types were analyzed to determine the inheritance of resistance. BBA2890, BBA809, Bigo, Cambrinus, Grannelose Zweizeilige, and Mazurka each have a single gene. Astrix, Abyssinian 14, Emir, Heils Franken, Hiproly, I 5, PI 548708, PI548734, PI548747, Stauffers Obersulzer, Trumpf, and Varunda each have two genes for resistance. Most of the genes were recessive. The gene in Cambrinus and the gene in Mazurka were dominant for resistance when tested using their first seedling leaves (the bottom leaves) and were recessive when tested using their second seedling leaves.
Based on segregation of the diallel crosses and the responses of the progeny to selected races, at least 27 of the 31 genes that were detected were uniquely different. The single genes in Bigo, Trumpf, Mazurka, and BBA 2890 and one of the genes in PI 548708, PI 548734, PI 548747, and Abyssinian 14 were linked. One of the two genes in PI 548734 was linked to one of the two genes in I 5. The single gene in Cambrinus and one of the genes in Heils Franken and Astrix were the same or closely linked. The single genes in Grannelose Zweizeilige and BBA 809 and the two genes in Stauffers Obersulzer, Emir, Hiproly, and Varunda were different from all other genes and different from each other.
Resistance gene analog polymorphism (RGAP) markers, in combination with AFLP, SSR, and RFLP markers were used to map genes in a double-haploid population of Shyri/Galena for resistance to stripe rust and other diseases. Identified genes for resistance to stripe rust were on chromosomes 2, 3, 5, and 6; to leaf rust on chromosome 1; to barley yellow dwarf on chromosomes 1, 3, 4, and 5; to net blotch on chromosomes 3 and 6; and scald on chromosomes 1 and 3. RGAP markers were either coincident or tightly linked to genes for stripe rust resistance on chromosomes 2 and 5, for scald on chromosomes 1 and 3, for BYDV on chromosome 1, and for net blotch on chromosome 3. RGAP markers were more closely linked to most of the other resistance genes than RFLP, AFLP, and SSR markers.
RGAP and RFLP markers were used to map the resistance genes in the double-haploid lines of Gobernadora/CMB 643. Stripe rust resistance genes were mapped on chromosomes 2, 3, 4, and 7. A single gene or a cluster of genes for resistance to leaf rust was mapped on chromosome 1. Resistance genes for scab resistance were mapped on chromosomes 1, 2, 3, 4, and 5. Coincident or tightly linked markers were detected for some of the disease resistance genes.