Arbuscular Mycorrhizal Fungi and Plant Resilience: Mechanisms of Drought and Salinity Stress Tolerance.
Terrestrial plants are frequently exposed to fluctuating abiotic stresses throughout their life cycle, and mycorrhizae can markedly enhance host plant resistance to such challenges. This review summarizes recent advances in our understanding of how arbuscular mycorrhizal fungi (AMF) enhance host plant tolerance through multiple mechanisms. AMF promote stress tolerance through diverse mechanisms, including nutrient solubilization, polyamine accumulation, reactive oxygen species scavenging, physiological improvements, maintenance of ultrastructural stability via membrane integrity, accumulation of osmolytes such as trehalose, proline, polyamine, and glycine betaine, and activation of antioxidant enzymes to alleviate oxidative stress. While substantial progress has been made, the underlying AMF-mediated stress tolerance mechanisms remain underexplored. Future research should focus on dissecting how signaling pathways interact to regulate gene expression in mycorrhizal plants and elucidating the complex regulatory networks operating at the plant-AMF interface. We also outline key research directions for clarifying plant-AMF interactions under stress conditions, as current research highlights the use of beneficial soil microbes to mitigate stress and enhance crop resilience.