Organic acids of crop plants in aluminium detoxification

Phytotoxicity of aluminium is one of the most serious problems in limiting plant growth in acidic soils. A number of plant species exhibit inheritable aluminium tolerance by the secretion of organic acids which is highly specific to aluminium stress and localized to the root apices. Organic acids have been considered to play an important role in the detoxification of aluminium, both externally and internally. Some plants detoxify aluminium by the secretion of organic acids from the roots. Other plant species that accumulate aluminium in their leaves, detoxify aluminium internally by forming complexes with organic acids. The kind of organic acids and the secretion pattern depends on plant species. This review summarizes current understanding of the mechanism and regulation of the secretion of organic acids from roots under aluminium stress. The advantages that plants get from the presence of organic acids in the rhizosphere are described and the biotechnological approaches to increase the secretion of organic acids are highlighted.