Function and mechanism of organic anion exudation from plant roots

The rhizosphere is the zone of soil immediately surrounding plant roots tha t is modified by root activity. In this critical zone, plants perceive and respond to their environment. As a consequence of normal growth and develop ment, a large range of organic and inorganic substances are exchanged betwe en the root and soil, which inevitably leads to changes in the biochemical and physical properties of the rhizosphere. Plants also modify their rhizos phere in response to certain environmental signals and stresses. Organic an ions are commonly detected in this region, and their exudation from plant r oots has now been associated with nutrient deficiencies and inorganic ion s tresses. This review summarizes recent developments in the understanding of the function, mechanism, and regulation of organic anion exudation from ro ots. The benefits that plants derive from the presence of organic anions in the rhizosphere are described and the potential for biotechnology to incre ase organic anion exudation is highlighted.