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Title: Identification of quantitative trait loci (QTL) for resistance to Fusarium crown rot (Fusarium pseudograminearum) in multiple assay environments in the Pacific Northwestern US

Author
item POOLE, GRANT - Washington State University
item SMILEY, RICHARD - Oregon State University
item Paulitz, Timothy
item CARTER, AARON - Washington State University
item See, Deven
item Campbell, Kimberly

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2012
Publication Date: 2/25/2012
Citation: Poole, G., Smiley, R., Paulitz, T.C., Carter, A., See, D.R., Campbell, K. 2012. Identification of quantitative trait loci (QTL) for resistance to Fusarium crown rot (Fusarium pseudograminearum) in multiple assay environments in the Pacific Northwestern US . Theoretical and Applied Genetics. 125:91-107.

Interpretive Summary: Fusarium crown rot (FCR), caused by F. pseudograminearum and F. culmorum, reduces wheat (Triticum aestivum L.) yields in the Pacific Northwest (PNW) of the U.S. by as much as 35%. Resistance to FCR has not yet been discovered in currently grown PNW wheat cultivars. Several significant quantitative trait loci (QTL) for FCR resistance have been documented on chromosomes 1A, 1D, 2B, and 4B in resistant Australian cultivars. In this work, we identified novel QTL from Sunco (Australian) crosses with Otis and Macon, two Pacific Northwest varieties. One QTL on Chromosome 3 B explained up to 36% of the varation. This is the first report of QTL associated with FCR resistance in the U.S.

Technical Abstract: Fusarium crown rot (FCR), caused by F. pseudograminearum and F. culmorum, reduces wheat (Triticum aestivum L.) yields in the Pacific Northwest (PNW) of the U.S. by as much as 35%. Resistance to FCR has not yet been discovered in currently grown PNW wheat cultivars. Several significant quantitative trait loci (QTL) for FCR resistance have been documented on chromosomes 1A, 1D, 2B, 3B, and 4B in resistant Australian cultivars. Our objective was to identify QTL and tightly linked SSR markers for FCR resistance in the partially resistant Australian spring wheat cultivar Sunco using PNW isolates of F. pseudograminerarum in greenhouse and field based screening nurseries. A second objective was to compare heritabilities of FCR resistance in multiple types of disease screening nurseries (seedling, terrace, and field) using multiple disease rating methods. Two recombinant inbred line (RIL) mapping populations were derived from crosses between Sunco and susceptible PNW spring wheat cultivars Macon and Otis. The Sunco/Macon population comprised 219 F6:F7 lines and the Sunco/Otis population comprised 151 F5:F6 lines. Plants were inoculated with a single PNW F. pseudograminearum isolate (006-13) in growth room(seedling), outdoor terrace (adult) and field (adult) assays conducted from 2008-2010. Crown and lower stem tissue of seedling and adult plants were rated for disease severity on several different scales, but mainly on a numeric scale from 0 to 10 where 0=no discoloration and 10=severe disease. Five significant QTL were identified on chromosomes 3B, 4B, 4A, and 7A with LOD scores ranging from 3 to 22. The most significant and consistent QTL across screening environments was located on chromosome 3BL, inherited from Sunco, with maximum LOD scores of 22 and 9 explaining 36% and 23% of the variation, respectively for the Sunco/Macon and Sunco/Otis populations. The SSR markers Xgwm247 and Xgwm299 flank this QTL and are being validated for use in marker assisted selection for FCR resistance. This is the first report of QTL associated with FCR resistance in the U.S.