Is Change in Electrical Potential or pH a Hatching Signal for Heterodera glycines?

ABSTRACT This study explored the possibilities that changes in the egg shell/lipid layer electrical potential or pH communicate external hatching conditions to the Heterodera glycines second-stage juvenile (J2) within the mature egg and that electrophysiology could measure effects of chemicals on emergence. Potentials were measured following application of the emergence inducers (ZnSO(4) and ZnCl(2)), ions that do not affect emergence, or synthetic emergence inhibitors. Results were compared with pH measurements and emergence bioassays.

Electrical potentials of plant cell walls in response to the ionic environment.

Electrical potentials in cell walls (psi(Wall)) and at plasma membrane surfaces (psi(PM)) are determinants of ion activities in these phases. The psi(PM) plays a demonstrated role in ion uptake and intoxication, but a comprehensive electrostatic theory of plant-ion interactions will require further understanding of psi(Wall). psi(Wall) from potato (Solanum tuberosum) tubers and wheat (Triticum aestivum) roots was monitored in response to ionic changes by placing glass microelectrodes against cell surfaces.

Rapid and Transient Activation of a Myelin Basic Protein Kinase in Tobacco Leaves Treated with Harpin from Erwinia amylovora.

Harpins are bacterial protein elicitors that induce hypersensitive response-like necrosis when infiltrated into nonhost plants such as tobacco (Nicotiana tabacum L.) (Z.-M.

Biological activity of harpin produced by Pantoea stewartii subsp. stewartii.

Pantoea stewartii subsp. stewartii causes Stewart's wilt of sweet corn. A hypersensitive response and pathogenicity (Hrp) secretion system is needed to produce water-soaking and wilting symptoms in corn and to cause a hypersensitive response (HR) in tobacco.

Inhibition of NO synthase activity in nervous tissue leads to decreased motor activity in the rat.

The nitric oxide/cGMP system has been shown to play a crucial role in the mechanism of learning and memory. The aim of the present study was to investigate whether the inhibition of NO synthase in brain regions leads to alterations of spontaneous behavior in rats. Male Wistar rats were treated with NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) at the dose of 40 mg/kg/day.

Water Relation Alterations Observed during Hypersensitive Reaction Induced by Bacteria.

Upon exposure to pathogenic bacteria, resistant and nonhost plants undergo a hypersensitive reaction (HR) that is expressed as rapid plant cell death. If sufficient concentrations of these bacteria are inoculated to such plant tissue, then that portion of the tissue rapidly collapses and becomes necrotic. As the tissue collapses the water relations of inoculated tissues become markedly disturbed.

Use of Dimethyl Sulfoxide to Detect Hydroxyl Radical during Bacteria-Induced Hypersensitive Reaction.

Excess active oxygen is generated during the hypersensitive reaction (HR), an incompatible reaction of plants to bacterial pathogens. During HR, lipid peroxidation correlates chronologically with production of the oxygen species, superoxide (O(2) (.-)).

Electrical Membrane Properties of Leaves, Roots, and Single Root Cap Cells of Susceptible Avena sativa: Effect of Victorin C.

The effect of the purified host-selective toxin victorin C, a cyclized penta peptide, was compared to that of CCCP and vanadate on membrane functions of susceptible leaves, roots, and single root cap cells of Avena sativa with conventional electrophysiology. The plasmalemma depolarized irreversibly by about 80 millivolts and to below the diffusion potential within 1 hour. Concentrations as low as 12.

Extra- and Intracellular pH and Membrane Potential Changes Induced by K, Cl, H(2)PO(4), and NO(3) Uptake and Fusicoccin in Root Hairs of Limnobium stoloniferum.

Short-term ion uptake into roots of Limnobium stoloniferum was followed extracellularly with ion selective macroelectrodes. Cytosolic or vacuolar pH, together with the electrical membrane potential, was recorded with microelectrodes both located in the same young root hair. At the onset of chloride, phosphate, and nitrate uptake the membrane potential transiently decreased by 50 to 100 millivolts.

