Elicitation of diosgenin production in Trigonella foenum-graecum L. seedlings by heavy metals and signaling molecules

Abstract

Seedlings of Trigonella foenum-graecum were treated with four heavy metal salts (CdCl2, CoCl2, K2Cr2O7 and NiCl2) to study the effect of heavy metals on growth and diosgenin production. It was found that CdCl2 increased diosgenin production up to 40-fold and CoCl2 increased diosgenin production up to 41-fold at concentrations which did not affect growth significantly. But K2Cr2O7 and NiCl2 were toxic to growth and inhibited diosgenin production. Effect of exogenously applied methyl jasmonate (MeJa) and calcium (Ca2+) on diosgenin production in seedlings of T. foenum-graecum was also investigated. MeJa enhanced the production of diosgenin. Maximum increase (10.5-fold) was found at 100 µL L−l concentration of MeJa. To study the role of Ca2+ on diosgenin production, seedlings of T. foenum-graecum were treated with a promoter of Ca2+ influx (calcium ionophore A23187), calcium depleted medium, Ca2+ channel blocker (verapamil) and antagonist (LaCl3), a divalent cation chelator (EGTA) and modulator of calcium release (caffeine). All the treatments were compared with a control containing 220 mg L−l concentration of CaCl2. The results suggest that the increase in cytosolic Ca2+ has an inhibitory role on diosgenin production. However, a calcium chelator or Ca2+ channel inhibitors could be used to elicit diosgenin production in this plant.