Root-Apex Proton Fluxes at the Centre of Soil-Stress Acclimation.

Proton (H) fluxes in plant roots play critical roles in maintaining root growth and facilitating plant responses to multiple soil stresses, including fluctuations in nutrient supply, salt infiltration, and water stress. Soil mining for nutrients and water, rates of nutrient uptake, and the modulation of cell expansion all depend on the regulation of root H fluxes, particularly at the root apex, mediated primarily by the activity of plasma membrane (PM) H-ATPases. Here, we summarize recent findings on the regulatory mechanisms of H fluxes at the root apex under three abiotic stress conditions - phosphate deficiency, salinity stress, and water deficiency - and present an integrated physiomolecular view of the functions of H fluxes in maintaining root growth in the acclimation to soil stress.