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Auxin

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Full-Text Articles in Cell Biology

The Correlation Of Profiles Of Surface Ph And Elongation Growth In Maize Roots, Winfried Peters, Hubert Felle Oct 1999

The Correlation Of Profiles Of Surface Ph And Elongation Growth In Maize Roots, Winfried Peters, Hubert Felle

Winfried S. Peters

High-resolution profiles of surface pH and growth along vertically growing maize (Zea mays) primary root tips were determined simultaneously by pH-sensitive microelectrodes and marking experiments. Methodological tests were carried out that proved the reliability of our kinematic growth analysis, while questioning the validity of an alternative technique employed previously. A distal acidic zone around the meristematic region and a proximal one around the elongation zone proper were detected. This pattern as such persisted irrespective of the bulk pH value. The proximal acidic region coincided with maximum relative elemental growth rates (REGR), and both characters reacted in a correlated manner to ...


The Temporal Correlation Of Changes In Apoplast Ph And Growth Rate In Maize Coleoptile Segments, Winfried Peters, Hartwig Lüthen, Michael Böttger, Hubert Felle Dec 1997

The Temporal Correlation Of Changes In Apoplast Ph And Growth Rate In Maize Coleoptile Segments, Winfried Peters, Hartwig Lüthen, Michael Böttger, Hubert Felle

Winfried S. Peters

Auxin induces extracellular acidification in growing shoot tissue. The causal relationship between this process and auxin-mediated growth is debated, partly because of contradicting previous reports on the temporal correlation of auxin-induced apoplast pH-drops and growth bursts. We have simultaneously measured both parameters on the background of spontaneously occurring endogenous changes in growth rate and apoplast pH in maize coleoptile segments. Our data demonstrate good temporal correlation, during both the ‘Spontaneous Growth Response’ and the response to exogenous auxin, which is transient under the conditions chosen due to rapid auxin metabolism. We suggest that cell wall pH and growth rate are ...


Wounding-Induced Cell Wall Ph Shifts In Coleoptile Segments Of Various Poaceae, Winfried Peters Jul 1997

Wounding-Induced Cell Wall Ph Shifts In Coleoptile Segments Of Various Poaceae, Winfried Peters

Winfried S. Peters

Wounding-induced extracellular pH shifts were characterized previously in excised segments of maize (Zea mays L.) coleoptiles. In the present study it is demonstrated that similar pH shifts also occur in Triticum aestivum L., Secale cereale L., Hordeum vulgare L., Avena sativa L., Sorghum durra (Forsk.) Stapf, and Setaria italica (L.) Beauv., with characteristic quantitative differences between the species. Indole-acetic acid induces pronounced drops of the medium pH in all species except Setaria italica.


The Epidermis Still In Control?, Winfried Peters, A. Tomos Aug 1996

The Epidermis Still In Control?, Winfried Peters, A. Tomos

Winfried S. Peters

This paper has no abstract; these are the first two paragraphs. The search for a molecular mechanism of auxin action has rendered the “Auxin-Binding-Protein 1” (ABP-1) the top candidate for a functional auxin receptor (Venis and Napier, 1995), although its status remains disputed (Jones, 1994; Hertel, 1995; Napier, 1995; Venis, 1995). ABP-1 had long been thought to be localized exclusively in epidermal cells in coleoptiles (Löbler and Klämbt, 1985), and thus had fitted nicely the “epidermal-growth-control-hypothesis” (Kutschera, 1987, 1992). The recent report from the same lab of its uniform distribution throughout the coleoptile (Kayser and Klämbt, 1995) not only rises ...


The History Of Tissue Tension, Winfried S. Peters, A. Deri Tomos Jun 1996

The History Of Tissue Tension, Winfried S. Peters, A. Deri Tomos

Winfried S. Peters

In recent years the phenomenon of tissue tension and its functional connection to elongation growth has regained much interest. In the present study we reconstruct older models of mechanical inhomogenities in growing plant organs, in order to establish an accurate historical background for the current discussion. We focus on the iatromechanic model developed in Stephen Hales' Vegetable Staticks, Wilhelm Hofmeister's mechanical model of negative geotropism, Julius Sachs' explanation of the development of tissue tension, and the differential-auxin-response-hypothesis by Kenneth Thimann and Charles Schneider. Each of these models is considered in the context of its respective historic and theoretical environment ...


The Electrical Response Of Maize To Auxin, Hubert Felle, Winfried Peters, Klaus Palme May 1991

The Electrical Response Of Maize To Auxin, Hubert Felle, Winfried Peters, Klaus Palme

Winfried S. Peters

The electrical response of Zea mays coleoptiles and suspension cultured cells to several growth-promoting auxins (IAA, IBA, 2,4-D, 2,4,5-T, 1-NAA) and some of their structural analogues (2,3-D, 2-NAA) has been tested. In coleoptiles two typical electrical responses to IAA are observed: an immediate rapid depolarization, and a hyperpolarization following 7–10 minutes after the first external addition of IAA. Of the other tested compounds only 1-NAA significantly depolarized the cells, whereas all auxins as well as the analogues evoked delayed hyperpolarizations. In contrast, the suspension cells were not hyperpolarized by any of the tested compounds, but ...