Identification of loci for resistance to Sclerotinia stem rot in a perennial relative of soybean
S. CHANG (1), C. Thurber (1), P. Brown (1), G. Hartman (1), L. L. Domier (1). (1) University of Illinois, Urbana, IL, U.S.A.
<i>Sclerotinia sclerotiorum</i> is a necrotrophic fungus that causes Sclerotinia stem rot (SSR, also known as white mold), which can cause significant yield losses in soybean (<i>Glycine max</i>) and other dicotyledonous annual crops. Quantitative trait loci (QTL) for partial resistance to SSR have been identified in soybean, but the loci have explained relatively low levels of the observed phenotypic variation. Unlike soybean, <i>Glycine latifolia</i>, a perennial wild relative of soybean in the subgenus <i>Glycine</i>, shows high levels of resistance to SSR. To generate molecular resources for gene mapping and identification in <i>G. latifolia</i>, a population of 186 <i>G. latifolia</i> F<sub>2</sub> individuals that segregated resistance to SSR was genotyped by high-throughput sequencing. The analysis generated more than 10,000 single nucleotide polymorphism (SNP) markers in a very cost effective manner. The markers formed 20 large linkage groups, many of which were syntenic with soybean chromosomes. The segregation of the SNP markers and phenotypic data for responses to inoculation with S. <i>sclerotiorum</i> and incubation in oxalic acid (a pathogenicity determinant for <i>S</i>. <i>sclerotiorum</i>) were combined to identify QTL for resistance to SSR and oxalic acid in <i>G. latifolia. Glycine latifolia</i> and other perennial wild relatives of cultivated soybean represent sources of genes that could be beneficial to soybean production, especially when resistance is lacking in the <i>G. max</i> primary gene pool as with SSR.
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