Differential physiological and biochemical responses of two Vigna species under enhanced UV-B radiation

Differential physiological and biochemical responses of two Vigna spp. i.e. Vigna mungo (L.) and Vigna acontifolia (Jacq.) seedlings exposed to enhanced ultraviolet-B (ambient+supplemental, 280–320 nm) radiation were studied. UV-B radiation accelerated the generation of ROS i.e. superoxide radical (O2–), hydrogen peroxide (H2O2) and hydroxyl radical (OH) in leaves, and concomitantly damaging effects on lipid peroxidation, electrolyte leakage and growth in both Vigna spp. were noticed in dose dependent manner, but V. mungo exhibited greater UV-B damaging effects. UV-B stress induced positive response on antioxidants: superoxide dismutase (SOD) and guaiacol peroxidase (GPX) activity, and contents of proline, ascorbic acid, total phenolic contents (TPCs) and total flavonoid contents (TFCs) in leaves of both spp., however, catalase (CAT) exhibited varied activity. The study concludes that substantially higher contents of TPCs and TFCs in epidermal layer, proline and ascorbic acid, and higher CAT activity before and after enhanced UV-B exposure probably attributed greater tolerance to V. acontifolia species, thus exhibited lesser UV-B induced damaging effects on cellular components and growth than that of V. mungo. This study also suggests that V. acontifolia is comparatively resistant to UV-B and thus may be useful for practical cultivation.