Journal ArticleDOI
Evidence against the acid-growth theory of auxin action.
Ulrich Kutschera,Peter Schopfer +1 more
TLDR
Results are incompatible with the acid-growth theory of auxin action and sucrose and other sugars can quantiatively substritute for IAA in inducing H+ excretion but are likewise ineffective in inducing elongation.Abstract:
Four experimental predictions of the ‘acid-growth theory’ of auxin (indole-3-acetic acid, IAA) action in inducing cell elongation were reinvestigated using abraded segments of maize (Zea mays L.) coleoptiles. i) Quantitative comparison of segment elongation and medium-acidification kinetics measured in the same sample of tissue reveals that these IAA-induced processes are neither correlated in time nor responding coordinately to cations present in the medium. ii) Exogenous protons are not able to substitute for IAA in causing segment elongation at the predicted pH of 4.5–5.0. Instead, external buffers induce significant segment elongation only below pH 4.5, reaching a maximal response at pH 1.75–2.5. Acid and IAA coact additively, and therefore independently, in the whole range of feasible pH values. iii) Neutral or alkaline buffers (pH 6–10) are unable to abolish the IAA-mediated growth response and have no effect on its lag-phase. iv) Fusicoccin, at a concentration producing the same H+ excretion as high concentrations of IAA, is ineffective in inducing segment elongation. Moreover, sucrose and other sugars can quantiatively substritute for IAA in inducing H+ excretion but are likewise ineffective in inducing elongation. It is concluded that these results are incompatible with the acid-growth theory of auxin action.read more
Citations
More filters
Journal ArticleDOI
Structural models of primary cell walls in flowering plants: consistency of molecular structure with the physical properties of the walls during growth
TL;DR: This review integrates information on the chemical structure of individual polymers with data obtained from new techniques used to probe the arrangement of the polymers within the walls of individual cells consistent with the physical properties of the wall and its components.
Journal ArticleDOI
pH and Ionic Conditions in the Apoplast
C. Grignon,H. Sentenac +1 more
TL;DR: The Apoplast as an Ion Exchanger as mentioned in this paper was used as a diffusion barrier in the early days of the Apollo project, and it has been used as an ion reservoir and an ion filter in the last few decades.
Journal ArticleDOI
Hydroxyl radical-induced cell-wall loosening in vitro and in vivo: implications for the control of elongation growth
TL;DR: It is concluded that OH fulfils basic criteria for a wall-loosening factor acting in auxin-mediated elongation growth of plant species with widely differing cell-wall polysaccharide compositions.
Journal ArticleDOI
Role of the plasma membrane H+-ATPase in auxin-induced elongation growth: historical and new aspects
TL;DR: Historical and recent aspects of reactions and mechanisms involved in the auxin-induced signalling cascade that terminates in the dramatic elongation growth of cells and plant organs are covered.
Journal ArticleDOI
Auxin induces exocytosis and the rapid synthesis of a high-turnover pool of plasma-membrane H(+)-ATPase.
TL;DR: It is suggested that auxin activates a cluster of genes responsible for the induction and acceleration of exocytotic processes, including for the synthesis of PM H+-ATPases, increasing the capacity for H-extrusion into the apoplast as a precondition for wall enlargement.
References
More filters
Journal ArticleDOI
Experiments and hypothesis concerning the primary action of auxin in elongation growth
TL;DR: The findings suggest that auxin induces a proton accumulation in a cell wall compartment and, as a consequence, enzymatic cell wall softening, which may be the last step in the process of cell elongation.
Journal ArticleDOI
Enhancement of Wall Loosening and Elongation by Acid Solutions
David L. Rayle,Robert E. Cleland +1 more
TL;DR: It is shown that the pH response can be clearly separated from the CO(2) response, and certain other aspects of the growth and wall-loosening responses, are described.
Journal ArticleDOI
Levels of indole-3-acetic acid in intact and decapitated coleoptiles as determined by a specific and highly sensitive solid-phase enzyme immunoassay.
TL;DR: Levels of IAA have been determined in coleoptiles of maize and oat using a specific solid-phase enzyme immunoassay for the detection of as little as 3–4 pg of indole-3-acetic acid (IAA).
Book ChapterDOI
Control of plant cell enlargement by hydrogen ions.
David L. Rayle,Robert E. Cleland +1 more
TL;DR: This chapter discusses the evidence that in Avena coleoptiles and pea stem tissues the hormone auxin induces cell enlargement, by activating proton extrusion, and that the resulting acidification of the wall leads to enzymic cell wall loosening and thus cell enlargements.
Journal ArticleDOI
Auxin-induced hydrogen-ion secretion in Avena coleoptiles and its implications.
TL;DR: It was found that auxin can rapidly (20–30 min) initiate H+ secretion and that the magnitude of auxin-induced secretion is sufficient to initiate considerable cell-extension growth.
Related Papers (5)
Experiments and hypothesis concerning the primary action of auxin in elongation growth
Enhancement of Wall Loosening and Elongation by Acid Solutions
David L. Rayle,Robert E. Cleland +1 more