Temporal transcriptomic and lipidomic analysis reveals multi-omics dynamic profiles of B. napus seed germination

Lipids represent the major storage reserve in Brassica napus seeds. During germination, lipid mobilization delivers indispensable energy to support seedling establishment, thereby profoundly influencing germination vigor and subsequent seedling growth capacity. Although lipid mobilization is fundamentally required for successful rapeseed germination, the temporal coordination between transcriptional reprogramming and lipid metabolic conversion remains largely elusive, and the underlying molecular regulatory network remains to be systematically deciphered.

We conducted an integrated transcriptomic and lipidomic analysis on dry B. napus seeds and germinating seeds at 6, 12, 24, and 48 h 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 (TGs) 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.

This work represents the first systematic integration of transcriptomic and lipidomic data focusing on dynamic changes during the germination stage in B. napus, systematically illustrating the global molecular and lipid metabolic features of rapeseed seeds across sequential imbibition stages. It further delineates stage-specific expression patterns of key functional genes and lipid metabolites throughout germination. Collectively, these results advance our comprehensive understanding of the regulatory networks controlling rapeseed seed germination, and offer reliable theoretical references and candidate gene resources for breeding high-yield and high-quality B. napus varieties.