How can mycorrhizal symbiosis mediate multiple abiotic stresses in woody plants?

Mycorrhizal symbiosis is an ancient association of plants and mycorrhizal fungi central to woody plant evolution and expansion. This symbiosis has established a complex exchange of services between plants and mycorrhizal fungi that ultimately helps plants thrive in extreme abiotic conditions and build resistance against lack of nutrients and water, pathogens, herbivores, or pollutants. Here, we briefly comment on the roles of mycorrhizal symbiosis as modulators of the responses of woody plants to multiple abiotic stress factors typical to ongoing global change. We comment on the most studied factors, i.e. drought, extreme temperatures, nutrient and light deficiency. There is a general lack of understanding of the interaction among stress factors and their combined effects on woody plants, their symbiotic interaction with mycorrhizal fungi and their impact on ecosystem processes. As a first step, identifying and ranking the severity of stress factors and situations/locations where multiple stress factors co-occur could guide initial expectations and hypotheses to comprehend the mycorrhizal benefits to woody species tolerance under multifactorial stress combinations. We finally highlight topical areas that require more information and research.CGB and YM have been funded by the Estonian Ministry of Education and Research (PRG1065) and an ERC incentive grant from the University of Tartu to CGB (PLTOMARENG70)