Turgor, solute import and growth in maize roots treated with galactose

2004 ◽  
Vol 31 (11) ◽  
pp. 1095 ◽  
Author(s):  
Jeremy Pritchard ◽  
A. Deri Tomos ◽  
John F. Farrar ◽  
Peter E. H. Minchin ◽  
Nick Gould ◽  
...  
Keyword(s):  
Turgor Pressure ◽  
Cortical Cell ◽  
Root Tip ◽  
Pressure Probe ◽  
Similar Response ◽  
Fixed Carbon ◽  
Cortical Cells ◽  
Maize Roots ◽  
Before And After ◽  
Cell Turgor

It has been observed that extension growth in maize roots is almost stopped by exposure to 5 mm d-galactose in the root medium, while the import of recent photoassimilate into the entire root system is temporarily promoted by the same treatment. The aim of this study was to reconcile these two apparently incompatible observations. We examined events near the root tip before and after galactose treatment since the tip region is the site of elongation and of high carbon deposition in the root. The treatment rapidly decreased root extension along the whole growing zone. In contrast, turgor pressure, measured directly with the pressure probe in the cortical cells of the growing zone, rapidly increased by 0.15 MPa within the first hour following treatment, and the increase was maintained over the following 24 h. Both tensiometric measurements and a comparison of turgor pressure with local growth rate demonstrated that a rapid tightening of the cell wall caused the reduction in growth. Single cell sampling showed cell osmotic pressure increased by 0.3 MPa owing to accumulation of both organic and inorganic solutes. The corresponding change in cell water potential was a rise from –0.18 MPa to approximately zero. More mature cells at 14 mm from the root tip (just outside the growing region) showed a qualitatively similar response. Galactose treatment rapidly increased the import of recently fixed carbon (RFC) into the whole root as deduced by 11C labelling of photoassimilate. In contrast, there was a significant decrease in import of recently fixed carbon into the apical 5mm concomitant with the increase in turgor in this region. No decrease in import of recently fixed carbon was observed 5–15 mm from the root tip despite the increase in cortical cell turgor. These data are consistent with direct symplastic connections between the growing cells and the phloem supplying the solutes in the apical, but not the basal, regions of the growing zone. Hence, the inhibition of growth and the elevation of solute import induced by galactose are spatially separated within the root.

scholarly journals Domain-specific and cell type-specific localization of two types of cell wall matrix polysaccharides in the clover root tip.

1992 ◽  
Vol 118 (2) ◽  
pp. 467-479 ◽  
Author(s):  
M A Lynch ◽  
L A Staehelin
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cellular Differentiation ◽  
Cortical Cell ◽  
Middle Lamella ◽  
Root Cap ◽  
Root Tip ◽  
Cortical Cells ◽  
Peripheral Cell ◽  
Clover Root

Using immunocytochemical techniques and antibodies that specifically recognize xyloglucan (anti-XG), polygalacturonic acid/rhamnogalacturonan I (anti-PGA/RG-I), and methylesterified pectins (JIM 7), we have shown that these polysaccharides are differentially synthesized and localized during cell development and differentiation in the clover root tip. In cortical cells XG epitopes are present at a threefold greater density in the newly formed cross walls than in the older longitudinal walls, and PGA/RG-I epitopes are detected solely in the expanded middle lamella of cortical cell corners, even after pretreatment of sections with pectinmethylesterase to uncover masked epitopes. These results suggest that in cortical cells XG and PGA/RG-I are differentially localized not only to particular wall domains, but also to particular cell walls. In contrast to their nonoverlapping distribution in cortical cells, XG epitopes and PGA/RG-I epitopes largely colocalize in the epidermal cell walls. The results also demonstrate that the middle lamella of the longitudinal walls shared by epidermal cells and by epidermal and cortical cells constitutes a barrier to the diffusion of cell wall and mucilage molecules. Synthesis of XG and PGA/RG-I epitope-containing polysaccharides also varies during cellular differentiation in the root cap. The differentiation of gravitropic columella cells into mucilage-secreting peripheral cells is marked by a dramatic increase in the synthesis and secretion of molecules containing XG and PGA/RG-I epitopes. In contrast, JIM 7 epitopes are present at abundant levels in columella cell walls, but are not detectable in peripheral cell walls or in secreted mucilage. There were also changes in the cisternal labeling of the Golgi stacks during cellular differentiation in the root tip. Whereas PGA/RG-I epitopes are detected primarily in cis- and medial Golgi cisternae in cortical cells (Moore, P. J., K. M. M. Swords, M. A. Lynch, and L. A. Staehelin. 1991. J. Cell Biol. 112:589-602), they are localized predominantly in the trans-Golgi cisternae and the trans-Golgi network in epidermal and peripheral root cap cells. These observations suggest that during cellular differentiation the plant Golgi apparatus can be both structurally and functionally reorganized.

