Arsenic-induced oxidative stress and its reversal by thiourea in mung bean (Vigna radiata (L.) Wilczek.) genotype

A pot culture experiment was conducted in mung bean (Vigna radiata (L.) Wilczek.) genotype PUSA Baisakhi to test the effect of sodium arsenate and thiourea (TU). Arsenic at 25 μM caused significant inhibition of growth as indicated by reduced shoot and root dry weight and reduction in photosynthetic capacity. Significant decline in ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase coupled with high superoxide dismutase seriously impeded scavenging of reactive oxygen species and led to reduction in glutathione redox state. This resulted in overaccumulation of H2O2 in leaves of arsenate-treated mung bean genotype and consequently, high level of lipid peroxidations, as the marks of onset of arsenic-induced oxidative stress. Priming of seeds and application of TU at 6.5mM and 13 mM was found highly effective not only in countering of oxidative stress but also in significant enhancement of shoot and root dry weight even under As exposure. Significant elevation in H2O2scavenging capacity accompanied by high GSH-regeneration though stimulated glutathione reductase activity in presence of TU certainly helped mung bean seedlings to counter As-induced oxidative stress and maintenance of normal to even better plant growth and photosynthesis under As exposure.