Boron induces hyperpolarization of sunflower root cell membranes and increases membrane permeability to k.

Although many studies have alluded to a role for boron (B) in membrane function, there is little evidence for a direct effect of B on the plasmalemma of higher plant cells. These studies were conducted to demonstrate, by electrophysiological techniques, a direct effect of B on the membrane potential (E(m)) of sunflower (Helianthus annuus [L.], cv Mammoth Grey Stripe) root tip cells and to determine if the response to B occurs rapidly enough to account for the previously observed effects of B on ion uptake.

Compatible and incompatible rhizobia alter membrane potentials of soybean root cells.

Inoculation with Rhizobium japonicum or R. meliloti reduced the electrical transmembrane potential (E(m)) of soybean (Glycine max [L.] Merr.

Phosphate uptake inLemna gibba G1: energetics and kinetics.

Phosphate uptake was studied by determining [(32)P]phosphate influx and by measurements of the electrical membrane potential in duckweed (Lemna gibba L.). Phosphate-induced membrane depolarization (ΔE m ) was controlled by the intracellular phosphate content, thus maximal ΔE m by 1 mM H2PO 4 (-) was up to 133 mV after 15d of phosphate starvation.

Effect of cyanide in dark and light on the membrane potential and the ATP level of young and mature green tissues of higher plants.

The effect of CN(-) and N(2) on the electrical membrane potential (E(m)) was compared with that of CN(-) on the ATP levels in cotyledons of Gossypium hirsutum and in Lemna gibba L. In mature cotton tissue, CN(-) depolarized E(m) to the energy-independent diffusion potential (E(D)) in the dark. In the light E(m) recovered transiently.

Relationship between Energy-dependent Phosphate Uptake and the Electrical Membrane Potential in Lemna gibba G1.

High rates of phosphate uptake into phosphate-starved Lemna gibba L. G1 were correlated with a high membrane potential (pd = -220 millivolts). In plants maintaining a low pd (-110 millivolts), the uptake rate was only 20% of that of high-pd plants.

Effect of abscisic acid on membrane potential and transport of glucose and glycine in Lemna gibba G1.

The membrane potential of Lemna gibba G1 was measured with a microelectrode; glucose and glycine uptake were measured with (14)C-labeled substances. The membrane potential was increased by 85 mV on the average, after the plants had been pretreated with 10 μM abscisic acid (ABA) for more than 30 min. This effect is not linked to the endogenous level of soluble sugars.

pH and membrane-potential changes during glucose uptake inLemna gibba G1 and their response to light.

Extracellular pH was measured with a microelectrode positioned over the lower surface of singleLemna gibba plants. Upon addition of glucose, a transient extracellular alkalinization occurred. Saturated extracellular pH changes were observed with 5 mM glucose.

Active hexose uptake in Lemna gibba G1.

Growth of autotrophically growing duck-weeds (Lemna gibba L., G1) was stimulated by sucrose. The rate of respiration increased when plants had been grown on sucrose (8.

Membrane potential changes during transport of hexoses in Lemna gibba G1.

The membrane potential (pd) of duck weed (Lemna gibba G1) proved to be energy dependent. At high internal ATP levels of 74 to 105 nmol ATP g(-1) FW, pd was between -175 and -265 mV. At low ATP levels of 23 to 46 nmol ATP g(-1) FW, pd was low, about -90 to -120 mV at pH 5.

Ultrastructure of soybean nodules. I: release of rhizobia from the infection thread.

Root nodules on soybeans (var. Clark 63) were examined by transmission electron microscopy 10-12 days after seed inoculation and planting. The cell infection process appeared identical in both effective nodules, induced by Rhizobium japonicum strain 138 (USDA) and in ineffective nodules, induced by strain 8-0 (Iowa).