Comparison Between Osmotic and Hydrostatic Water Flows in a Higher Plant Cell: Determination of Hydraulic Conductivities and Reflection Coefficients in Isolated Epidermis of Tradescantia virginiana

1982 ◽  
Vol 9 (4) ◽  
pp. 461 ◽  
Author(s):  
SD Tyerman ◽  
E Steudle
Keyword(s):  
Osmotic Pressure ◽  
Turgor Pressure ◽  
Water Volume ◽  
Pressure Probe ◽  
Reflection Coefficients ◽  
Higher Plant ◽  
Bathing Medium ◽  
Tradescantia Virginiana ◽  
Cell Turgor

Hydraulic conductivity (Lp), volumetric elastic modulus (ε) and reflection coefficients (δ) have been determined for cells from isolated strips of the lower epidermis of leaves of Tradescantia virginiana using the pressure probe. Lp was (6.4 � 4.5) × 10-8 ms-1 Mpa-1 [(6.4 � 4.5) × 10-7 cm s-1 bar-1; mean � s.d., n = 15 cells] and was independent of the cell turgor pressure (P) and of osmotic pressure of the bathing medium. P in Johnson's solution (π° = 0.09 MPa) was 0.42-0.67 MPa (4.2-6.7 bar), which was somewhat larger than in the intact tissue. ε increased linearly with increasing P in the pressure range from zero to full turgor. Reflection coefficients of some non-electrolytes were determined by measuring the ΔP in response to a change in external osmotic pressure (Δπ°) after the addition of the solutes. The data were corrected for solute flow. For sucrose, mannitol, urea, acetamide, formamide, glycerol and ethylene glycol, δ was close to unity and the cells behaved like ideal osmometers. For the monohydroxyalcohols n-propanol ( δ = -0.58), isopropanol (δ = 0.26), ethanol (δ = 0.25) and methanol (δ = 0.15), rather low reflection coefficients were found which were even negative for some solutes and cells. Values of δ obtained from measuring the inital water (volume) flow were in agreement with those determined from the ΔP/Δπ° ratios. For the rapidly permeating substances, the changes in turgor after the addition of solute were transient and the equilibration of solutes between cell and medium could be measured using the probe. Although unstirred layers may affect the equilibration of solute it should, in principle, be possible to use the technique for the determination of permeability coefficients of membranes of higher plant cells.

scholarly journals The Relationship between Turgor Pressure Change and Cell Hydraulics of Midrib Parenchyma Cells in the Leaves of Zea mays

Cells ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 180 ◽  
Author(s):  
Yangmin X. Kim ◽  
Burkhard Stumpf ◽  
Jwakyung Sung ◽  
Sang Joon Lee
Keyword(s):  
Zea Mays ◽  
Water Potential ◽  
Turgor Pressure ◽  
Root Systems ◽  
Large Degree ◽  
Pressure Change ◽  
Pressure Chamber ◽  
Pressure Probe ◽  
Parenchyma Cells ◽  
Cell Turgor

Leaf dehydration decreases water potential and cell turgor pressure. Therefore, changes in cell turgor pressure may regulate water transport across plant cell membranes. Using a cell pressure probe, the hydraulic properties of parenchyma cells in the midrib of maize (Zea mays L.) leaves were measured (half time of water exchange in cells as a measure of hydraulic conductivity Lp). Using intact plants with root systems encased in a pressure chamber, the root systems were pressurized and the turgor pressure in leaf cells increased by increments up to 0.3 MPa. However, the increase in the cell turgor did not increase but stabilized values. Increased water potential in leaf cells seemed to have stabilizing effects on the probably due to enhanced water availability. When the cell turgor decreased by 0.1 MPa to 0.3 MPa with releasing the pressure in the pressure chamber, was temporarily increased to a large degree,a factor of up to 13 within 30 min.

