Battle of Arbuscular Mycorrhizal Fungi Against Drought Stress: A Gateway to Sustainable Agriculture

Around 85% of all land plants have symbiotic relationships with arbuscular mycorrhizal (AM) fungi, microscopic soil fungi that build extensive filamentous network in and around the roots. These links strongly influence plant development, water uptake, mineral nutrition, and defense against abiotic stresses. In this context, the use of AMF as a biological instrument to enhance plant drought resistance and phenotypic plasticity, through the formation of mutualistic associations, seems like a novel strategy for sustainable agriculture. This review synthesizes current understanding on the mechanisms through which AMF alleviates drought stress in agriculture. We focus on how AMF help maintain nutrient and water homeostasis by modulating phytohormones and signaling molecules, and by orchestrating associated biochemical and physiological responses. Particular emphasis is placed on aquaporins (AQPs) as key water-and stress-related channels whose expression and activity are modulated by AMF to maintain ion, nutrient, and water balance. AMF-mediated host AQP responses exhibit three unique patterns under stressful conditions: either no changes, downregulation to limit water loss, or upregulation to promote water and nutrient uptake. Nevertheless, little is known about cellular and molecular underpinnings of AMF effect on host AQPs. We also summarize evidence that AMF enhance antioxidant defenses, osmotic adjustment, soil structure, and water retention, thereby jointly improving plant drought tolerance. This review concludes by outlining the potential of AMF to support sustainable agriculture, offering critical research gaps, such as mechanistic studies on fungal AQPs, hormonal crosstalk, and field-scale performance, which propose future directions for deploying AMF in drought-prone agroecosystems.