Genetic optimization of the source, sink and flow for increasing seed oil content in rapeseed

Rapeseed (Brassica napus) is one of the most important oilseed crops worldwide, with its seed oil content (SOC) and quality directly determining its economic value. To resolve the challenges of growing demand for vegetable oil and advancements in rapeseed production, substantial progress has been achieved in the genetic improvement of SOC. This review systemizes genetic optimization strategies across three hierarchical processes: source expansion via enhanced photosynthesis, optimized carbon allocation, and metabolic redirection of photoassimilates; sink enhancement through targeted elevation of fatty acid (FA) synthesis, triacylglycerol (TAG) assembly, and seed coat development coupled with suppression of lipolytic pathways; flow optimization by modifying carbon partitioning, sucrose phloem loading and channeling to developing seeds. We synthesize reported genetic determinants of these processes and underscore their potential for enhancing SOC. Furthermore, we postulate that synergistic integration of source-flow-sink coordination with push-pull-package-protect frameworks could maximize oil accumulation, thereby establishing a multi-tiered roadmap for transcending SOC ceilings in rapeseed.