Genome-wide association study identifies new loci for 1000-seed weight in Brassica napus

Abstract

Oilseed rape (Brassica napus L.) is an important oilseed crop worldwide and 1000-seed weight (SW) is the important determinant of seed yield of B. napus. To elucidate the genetic mechanism of SW and mining candidate genes, a panel of 403 diverse B. napus accessions was screened in a genome-wide association study (GWAS) using 1.60 million single-nucleotide polymorphisms (SNPs). This study identified 340 SNPs significantly associated with SW by general linear model (GLM) and mixed linear model (MLM). Through GWAS combined with transcriptome data, two significantly differentially expressed genes were identified as candidate genes (BnaA02g06870D and BnaC06g28920D). Candidate gene association analysis and haplotype analysis showed that the inbred lines carrying ACCC at BnaA02g06870Hap1 and TTGG at BnaC06g28920Hap1 had greater SW than lines carrying other haplotype alleles. Candidate genes and favourable haplotypes identified in this study will be useful for large-seed breeding of B. napus.