Roles of plasma membrane H⁺-ATPases in plant mineral nutrition

Plasma membrane H⁺-ATPase (PMA), a kind of essential proton pump in plants, is an extremely critical transporter playing vital roles during the whole life of plants. This paper reviews the regulatory mechanism of PMA activity, and the role of PMA in plant root growth, organic acid exudation, mineral nutrient absorption and nutrient stress adaptation, and provides perspective on future research and the potential application in agricultural production by modulating the expression of PMA genes in crops. PMA pumps H⁺ out of the cytoplasm by consuming ATP to establish membrane potential and provide electrochemical gradient and proton driving force for the transmembrane transport of various nutrient ions, as well as for the secretion of organic acids and hydrophilic biological nitrification inhibitors. Under nutritional stress such as phosphorus deficiency, iron deficiency and aluminum toxicity, PMA is induced and acidifies the rhizosphere by excreting H⁺, thus improving the availability of phosphorus and iron. PMA also helps to release phosphorus from phosphate rocks and reduces the toxicity of aluminum ions by promoting the exudation of organic acid. In addition, PMA is involved in regulating the growth of plant roots and the establishment of symbiosis between plants and arbuscular mycorrhizal fungi. Modulating the expression of PMA genes, and genes encoding protein kinases and/or phosphatases that regulate PMA activities, or modifying the specific amino acid of PMA proteins can regulate the activity of PMA, and this is a potential strategy to improve nutrient utilization efficiency and nutrient stress resistance in crops.