Plant Cell Membrane Permeability Research Articles

Plant and pathogen nutrient acquisition strategies.

Nutrients are indispensable elements required for the growth of all living organisms including plants and pathogens. Phyllosphere, rhizosphere, apoplast, phloem, xylem, and cell organelles are the nutrient niches in plants that are the target of bacterial pathogens. Depending upon nutrients availability, the pathogen adapts various acquisition strategies and inhabits the specific niche. In this review, we discuss the nutrient composition of different niches in plants, the mechanisms involved in the recognition of nutrient niche and the sophisticated strategies used by the bacterial pathogens for acquiring nutrients. We provide insight into various nutrient acquisition strategies used by necrotrophic, biotrophic, and hemibiotrophic bacteria. Specifically we discuss both modulation of bacterial machinery and manipulation of host machinery. In addition, we highlight the current status of our understanding about the nutrient acquisition strategies used by bacterial pathogens, namely targeting the sugar transporters that are dedicated for the plant’s growth and development. Bacterial strategies for altering the plant cell membrane permeability to enhance the release of nutrients are also enumerated along with in-depth analysis of molecular mechanisms behind these strategies. The information presented in this review will be useful to understand the plant–pathogen interaction in nutrient perspective.

Water and nonelectrolyte permeability of plant cell membranes after short term application of amino acids and phosphorylated amino acids

The effects of amino acids (aa) and N-(diisopropyloxyphosphoryl)-amino acids (DIPP-aa) on cell membranes were investigated by evaluating water and methyl urea permeability. Permeability coefficients Pf and Ps were determined by standard osmotic methods for cells ofPisum sativum stem base epidermis after 20 min exposure to a 5 mM solution of each aa and DIPP-aa. The Pf value ofP. sativum epidermal cells (untreated controls) was 1.3 ± 0.4 × 10-3 μm s-1. Treat ments with the diisopropyl-oxyphosphoryl derivatives of three one charged and three polar amino acids (serine, threonine, asparagine, and aspartic acid) and unsubstituted (free) serine and threonine increased water permeability up to about two fold of the control value. Serine and threonine and their DIPP-derivatives increased methyl urea permeability (controls 1.03 ± 0.09 × 10-3 μm s-1) 30 to 80 percent Other amino acids and their DIPP-derivatives caused small or insignificant changes of water permeability. Only certain polar amino acids and their DIPP-derivatives increased the osmotic water and methyl urea permeation through the plasma membrane. The specificity of these molecules on plasma membranes suggests that the active amino acids (serine and threonine) and their DIPP-derivatives interact with charged membrane molecules. The relatively small changes in water and methyl urea permeability may indicate that the effective aa’s and their DIPP-derivatives interact with phospholipids rather than aquaporin. A concurring alteration of water channel proteins, however, cannot excluded.

Changes in Cucumber Cotyledon Membrane Lipid Fatty Acids During Paraquat Treatment and a Bacteria-Induced Hypersensitive Reaction

Fatty acyl groups from galactolipids (a lipid found specifically in plastids) and polar lipids (found in all cell membranes) were analyzed in a total lipid extract. (…) Fatty acid unsaturation decreased in the enriched plasma membrane fraction during both paraquat treatment and the hypersensitive reaction. We suggest that O 2 − -initiated lipid peroxidation produced the altered plant cell membrane permeability observed in both paraquat treatment and bacteria-induced hypersensitive reaction

Effect of Trifluralin Synthesis Intermediates on Plant Cell Membrane Permeability and Growth of Plants and Fungi

AbstractThe phytotoxicity of the intermediates of (i) trifluralin synthesis, (ii) 4‐chloro‐α,α,α‐trifluorotolouene, (iii) 4‐chloro‐3‐nitro‐α,α,α‐trifluorotoluene, and (iv) 4‐chloro‐3,5‐dinitro‐α,α,α‐trifluorotoluene, in comparison with that of trifluralin, was studied. All the intermediates affected the permeability of cell membranes and inhibited corn root growth. Compound (iv) was more toxic than (iii) and (ii), and monocotyledons were more sensitive than dicotyledons. (iv) also inhibited the mycelial growth of some fungi. On the contrary, trifluralin (i) did not affect membrane function. It is suggested that the mechanism of action of (ii), (iii), and (iv) is different to that postulated for trifluralin.

