The aluminium signal: New dimensions to mechanisms of aluminium tolerance

The physiological basis of plant reaction to and tolerance of aluminium (Al) is poorly understood. We review the results of investigations into Al toxicity and root physiology to develop a theoretical basis for explaining the reaction of the root to Al, including suggested roles for Ca2+, mucilaginous cap secretions and endogenous growth regulators in mediating a transmitted response between Al-damaged cap cells and the interacting cell populations of the cap and root.