Alleviation of chromium toxicity in rice seedling using Phyllanthus emblica aqueous extract in relation to metal uptake and modulation ofantioxidative defense

Abstract

Chromium is a key metal pollutant of the environment. When present in high concentrations in soil it adversely affects plant growth and productivity. Phyllanthus emblica(P.emblica) aqueous extract contains many natural antioxidants, and it has been widely used in traditional medicine for the treatment of severe oxidative stress-related diseases and disorders. The present study was aimed to investigate the possible role of P.emblica aqueous extract in alleviating Cr toxicity effects in rice (Oryza sativa) seedlings in relation to growth attributes, Cr uptake, production of reactive oxygen species (ROS), lipid peroxidation, and activities of antioxidative enzymes. Rice seedlings were raised for 4–8days in Yoshida nutrient medium in hydroponics containing either 100μM Cr (K2Cr2O7) or Cr+P.emblica aqueous extract. Cr treatment to the seedlings caused decrease in root and shoots length and fresh biomass, decline in relative water content (RWC) and photosynthetic pigments and increase in root membrane permeability. Uptake of Cr was more in roots than in shoots. Increased production of ROS, increase in lipid peroxidation and increased activities of antioxidative enzymes superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) were observed in Cr-treated seedlings as compared to controls. With the addition of aqueous extract of P.emblica(5mgml−1) in the Cr treatment medium, significant alleviation of Cr-induced decline in growth, biomass, photosynthetic pigments, and reduction in Cr-induced elevated activities of antioxidative enzymes in the seedlings was observed. Our results suggest that P.emblica aqueous extract considerably alleviates the effects of Cr in rice seedlings by suppressing Cr uptake, reducing oxidative stress and modulating activities of antioxidative enzymes.