Copyright 2006 Accademia dei Georgofili
It is known that the chemical composition of the rhizosphere can affect plant growth, influencing the process of nutrient uptake that ensures the plant's adequate development. Plants have evolved mechanisms that allow them to adjust to uneven distributions of the nutrients at the rhizosphere, by altering their root architecture, morphology and functionality: proof of this is their ability to modulate the transmembrane mechanisms for ion transport and release organic molecules into the rhizosphere that can modify the chemical, physical and biological characteristics of the soil. This picture is further complicated by the presence at the rhizosphere of different ions at the same time and of natural substances such as humic molecules that can interfere with the mechanisms for nutrient uptake and those involved in root development. In this short review the effects of changes in nutrient availability and of the presence of humic substances on plasma membrane-bound activities of root cells are discussed. Evidence is provided which supports the role of these rhizospheric components as molecular signals inducing morpho-physiological changes in the roots.
