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Quantitative Trait Loci from Two Genotypes of Oat (Avena sativa) Conditioning Resistance to Puccinia coronata

First, second, and eighth authors: USDA-ARS, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID 83210; third author: General Mills Inc., 150 Research Drive, Kannapolis, NC 28081; fourth author: USDA-ARS, Cereal Crops Research, 1605 Albrecht Blvd., Fargo, ND 58102; fifth author: Louisiana State University Agricultural Center, 104 M.B. Sturgis Hall, Baton Rouge, LA 70803; sixth author: USDA-ARS, Cereal Disease Laboratory, St. Paul 55108; and seventh author: Limagrain Cereal Seeds, 9020 Grant Road, Battle Ground, IN 47920.

Developing oat cultivars with partial resistance to crown rust would be beneficial and cost-effective for disease management. Two recombinant inbred-line populations were generated by crossing the susceptible cultivar Provena with two partially resistant sources, CDC Boyer and breeding line 94197A1-9-2-2-2-5. A third mapping population was generated by crossing the partially resistant sources to validate the quantitative trait locus (QTL) results. The three populations were evaluated for crown rust severity in the field at Louisiana State University (LSU) in 2009 and 2010 and at the Cereal Disease Laboratory (CDL) in St. Paul, MN, in 2009, 2010, and 2011. An iSelect platform assay containing 5,744 oat single nucleotide polymorphisms was used to genotype the populations. From the 2009 CDL test, linkage analyses revealed two QTLs for partial resistance in the Provena/CDC Boyer population on chromosome 19A. One of the 19A QTLs was also detected in the 2009 LSU test. Another QTL was detected on chromosome 12D in the CDL 2009 test. In the Provena/94197A1-9-2-2-2-5 population, only one QTL was detected, on chromosome 13A, in the CDL 2011 test. The 13A QTL from the Provena/94197A1-9-2-2-2-5 population was validated in the CDC Boyer/94197A1-9-2-2-2-5 population in the CDL 2010 and 2011 tests. Comparative analysis of the significant marker sequences with the rice genome database revealed 15 candidate genes for disease resistance on chromosomes 4 and 6 of rice. These genes could be potential targets for cloning from the two resistant parents.

Additional keywords: oat resistance, Puccinia coronata, single nucleotide polymorphism.