Arbuscular Mycorrhizal Fungi as Potential Bioprotectants Against Aerial Phytopathogens and Pests

In the context of an increasing worldwide food requirement, the control of crop diseases is crucial to guarantee high and stable yield, as well as sanitary quality. An environmentally friendly contribution to this could be biocontrol using beneficial microorganisms, such as arbuscular mycorrhizal fungi (AMF). AMF establish symbiosis with their host plants, thus influencing their growth, but they also induce tolerance to environmental stresses. Among stresses that can be alleviated through AMF inoculation, plant attacks by aerial pathogens and pests have so far been underestimated. Therefore, we present here an overview of studies focusing on AMF-mediated bioprotection against aerial pathogens and pests. Obtained protection is mainly due to changes in host nutrition and induction of defense following the establishment of arbuscular mycorrhizal symbiosis. This protection can vary greatly depending on different factors such as host genotype, AMF species involved, pest and pathogen lifestyles, interactions between AMF and other microorganisms, or even crop management practices. Finally, some future challenges for the use of AMF in biocontrol are discussed.