Temporal Transcriptomic and Lipidomic Analysis Reveals Multi-Omics Dynamic Profiles of Brassica napus Seed Germination

Background Lipids constitute a major component of Brassica napus seeds. During seed germination, lipid mobilization serves as a critical energy source for seedling establishment, which directly impacts germination vigor and the subsequent growth potential of seedlings. Although lipid mobilization is essential for rapeseed germination, the time-dependent coordination between transcriptional regulation and lipid conversion remains largely unclear, and the corresponding molecular regulatory network still needs to be systematically explored. Results We conducted an integrated transcriptomic and lipidomic analysis on dry B. napus seeds and germinating seeds at 6, 12, 24, and 48 hours after imbibition. The results revealed distinct stage-specific characteristics of gene expression and lipid metabolism during germination. In the early imbibition stage, differentially expressed genes (DEGs) were primarily enriched in biological processes related to water transport, stress response, and signal transduction, whereas significant changes in lipid metabolism were observed to be relatively delayed. During the initiation of germination, triacylglycerols (TAGs) underwent rapid degradation, accompanied by a significant up-regulation of genes involved in the β-oxidation and gluconeogenesis pathways. In the late germination stage, genes responsible for membrane lipid synthesis were sharply up-regulated, which induced extensive membrane lipid remodeling. Conclusion This study is the first to depict the dynamic multi-omics profile during B. napus seed germination, systematically illustrating the global molecular and metabolic features of B. napus seeds at different imbibition stages. It also clarifies the expression patterns of characteristic genes and lipid metabolites at each stage of germination. These findings further deepen our systematic understanding of the regulatory mechanisms governing B. napus seed germination, and provide valuable theoretical support as well as candidate gene resources for the breeding of high-yield and high-quality B. napus varieties.