Influx and Efflux of Phosphorus in Roots of Wheat Plants in Non-Growth-Limiting Concentrations of Phosphorus
- 1 May 1990
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Experimental Botany
- Vol. 41 (5), 601-607
- https://doi.org/10.1093/jxb/41.5.601
Abstract
The regulation of net phosphorus uptake was studied in wheat plants at ambient non-growth-limiting P-concentrations. Wheat (Triticum aestivum cv. Klein Atalaya) seedlings were grown from germination in culture solutions containing 0.05, 0.5 and 5.0 mol m−3 phosphate. Only small increments in plant P-concentration and specific accumulation rate for phosphorus were found when ambient P-concentration was increased 100 times. P-influx, estimated by 32P-uptake, was markedly greater with increased external P-concentration, but only small changes in Vmax and no changes in Km were found. Indirect estimation of P-efflux in a time-course of 32P-uptake, and direct P-efflux measurements in ‘wash out’ experiments indicated that P-efflux markedly increased in higher ambient P-concentration. The increase in P-efflux almost completely neutralized the higher P-influx observed in 5.0 mol m−3 relative to 0.05 mol m−3 phosphate. It is postulated that in non-limiting P-concentration net P-uptake is mainly controlled by P-efflux.Keywords
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