Aluminium tolerance in plants and the complexing role of organic acids

The aluminium cation Al3+ is toxic to many plants at micromolar concentrati ons. A range of plant species has evolved mechanisms that enable them to gr ow on acid soils where toxic concentrations of Al3+ can limit plant growth, Organ ic acids play a central role in these aluminium tolerance mechanisms . Some plants detoxify aluminium in the rhizosphere by releasing organic ac ids that chelate aluminium. In at least two species, wheat and maize, the t ransport of organic acid anions out of the root cells is mediated by alumin ium-activated anion channels in the plasma membrane. Other plants, includin g species that accumulate aluminium in their leaves, detoxify aluminium int ernally by forming complexes with organic acids.