Gramicidin-D-stimulated influx of monovalent cations into plant roots |
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Authors: | T. K. Hodges R. L. Darding T. Weidner |
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Affiliation: | (1) Department of Horticulture, University of Illinois, Urbana;(2) Department of Botany, Eastern Illinois University, 61920 Charleston, Illinois, USA |
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Abstract: | Summary Gramicidin D and nigericin were found to stimulate K+ influx into oat roots. Valinomycin and nonactin had little effect on K+ influx. The region of the root most sensitive to gramicidin was the elongation zone. Monocot roots were more sensitive to gramicidin than dicot roots. At 0.2 mM KCl, gramicidin stimulated K+ influx by 4- to 8fold over a 30-min absorption period. Although a gramicidin response is detectable within one minute, maximum stimulation occurred after a slight (approximately 2-min) lag period. The gramicidin effect was much greater at 0.2 mM KCl than at 20 mM KCl. Respiratory inhibitors reduced the gramicidin-stimulated K+ influx by 50–80%. The results are discussed in terms of possible mechanisms of action of the various ionophores on ion transport in roots.This work was supported by National Science Foundation Grants GB-5549 and GB-12674 and by the Illinois Agriculture Experiment Station. |
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