| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
|
First published online October 1, 2004; 10.1104/pp.104.049197 Plant Physiology 136:2948-2960 (2004) © 2004 American Society of Plant Biologists The Roles of Ethylene, Auxin, Abscisic Acid, and Gibberellin in the Hyponastic Growth of Submerged Rumex palustris Petioles1Plant Ecophysiology, Utrecht University, 3584 CA Utrecht, The Netherlands (M.C.H.C., J.J.B., R.A.M.V., C.A.M.W., A.J.M.P., L.A.C.J.V.); and Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90 1 83 Umea, Sweden (T.M.)
Rumex palustris responds to complete submergence with upward movement of the younger petioles. This so-called hyponastic response, in combination with stimulated petiole elongation, brings the leaf blade above the water surface and restores contact with the atmosphere. We made a detailed study of this differential growth process, encompassing the complete range of the known signal transduction pathway: from the cellular localization of differential growth, to the hormonal regulation, and the possible involvement of a cell wall loosening protein (expansin) as a downstream target. We show that hyponastic growth is caused by differential cell elongation across the petiole base, with cells on the abaxial (lower) surface elongating faster than cells on the adaxial (upper) surface. Pharmacological studies and endogenous hormone measurements revealed that ethylene, auxin, abscisic acid (ABA), and gibberellin regulate different and sometimes overlapping stages of hyponastic growth. Initiation of hyponastic growth and (maintenance of) the maximum petiole angle are regulated by ethylene, ABA, and auxin, whereas the speed of the response is influenced by ethylene, ABA, and gibberellin. We found that a submergence-induced differential redistribution of endogenous indole-3-acetic acid in the petiole base could play a role in maintenance of the response, but not in the onset of hyponastic growth. Since submergence does not induce a differential expression of expansins across the petiole base, it is unlikely that this cell wall loosening protein is the downstream target for the hormones that regulate the differential cell elongation leading to submergence-induced hyponastic growth in R. palustris.
1 This work was supported by the Dutch Science Foundation (PIONIER grant no. 800.84.470). 2 Present address: Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, St. Lucia, QLD 4072, Australia. 3 Present address: Molecular Genetics, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. 4 Present address: Edinburgh Cell Wall Group, ICMB, University of Edinburgh, Daniel Rutherford Building, The Kings Buildings, Edinburgh EH 93JH, UK. 5 Present address: Department of Aquatic Ecology and Environmental Biology, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.049197. * Corresponding author; e-mail l.a.c.j.voesenek{at}bio.uu.nl; fax 0031–30–2518366. Received July 6, 2004; returned for revision August 10, 2004; accepted August 22, 2004. Related articles in Plant Physiol.:
This article has been cited by other articles:
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ASPB Publications | PLANT PHYSIOLOGY | THE PLANT CELL | |
|---|---|---|---|
