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

G J Poole,T C Paulitz,C A Walker,A H Carter,R W Smiley,D R See,K Garland-Campbell

doi:10.1007/s00122-012-1818-6

Abstract

Fusarium crown rot (FCR), caused by Fusarium pseudograminearum and F. culmorum, reduces wheat (Triticum aestivum L.) yields in the Pacific Northwest (PNW) of the US 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 assaying environments (seedling, terrace, and field) using multiple disease rating methods. Two recombinant inbred line (RIL) mapping populations were derived from crosses between Sunco and 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 through 2010. Crown and lower stem tissues 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. Significant QTL were identified on chromosomes 2B, 3B, 4B, 4D, 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 the PNW cultivars Macon and Otis, 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 these 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 USElectronic supplementary materialThe online version of this article (doi:10.1007/s00122-012-1818-6) contains supplementary material, which is available to authorized users.

Highlights

Fusarium crown rot (FCR) is one of the most persistent soil-borne diseases of dryland wheat (Triticum aestivum L.)Theor Appl Genet (2012) 125:91–107 in the Pacific Northwest (PNW) of the United States, as well as world-wide (Cook 1992; Burgess et al 2001; Backhouse et al 2004; Nicol et al 2007; Smiley et al 2005a)
This research reports several significant quantitative trait loci (QTL) for FCR resistance inherited from Sunco, Macon, and Otis across growth room, terrace, and field testing environments
The most significant QTL, Qcrs.wsu-3BL, for FCR resistance identified in the current study were inherited from the PNW cultivars Macon and Otis

Summary

Introduction

Fusarium crown rot (FCR) is one of the most persistent soil-borne diseases of dryland wheat (Triticum aestivum L.). Theor Appl Genet (2012) 125:91–107 in the Pacific Northwest (PNW) of the United States, as well as world-wide (Cook 1992; Burgess et al 2001; Backhouse et al 2004; Nicol et al 2007; Smiley et al 2005a). In the %PNW, yield losses have been documented as high as 35%, with an accepted average of 9%, while world-wide losses exceeding 30% have been reported (Cook 1968, 1992; Kane et al 1987; Burgess et al 2001; Dodman and Wildermuth 1987; Klein et al 1990; Nicol et al 2007)

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