Nutrient cycling in the mycorrhizosphere

Optimizing the turnover and recycling of nutrients, a fundamental issue for the sustainability and productivity of agro-ecosystems is depending on the functionality of a framework of plant-soil interactions where microbial populations are involved.Both mutualistic symbionts and saprophytic microorganisms living at the root-soil interfaces, the rhizosphere, or in the plant-associated soil, are recognized as essential drivers of nutrient cycling, availability and capture.Among the mutualistic symbionts, arbuscular mycorrhizal (AM) fungi are one of the most influential groups of soil biota because after establishing the AM symbiosis with most plant species they enhance plant nutrient uptake properties.Saprophytic microorganisms are recognized for their abilities to propel nitrogen (N) fixation and/or phosphorus (P) mobilization, two fundamental processes for sustain plant productivity.Mycorrhiza establishment changes the biological and physical-chemical properties of the rhizosphere, developing the socalled mycorrhizosphere.Particularly relevant is the mycorrhizosphere of legume plants since it also involves the symbiosis with N 2 -fixing nodulating rhizobial bacteria.In this overview of mycorrhizosphere interactions related to nutrient cycling, after describing the protagonist microorganisms, the mechanisms responsible for nutrient acquisition by AM-plants are first analyzed.Then, the processes involved in mycorrhizosphere establishment and functions are described.Finally, the achievements derived from managing selected AM fungi and beneficial bacteria interactions (mycorrhizosphere tailoring) are discussed.The use of 15 N and 32 P to elucidate the contribution of the mycorrhizosphere components to plant nutrient acquisition is detailed.