The effects of methyl jasmonate on growth, gene expression and metabolite accumulation in Isatis indigotica Fort.

Methyl jasmonate (MeJA) plays important roles on growth, gene expression and metabolite accumulation in plants. In this study, the physiological and biochemical characteristics, transcriptome and metabolome profiles of Isatis indigotica Fort., responded to MeJA were explored. Under the treatment, the contents of dry matter, chlorophyll and carotenoids increased significantly, while the water content did not. And the contents of soluble protein, flavonoid and lignin were also raised significantly, but the soluble sugar decreased. Besides, the enzyme activities of phenylalanine ammonia lyase (PAL), lipoxygenase (LOX), polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) increased, showing certain resistance characteristics of this plant. Based on RNA-seq, 31,769 unigenes were functionally annotated, and 2725 differential expressed genes (DEGs) identified. Among them, 57 DEGs covered most of the catalytic steps in general biosynthesis pathways of jasmonic acid, glucosinolates and phenylpropanoid. Referring to the metabolomics analysis, 175 significant differential metabolites were detected by GC-MS, combined with LC-MS method. Moreover, 53 differential metabolites were identified by the multivariate statistical analysis, mainly enriched in 37 different metabolic pathways, with most differential metabolites found in phenylalanine metabolism pathway. The results provided the comprehensive analysis on growth, transcriptome and metabolite profiles responded to MeJA, and gave new insights into revealing and enriching the functions of MeJA, contributing to explore the key genes and their functions on growth and metabolite accumulation and regulation process in I. indigotica.