Tissue culture of safflower and analysis of secondary metabolites in suspension cells

Safflower(Carthamus tinctorius), a valuable traditional Chinese medicinal plant, has attracted much attention in recent years. This study established a stable tissue culture system of safflower and analyzed the chromatogram of its secondary metabolites, providing high-quality experimental materials for further research on natural products in safflower. The calluses were established from the safflower seeds germinated in a sterile environment, and then they were differentiated into the aseptic seedlings, or cultured to obtain suspension cells in liquid medium. The ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry(UPLC-Q-TOF-MS), Progenesis QI, and principal component analysis(PCA) were used to detect and analyze the secondary metabolites in the suspension cells before and after induction with different elicitors(methyl jasmonate, silver nitrate, salicylic acid and yeast extract). A total of 23 secondary metabolites including flavonoids, phenylpropanoids, alkaloids, fatty acids and aromatic glycosides were detected in safflower suspension cells. In response to the four elicitors, 11 compounds showed increased or decreased relative content. The results indicate that different elicitors have various effects on the accumulation of secondary metabolites in safflower suspension cells, and yeast extract shows more obvious positive induction. Therefore, different elicitors may play a role in the expression of related genes in the biosynthetic pathway of specific secondary metabolites. The results facilitate the discovery of targeted elicitors and the large-scale production of valuable secondary metabolites in the future.