Overexpression of a Plasma Membrane H-ATPase Gene Stimulates the Uptake of Primary Macronutrients in Rice Roots.

Plasma membrane (PM) H-ATPase is a master enzyme involved in various plant physiological processes, such as stomatal movements in leaves and nutrient uptake and transport in roots. Overexpression of PM H-ATPase 1 () has been known to increase NH uptake in rice roots. Although electrophysiological and pharmacological experiments have shown that the transport of many substances is dependent on the proton motive force provided by PM H-ATPase, the exact role of PM H-ATPase on the uptake of nutrients in plant roots, especially for the primary macronutrients N, P, and K, is still largely unknown. Here, we used overexpression lines (-oxs) and gene-knockout mutants to investigate the effect of modulation of PM H-ATPase on the absorption of N, P, and K nutrients through the use of a nutrient-exhaustive method and noninvasive microtest technology (NMT) in rice roots. Our results showed that under different concentrations of P and K, the uptake rates of P and K were enhanced in -oxs; by contrast, the uptake rates of P and K were significantly reduced in roots of mutants when compared with wild-type. In addition, the net influx rates of NH and K, as well as the efflux rate of H, were enhanced in -oxs and suppressed in mutants under low concentration conditions. In summary, this study indicated that overexpression of stimulated the uptake rate of N, P, and K and promoted flux rates of cations (i.e., H, NH, and K) in rice roots. These results may provide a novel insight into improving the coordinated utilization of macronutrients in crop plants.