Structural, chemical, and permeability changes following wounding in onion roots

1984 ◽  
Vol 62 (11) ◽  
pp. 2253-2259 ◽  
Author(s):  
G. J. Moon ◽  
Carol A. Peterson ◽  
R. L. Peterson
Keyword(s):  
Cell Walls ◽  
Cortical Cell ◽  
Root Tip ◽  
Cortical Cells ◽  
Calcofluor White ◽  
Suberin Lamellae ◽  
Histochemical Tests ◽  
Apoplastic Barrier ◽  
Tip Cells ◽  
Root Tip Cells

Onion roots were wounded by scoring them with a needle 80 to 120 mm proximal to the root tip. Cells in the region of the wound were studied immediately after wounding and daily for the next 6 days. By the 2nd day, cortical cells near the wound had produced pit callose and deposited suberin in their walls and air spaces. The amount of suberin deposited increased until 4 days after wounding. No suberin lamellae were observed in cortical cell walls, but histochemical tests and acid digestion confirmed the presence of suberin within the existing wall. Intercellular air spaces adjacent to the wound were totally occluded with an electron-dense material which had characteristics of suberin. Penetration studies using Calcofluor white M2R, a fluorescent apoplastic dye, showed that the wound was completely sealed 4 days after wounding. Thus, in response to wounding, nonlamellar suberin was deposited in the cortical cell walls and air spaces surrounding the wound and was continuous with the suberin present in the normal hypodermis, forming a complete apoplastic barrier.

Microscopic Examination of Chilling Injury Symptoms in Ethanol-treated Cucumber Seedling Roots

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 454e-454
Author(s):  
Windy A. Boyd ◽  
Paul H. Jennings
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Chilling Injury ◽  
Light And Electron Microscopy ◽  
Ethanol Solution ◽  
Root Tip ◽  
Cucumber Seedling ◽  
Cortical Cells ◽  
Before And After ◽  
Seedling Roots

Cucumber seedlings were germinated for 24 h at 25 °C and half were immersed in a 500 mM ethanol solution for 2 h. After rinsing, seedlings were chilled for 96 h at 2 °C. Control and ethanol-treated samples were taken for light and electron microscopy immediately before and after chilling, and after re-warming for 24 and 72 h. Preliminary experiments revealed visual chilling symptoms such as pinching of the root in a region just above the root tip. This region was excised under a microscope, fixed, and mounted for microscopic observations. The cortical cells of ethanol-treated seedlings before chilling appeared to be irregular in shape with irregular edges, and some epidermal damage was evident. Chilling caused much more epidermal damage in the control seedlings when compared to the ethanol-treated seedlings. After chilling, cortical cells in the control seedlings were observed to be irregularly shaped while those treated with ethanol had round cells. Upon re-warming, control seedlings exhibited increasing epidermal damage with broken cell walls, while ethanol-treated seedlings exhibited more differentiation in the stele.

Cytochalasin B: effects on root morphogenesis in Allium cepa

1973 ◽  
Vol 51 (12) ◽  
pp. 2269-2273 ◽  
Author(s):  
D. des S. Thomas ◽  
N. M. Lager ◽  
E. K. Manavathu
Keyword(s):  
Allium Cepa ◽  
Root Length ◽  
Cytochalasin B ◽  
Morphological Changes ◽  
Cortical Cell ◽  
Root Tip ◽  
Metabolic Inhibitor ◽  
High Concentration ◽  
Cortical Cells ◽  
Cell Counts

Cytochalasin B (CB) applied at 30 μg/ml to seeds of onion, Allium cepa, from the start of imbibition, produced a reversible inhibition of mitosis and axis elongation. Inhibition appeared only after the 4th day and increased progressively thereafter. Mitotic inhibition by a 24-h pulse of CB applied to 6-day-old seedlings increased with root length. These results suggest that CB affects plant mitosis indirectly, possibly via inhibition of transport. CB did not produce polyploid or multinucleate cells.Cytochalasin B (30 μg/ml) supplied for 3 days to roots of onion bulbs, growing in water, produced morphological changes which are expressed here as percentages of the controls. Root length decreased (44%) while diameter increased (148%). Cortical cell lengths decreased (53%) and diameters increased (128%) when measured at 9 mm from the root tip. These compensatory changes resulted in comparatively minor decreases in root (97%) and cell (90%) volume, indicating that CB, even at the high concentration used, was not acting primarily as a general metabolic inhibitor. Cell counts along diameters at comparable distances, 130 cortical cells from the apical initial region, showed no change in the number of cells representing cortex and stele.

