Regulation of Rubidium Uptake in Sunflower Roots |
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Authors: | SUNE PETTERSSON PAUL JENSÉN |
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Institution: | Department of Plant Physiology, University of Lund, Sweden |
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Abstract: | Uptake of Rb+ was investigated in 12-day-old intact plants of sunflower (Helianthus annum L. var. californicus) which had been cultivated or pretreated in nutrient solutions with various K+ concentrations. The relationship between Rb+ influx and K+ concentration of the roots indicated regulation of Rb+ uptake by allosteric inhibition of the uptake mechanism. A constant passive influx occurred contemporaneously with the active uptake as shown by experiments at 0°C or with 2,4-dinitrophenol. The allosteric regulation of ion carrier activity occurred after a time lag of up to 1 h after the change of external solution. In experiments involving Rb+ treatments of K+-deficient plants, the synthesis of carriers for transport of Rb+ could be demonstrated. A model including allosteric regulation of Rb+ uptake in roots is discussed. |
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