BnaC07.KCS9, a New Gene Regulating Erucic Acid Metabolism in Rapeseed.

Oil quality improvement is a primary target for rapeseed breeding, with particular emphasis on erucic acid. Although some QTLs for fatty acid metabolism have been identified, the genetic network of erucic acid remains poorly explored, except for FAE1. The present study constructed a high-density genetic map using an F2 population of 200 individuals from a cross between high-erucic and high-oleic parents and identified a novel QTL (HO/HE17) for erucic acid content, which was validated in the F2:3 population. Fine mapping refined HO/HE17 to a 552 kb region flanked by markers 17SNP2 and loc9 on chromosome C07, encompassing 17 annotated genes, with functional annotation and experimental validation highlighting BnaC07.KCS9 as the most promising candidate gene. Meanwhile, we identified the transcription factor BnaA06.RGA, which positively regulates BnaC07.KCS9. Therefore, this study proposed an RGA-KCS9 regulatory module for erucic acid, providing a new insight into the genetic improvement of very-long-chain fatty acid metabolism and valuable germplasm for developing ultra-high erucic acid varieties.