Geographical variations in Polygonatum polysaccharides and saponins biosynthesis in Polygonatum species

Abstract

Polygonatum is an important source of polygonatum polysaccharides (PSPs) and saponins. However, the low environmental adaptability of plants producing bioactive components impedes their industrial development. In this study, three Chinese pharmacopoeias of Polygonatum were collected from three important populations covering a wide geographical area from northwest to south China. Variations in metabolites of PSPs and saponins biosynthesis pathway were determined. Moreover, the specialized metabolites showed regional variations across a large geographical scale. Among the environmental variables assessed, daily precipitation amount and elevation appear to have a significant impact on total saponins content. Similarly, sunshine duration and relative humidity appear to have a significant impact on the variation in PSPs content. Furthermore, correlation analysis of transcriptome and important metabolites reveals differences in the expression of genes related to the biosynthetic pathway of three Polygonatum species. Two potential candidate genes, GPI and CAS, have been identified as being respectively involved in the biosynthesis and regulation of PSPs and saponins. This study provides valuable information to understand the effect of environmental factors and key genes on the production of bioactive chemicals in medicinal crops.