Influence of arbuscular mycorrhiza on antioxidative system of wheat (Triticum aestivum) under drought stress

The effect of arbuscular mycorrhizal fungi (AMF) on antioxidative system in drought tolerant (WH 1025) and drought susceptible (WH 1105) wheat varieties was investigated in screen house under control and stress conditions. Mycorrhizal and non-mycorrhizal wheat (Triticum aestivum L.) plants were subjected to water stress by withholding irrigation at different stages of plant growth (i.e. jointing and heading stages). The antioxidant and antioxidative enzymes were estimated in leaves of water stressed and control plants. It was found that drought tolerant and drought susceptible varieties showed different response under drought conditions. Variety WH 1105 suffered greater damage to cellular membrane due to high level of reactive oxygen species (ROS) as indicated by superoxide radical (O-), hydrogen peroxide (H2O2) and malondialdehyde (MDA) content under stress conditions. Antioxidative enzymes viz. superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT) and peroxidase (POX) were higher in drought tolerant variety. Antioxidative metabolites viz. ascorbic acid and glutathione content was increased in both tolerant and susceptible variety under water stress but with higher magnitude in WH 1025 than WH 1105. Results showed that under water stress conditions, mycorrhizal inoculation significantly decreased the O-2(-), H2O2, and MDA content and enhance the activities of antioxidative enzymes in both the varieties. But it was found that the activity was higher in tolerant variety than susceptible variety under water stress conditions. Hence, overall results suggest that mycorrhizal symbiosis play a vital role in enhancing the activities of antioxidative enzymes and decreasing the ROS content that enables the host plant to sustain the drought conditions.