Molecular mechanisms of seed germination in Hippophae rhamnoides L. based on transcriptomics

Hippophae rhamnoides L. is extensively distributed throughout China and plays a pioneering role in combating desertification and soil erosion in northern regions. H. rhamnoides contains abundant nutrients and is of medical and economic value. However, there has been a lack of research on sea buckthorn seeds, both domestically and internationally, particularly regarding the mechanisms governing their growth and germination. Therefore, to explore the growth of sea buckthorn seeds, this study analyzed and studied the molecular mechanism of seed germination process of sea buckthorn. To better understand the molecular mechanism underlying seed germination in sea buckthorn, we used transcriptomics to compare gene expression before and after seed germination in H. rhamnoides subsp. sinensis Rousi. We identified 9,988 differentially expressed genes (5,593 upregulated and 4,395 downregulated). A bioinformatics-based analysis revealed that changes in plant hormone signal transduction and starch and sucrose metabolism-related gene expression may regulate seed germination in this species. Notably, the levels of auxin (IAA), cytokinin (CTK), and brassinosteroids (BR) increased during seed germination while those of ABA decreased. Exogenous application of IAA, CTK, and BR promoted sea buckthorn seed germination, while ABA inhibited it. These findings suggested that hormones play an important role in the process of sea buckthorn seed germination. This study provides preliminary information about the seed germination mechanism in sea buckthorn, offering an essential reference for improving seed breeding and germplasm and laying the foundation for further resistance research on the molecular mechanism of seed germination of sea buckthorn in this species.