Molecular mapping of loci conferring resistance to spot blotch and powdery mildew in barley using the genotyping by sequencing approach
Yueqiang Leng: North Dakota State University
<div>Spot blotch caused by <em>Cochliobolus sativus</em> and powdery mildew caused by <em>Blumeria graminis</em> f. sp. <em>hordei</em> are two important diseases in barley. To map genetic loci controlling the resistance to these diseases, a mapping population consisting of 138 recombinant inbred lines from the cross between barley cultivar Bowman and line ND5883 was developed and genotyped using the genotyping by sequencing approach. A total of 2,951 polymorphic SNP markers between Bowman and ND5883 were generated, and 1,821 markers having less than 10% missing genotypes were used to construct a genetic map. The resulted linkage map consisted of 10 linkage groups covering 865.14 cM in length with a 1.6 cM average distance between markers. This population was then evaluated for infection responses (IRs) at the seedling stage to two pathotype isolates of <em>C. sativus</em> and one isolate of <em>B. graminis</em> f. sp. <em>hordei</em>. QTL analysis identified three loci (<em>QRcs-1H-P2</em>, <em>QRcs-1H-P1</em> and <em>QRcs-7H-P1</em>) controlling resistance to spot blotch and one locus (<em>Mla</em> <em>8</em>) conferring resistance to powdery mildew. <em>QRcs-1H-P2</em> located on chromosome 1H was derived from ND5883 and effective against isolate ND90Pr, while <em>QRcs-1H-P1</em> and <em>QRcs-7H-P1</em>, located on chromosome 1H and 7H, respectively, were derived from Bowman and effective against isolate ND85F. The powdery mildew resistance gene <em>Mla</em> <em>8</em> is tightly linked to QTL (<em>QRcs-1H-P2</em>) at the short arm of chromosome 1H. Identification and mapping of the QTL and DNA markers associated them will facilitate development of barley cultivars with resistance to spot blotch and powdery mildew.</div>
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