EuRBG10 involved in indole alkaloids biosynthesis in Eucommia ulmoides induced by drought and salt stresses

Alkaloids are natural products with many important medicinal activities. To explore the mechanism of abiotic stress promoting alkaloid biosynthesis in Eucommia ulmoides, transcriptomic analysis and metabonomic analysis were used, virus-induced gene silencing (VIGS) lines of target gene were constructed. The results showed that drought and salt stress caused wilting and blackening of leaves, decreased chlorophyll level, and significantly induced MDA and relative conductivity. To resist the damage of stress to cells, the level of secondary metabolites such as alkaloids increased significantly with the extension of stress time. Transcriptomic results showed that, were. Six alkaloid related genes (AWGs) were gathered in five modules positively correlated with either salt stress or alkaloid contents by WGCNA. Results of GO and KEGG enrichment revealed that biosynthesis of alkaloid, especially indole alkaloid was induced, and degradation of alkaloid was inhibited under salt stress. Combining the results of transcriptome and metabolomics, it was suggested that EuRBG10 promotes the production of indole alkaloids and EuAMO5 inhibits the degradation of alkaloids, which may be the core mechanism of the indole alkaloid biosynthesis pathway (map00901) induced by salt stress. The results of these hub proteins were also consistent with the chordal graph of KEGG enrichment. Hub roles of EuRGB10 was checked in E. ulmoides by VIGS. Our findings provide a preliminary understanding of abiotic stress regulating secondary metabolites such as alkaloids, and propose hub genes that can be used to improve the level of bioactive components in medicinal plant.