Arbuscular Mycorrhizal Fungi in Conferring Tolerance to Biotic Stresses in Plants

Mycorrhiza is a symbiotic association between the roots of plants with fungi. Among the various types of mycorrhizal fungi, arbuscular mycorrhizal fungi (AMF) are the most prominent as they are obligate symbionts with a wide host range, and they play a major role in shaping ecosystems and associated productivity. Approximately 71% of vascular plant species are able to form symbiotic association with AMF. AMF primarily rely on the host for photosynthates but give much more in return for the well-being of the host plant. Most importantly they are able to improve tolerance of host plants against various biotic stresses, such as—bacterial, fungal, viral, nematode phytopathogens and herbivores. The underlying mechanism includes—competition for nutrients, space, and host photosynthates, rhizosphere alteration and host defense induction. The effectiveness of an AM association in conferring biotic stress tolerance is context dependent, affected by various biotic and abiotic factors. This review describes various mechanisms involved in AMF mediated biotic stress tolerance in plant and the biotic and abiotic factors which influences the performance of AM association.