Influence of Abiotic Salt Stress and Salicylic Acid on callus metabolic study of Bacopa monnieri during In Vitro Culture

Abstract

This study aimed to examine the morphological, physiological, biochemical and secondary metabolite responses of an important medicinal plant, Bacopa monnieri, under salt stress conditions and salicylic acid elicitation in In vitro micropropogation. This study investigated the effect of the association of sodium chloride (NaCl) and salicylic acid (SA) on the growth of callus and the accumulation of bacoside in Bacopa monnieri explants by growing them on Murashige and Skoog (MS) medium containing various concentrations of these salts. Significant differences in the callus proliferation, biomass production, growth rate and metabolite production were noted between different treatment conditions with the callus. Concentrations of salt (50 and 100 mM) stimulated callus proliferation and adaptive physiological responses. Conversely, 150 mM salt concentrations reduced callus growth, browning and necrosis of tissue. Salicylic acid was used as an elicitor which promoted stress resistance, healthy green callus and improved tissue vitality. The moderate stress of salt and salicylic acid (SA) produced a significant increase in both fresh and dry weights and growth index of the cultures. Biochemical analyses suggest that optimization of stress and elicitation conditions were advantageous with respect to production of bacoside. The treatment comprising 100 mM NaCl and 1.0 mM salicylic acid produced a maximum bacoside content which was verified by HPLC as compared to the control and treatments. To conclude, it has been established that controlled salt stress along with salicylic acid elicitation affected the growth responses of Bacopa monnieri callus and enhanced the amount of accumulation of bacoside in the cultures. The results offer a new strategy to improve the production of valuable bioactive compounds in plant tissue culture and for abiotic stress-induced elicitation strategies.