Investigating the induction of polyphenol biosynthesis in the cultured cells and the stimulatory mechanism of co-induction with 5-aminolevulinic acid and salicylic acid.

Plant cell culture technology is a potential way to produce polyphenols, however, this way is still trapped in the dilemma of low content and yield. Elicitation is regarded as one of the most effective ways to improve the output of the secondary metabolites, and therefore has attracted extensive attention. Five elicitors including 5-aminolevulinic acid (5-ALA), salicylic acid (SA), methyl jasmonate (MeJA), sodium nitroprusside (SNP) and Elicitor (ROE) were used to improve the content and yield of polyphenols in the cultured cells, and a co-induction technology of 5-ALA and SA was developed as a result. Meanwhile, the integrated analysis of transcriptome and metabolome was adopted to interpret the stimulation mechanism of co-induction with 5-ALA and SA. Under the co-induction of 50 μM 5-ALA and SA, the content and yield of total polyphenols of the cultured cells reached 8.0 mg/g and 147.12 mg/L, respectively. The yields of cyanidin-3-O-galactoside, procyanidin B1 and catechin reached 28.83, 4.33 and 2.88 times that of the control group, respectively. It was found that expressions of TFs such as and increased significantly, while and decreased. These great changes might further make the expression of (flavonoid 3'-monooxygenase), (flavonol synthase), (leucoanthocyanidin reductase), (anthocyanidin synthase) and (4-coumarate coenzyme A ligase) increase while CpANR (anthocyanidin reductase) and (flavonoid 3', 5'-hydroxylase) reduce, ultimately enhancing the polyphenols accumulation The co-induction of 5-ALA and SA can significantly promote polyphenol biosynthesis in the cultured C. cells by regulating the expression of key transcription factors and structural genes associated with polyphenol synthesis, and thus has a promising application.