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Genome-wide association mapping of resistance to Fusarium proliferatum in soybean

Paul Okello: South Dakota State University

<div>Fusarium root rot is an important constraint to soybean (<em>Glycine max</em> L.) production in the United States. In 2014, yield losses due to Fusarium root rot in the United States were 116,000 tonnes (58.4 million dollars). In South Dakota, 10 species of <em>Fusarium</em> were identified causing root rot of soybean, and among a collection of 59 <em>Fusarium</em> isolates representing the 10 species, <em>Fusarium proliferatum</em> isolate FUS026 was determined to be the most aggressive on a susceptible soybean cultivar. In this study, 146 plant introductions from 21 countries and from maturity groups 0 (90) and I (56) in the USDA Soybean Germplasm Collection, were inoculated with isolate FUS026 at planting using the inoculum layer method. At 14 days after inoculation, lesion length caused by <em>F. proliferatum</em> on the soybean roots were measured. One hundred and twenty genotypes in this collection were significantly less susceptible (<em>P < </em>0.05<em>) </em>to isolate FUS026 when compared to the susceptible soybean cultivar, which indicated that these 120 genotypes could be used as potential parental lines to develop soybean varieties with resistance to <em>F. proliferatum</em>. A genome-wide association mapping analysis was performed with a total of 34,604 single nucleotide polymorphic (SNP) markers. Thirty five significant markers-trait associations (-log<sub>10</sub> (<em>P</em>) > 3.0) were identified across five chromosomes (1, 8, 9, 10 and 13). The discovery of these loci through association mapping is a significant step to identify sources of resistance to <em>F. proliferatum</em>.</div>