Arbuscular Mycorrhizal Fungi Mitigate Crop Multi-Stresses Under Mediterranean Climate: A Systematic Review

Agricultural systems in Mediterranean-type climates are increasingly threatened by drought, salinity, extreme temperatures, heavy metal contamination, and pathogen pressure, all of which undermine crop productivity and agroecosystem stability. In this context, arbuscular mycorrhizal fungi (AMF), natural symbionts of most terrestrial plants, emerge as key biological agents capable of enhancing crop resilience. Following PRISMA guidelines, this systematic review synthesizes current knowledge on the role of AMF in mitigating abiotic and biotic stresses, highlighting their potential as a central component of sustainable Mediterranean agriculture. The available evidence demonstrates that AMF symbiosis significantly increases plant tolerance to multiple stressors across major crop families, including Poaceae, Fabaceae, Solanaceae, and Asteraceae. Under abiotic constraints, AMF improve water and nutrient uptake via extensive hyphal networks, modulate ion homeostasis under salinity, enhance tolerance to thermal extremes, and reduce heavy metal toxicity by immobilizing contaminants. Regarding biotic stresses, AMF induce systemic resistance to pathogens, stimulate secondary metabolite production that deters herbivores, and suppress parasitic nematode populations. Moreover, co-inoculation with other biostimulants, such as plant growth-promoting rhizobacteria, shows synergistic benefits, further improving crop productivity and resource-use efficiency. Overall, AMF represent an effective and multifunctional nature-based tool for improving the sustainability of Mediterranean agroecosystems. However, further research is required to evaluate AMF performance under simultaneous multiple stress factors, thereby reflecting real-world conditions and enabling a more integrated understanding of their agronomic potential.