Molecular mechanism of the effect of PEG and UV stress on the metabolism of arecoline in Areca catechu callus

As the main active ingredient in Areca catechu, arecoline has broad medicinal value. Currently, research on arecoline mainly focuses on its pharmacological and toxicological effects, while its biosynthesis mechanism is rarely reported. In this study, A. catechu callus was used to systematically study the molecular mechanisms of arecoline biosynthesis in response to drought and UV stress. The results showed that under drought stress, the content of arecoline reached the highest level (0.7618%) when the concentration of PEG-6000 was 15%. Under UV stress, the content of arecoline increased and reached the highest level (0.6729%) when irradiated for 30 min daily. RNA-seq analysis of A. catechu callus tissue subjected to 15% PEG-6000 and 30 min UV stress showed that the metabolic pathways were significantly enriched in phenylpropanoid biosynthesis and biosynthesis of secondary metabolites. The experiment also verified that the addition of phenylalanine and tyrosine in the culture medium significantly increased the content of arecoline in A. catechu callus. And the effect of phenylalanine addition was more significant compared to tyrosine addition. Based on the analysis above, it can be inferred that phenylalanine is likely an important precursor for arecoline synthesis.