Arbuscular mycorrhizal fungi and tolerance of drought stress in plants

Abstract

Drought stress has strong inhibition in plant growth and crop production. Arbuscular mycorrhizal fungi (AMF) can colonize the roots of 80% of land's plants to establish arbuscular mycorrhizal symbiosis. A relative short-term soil drought did not appear to discourage root AMF colonization, whereas a long-term soil drought intensity considerably decreased root colonization and hyphal growth in the soil. Such change in mycorrhizal development still strongly stimulated the improvement of plant growth and increased plant survival under drought stress. AMF had shown to enhance drought tolerance in various plants. Firstly, mycorrhizal plants could adapt the drought stress in morphology, especially leaf epicuticular wax and root morphology. And mycorrhizal plants possessed direct pathway of water uptake by extraradical hyphae. In addition, AMF enhanced drought tolerance of the host plant through physiological mechanisms in nutrient uptake and biochemical mechanisms regarding hormones, osmotic adjustment, and antioxidant systems. AMF also released glomalin into soil, defined as glomalin-related soil protein, to improve soil structure, thereby regulating water relations of plant/soil. Molecule mechanisms about expression of relevant stressed genes were clarified a bit more detail. Future perspectives in this field are provided.