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POSTERS: Genetics of Resistance I

P-257 - Genome-wide association mapping complements QTL analysis in identification of markers associated with reaction to Sclerotinia stem rot on canola

Monday, August 4, 2025
3:45 PM - 4:30 PM HST
Location: Exhibit Hall 3
Abstract Text: Sclerotinia sclerotiorum causes Sclerotinia stem rot (SSR) disease on canola (Brassica napus) which can result in severe yield and quality losses. Resistance to SSR is quantitative meaning that the identification of molecular markers associated with reaction to this disease is paramount but challenging. Genetic markers associated with reaction to a disease can be identified using two main approaches, Genome-wide association mapping (GWAS) and quantitative trait loci (QTL) analyses. These two approaches could be used in a complementary way to improve the information obtained from sets of germplasm. In this study, data from two biparental mapping populations, T54DH and T63DH with 127 and 201 lines, respectively, were analyzed using GWAS. The populations were evaluated phenotypically using the stem agar plug technique at flowering and genotyped using Genotyping by sequencing (GBS) analysis. GWAS was conducted using the GAPIT R package (version 3.0) and GEMMA-MLM. Based on the analysis, single-locus (SL) and multi-locus (ML) algorithms, a total of 420 significantly associated and 494 independent SNP markers were identified. This contrast with the 16 markers identified in these populations using QTL analysis. GWAS markers were detected in chromosomes A02, A05, A07, A08, A09, C01 and C08 while QTL markers were in A02, A07, A09, C01 and C03. These results highlight the benefits of using GWAS as a complementary tool for marker identification on biparental mapping populations.