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United States Department of Agriculture

Agricultural Research Service

Research Project: CEREAL RUST FUNGI: GENETICS, POPULATION BIOLOGY, AND HOST-PATHOGEN INTERACTIONS

Location: Cereal Disease Laboratory

Title: Epistatic adult plant resistance in wheat to stem rust cosegregates with Sr12 seedling resistance

Authors
item Rouse, Matthew
item Sherman, Jamie -
item Talbert, Luther -

Submitted to: Abstracts of International Powdery Mildew Conference
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2012
Publication Date: August 28, 2012
Citation: Rouse, M.N., Sherman, J., Talbert, L. 2012. Epistatic adult plant resistance in wheat to stem rust cosegregates with Sr12 seedling resistance. Abstracts of International Powdery Mildew Conference. p. 156.

Technical Abstract: Wheat adult plant resistance (APR) to stem rust is desirable. Researchers have characterized the inheritance of APR in cultivar Thatcher as complex. In order to identify the loci providing APR in Thatcher, we evaluated 160 RILs derived from Thatcher/McNeal for stem rust reaction in the field in Kenya for two seasons, in the field in St. Paul for one season, and at the seedling stage with races TTKSK, SCCSC, and RKQQC. The population was previously genotyped with a total of 618 SSR and DArT markers. Segregation of seedling resistance to race SCCSC was consistent with the presence of a single major gene: Sr12. All RILs and parents were susceptible as seedlings to race TTKSK. However, adult plant stem rust severities in Kenya varied from 5% to 80%. QTL mapping identified 4 QTL with an LOD greater than 3.0 in at least one year. The markers closest to the QTL peaks were used in an ANOVA to determine the additive and epistatic effects. A QTL on 3BS was detected in all three environments and explained 27-35% of the variation. The peak of this QTL was at the same location as Sr12. Epistatic interactions were significant especially between Sr12 and QTL on chromosome arms 1AL and 2BS. Though Sr12 cosegregated with the largest effect QTL, lines with Sr12 were not always resistant. The data suggest that Sr12 or a closely linked gene, though not effective to race TTKSK alone, confers APR when combined with other resistance loci.

Last Modified: 9/22/2014
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