Comparison of plant cell turgor pressure measurement by pressure probe and micromanipulation

2006 ◽  
Vol 28 (15) ◽  
pp. 1147-1150 ◽  
Author(s):  
Lan Wang ◽  
David Hukin ◽  
Jeremy Pritchard ◽  
Colin Thomas
Keyword(s):  
Plant Cell ◽  
Pressure Measurement ◽  
Turgor Pressure ◽  
Pressure Probe ◽  
Cell Turgor

Modification of the pressure-probe technique permits controlled intracellular microinjection of fluorescent probes

1991 ◽  
Vol 98 (4) ◽  
pp. 539-544
Author(s):  
K. J. OPARKA ◽  
R. MURPHY ◽  
P. M. DERRICK ◽  
D. A. M. PRIOR ◽  
J. A. C. SMITH
Keyword(s):  
Fluorescent Probes ◽  
Lucifer Yellow ◽  
Turgor Pressure ◽  
Plant Cells ◽  
Pressure Probe ◽  
Simple Modification ◽  
Symplastic Transport ◽  
Probe Technique ◽  
Cell Turgor ◽  
Leaf Trichome

The pressure probe has been widely used to study the water relations of plant cells. Here we describe a simple modification of the pressure-probe technique that permits the controlled microinjection of fluorescent probes into plant cells while simultaneously measuring cell turgor pressure. Using the pressure probe, less than 1 nl of the membrane-impermeant fluorescent dye Lucifer Yellow CH was introduced into micropipettes and subsequently injected into leaf trichome cells of Nicotiana clevelandii. Disruption of cell contents could be minimized by raising the hydrostatic pressure in the probe prior to impalement to a value approaching the anticipated cell turgor pressure. Injections to the cytosol resulted in intercellular symplastic transport of the dye in both acropetal and basipetal directions. In contrast, no symplastic transport was observed following an injection of dye into the vacuole. As measured with the pressure probe, cell turgor pressures were in the range 0.18 to 0.36 MPa; the half-time for water exchange across the cell boundary was approximately 10 s. The potential of this technique for the study of turgor-pressure-dependent intercellular transport and the hydraulic conductivities of the tonoplast, plasmalemma and plasmodesmata is discussed.

Response to oxygen deficiency in primary maize roots. II. Development of oxygen deficiency in the stele has limited short-term impact on radial hydraulic conductivity

1998 ◽  
Vol 25 (6) ◽  
pp. 759 ◽  
Author(s):  
J. Gibbs ◽  
D. W. Turner ◽  
W. Armstrong ◽  
K. Sivasithamparam ◽  
H. Greenway
Keyword(s):  
Hydraulic Conductivity ◽  
Driving Forces ◽  
Oxygen Deficiency ◽  
Pressure Probe ◽  
Similar Response ◽  
Short Term ◽  
Root Hydraulic Conductivity ◽  
Maize Roots ◽  
Dissolved O2

The short-term impact of oxygen deficiency on root hydraulic conductivity (Lpr), was evaluated in excised maize roots using hydrostatic and osmotic driving forces, after exposing the roots to a flowing medium containing 0.05 mol m-3 dissolved O2. Hypoxia reduced hydrostatically-determined Lpr of roots in a pressure probe, but this reduction was transient, usually recovering to values for aerated roots after 4–6 h of exposure to 0.05 mol m-3 O2. The Lpr of exuding maize roots, calculated using the rate of exudation and osmotic pressure of exuding sap, was depressed after 24 h exposure to 0.05 mol m-3 dissolved O2, but only marginally so. The data suggested that a reduction in Lpr is not a principal effect of exposure of these roots to hypoxia, and that long term changes in water fluxes in O2 deficient roots, reported in the literature, may be an indirect, rather than direct effect of O2 deficiency on roots. Despite a similar response to O2 deficiency, Lpr calculated for exuding roots was 1/30th of that for roots attached to the pressure probe. The reduction in hydrostatically determined Lpr in response to O2 deficiency, although transient, suggests that under a hydrostatic driving force, there is a substantial flow of water via the protoplastic pathway, in addition to the generally accepted apoplastic component.

Sign in / Sign up

Export Citation Format

Share Document