Refinement of four major QTL for oil content in Brassica napus by integration of genome resequencing and transcriptomics

Rapeseed(Brassica napus)supplies about half of the vegetable oil in China.Increasing oil production and searching for genes that control oil content in the crop are research goals.In our previous studies,four major QTL for oil content located on A08,A09,C03 and C06 in the Ken C-8×N53-2(KN DH)mapping population were detected.The parental lines were resequenced to identify structural variations and candidate genes affecting oil content in these four major QTL regions.Insertion-deletion(In Del)markers were developed and used to narrow the regions.Differentially expressed genes located in the regions were investigated.GO and KEGG analysis showed that several genes were associated with lipid metabolism.Several transcription factors with higher expression in N53-2 than in Ken C-8 were identified.These results shed light on the genetic control of oil content and may be helpful for the development of highoil-content cultivars.

3D genome structural variations play important roles in regulating seed oil content of Brassica napus

Dissecting the complex regulatory mechanism of seed oil content(SOC)is one of the main research goals in Brassica napus.Increasing evidence suggests that genome architecture is linked to multiple biological functions.However,the effect of genome architecture on SOC regulation remains unclear.Here,we used high-throughput chromatin conformation capture to characterize differences in the three-dimen-sional(3D)landscape of genome architecture of seeds from two B.napus lines,N53-2(with high SOC)and Ken-C8(with low SOC).Bioinformatics analysis demonstrated that differentially accessible regions and differentially expressed genes between N53-2 and Ken-C8 were preferentially enriched in regions with quantitative trait loci(QTLs)/associated genomic regions(AGRs)for SOC.A multi-omics analysis demonstrated that expression of SOC-related genes was tightly correlated with genome structural varia-tions in QTLs/AGRs of B.napus.The candidate gene BnaA09g48250D,which showed structural variation in a QTL/AGR on chrA09,was identified byfine-mapping of a KN double-haploid population derived from hybridization of N53-2 and Ken-C8.Overexpression and knockout of BnaA09g48250D led to significant in-creases and decreases in SOC,respectively,in the transgenic lines.Taken together,our results reveal the 3D genome architecture of B.napus seeds and the roles of genome structural variations in SOC regulation,enriching our understanding of the molecular mechanisms of SOC regulation from the perspective of spatial chromatin structure.