Journal Article

Auxin- and Abscisic Acid-Dependent Osmoregulation in Protoplasts of <i>Phaseolus vulgaris</i> Pulvini

Moritoshi Iino, Chen Long and Xiaojing Wang

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 11, pages 1219-1227
Published in print November 2001 | ISSN: 0032-0781
Published online November 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce157
Auxin- and Abscisic Acid-Dependent Osmoregulation in Protoplasts of Phaseolus vulgaris Pulvini

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Protoplasts isolated from the laminar pulvinus of Phaseolus vulgaris and bathed in a medium containing KCl as the major salt were found to swell in response to IAA and to shrink in response to ABA. The protoplasts of flexor cells and those of extensor cells responded similarly. The results indicate that the cellular content of osmotic solutes is enhanced by IAA and reduced by ABA. The IAA-induced swelling was abolished when either the K+ or the Cl of the bathing medium was replaced by an impermeant ion or when the medium was adjusted to neutral pH (instead of pH 6). The response was inhibited by vanadate. It is concluded that the swelling is caused by enhanced influxes of K+ and Cl, which probably occur through K+ channels and Cl/H+ symporters, respectively. The ABA-induced shrinking was inhibited by 5-nitro-2-(3-phenylpropylamino)-benzoic acid, an anion-channel inhibitor, suggesting that it is caused by Cl efflux through anion channels and charge-balancing K+ efflux through outward-rectifying K+ channels. It appears that the two plant hormones act on pulvinar motor cells to regulate their turgor pressure, as they do in stomatal guard cells. The findings are discussed in relation to the pulvinar movements induced by environmental stimuli.

Keywords: Key words: Abscisic acid — Auxin — Ion transporters — Leaf movements — Phaseolus vulgaris — Pulvini.

Journal Article.  6533 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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