title: Apoplastic alkalinization is instrumental for the inhibition of cell elongation in the Arabidopsis root by the ethylene precursor 1-aminocyclopropane-1-carboxylic acid.
abstract: In Arabidopsis (Arabidopsis thaliana; Columbia-0) roots, the so-called zone of cell elongation comprises two clearly different domains: the transition zone, a postmeristematic region (approximately 200-450 μm proximal of the root tip) with a low rate of elongation, and a fast elongation zone, the adjacent proximal region (450 μm away from the root tip up to the first root hair) with a high rate of elongation. In this study, the surface pH was measured in both zones using the microelectrode ion flux estimation technique. The surface pH is highest in the apical part of the transition zone and is lowest at the basal part of the fast elongation zone. Fast cell elongation is inhibited within minutes by the ethylene precursor 1-aminocyclopropane-1-carboxylic acid; concomitantly, apoplastic alkalinization occurs in the affected root zone. Fusicoccin, an activator of the plasma membrane H(+)-ATPase, can partially rescue this inhibition of cell elongation, whereas the inhibitor N,N'-dicyclohexylcarbodiimide does not further reduce the maximal cell length. Microelectrode ion flux estimation experiments with auxin mutants lead to the final conclusion that control of the activity state of plasma membrane H(+)-ATPases is one of the mechanisms by which ethylene, via auxin, affects the final cell length in the root.
authors.affiliation: Center for Ecological and Evolutionary Studies, Laboratory of Plant Physiology, University of Groningen, 9750 AA Haren, The Netherlands.
authors.forename: Marten
authors.initials: M
authors.lastname: Staal
authors.forename: Tinne
authors.initials: T
authors.lastname: De Cnodder
authors.forename: Damien
authors.initials: D
authors.lastname: Simon
authors.forename: Filip
authors.initials: F
authors.lastname: Vandenbussche
authors.forename: Dominique
authors.initials: D
authors.lastname: Van der Straeten
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Verbelen
authors.forename: Theo
authors.initials: T
authors.lastname: Elzenga
authors.forename: Kris
authors.initials: K
authors.lastname: Vissenberg
mesh_terms: D000598:Amino Acids, Cyclic / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism; D049108:Cell Enlargement; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D006027:Glycosides / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008839:Microelectrodes; D018517:Plant Roots / Q000166:cytology* / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism
chemical_list: D000598:Amino Acids, Cyclic; D006027:Glycosides; C007808:fusicoccin; C023863:1-aminocyclopropane-1-carboxylic acid; D004024:Dicyclohexylcarbodiimide; D006180:Proton-Translocating ATPases