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 Oryza… Click to show full abstract
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 Oryza sativa PM H+-ATPase 1 (OSA1) has been known to increase NH4+ 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 OSA1 overexpression lines (OSA1-oxs) and gene-knockout osa1 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 OSA1-oxs; by contrast, the uptake rates of P and K were significantly reduced in roots of osa1 mutants when compared with wild-type. In addition, the net influx rates of NH4+ and K+, as well as the efflux rate of H+, were enhanced in OSA1-oxs and suppressed in osa1 mutants under low concentration conditions. In summary, this study indicated that overexpression of OSA1 stimulated the uptake rate of N, P, and K and promoted flux rates of cations (i.e., H+, NH4+, and K+) in rice roots. These results may provide a novel insight into improving the coordinated utilization of macronutrients in crop plants.
               
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