Potential of antioxidant enzymes in depicting drought tolerance of wheat (Triticum aestivum L.).

In an effort to determine the biochemical markers for identifying genotypes before sowing for drought tolerance, changes in activities of antioxidant enzymes were determined in the seedlings of five drought-tolerant and five drought-sensitive wheat (Triticum aestivum L.) genotypes, each with different genetic background growing under normal and water deficit conditions induced by 6% mannitol. In comparison with non-stressed seedlings, the catalase (CAT) activity was upregulated by more than 50% in the roots of water-stressed seedlings in drought-tolerant genotypes. Water deficit stress also led to the upregulation of ascorbate peroxidase (APX) in the endosperms and glutathione reductase (GR), CAT and peroxidase (POD) in the shoots of stressed seedlings in drought-tolerant genotypes. Superoxide dismutase (SOD) activity was very low in roots and shoots and showed non-significant increase under water-stress in tolerant genotypes. Out of five specified enzyme activities (CAT in roots and shoots, APX in endosperms, GR and POD in shoots), if any three are upregulated in the specified tissues under water deficit conditions, the genotype is likely to be drought-tolerant. Wheat seedlings with low GR and APX activities and high POD activity in shoots with a low ratio of GR activity of shoot to root of non-stressed seedlings are likely to perform better under rainfed conditions. The observed data showed that status of antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of a wheat genotype.