Understanding Biosynthesis of Major Chemical Constituents in Swertia chirayita

Abstract

Swertia chirayita is a valued medicinal herb of the North-Western Himalayas exhibiting a wide range of therapeutic traits. Swertiamarin, amarogentin and mangiferin are the major secondary metabolites. Unscientific collection and overexploitation has placed the plant in the category of endangered species. Molecular basis of biosynthesis of the aforementioned phytochemicals is still not clear. Growing demand and unorganized cultivation necessitate improved genetic intervention strategies, which can be implemented to positively influence the biosynthetic machinery, and its regulatory network. The study therefore assessed the relative contribution of biosynthesis pathway genes vis-à-vis major secondary metabolites in S. chirayita. Additionally, the effect of altered physiological and biochemical processes, and miRNAs in in vitro versus in vivo grown plants on production levels of secondary metabolites in S. chirayita was also assessed. Phytochemical screening revealed that the highest accumulations of secoiridoids were observed in the root tissues of green house grown plants, whereas maximum amount of mangiferin was detected in the floral tissues. Ten genes of the secoiridoid biosynthesis pathway and five genes of mangiferin biosynthesis pathway showed increased transcript levels in respect to the related metabolite levels. Ten out of sixteen genes from the primary metabolism showed higher expression in tissues of green house grown plants, possibly indicating their involvement in regulating the central carbon pool. Computational approach identified ten miRNAs and eleven potential targets having putative roles in secondary metabolism. The study identified some key genes having potential implications in metabolic engineering of S. chirayita. Again, various altered physiological and biochemical processes, and miRNAs in in vitro versus in vivo grown Chirata plants were also identified having possible role in deciding the final production levels of secondary metabolites. newline