Effect of chromium on protein oxidation, protease activity, photosynthetic parameters and alleviation of toxicity in growing rice seedlings

Increasing concentration of Cr in soil and water creates a hazardous situation for agriculture across the world. The present study was aimed to examine the effect of toxic concentration of Cr on protein oxidation, protease activity and photosynthesis in rice at seedling stage. Protein oxidation was observed in terms of extent of protein thiolation and its carbonylation. Rice seedlings exposed to 100μM Cr for 8 days in hydroponics were marked by reduced growth, a significant elevation in non-protein thiols (NPTs), protein carbonyls and protease activity and decline in the level of protein thiols, photosynthesis rate (Ps), stomatal conductance (gs), intracellular CO₂ concentration (Ci) and transpiration rate (E). When aqueous extract of the fruits of Phyllanthus emblica was added in the growth medium of Cr-stressed seedlings, a marked restoration in the growth of seedlings along with restoration of Cr-induced alterations was observed. Results indicate that P. emblica extract alleviates Cr-toxicity in rice by preventing oxidation of proteins and restoring photosynthetic activity.