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Title: Identification of a major quantitative trait locus (QTL) for high-temperature adult-plant (HTAP) resistance against Puccinia striiformis f. sp. hordei in ‘Bancroft’ barley

Author
item YAN, G - WASHINGTON STATE UNIV
item Chen, Xianming

Submitted to: Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2007
Publication Date: 1/1/2008
Citation: Yan, G.P., Chen, X. 2008. Identification of a major quantitative trait locus (QTL) for high-temperature adult-plant (HTAP) resistance against Puccinia striiformis f. sp. hordei in ‘Bancroft’ barley. Phyto 98:120-127.

Interpretive Summary: Stripe rust is an important barley disease in the western United States. Growing cultivars with durable resistance is the best approach for sustainable control of the disease. Barley cultivar Bancroft was identified to have durable high-temperature, adult-plant (HTAP) resistance to stripe rust. To identify the resistance gene and develop molecular markers, we made a cross between Bancroft and a standard malting barley cultivar, Harrington that is highly susceptible to stripe rust. The parents and progeny lines were tested for resistance in the greenhouse and in three field sites in the state of Washington in 2004 and 2005. Genetic analyses of infection type data of the progenies identified a dominant gene for the HTAP resistance. There were no significant differences among the locations, indicating that the HTAP resistance is non-race specific. The resistance gene analog polymorphism, which was developed in our lab, and microsatellite techniques were used to identify molecular markers for the resistance gene and map the gene on the long arm of barley chromosome 3H. The gene is a major quantitative trait locus (QTL) that explained more than 70% of the total phenotypic variation of the resistance trait. The two flanking markers that were tightly linked to the gene detected polymorphisms in 84% and 88% of the 25 additional tested barley cultivars when used individually, and detected polymorphism in 100% of the cultivars when used in combination. The results show that the markers are useful in incorporating the HTAP resistance into other barley cultivars.

Technical Abstract: Bancroft barley has durable high-temperature, adult-plant (HTAP) resistance to stripe rust caused by Puccinia striiformis f. sp. hordei. To characterize and map quantitative trait loci (QTL) for the HTAP resistance, Bancroft was crossed with the susceptible barley Harrington. The parents and F4 lines, and the parents and F5 lines were evaluated in 2004 and 2005 in one and three field sites, respectively, in Washington State. Infection type (IT) and disease severity (DS) were recorded three times at each location during each growing season. Area under the disease progress curve (AUDPC) was calculated for each parent and progeny line based on the DS data. Genetic analyses of IT data in the F4 and F5 populations indicated that one dominant gene appears to control the HTAP resistance in Bancroft. Analyses of variance of the IT data showed no significant differences among the locations, indicating that the HTAP resistance is non-race specific. Using 119 F6 lines and IT data, a linkage map on chromosome arm 3H L was constructed with eight resistance gene analog polymorphism (RGAP) markers and three simple sequence repeat (SSR) markers. A QTL for DS and AUDPC was mapped on the same chromosome location as for IT. The QTL explained more than 70% of the total phenotypic variation for the traits of DS and AUDPC. The two flanking markers detected polymorphisms in 84% and 88% of the 25 additional tested barley genotypes when used individually, and detected polymorphism in 100% of the genotypes when used in combination, indicating that the markers are useful in incorporating the HTAP resistance into these barley genotypes.