Enhanced accumulation of trigonelline by elicitation and osmotic stresses in fenugreek callus culture

Abstract

Trigonelline is the major secondary metabolite of fenugreek (Trigonella foenum-graecum L.), the exploitation of which is of great importance in the cosmetic and pharmaceutical industries. Therefore, there is a vital demand for improving the production of this metabolite. In this way, elicitation in the in vitro conditions is a compelling approach. The present study was conducted for the first time to investigate the effect of osmotic stresses (salinity and drought) and elicitors (pectin, chitin, methyl jasmonate (MJ), and salicylic acid (SA)) on the trigonelline production in callus culture of fenugreek. Most potential stimulation was done by MJ and SA; elicitation by 50 μM of methyl jasmonate for 15 days resulted in a substantial improvement (2.27 mg g⁻¹ dry weight (DW) that is 5.6-folds over the control). The two abiotic elicitors, i.e. MJ and SA, failed to stimulate trigonelline production except for elicitation by 100 μM of pectin for 10 days and elicitation by 50 μM of chitin for 5 days. Nonetheless, a profound effect was observed between the osmotic stresses, using 200 mM of NaCl (1.93 mg g⁻¹ DW), which was 4.7-folds over the control; however, the drought stress resulted in a maximum of twofold increase. Given the suppressing effect of osmotic stresses on callus growth, the total production of trigonelline in the calli was restricted under these treatments. Thus, our findings revealed that the elicitation by SA and MJ provides the most potent conditions to induce trigonelline production in fenugreek callus culture, as well as simultaneous increasing of callus growth.