Abiotic elicitation of cowpea (Vigna unguiculata L.) cell suspension cultures enhances biomass, isoflavone aglycone production, and antioxidant activity

Abstract

An in vitro cell suspension culture system for cowpea (Vigna unguiculata L.) was developed to optimize pharmaceutically valuable total isoflavones and aglycone compounds (daidzein, genistein, glycitein) via HPLC profiling. Evaluated metrics included net fresh weight changes, proportional growth index, total biomass expansion fold change, post-harvest dry weight percentage, and daily volumetric biomass productivity. Kinetic parameters comprised maximum and exponential specific growth rates, minimum and exponential doubling times, area under the growth curve, mean standing biomass, and growth phases (lag, exponential, deceleration, stationary, decline). Day 18 was optimal for administering six abiotic elicitors: jasmonic acid (JA)/salicylic acid (SA) (50−250 μM), L-proline (25−100 mg L⁻¹), sorbitol/mannitol (5−50 g L⁻¹), and silver nitrate (AgNO₃; 5−40 μM). JA proved most effective; 100 μM maximized biomass and productivity, yielding 3776 mg L⁻¹ of total isoflavones, while 150 μM enhanced intracellular accumulation and ferric reducing antioxidant power (FRAP). SA favored growth at 100 μM but boosted metabolites at 150 μM. L-proline at 50 mg L⁻¹ balanced growth and metabolite production. Osmotic agents supported biomass at 5 g L⁻¹ and enhanced accumulation at 10 g L⁻¹, with glycitein peaking under 25 g L⁻¹ mannitol. AgNO₃ optimized biomass at 5 μM, whereas 10–20 μM improved metabolite levels and FRAP. Multivariate analyses (Pearson correlation, Hierarchical Cluster, Principal Component) identified two distinct functional modules: a biomass–productivity module and a metabolic content–antioxidant activity module, highlighting a physiological trade-off between biomass yield and intracellular concentration. Ultimately, 100 μM JA offers an efficient, scalable platform for sustainable cowpea isoflavone manufacturing.