Elucidation of the genetic basis of variation in flowering time in Brassica napus via genome-wide association studies and gene coexpression analysis.

Abstract

Background: An optimal flowering time of Brassica napus L. (B. napus) plants leads to greater yield stability across multiple growing conditions and is therefore highly important for plant breeders.

Results: A genome-wide association study was performed for flowering time (FT) using a natural population comprising 157 inbred lines of rapeseed. A total of 126 associations between single nucleotide polymorphisms (SNPs) and the flowering time trait were identified with a P value < 1e-5, resulting in the identification of 12 QTLs named qFT1 to qFT12. Using transcripts of 205 genes in 12 QTL intervals and 922 homologs of known genes from Arabidopsis, we developed a gene coexpression network for flowering time in rapeseed and prioritized candidate genes in 12 QTL intervals. Furthermore, a candidate gene-based association study suggested that the role of BnaC08. UXS1 is involved in controlling flowering time, and two CAPS/dCAPS markers were developed to distinguish different haplotypes.

Conclusions: This study contributes to the wealth of knowledge that genetic locus controlling flowering time in rapeseed. It also provides practical information for breeders to better predict the results of using two CAPS/dCAPS markers in future breeding programs.