Rapid Effects of Abscisic Acid on Ion Uptake in Sunflower Roots |
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Authors: | GUNVOR ERLANDSSON SUNE PETTERSSON SVEN-BÖRJE SVENSSON |
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Affiliation: | Department of Plant Physiology, University of Lund, Fack, S-220 07 Lund 7, Sweden |
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Abstract: | Short-term effects of ABA, ABA + kinetin and kinetin on ion (86Rb-potassium and phosphate) and water uptake in sunflower plants (Helianthus annuus var. californicus) were examined with a continuous-recording technique. Ion uptake in the roots and transport to the shoots were also investigated by conventional tracer uptake experiments and by sap bleeding experiments with excised roots. After addition of 5 × 10?6-4 × 10?5M ABA to the root medium there was an immediate decrease (30–70%) in the rate of ion uptake which lasted 30–70 min. The rate of water uptake was not significantly affected as measured with this method. Ion transport to the shoots and to the bleeding sap of excised roots was decreased by ABA. ABA-induced inhibition of ion uptake was abolished by the presence of kinetin, and uptake was slightly stimulated by 2 × 10?5M kinetin alone. We suggest that concentration gradients of ABA or rapid changes in the ABA-kinetin balance in the roots affect ion uptake and transport. |
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