The Mechanism of the Action of Indole-3-Acetic Acid on the Water Absorption by Avena Coleoptile Sections

Ketellapper, H. J.

doi:10.1111/j.1438-8677.1953.tb00282.x

Cited by 34 publications

(10 citation statements)

References 56 publications

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“…This idea has been supported circumstantially by observations that stem elongation is accompanied by massive hydrolysis of storage products in some tissues (23,26). Most of the actual measurements of tissue solute, however, show that the expanding tissue declines in osmolar concentration (13,22,34). This was also true here in elongating internodes of A vena stem segments.…”

Section: Discussionsupporting

confidence: 62%

Effects of Gibberellic Acid and Sucrose on the Growth of Oat (Avena) Stem Segments

Adams¹,

Kaufman²,

Ikuma³

1973

Plant Physiol.

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MATERIALS AND METHODSGibberellic acid induced growth in Avena (oat) stem segments within 35 minutes after hormone application. The total elongation elicited by gibberellic acid was greater than 15 times the control growth. The sensitivity of the segments to low concentrations of gibberellic acid (1 pmole) and the specificity of the segments to the gibberellin class of hormones suggest that oat stem segments would be a valuable tool for gibberellin bioassays. Both gibberellic acid-induced growth and control growth are temperature-dependent and showed a Qlo of two or greater. Although the most apparent effect of gibbereilic acid was to promote the uptake of water into the internode, the hormone also promoted transport of endogenous substrate and the uptake of exogenous substrate into the growing region. The growth promotion was accomplished without an apparent increase in osmotic pressure.The internodal growth in excised A vena stem segments which contain the intercalary meristems has been shown to be strikingly stimulated by exogenous applications of gibberellins, whereas little elongation is induced by auxins and cytokinins when applied singly (15, 17). The GA-promoted growth in these segments was found to be primarily due to an increase in rate of cell elongation (18). Since gibberellins generally promote the growth of intact plant stems much more markedly than the growth of excised plant stems (5,25,29), the exceptionally large response and specificity to gibberellins observed in excised Avena stem segments presents a unique opportunity to study the mechanism of gibberellin-stimulated stem growth.An earlier attempt to correlate the gibberellin-promoted growth with the gibberellin-stimulated invertase activity indicated that the GA-enhanced invertase activity does not account for all of the gibberellin promoted growth in the segments (21). We are, thus, far from understanding the primary mode of action of gibberellins in growth stimulation of Avena segments. Therefore, attempts are made here to analyze the basic physiologic processes associated with gibberellin-stimulated growth in order to shed light on the mechanism of gibberellin action in stem elongation. 'Present address: Department of Biology, University of Michigan-Flint, Flint, Mich. 48503.

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Section: Discussionsupporting

confidence: 62%

Effects of Gibberellic Acid and Sucrose on the Growth of Oat (Avena) Stem Segments

Adams¹,

Kaufman²,

Ikuma³

1973

Plant Physiol.

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“…However, these are apparently absent where the diffusing substance is isotopically labelled water (1,4,5). In such cases we may use the methods of the above analysis to arrive at a value for the apparent diffusivity of the labelled water (and, presumably, the apparent coefficient of self-diffusion …”

mentioning

confidence: 99%

Propagation of Turgor and Other Properties Through Cell Aggregations.

Philip

1958

Plant Physiol.

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“…We shall treat D as constant, and regard the tissue as isotropic. Our aim is to analyze the way in which the half-times of tissues as a whole vary with tissue dimensions, and in which the half-times of individual cells vary with position within the tissue, and how these various half-times connect with D. Such a study has obvious relevance to recent physiological work in which observed half-times have referred to tissues of different dimensions, and to cells in various locations (1,5,6).…”

mentioning

confidence: 99%

Osmosis and Diffusion in Tissue: Half-times and Internal Gradients.

Philip¹

1958

Plant Physiol.

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THE INDIVIDUAL CELL: The use of the "halftime" to describe the dynamics of diffusion between an individual cell and a large body of solution in which it is placed seems to have originated with Collander and Birlund (4). The concept depends on the primary resistance to diffusion residing in the membrane or wall enclosing the cell. It is simply shown that, if such a cell is suddenly immersed in the solution, the concentration of solute inside the cell, 9, is given by the equation(1) where 00 is the initial concentration of solute within the cell, 01 is the concentration in the external solution, K8 is the permeability of the cell surface to the solute (cm sec-1), A is the area of the cell (cm2), V is the volume of the cell (cm3) and t is the time (sec), with the origin of time at the instant of immersion of the cell in the solution. It follows that approach to the new equilibrium concentration withlin the cell is half accomplished at t = t1/2 = (loge2)V/K8A = 0.693 V/K8A(2) and t1/2 is called the "half-time." The analysis neglects changes in A and V due to osmotic effects, so that it might be expected to describe self-diffusion (e.g., diffusion of labelled water) more closely than the diffusion of other solutes.

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The Mechanism of the Action of Indole-3-Acetic Acid on the Water Absorption by Avena Coleoptile Sections

Cited by 34 publications

References 56 publications

Effects of Gibberellic Acid and Sucrose on the Growth of Oat (Avena) Stem Segments

Effects of Gibberellic Acid and Sucrose on the Growth of Oat (Avena) Stem Segments

Propagation of Turgor and Other Properties Through Cell Aggregations.

Osmosis and Diffusion in Tissue: Half-times and Internal Gradients.

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