Exploration on QTL and SNP Molecular Markers for Oleic Acid Content in Brassica napus Based on Genome-wide Association Analysis

In this study, 300 Brassica napus germplasms collected from both domestic and international sources were planted in two environments. By integrating phenotypic and genotypic data of oleic acid content, genome-wide association analysis was conducted using EMMAX software. The results indicated that the distribution of oleic acid content in the associated populations presented a continuous bimodal pattern and was controlled by two major gene loci. GWAS analysis identified a dominant QTL locus regulating oleic acid content, situated between the 53853975 and 57808820 bases of chromosome C03, with a contribution rate of 62.51%. It was correlated with the SNP marker and peak values of chrC03＿53853975（A/G） and chrC03＿57808820（C/T）, and the SNP molecular marker chrC03＿56392730（G/T） was closely linked. The corresponding base mutation resulted in polymorphism. When the peak SNP allele was TT, the phenotypic effect value of this trait was 57.93%. This study disclosed for the first time the dominant QTL locus of the C03 chromosome and its SNP molecular marker for the oleic acid content trait of glycole-type rapeseed, with a high contribution rate, providing a crucial theoretical basis for the efficient improvement of this trait and marker-assisted selection.