A metabolic reprogramming in Bacopa monnieri plants induced by methyl-jasmonate and enhanced biosynthesis of triterpene saponins

Abstract

The bacoside-A is the main bioactive metabolite present in Bacopa monnieri L. The yield of bacoside-A from plant sources is too less to meet industrial demand. This study investigated the effect of methyl jasmonate (MeJA) on metabolic profiles and bacoside-A biosynthesis in greenhouse-grown plants of B. monnieri. The greenhouse-grown plants were kept inside a closed plastic container and then elicited with MeJA vapour. It was found that MeJA treatment (200 µM for 2 h on day zero) followed by harvesting leaves on day three was the optimum treatment, resulting in an increase of 1.8-fold, 2.2-fold, 3.1-fold, and 2.5-fold in bacoside A3, bacopaside II, bacopaside X, and bacopasaponin C in comparison with control plants, respectively. The transcript levels of squalene synthase (SQS), a key gene involved in bacoside-A biosynthesis was transiently induced by MeJA and reached a peak of up to 3.7-fold at 24 h. The relationships between bacosides content and primary metabolites in plants treated with MeJA were analyzed by gas chromatography-mass spectrometry. MeJA enhances glycolysis and TCA cycles, generating acetyl-CoA, which acts as a precursor for bacosides synthesis, as revealed by untargeted metabolomics. Therefore, in planta application of MeJA appears to have a great impact on enhanced bacoside-A accumulation, in the greenhouse-grown plants of B. monnieri. In this study, farmers and the pharmaceutical industry will have access to a simple and time-saving elicitation strategy for improving bacosides production from greenhouse-grown plants without the need for expensive and time-consuming in vitro culture techniques.