Genome-Wide Association Mapping of Quantitative Resistance to Sudden Death Syndrome in Soybean

Sudden death syndrome (SDS) is a serious threat to soybean production that can be controlled by host plant resistance. To dissect the genetic architecture of quantitative resistance in soybean, two independent association panels of soybean elite cultivar, consisting of 392 and 300 unique accessions, were evaluated for resistance to SDS in multi-environments. Genome-wide association mapping was conducted by genotyping 52041 and 5361 SNPs variants across two association panels respectively. A total of 20 loci underling SDS resistance were identified in two independent studies, including 7 loci localized in mapped QTL intervals and 13 novel loci. One strong peak of association on chromosome 18, associated with all disease assessment criteria across two panels, spanned a physical region of 1.2 Mb around previously cloned SDS resistance gene (GmRLK18-1), and there was an additional variants independently associated with SDS resistance in this genomic region. Other peak SNPs were within or close to sequences annotated as homologous to genes previously shown to be involved in plant disease resistance. Peak SNPs at the identified loci could explain ~54.5% of the phenotypic variance on average measured by different disease assessment criteria. The identification of such associations may provide substantial insight into soybean resistance to SDS and may also facilitate marker-assisted selection in soybean.