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ARS Home » Pacific West Area » Aberdeen, Idaho » Small Grains and Potato Germplasm Research » Research » Publications at this Location » Publication #336149
Title: Characterization and genome-wide association mapping of resistance to leaf rust, stem rust and stripe rust in a geographically diverse collection of spring wheat landraces

Author
item KANKWATSA, P - University Of Sydney
item SINGH, D - University Of Sydney
item THOMSON, P - University Of Sydney
item NEWCOMB, MARIA - University Of Arizona
item Babiker, Ebrahiem
item Bonman, John
item PARK, R - University Of Sydney

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2017
Publication Date: 8/19/2017
Citation: Kankwatsa, P., Singh, D., Thomson, P., Newcomb, M., Babiker, E.M., Bonman, J.M., Park, R.F. 2017. Characterization and genome-wide association mapping of resistance to leaf rust, stem rust and stripe rust in a geographically diverse collection of spring wheat landraces. Molecular Breeding. 37(9):1-24. doi:10.1007/s1103201707078.

Interpretive Summary: Stem, leaf, and stripe rusts are key constraints to wheat production worldwide and new sources of resistance are needed to effectively manage these important diseases. Wheat landraces are a valuable and relatively unexploited source of new genes for managing cereal rusts. Landraces were developed in antiquity by farmer selection and are analogous to ‘heirloom’ crop varieties. The USDA-ARS National Small Grains Collection (NSGC) maintains a large number of landrace wheats for use by plant scientists worldwide. To identify resistance genes within a set of spring habit wheat landraces from the NSGC, we cooperated with colleagues in Australia to screen a set of 159 accessions of diverse geographic origin against all three rust diseases. Screening in Australia enabled us to test for resistance to a unique group of pathogen races. The study revealed many promising new sources of resistance that will benefit wheat breeders in the US and elsewhere.

Technical Abstract: The challenge posed by rapidly changing wheat rust pathogens, both in virulence and in environmental adaptation, calls for the development and application of new techniques to accelerate the process of breeding for durable resistance. To expand the wheat resistance gene pool available for germplasm improvement, a panel of 159 international spring wheat landraces collected from 29 countries were evaluated for seedling resistance to 35 Australian pathotypes of Puccinia triticina (11), Puccinia graminis f. sp. tritici (12) and Puccinia striiformis f. sp. tritici (12) and for adult plant resistance (APR) to a subset of these pathotypes. Several known seedling resistance genes for leaf rust (Lr2a, Lr3a, Lr13, Lr23, Lr16, Lr20); stem rust (Sr12, Sr13, Sr23, Sr30, Sr36) and stripe rust (Yr3, Yr4, Yr5, Yr9, Yr10, Yr17, Yr27) were postulated singly or in combination in the landraces. Known APR genes identified via field experiments and marker analyses included the pleiotropic linked genes Lr34/Yr18/Sr57, Lr46/Yr29/Sr58, Lr67/Yr46/Sr55 and Sr2/Lr27/Yr30, as well as Lr68 and Lr74. A genome-wide association analysis of field data using the mixed linear models detected 77 SNP markers significantly associated with rust resistance genes/ quantitative trait loci (QTLs), which were mapped to chromosomes, 1A, 1B, 1D, 2A, 2B, 3A, 3B, 3D, 4A, 5A, 5B, 6A, 6B, 6D, 7A and 7D. In addition to SNPs associated with multiple rust pathogens that probably indicate the presence of new pleiotropic linked genes, SNPs were also detected in chromosome positions not known to carry rust resistance genes. Overall, the study revealed the presence of a range of unidentified seedling resistances and APR among the landraces, which represent promising new sources of resistance in the ongoing effort to develop improved wheat cultivars with rust resistance.