Osmotic Properties of Pea Internodes in Relation to Growth and Auxin Action

Cosgrove, Daniel J.; Cleland, Robert E.

doi:10.1104/pp.72.2.332

Cited by 87 publications

(46 citation statements)

References 27 publications

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“…kg-' in their infiltrated wall space (Table I, exp. C), and that FS solutes (but not intracellular solutes) were greatly diminished by previous excision ofthe cotyledons, further supports the conclusion that young stem tissues normally have a significant vCW. Additional evidence to support this conclusion comes from direct turgor pressure measurements of pea cortical cells which implicate a 7TCW of about 3 bars (4,5).…”

Section: Discussionmentioning

confidence: 97%

Solutes in the Free Space of Growing Stem Tissues

Cosgrove¹,

Cleland²

1983

Plant Physiol.

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149

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The concentration of osmotically acthve solutes in the cell wall free space of young stem tissues was studied using a variety of extraction methods. When the intercellular air spaces of etiolated pea (Piswm sauivwm L.) internodes were perfused with distilled H20, the resulting solion contained a solute concentration of about 70 miliosmoles per kiogram. A second procedure involving vacuum infiltration of segments followed by centrifugation to coDlect the free space solution gave similar results. Apical stem segments yielded free space extracts about twice as concentrated as those from basal portions of the stem. After correcting for dilution of the free space solution by the infiltrated water, the osmotic pressure of the undiluted free space in pea stem tissue was estimated to be 2.9 bars for apical segments, Wayne) seedlings were grown in wet vermiculite in complete darkness at 27 ± 1 C and low RH (20-500o, not controlled). Plants were handled under dim green light obtained from a 40-w cool-white fluorescent lamp filtered through one amber and two green acetate filters (Roscolene No. 813 and No. 874; Roscoe, Port Chester, NY). Seedlings 6 to 8 cm tall were selected for experimentation; all subsequent operations were performed in the light. In some cases, pea seedlings were carefully removed from the vermiculite, the cotyledons excised with a new razor blade (under dim green light), and the seedlings replanted in vermiculite to grow for 2 d more in complete darkness.Osmotic Pressure of FS (e). The solution which makes up the cell wall FS was collected by three different methods, and 8-,ul samples were measured in a vapor pressure osmometer (Wescor model 5100; Wescor, Logan, UT). The osmometer was calibrated in the 0 to 100 mOs.kg-' range before and after all measurements.Osmolality was converted to osmotic pressure (at 20°C) by multiplying the value in Os.kg-' by 24.37 bar.Os`kg.The FS solution was collected in the first method by forced perfusion of the intercellular air channels with water. In this method, the basal ends of five excised segments were sealed with quick-setting epoxy (Qwik-Stik; GC Electronics, Rockford, IL) into a pressure vessel completely filled with water (Fig. 1). The vessel was pressurized using a gas cylinder, and the fluid which exuded from the ends of the segments was collected with a capillary tube. Excision was made under water (so the contents of the cut cells would be immediately released to the water), and the segments were incubated on water for 30 to 40 min on a rotary shaker before being placed in the apparatus. In a variation of this method, intact pea seedlings were sealed with epoxy into the lid of the pressure vessel, such that 4 to 5 cm of the shoot extended outside ofthe vessel (Fig. 1)

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Section: Discussionmentioning

confidence: 97%

Solutes in the Free Space of Growing Stem Tissues

Cosgrove¹,

Cleland²

1983

Plant Physiol.

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149

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“…The growing stem cells apparently coordinate growth with these cellular processes more closely than do Arabidopsis hypocotyls (Refrégier et al, 2004), whose cell walls thinned during elongation, or pea (Pisum sativum) epicotyls (Cosgrove and Cleland, 1983), whose cell osmotic pressure declined slightly along the elongation zone. The last two examples notwithstanding, plant cell growth is generally well coordinated with the production of cellular materials needed for mechanical stability, and the Arabidopsis inflorescence is a fine example of such coordination.…”

Section: Discussionmentioning

confidence: 99%

Gradients in Wall Mechanics and Polysaccharides along Growing Inflorescence Stems

et al. 2017

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At early stages of Arabidopsis (Arabidopsis thaliana) flowering, the inflorescence stem undergoes rapid growth, with elongation occurring predominantly in the apical ;4 cm of the stem. We measured the spatial gradients for elongation rate, osmotic pressure, cell wall thickness, and wall mechanical compliances and coupled these macroscopic measurements with molecular-level characterization of the polysaccharide composition, mobility, hydration, and intermolecular interactions of the inflorescence cell wall using solid-state nuclear magnetic resonance spectroscopy and small-angle neutron scattering. Force-extension curves revealed a gradient, from high to low, in the plastic and elastic compliances of cell walls along the elongation zone, but plots of growth rate versus wall compliances were strikingly nonlinear. Neutron-scattering curves showed only subtle changes in wall structure, including a slight increase in cellulose microfibril alignment along the growing stem. In contrast, solid-state nuclear magnetic resonance spectra showed substantial decreases in pectin amount, esterification, branching, hydration, and mobility in an apical-to-basal pattern, while the cellulose content increased modestly. These results suggest that pectin structural changes are connected with increases in pectin-cellulose interaction and reductions in wall compliances along the apical-to-basal gradient in growth rate. These pectin structural changes may lessen the ability of the cell wall to undergo stress relaxation and irreversible expansion (e.g. induced by expansins), thus contributing to the growth kinematics of the growing stem.

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“…Under such conditions, it is expected that tissue hydration would be essentially complete and that cell turgor and cell osmotic potentials would be equal and opposite. It is possible that damage to the cell wall during penetration could result in erroneously low measured turgors, but the turgor of sequentially penetrated cells was uniform (as described by Cosgrove and Cleland [5]) and stable immediately after penetration (as described by Shackel et al. [15]) for all reported turgor values.…”

Section: Measurement Of Fruit Color and Water Relationsmentioning

confidence: 89%

Cell Turgor Changes Associated with Ripening in Tomato Pericarp Tissue

Shackel¹,

Greve²,

Labavitch³

et al. 1991

Plant Physiol.

146

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The pressure microprobe was used to determine whether the turgor pressure in tomato (Lycopersicon esculentum Mill., variety "Castelmart") pericarp cells changed during fruit ripening. The turgor pressure of cells located 200 to 500 micrometers below the fruit epidermis was uniform within the same tissue (typically ± 0.02 megapascals), and the highest turgors observed (<0.2 megapascals) were much less than expected, based on tissue osmotic potential (-0.6 to -0.7 megapascals). These low turgor values may indicate the presence of apoplastic solutes. In both intact fruit and cultured discs of pericarp tissue, a small increase in turgor preceded the onset of ripening, and a decrease in turgor occurred during ripening. Differences in the turgor of individual intact fruit occurred 2 to 4 days before parallel differences in their ripening behavior were apparent, indicating that changes in turgor may reflect physiological changes at the cell level that precede expression of ripening at the tissue level.

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Osmotic Properties of Pea Internodes in Relation to Growth and Auxin Action

Cited by 87 publications

References 27 publications

Solutes in the Free Space of Growing Stem Tissues

Solutes in the Free Space of Growing Stem Tissues

Gradients in Wall Mechanics and Polysaccharides along Growing Inflorescence Stems

Cell Turgor Changes Associated with Ripening in Tomato Pericarp Tissue

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