Arbuscular mycorrhizal fungi and antioxidant enzymes in ameliorating drought stress: a meta-analysis

Purpose Drought is becoming one of the most important environmental stresses and is causing the metabolic imbalance in plants as a result of reactive oxygen species (ROS) accumulation, and a substantial reduction in agriculture productivity. It has been reported for several decades that when plants are inoculated with arbuscular mycorrhizal fungi (AMF), the extent of ROS accumulation due to drought stress is reduced and AMF-inoculated plants have greater antioxidant defense mechanisms. Nevertheless, a comprehensive description of correlating drought stress and antioxidant enzymatic roles in mitigation remains unraveled. Methods In the present study, we used meta-analysis in evaluating the AMF inoculation and the prospective antioxidant enzyme responses in alleviating drought stress. Results Overall analysis showed that AMF inoculation significantly increased the drought stress alleviation by 17% more than the non-mycorrhizal controls. In addition, antioxidant enzymes analysis showed that SOD enzyme activity increased significantly by 32%, followed by CAT (23%), POD (28%), and APX (27%) across all studies compared to non-inoculated controls whereas the accumulation of H2O2 reduced significantly by 20%. Moreover, the beneficial effects of AMF differed depending on the identity of the host plant, AMF species, and level of drought stress. Conclusion Thus, our meta-analysis study suggests that AMF plays a pivotal role in the elimination of H2O2 through the upregulation of antioxidant enzymes but it depends upon the identity of AMF and plant species under drought stress conditions.