Exogenous Application of Indole Acetic Acid Differentially Modulates Hexavalent Chromium Tolerance in Pisum sativum L. Seedlings
In the present study, impact of exogenous application of indole acetic acid (IAA; 10 and 100 & M) on Pisum sativum L. under hexavalent chromium toxicity (Cr VI; 50, 100 and 250 & M) was studied. Chromium and 100 & M IAA decreased seed germination rate, growth and photosynthetic pigments which was accompanied by an increase in hydrogen peroxide and malondialdehyde. Treatment of Cr enhanced accumulation of this metal, and accumulation further increased when 100 & M IAA and Cr were applied simultaneously. Under Cr and 100 & M IAA treatments, activities of superoxide dismutase and ascorbate peroxidase (except at 250 & M Cr + 100 & M IAA) were increased while that of catalase, glutathione reductase (except at 100& M IAA alone) and dehydroascorbate reductase decreased. Ascorbate, glutathione and their reduced/oxidized ratios in pea treated with Cr and 100 & M IAA were significantly decreased. In contrast, application of 10 & M IAA alleviated inhibition in growth, increased antioxidants and led to decrease in Cr accumulation and oxidative stress induced by Cr. The data indicate that application of 10 & M IAA increases Cr tolerance of pea during early stage of growth by regulating Cr accumulation and oxidative stress, and maintaining levels of the antioxidants while 100 & M IAA showed opposite response.