Introduction to Arbuscular Mycorrhizal Fungi and Higher Plant Symbiosis: Characteristic Features, Functions, and Applications

Abstract

AbstractArbuscular mycorrhizal fungi (AMF) are ubiquitous, soil-borne, endophytic, obligate biotrophs that colonize the roots of most terrestrial plants to establish mutually beneficial relationships. The colonization of host roots by AMF improves the access of plant roots to nutrients, mainly phosphorus (P) and nitrogen (N). In return, host plants provide the colonizing fungus with carbon (C)-rich photosynthates such as sugar and lipids. This nutrient exchange strongly impacts plant and microbial ecosystems by influencing plant fitness, core soil processes, and the C cycle. Crucially, both mutualism and ecosystem services largely rely on the bidirectional flow of resources. The AMF symbiosis not only provides plants with nutrients but also supplies water and enhances their resistance to environmental and biotic challenges. The physiological and molecular processes by which AMF aids plants in nutrient foraging and stress resilience have been extensively studied. Recent work has established the framework for nutrient exchange and regulatory interactions between host plants and AMF, but the mechanisms underlying AMF-mediated host plant tolerance to stress still remain unclear. AMF are of potential applications in crop production, forestry management, bioremediation, and ecological restoration as biofertilizers and bioprotectors. In the first chapter, we introduce AMF, plant-AMF symbioses and their characteristic features, functions, and potential applications.