Effect of auxins on spermidine uptake into carrot protoplasts |
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Authors: | Malee Kanchanapoom Fabiana Antognoni Rossella Pistocchi Nello Bagni |
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Affiliation: | Dept of Biology, Faculty of Science, Prince of Songkla Univ., Had-Yai 90112, Thailand;;Dept of Biology, Univ. of Bologna, Via Irnerio 42, 1-40126 Bologna, Italy. |
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Abstract: | The effect of an auxin, indole-3-acetic-acid (IAA), on spermidine uptake into protoplasts of carrot ( Daucus carota L. cv. Ingrid) was studied. In the presence of 1 m M Ca2+, IAA (10−7 to 10−4 M ) enchances [14C]-spermidine uptake into carrot protoplasts, while no stimulation occurs in the absence of Ca2+. The time course of the uptake with and without IAA is very rapid and reaches saturation within 1 to 2 min. Preincubation of protoplasts with IAA inhibits the spermidine uptake. La3+, known not to penetrate the plasmalemma, exerts the same effect as Ca2+, but gives lower uptake values than Ca2+. The application of vanadate, an ATPase inhibitor, strongly inhibits IAA-stimulated spermidine uptake, suggesting that an energy-dependent mechanism may be involved in this transport. Neither spermidine nor Ca2+ alone stimulate IAA uptake. The synthetic auxin 2,4-dichlorophenoxyacetic acid, yields the same results as IAA with regard to time course of spermidine uptake with and without preincubation while, unlike IAA, no significant effect was observed on the Ca2+ -induced increase of spermidine uptake. |
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Keywords: | ATPase inhibitor auxin carrot Daucus carota protoplast spermidine uptake |
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