The role of the plasma membrane H⁺-ATPase in plant responses to aluminum toxicity

Aluminum (Al) toxicity is a key factor limiting plant growth and crop production on acid soils. Increasing the plant Al-detoxification capacity and/or breeding Al-resistant cultivars are a cost-effective strategy to support crop growth on acidic soils. The plasma membrane H⁺-ATPase plays a central role in all plant physiological processes. Changes in the activity of the plasma membrane H⁺-ATPase through regulating the expression and phosphorylation of this enzyme are also involved in many plant responses to Al toxicity. The plasma membrane H⁺-ATPase mediated HC influx may be associated with the maintenance of cytosolic pH and the plasma membrane gradients as well as Al-induced citrate efflux mediated by a HC-ATPase-coupled MATE co-transport system. In particular, modulating the activity of plasma membrane H⁺-ATPase through application of its activators (e.g., magnesium or IAA) or using transgenics has effectively enhanced plant resistance to Al stress in several species. In this review, we critically assess the available knowledge on the role of the plasma membrane H⁺-ATPase in plant responses to Al stress, incorporating physiological and molecular aspects.