Ascorbic acid is essential for inducing chromium (VI) toxicity tolerance in tomato roots

Problem of chromium (Cr) pollution is of great scientific concern as it adversely affects crop productivity worldwide. Therefore, scientific efforts are being made to minimize Cr toxicity in crop plants by using various methods. Of these methods, use of certain chemicals like ascorbic acid (ASC), glutathione, proline, nutrients, etc. has shown promising results. Therefore, in this study, we have tested a role of ASC in regulating hexavalent chromium [Cr(VI)] toxicity in tomato roots. Chromium (VI) reduced length, dry weight, fitness and tissue density of roots due to enhanced cellular accumulation of Cr which leads to the cell death. Chromium (VI) also declined ASC pool and activity of its regenerating enzymes along with enhanced level of oxidative stress and damage to lipids and proteins. However, exogenous addition of ASC significantly reversed toxic effects of Cr(VI) in tomato roots. Furthermore, addition of lycorine (inhibitor of ASC biosynthesis) interestingly augmented Cr (VI) toxicity. However, exogenous addition of ASC reversed toxic effect of lycorine suggesting that endogenous ASC has role in alleviating Cr(VI) toxicity in tomato roots.