OZONE‐INDUCED MEMBRANE PERMEABILITY CHANGES

The effect of 0.5 ppm ozone for 0.5‐1 hr on plant cell membrane permeability was ascertained. Permeabilities to both water and solutes were estimated by measuring leaf disc weight changes and following tritiated water and 86Rb fluxes. Measurements were made immediately after ozone exposure and 24 hr after exposure. The reflection coefficient, σ, an index of solute permeability, decreased in ozone‐treated primary leaves of pinto bean (Phaseolus vulgaris). The latter indicates an increase in membrane solute permeability or internal solute leakage. Water and THO flux estimates both indicated a decrease in membrane permeability to water; both the hydraulic conductivity (Lp) and the water diffusional coefficient (LD) apparently decreased, an anomaly which is discussed. These data indicate that ozone has a direct effect on membrane function by altering permeability characteristics. We assume from these data that cell membranes are primary target sites for ozone injury.

Ozone-Induced Membrane Permeability Changes

The effect of 0.5 ppm ozone for 0.5-1 hr on plant cell membrane permeability was ascertained. Permeabilities to both water and solutes were estimated by measuring leaf disc weight changes and following tritiated water and 86Rb fluxes. Measurements were made immediately after ozone exposure and 24 hr after exposure. The reflection coefficient, σ, an index of solute permeability, decreased in ozone-treated primary leaves of pinto bean (Phaseolus vulgaris). The latter indicates an increase in membrane solute permeability or internal solute leakage. Water and THO flux estimates both indicated a decrease in membrane permeability to water; both the hydraulic conductivity (Lp) and the water diffusional coefficient (LD) apparently decreased, an anomaly which is discussed. These data indicate that ozone has a direct effect on membrane function by altering permeability characteristics. We assume from these data that cell membranes are primary target sites for ozone injury.

The mode of action of helminthosporal. II. Effect on the permeability of plant cell membranes

The phytotoxin, helminthosporal (H-al), can damage the permeability of plant cell membranes and it is suggested that this may be an important factor in the susceptibility or predisposition of cereal tissues to attack by Bipolaris sorokiniana, the fungus which produces the toxin. Helminthosporal was tested for its effect on the apparent free space (AFS) of barley roots and the efflux of betacyanin from red beet root tissue. Cell membrane disruption was indicated by an increase in the AFS of H-al-treated barley roots. The effect of H-al on the AFS of barley roots did not appear to be correlated with respiratory inhibition by the toxin since cyanide, azide, and 2,4-dinitrophenol failed to increase the AFS. Oxygen uptake by red beet root tissue was strongly inhibited by H-al at concentrations of 1.0 mM and 2.0 mM, and was accompanied by an immediate and large efflux of betacyanin. No correlation was found, however, between the extent of respiratory inhibition and the amount of pigment released. Helminthosporal reacts directly with both the plasmalemma and the tonoplast membranes of the beet root cell, exclusive of effects on respiration, since the loss of betacyanin was equally rapid under aerobic or anaerobic conditions. The integrity of the beet cell tonoplast membrane appeared to be unrelated to respiration and energy supply. Calcium ions, which act to stabilize membranes, partially alleviated the loss of pigment from red beet tissue exposed to n-propanol and H-al. Permeability change in the plant cell membrane may be as important in the mode of action of H-al as are the effects of the toxin on respiration and oxidative phosphorylation.

Induced Changes in Permeability of Plant Cell Membranes to Water

The half-time for THO equilibration was three times longer for a living carrot (Daucus carota L.) cylinder than for a dead one. Furthermore, the energy of activation of THO flux was more than twice as high for the living cylinder. Passage through living membranes thus constitutes a rate-limiting step for THO flux in carrot tissue.CO(2) increased the half-time (t((1/2))) for THO equilibration. Treatment with abscisic acid or with tertiary butanol decreased t((1/2)). In neither case was the selective permeability of the membrane destroyed.p-Chloromercuribenzoate and carbonyl cyanide m-chlorophenylhydrazone, if supplied together with abscisic acid or tertiary butanol, abolished their action. If abscisic acid or butanol was first allowed to act alone, its effect was stable to subsequent treatment with the inhibitors. p-Chloromercuribenzoate and carbonyl cyanide m-chlorophenylhydrazone at concentrations at which they affected abscisic acid and butanol action, did not influence THO flux in control tissue. At considerably higher concentrations, however, 2, 4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone raised t((1/2)). The CO(2) effect was very rapidly reversible. Full reversal of the butanol effect required 3 hours, and that of abscisic acid required 4 days.

The polar permeability of plant cell membranes to water

Unstirred layers of solution adjacent to a membrane cause a decrease in the effective driving forces on water (or solutes) during permeability-type experiments. These effects are discussed in relation to transcellular-osmosis studies from which it had been previously deduced that the permeability (strictly hydraulic conductivity) of the membranes of Characean cells to water was greater when water was entering the cell (endosmosis) than when it was leaving the cell (exosmosis). Quantitative theory shows that this polar permeability is not so pronounced as had previously been claimed.