Feng Chen

Thousand-seed weight (TSW) is one of the important component of seed yield. In this study, a collection of 496 representative rapeseed accessions were genotyped by the high-throughput 60K SNP array for TSW in three environments (14NJ, 15TZ, 16TZ). The genome-wide association study (GWAS) of TSW was performed via the MLM (Mixed linear model) and GLM (General linear model). The results showed that the broad sense heritability of TSW was 63.12% in three environments. Six and 61 loci were detected with MLM and GLM, which explained 28.92% and 47.08% of the phenotypic variance, respectively. Combining the common loci between two models, 62 significant loci were obtained and accounted for 47.31% of the phenotypic variance. These loci were distributed on all chromosomes of the genome, with the largest number of 9, 8, and 7 loci detected on Chromosome A07, A03, and C06, respectively. The most significant locus Bn-scaff_17526_1-p1066214 was detected on C09, and accounted for 5.55% and 15.26% of the phenotypic variance in MLM and GLM, respectively. Among them, 21 loci overlapped with previously reported QTLs, of which 8 loci were verified by at least two populations. The remaining 41 loci were newly detected, and many of them had high effects and were detected in multiple environments, such as Bn-A03-p560769, Bn-scaff_15743_1-p599416 and Bn-scaff_15743_1-p590955. Besides, 11 candidates orthologous to documented Arabidopsis seed weight genes, like DGAT, EOD3, AGL61, WRI1, DA2, and RAV1, were found near our GWAS loci. The results are helpful for analyzing the genetic basis of TSW of rapeseed and lay a foundation for studying the regulation mechanism and guiding the genetic improvement of TSW.