Photoinhibition of Stem Elongation by Blue and Red Light : Effects on Hydraulic and Cell Wall Properties (original) (raw)
Related papers
Physiologia Plantarum, 1992
Inhibition of Pisum sativum epicotyl elongation by white light-Differeni effects of light on the mechanical properties of cell walls in the epidermal and inner tissues,-PhysioL Plant, 84: 380-385, White fluorescent light (5 W m^-) inhibited subhook growth in derooted Alaska pea cuttings, in the inner tisstie of the subhook, it inhibited the increase in osmotic potential during 18 h incubation, in the epidermis, on the other hand, hght did not affect the osmotic potential. Light increased the minimum-stress relaxation time (T)) of the inner tissue cell walls, but did not change T,, of the epidermal cell wall. Light decreased tissue stress determined by the split test and the ability of the inner tissue to extend by water absorption. The short-term light effect on subhook growth. T,. and the tissue stress almost disappeared when pea cuttings were transferred to darkness. These facts soggest that light changes the mechanical properties of the cell wall in the inner tissue of shoots, and decreases tissue stress, which is considered to be the driving force of shoot growth.
Growth, in-vivo extensibility and tissue tension in mung bean seedlings subjected to water stress
Plant Science, 1989
The relationship between growth, in vivo extensibility, and tissue tension in the first 3 internodes of 5, 6, and 7 day-old pea plants (Pisum sativum L. cv Alaska), grown under continuous red light was investigated. The upper 15 millimeters of each internode was marked with ink and its elongation growth measured over the next subsequent 8 hours. In vivo extensibility was measured by stretching living tissue at constant force (creep test) in a custom-built extensiometer. Tissue tension was determined by (a) measuring the rate of expansion of the isolated cortical cylinder after adding water and the amount ofcontraction ofthe epidermis after peeling, and (b) by use of the 'split section test.' A good correlation between rate ofelongation growth, in vivo extensibility, and tissue tension was established. The epidermis peeled from the growing third internode of 7 day-old plants and measured immediately showed a plastic extensibility (Ep, twice that of peels from nongrowing excised sections. This high E,rvalue was lost on incubation of the sections in distilled water, and was subsequently restored by incubating the sections in auxin (indole-3acetic acid). We conclude that the in situ growth of the internodes is a function of tissue-tension, which provides the driving force of organ growth, and the extensibility (Ep, of the outer epidermal wall, which is in the growing plant in a 'loosened' state. We furthermore suggest that in the intact plant auxin is causally involved in the wall loosening process in the epidermis.
Red Light Enhancement of the Phototropic Response of Etiolated Pea Stems
Plant Physiology, 1974
In the subapical third internode of 7-day-old etiolated pea seedlings, the magnitude of phototropic curvature in response to continuous unilateral blue illumination is increased when seedlings are pre-exposed to brief red light. The effect of red light on blue light-induced phototropism becomes manifest maximally 4 or more hours after red illumination, and closely parallels the promotive action of red light on the elongation of the subapical cells. Ethylene inhibits phototropic curvature by an inhibitory action on cell elongation without affecting the lateral transport of auxin. Pretreatment of seedlings with gibberellic acid causes increased phototropic curvature, but experiments using "C-gibberellic acid indicate that gibberellic acid itself is not laterally transported under phototropic stimuli.
