Unlocking the Genetic Blueprint of Erucic Acid Content in Mustard (Brassica napus): A Meta-QTL Exploration

Brassica napus is a major oilseed crop used for edible oil and industrial applications. Because high-erucic acid (EA) levels reduce oil quality, identifying robust loci controlling EA is a priority for breeding low-EA rapeseed cultivars. Here, we performed a meta-quantitative trait locus (meta-QTL; MQTL) analysis using 57 published EA QTLs compiled from 12 independent mapping studies. A consensus genetic map spanning 487.24 cM was constructed with 399 markers across two linkage groups (LgA08 and LgC03). Of the 57 QTLs, 37 were successfully projected onto the consensus map and consolidated into 10 MQTL regions. MQTL confidence intervals (CIs) were substantially narrower than those of the projected QTLs (mean CI 3.75 cM vs. 8.56 cM), representing a 2.28-fold (56.19%) reduction. Candidate gene mining within MQTL intervals identified 67 genes, including eight prioritized candidates associated directly or indirectly with EA metabolism, located in MQTL1.1, MQTL1.2, MQTL1.3, MQTL2.1, and MQTL2.4. Notably, MQTL1.2 and MQTL2.4 contained KCS/FAE1-pathway candidates encoding 3-ketoacyl-CoA synthase (KCS), a key enzyme class in very-long-chain fatty acid elongation. The MQTLs and prioritized candidate genes identified here provide a valuable foundation for marker-assisted selection and future functional validation aimed at developing low-EA rapeseed cultivars with improved oil quality.