Mycorrhizal Colonization Enhanced <i>Sorghum bicolor</i> Tolerance under Soil Water Deficit Conditions by Coordination of Proline and Reduced Glutathione (GSH)

Abstract

Drought stress is an important limiting factor in crop production. Arbuscular mycorrhizal fungi (AMF) enhance plant drought tolerance through antioxidant activities. However, the coordination of nonenzymatic antioxidants against drought remains unclear. Here, we investigated the AMF symbiosis in drought tolerance of <i>Sorghum bicolor</i> by increasing proline and reducing glutathione (GSH). <i>Glomus mosseae</i> inoculation increased grain yield, biochemical content, and bioactivities of millets. Under drought conditions, seedlings inoculated with <i>G. mosseae</i> had higher SOD, POD, CAT, PPO, proline, and GSH activities compared to noninoculated controls. Meanwhile, a lower accumulation of MDA and H₂O₂ was observed in the <i>G. mosseae</i> seedlings. Furthermore, genes attributed to nonenzymatic antioxidants, such as <i>GST29</i>, <i>P5CS2</i>, <i>FD3</i>, <i>GST</i>, and <i>GAD</i>, were significantly up-regulated by <i>G. mosseae</i> under drought conditions. In conclusion, <i>G. mosseae</i> inoculation enhanced the drought tolerance of <i>S. bicolor</i> by improving reactive oxygen species (ROS) scavengers, including proline and GSH, that regulate ROS production and prevent oxidative damage.