Characterizing the variation in safflower seed viability under different storage conditions through lipidomic and proteomic analyses

The aging of seeds seriously affects their yield. Vacuum and low temperatures have been shown to prolong seed life and delay seed senescence. However, the underlying mechanisms that control these processes in safflower have yet to be explored. Therefore, this study aimed to study the structural, physiological and biochemical changes that occur in safflower seeds stored for one year at different temperatures and sealing conditions. X-ray imaging, germination percentage determination, determination of water content, and TTC staining were utilized to analyze seed structure and viability. The structure of its outer surface was observed by scanning electron microscope, and the changes of catalase activity and malondialdehyde content were determined to understand its physiological and biochemical status. In addition, lipidomic and proteomic analyses were performed. The results showed that the germination percentage was improved under vacuum and low temperature conditions. Compared with high-temperature storage, low-temperature storage not only reduces the level of reactive oxygen species, but also facilitates the preservation of intact seed structure. Lipidomic analysis indicated the levels of PA reduced at low temperatures, while the content of PC, PE, PS, and PG exhibited an inverse correlation, increasing as temperatures decreased. Proteomic analysis identified two proteins (HH-013791-RA, HH-017308-RA) that may be involved in fatty acid metabolism and carbon metabolism respectively. Expression levels of these proteins were found to be lower at -18 °C, but increased with increasing storage temperatures. Storing safflower seeds under low-temperature and vacuum conditions significantly enhances germination rates and preserves seed structure by reducing reactive oxygen species levels. Two proteins (HH-013791-RA, HH-017308-RA) in the fatty acid metabolism and carbon metabolism pathways are temperature-regulated, and are involved in lipid metabolism, affecting seed structure and vitality.