Light-induced inhibition of elongation growth in sunflower hypocotyls
Protoplasma, 1992
The long-term effects of white light (WL) on epidermal cell elongation and the mechanical properties and ultrastructure of cell walls were investigated in the subapical regions of hypocotyls of sunflower seedlings (Helianthus annuus L.) that were grown in darkness. Upon transition to WL a drastic inhibition of epidermal cell elongation was observed. However, the mechanical properties of the inner tissues (cortex, vascular bundles, and pith) were unaffected by WL. Thus, the light-induced decrease in cell wall plasticity measured on entire stems occurs exclusively in the peripheral tissues (epidermis and 2 to 3 subepidermal cell layers). An electronmicroscopic investigation of the epidermal cell walls showed that they are of the helicoidal type with the direction of microfibrils monotonously changing during deposition. This cell wall type was identified by the appearance of arced patterns ofmicrofibrils in cell walls sectioned oblique to the plane of their synthesis. WL irradiation did not change the periodicity of this pattern nor the thickness of the lamellae. Thus, the inhibition of cell elongation was not caused or accompanied by a shift in the direction of microfibril deposition in the growth-limiting outer tissues. However, cell wall thickness, the number of lamellae and hence the amount of cellulose oriented parallel and transverse to the longitudinal cell axis increased in WL. This may account for the effect of WL on the reduction of cell wall plasticity and growth.
Inhibition of Stem Elongation in Cucumis Seedlings by Blue Light Requires Calcium
PLANT PHYSIOLOGY, 1988
The effects of blue light and calcium on elongation of hypocotyl segments of Cucumber (Cucumis sativa L. cv Burpee's Pickier) were studied. Cucumber seedlings grown in dim red light showed a rapid decline in the rate of hypocotyl elongation when irradiated with high intensity (100 micromoles per square meter per second) blue light. In intact, 4-day-old seedlings the inhibition began within 2 minutes after the onset of bluelight irradiation and reached a maximum of approximately 55% within 4 minutes. Hypocotyl segments cut from 4-day-old seedlings also showed an inhibition of elongation in response to blue light when segments were floated on aqueous buffer and exposed to blue light for 3 hours. In the presence of 2 micromolar indole-3-acetic acid, blue light caused a 50% inhibition of elongation. Buffering free calcium in the incubation medium with 0.1 millimolar ethylene glycol bis(-aminoethyl ether)-N,N,N',N'tetraacetic acid eliminated the blue-light inhibition of segment elongation. Several experiments confirmed a specific requirement for calcium for the blue-light-induced inhibition of segment elongation. Treating segments with 0.2 micromolar fusicoccin abolished the inhibition of elongation by blue light as did buffering the medium at pH 4. Adding 1 milimolar ascorbate to incubation medium also eliminated the inhibition of segment elongation caused by blue light. Several compounds implicated in cellwall redox reactions alter the magnitude of the blue-light-induced inhibition. The activity of peroxidase isolated from the cell-wall free space of cucumber hypocotyls was inhibited by ascorbate and low pH. The results are consistent with the hypothesis that blue light inhibits elongation by inducing an increase in cell-wall peroxidase activity and implicate calcium ions in the response to blue light.
Ethylene Is Not Involved in the Blue Light-Induced Growth Inhibition of Red Light-Grown Peas
PLANT PHYSIOLOGY, 1992
Although the growth of intact plants is inhibited by irradiation with blue light, the growth rate of isolated stem segments is largely unaffected by blue light. We hypothesized that this loss of responsiveness was a result of ethylene production as part of the wounding response. However, we found no interaction between ethylene-and blue light-induced growth inhibition in darkor red light-grown seedlings of pea (Pisum sativum L.). Inhibition of growth begins in dark-grown seedlings exposed to blue light within 3 min of the onset of blue light, as was known for red light-grown seedlings. By contrast, ethylene-induced inhibition of growth occurs only after a lag of 20 to 30 min or more (dark-grown seedlings) or 60 min (red light-grown seedlings). Also, the inhibition response of red light-grown seedlings is the same whether ethylene is present from the onset of continuous blue-light treatment or not. Finally the spatial distribution of inhibition following blue light was different from that following ethylene treatment. 97 50 1 www.plantphysiol.org on July 28, 2016 -Published by www.plantphysiol.org Downloaded from
Effect of temperature on plant elongation and cell wall extensibility
General Physiology and Biophysics
Lockhart equation was derived for explaining plant cell expansion where both cell wall extension and water uptake must occur concomitantly. Its fundamental contribution was to express turgor pressure explicitly in terms of osmosis and wall mechanics. Here we present a new equation in which pressure is determined by temperature. It also accounts for the role of osmosis and consequently the role of water uptake in growing cell. By adopting literature data, we also attempt to report theoretically the close relation between plant elongation and cell wall extensibility. This is accomplished by the modified equation of growth solved for various temperatures in case of two different species. The results enable to interpret empirical data in terms of our model and fully confirm its applicability to the investigation of the problem of plant cell extensibility in function of environmental temperature. Moreover, by separating elastic effects from growth process we specified the characteristic temperature common for both processes which corresponds to the resonance energy of biochemical reactions as well as to the rapid softening of the elastic modes toward the high temperature end where we encountered viscoelastic and/or plastic behavior as dominating. By introducing analytical formulae connected with growth and elastic properties of the cell wall, we conclude with the statement how these both processes contribute quantitatively to the resonancelike shape of the elongation curve. In addition, the tension versus temperature "phase diagram" for a living plant cell is presented.
