Fast root growth responses, root exudates, and internal detoxification as clues to the mechanisms of aluminium toxicity and resistance: a review

This review on aluminium stress in plants specifically addresses the dynamism of early root growth responses to Al. Three response models, threshold for toxicity, hormesis, and threshold for tolerance, are related to current knowledge on the mechanisms of Al toxicity and resistance. Aluminium exclusion by the production of root exudates and rhizodepositions, as well as internal detoxification mechanisms are considered. Special attention is paid to the central role of chelation of Al by organic acid anions and flavonoid type phenolics outside and inside plant cells.