Relationship between energy-dependent phosphate uptake and the electrical membrane potential in Lemna gibba G1

High rates of phosphate uptake into phosphate-starved Lemna gibba L. G1 were correlated with a high membrane potential (pd = -220 millivolts). In plants maintaining a low pd (-110 millivolts), the uptake rate was only 20% of that of high-pd plants. At the onset of phosphate transport, the membrane o...

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Veröffentlicht in:Plant physiology (Bethesda) 1981-04, Vol.67 (4), p.797-801
Hauptverfasser: Ullrich-Eberius, C I, Novacky, A, Fischer, E, Lüttge, U
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Sprache:eng
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Zusammenfassung:High rates of phosphate uptake into phosphate-starved Lemna gibba L. G1 were correlated with a high membrane potential (pd = -220 millivolts). In plants maintaining a low pd (-110 millivolts), the uptake rate was only 20% of that of high-pd plants. At the onset of phosphate transport, the membrane of high-pd plants was transiently depolarized. This effect was much smaller in low-pd plants. Light stimulated phosphate uptake and the repolarization upon phosphate-induced depolarization, especially in plants grown without sucrose. The phosphate uptake rate was optimal at pH 6 and decreased with increasing pH, corresponding to the phosphate-induced pd changes. Phosphate starvation stimulated the uptake and increased the phosphate-induced depolarization, thus indicating that phosphate uptake depends on the intracellular phosphate level. It is suggested that uptake of monovalent phosphate in Lemna gibba proceeds by an H+ cotransport dependent on the proton electrochemical potential difference and, hence, on the activity of an H+-extrusion pump.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.67.4.797