PLANT PHYSIOLOGY, 1989
Irradiation with blue light causes a rapid decrease in ster. elongation in Pisum sativum. Growing plants under continuous red light allowed us to study the fluence dependence and spatial distribution of blue-induced growth effects without interference from large changes in the ratio of the far-red absorbing form of phytochrome to total phytochrome. The magnitude of the inhibition generated by a 30-second pulse of blue light was linearly related to the log of the fluence applied over two orders of magnitude. Reciprocity held for irradiations with a pulse length shorter than the lag time for the response. The spatial distribution of inhibition was studied by marking the growing zone and photographing the stem at 10-minute intervals before, during, and after a 1-hour exposure to blue light. The region just below the hook does not undergo any perceptible change in growth rate while growth is nearly 100% inhibited in the base of the third intemode.
Plant water relations and control of cell elongation at low water potentials
Journal of Plant Research, 1998
Recent developments in water status measurement techniques using the psychrometer, the pressure probe, the osmometer and pressure chamber are reviewed, and the process of cell elongation from the viewpoint of plant-water relations is discussed for plants subjected to various environmental stress conditions. Under water-deficient conditions, cell elongation of higher plants can be inhibited by interruption of water flow from the xylem to the surrounding elongating cells. The process of growth inhibition at low water potentials could be reversed by increasing the xylem water potential by means of pressure application in the root region, allowing water to flow from the xylem to the surrounding cells. This finding confirmed that a water potential field associated with growth process,i.e., the growth-induced water potential, is an important regulating factor for cell elongation other than metabolic factors. The concept of the growth-induced water potential was found to be applicable for growth retardation caused by cold stress, heat stress, nutrient deficiency and salinity stress conditions. In the present review, the fact that the cell elongation rate is primarily associated with how much water can be absorbed by elongating cells under water-deficiency, nutrient deficiency, salt stress, cold stress and heat stress conditions is suggested.
PLANT PHYSIOLOGY, 1983
Treatment of etiolated pea (Pisum sativum L.) internode tissue with ethylene gas inhibits elongation and induces lateral expansion. Precise kinetics of the induction of this altered mode of gro4vth of excised internode segments were recorded using a double laser optical monitoring device. Inhibition of elongation and promotion of lateral expansion began after about 1 hour of treatment and achieved a maximum by 3 hours. Similar induction kinetics were observed after treating internodes with coichicine and 2,6-dichlorobenzonitrile, an inhibitor of cellulose synthesis. In sealed flask experiments, ethylene had no detectable effect on incorporation of label from '4Cqglucose into any of the classical pectin, hemicellulose, or cellulose wall fractions. Ethylene inhibited fresh weight increase (total cell expansion) of both excised internode segments (in sealed flasks) and intact seedlings. Ethylene treatment resulted in an increase in cell sap osmolality in those tissues (intact and excised) which are inhibited by the ps. A model for ethylene-induced inhibition of