Apoplastic Alkalinization Is Instrumental for the Inhibition of Cell Elongation in the Arabidopsis Root by the Ethylene Precursor 1-Aminocyclopropane-1-Carboxylic Acid

• Published in: Plant physiology (Bethesda) 2011-04, Vol.155 (4), p.2049-2055
• Main Authors: Staal, Marten, De Cnodder, Tinne, Simon, Damien, Vandenbussche, Filip, Van Der Straeten, Dominique, Verbelen, Jean-Pierre, Elzenga, Theo, Vissenberg, Kris
• Format: Article
• Language: English
• Subjects: Adenosine triphosphatases; Amino Acids, Cyclic - metabolism; Arabidopsis - cytology; Arabidopsis - metabolism; Auxins; Biological and medical sciences; Cell Enlargement; Cell growth; Cell membranes; Cell walls; Corn; DEVELOPMENT AND HORMONE ACTION; Dicyclohexylcarbodiimide - pharmacology; Fundamental and applied biological sciences. Psychology; Glycosides - pharmacology; Hydrogen-Ion Concentration; Microelectrodes; Plant cells; Plant physiology and development; Plant roots; Plant Roots - cytology; Plant Roots - metabolism; Plants; Proton-Translocating ATPases - metabolism; Root tips
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.110.168476

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-l-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.