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Research article2004Peer reviewedOpen access

The roles of ethylene, auxin, abscisic acid, and gibberellin in the hyponastic growth of submerged Rumex palustris petioles

Cox MCH, Benschop JJ, Vreeburg RAM, Wagemakers CAM, Moritz T, Peeters AJM, Voesenek LACJ

Abstract

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

Published in

Plant Physiology
2004, Volume: 136, number: 2, pages: 2948-2960
Publisher: AMER SOC PLANT BIOLOGISTS

    UKÄ Subject classification

    Forest Science

    Publication identifier

    DOI: https://doi.org/10.1104/pp.104.049197

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/3254