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Two major and five minor QTL confer adult plant resistance to stripe rust in winter wheat cultivar Skiles

Lu Liu: Washington State University

<div>Stripe rust, caused by <em>Puccinia striiformis</em> f. sp. <em>tritici</em> (<em>Pst</em>), is one of the most destructive diseases of wheat in the world. Wheat cultivar Skiles has been highly resistant to stripe rust since its release in 2008 in the US Pacific Northwest, but the genetics of its resistance was unknown. This study was conducted to determine the genetics of stripe rust resistance in Skiles. Testing Skiles with various <em>Pst</em> races at seedling and adult-plant stages at different temperatures showed that it has only adult plant resistance against predominant races. To map resistance genes, a doubled haploid (DH) population was developed from a cross between Skiles and susceptible wheat AvS. The DH population was phenotyped under natural infection of <em>Pst</em> in the fields of Pullman and Mt Vernon in 2016 and 2017 and at adult-plant stage with predominant race PSTv-37 under controlled conditions, and genotyped with the 90K Illumina iSelect wheat SNP chip. Molecular mapping identified two major QTL on chromosomes 3BS and 4BL. In addition, five minor QTL were mapped on chromosomes 1BL, 5AL, 5BL, 6BS, and 7DL. Testing the DH population with SSR markers specific to the chromosome arms confirmed the major QTL. Genotyping various wheat lines with the flanking markers of the two major QTL validated the usefulness of the markers. The QTL and closely linked markers are useful in developing wheat cultivars with high-level and potentially durable resistance to stripe rust.</div>