The arbuscular mycorrhizal symbiosis enhances the photosynthetic efficiency and the antioxidative response of rice plants subjected to drought stress

Rice (Olyza sativa) is the most important crop for human consumption, providing staple food for more than half of the world's population. Rice is conventionally grown under flooded conditions for most of its growing cycle. However, about half of the rice area in the world does not have sufficient water to maintain optimal growing conditions and yield is reduced by drought. One possible way to increase rice production in order to meet the rice demand is to improve its drought tolerance by means of the arbuscular mycorrhizal (AM) symbiosis. Thus, AM and non-AM rice plants were maintained under well-watered conditions or were subjected to moderate and severe drought stress for 15 d. After that, half of the plants from each treatment were harvested, while the other half were allowed to recover from drought for additional 25 d. The results showed that rice can benefit from the AM symbiosis and improve their long-term development after a drought stress period. In fact, at each watering level, AM plants showed about 50% enhanced shoot fresh weight as compared to non-AM plants. The AM symbiosis enhanced the plant photosynthetic efficiency under stress over 40%, induced the accumulation of the antioxidant molecule glutathione and reduced the accumulation of hydrogen peroxide and the oxidative damage to lipids in these plants. Thus, these combined effects enhanced the plant performance after a drought stress period. (C) 2010 Elsevier GmbH. All rights reserved.