Dynamic Lipidomics and Transcriptome Profiling Reveals the Transcriptional Regulatory Mechanism Governing TAGs Formation in Seeds of Safflower

Safflower (Carthamus tinctorius L.) is a valuable oil crop due to its bioactive ingredients and high linoleic acid content, which contribute to its antioxidant properties and potential for preventing atherosclerosis. Current research on safflower focuses on understanding the biosynthesis of seed oil through omics strategies, yet there is a lack of comprehensive knowledge of the dynamic changes in lipids and the regulatory mechanisms during seed development. Here, we performed combined quantitative lipidomics profiles and transcriptomic analyses to characterize the lipid accumulation patterns of safflower seeds, investigate gene networks, and identify vital candidate genes and transcription factors (TFs) involved in triacylglycerol (TAGs) biosynthesis in safflower. A total of 417 lipid compounds and their corresponding coexpressed genes were categorized into seven distinct lipid metabolite vs gene modules. By integrating bioinformatic analyses, one TFs-genes transcriptional regulatory network for major lipid compounds was proposed, involving 10 hub transcription factors and 12 structure genes that participate in regulating the accumulation of triacylglycerols (TAGs) and fatty acids (FAs). Furthermore, the results of yeast one-hybrid assay suggested that CtAP2.1 and CtAP2.4, the homologous genes of AINTEGUMENTA-Like 5 and 6 (AIL5 and AIL6) in Arabidopsis thaliana, may play important roles in the TAGs biosynthesis in safflower seeds. Our findings provide insight into the regulatory network of lipid compounds in safflower seeds and offer potential gene resources for enhanced oil content through targeted crop breeding.