Exploring the Roles of Arbuscular Mycorrhizal Fungi in Plant–Iron Homeostasis

Abstract

Arbuscular mycorrhizal fungi (AMF) form a vital symbiotic relationship with plants. Through their extensive hyphal networks, AMF extend the absorptive capacity of plant roots, thereby allowing plants to reach otherwise inaccessible micronutrient sources. Iron, a critical micronutrient involved in photosynthesis and other metabolic processes, often becomes inaccessible owing to its tendency to form insoluble complexes in soil. AMF symbiosis significantly ameliorates this challenge by enhancing iron uptake and homeostasis in plants, altering root architecture, and producing root exudates that improve iron solubility. Moreover, the interaction with diverse soil bacteria, particularly plant growth-promoting rhizobacteria, can potentiate the benefits of AMF symbiosis. Siderophores are low-molecular-weight chelators with iron-binding capacities produced by various microorganisms and plant roots. They play pivotal roles in regulating intracellular iron and have been identified in different mycorrhizal associations, including AMF. While molecular mechanisms behind AMF-mediated iron uptake have been partially explored, the intricate networks involving AMF, plants, siderophores, and other soil microbiota are largely unknown. This review focuses on the multifaceted roles of AMF in plant–iron homeostasis, interactions with soil bacteria, and the potential of siderophores in these processes, emphasizing the possibilities for harnessing these relationships for sustainable agriculture and enhancing plant productivity.