Deciphering Transcriptional Dynamics of Angelica sinensis Seed Development to Define the Optimal Harvesting Stage

The root of Angelica sinensis (Oliv.) Diels is a traditional Chinese medicine. While physiological and biochemical approaches to improve seed quality during maturation have been explored, the regulatory mechanism governing the optimal harvesting stage remains uncovered. Here, transcriptomic profiling was conducted across four maturity stages (i.e., S1 milk stage, S2 wax stage, S3 ripe stage, and S4 straw stage), and the expression of key genes was validated by qRT-PCR. A total of 3949, 10,068, and 19,256 differentially expressed genes (DEGs) were detected at S2, S3, and S4 compared with S1, respectively. A core set of 960 DEGs was shared across all three comparisons (i.e., S2 vs. S1, S3 vs, S1, and S4 vs. S1). Functional annotation identified six genes related to seed development, 45 to polysaccharide metabolism, seven to starch metabolism, 21 to protein metabolism, 37 to amino acid metabolism, and 11 to hormone metabolism. The expression levels of genes related to seed development (e.g., ANAO2, GMPM1, and LEA34), metabolites (e.g., E131, BAM1, and AP25) and hormones (e.g., AUL1, AUX22D, and ILL4) were largely consistent with the corresponding metabolite and hormone contents. Integrating physiological and transcriptional evidence, a model of the optimal harvest stage for A. sinensis seeds was proposed. It can be concluded that the seed quality of A. sinensis is controlled by multiple genes. This transcriptomics analysis provides new insights into the regulation of the optimal harvesting stage for A. sinensis seeds.