The effect of melamine salt of bis(oxymethyl)phosphinic acid (melafen) on the growth processes and plasma membrane function in potato tuber cells

The effects of a new synthetic growth regulator, preparation melafen, on the growth processes in potato plant tubers and the H⁺-ATPase activity in cell plasmalemma were studied. It was demonstrated that melafen could both stimulate and inhibit the growth of potato tubers depending on its concentration and the physiological state of the tubers. It is likely that one of the manifestations of melafen action is its influence on the division and extension of apical meristem cells. The growth stimulation caused by melafen is connected with modifications of the plasmalemma of potato tuber cells, namely, the activation of H⁺-ATPase and increase in the membrane proton permeability.     

Effect of jasmonic acid on Ca<Superscript>+2</Superscript> transport through the plasmalemma of potato tuber cells

The rate of Ca²⁺ accumulation in plasmalemma vesicles isolated from quiescent and sprouting potato (Solanum tuberosum L.) tubers and the effect of 10^?5–10^?10 M jasmonic acid on the accumulation of Ca⁺² in plasmalemma vesicles and its efflux were studied. It was found that potato tuber plasmalemma contains a Ca⁺²,Mg⁺²-ATPase whose activity decreases upon the transition from forced quiescence to growth. The direction of the effect of jasmonic acid on Ca⁺²,Mg⁺²-ATPase (stimulation or suppression) depends on the physiological state of tubers and the phytohormone concentration.     

Effect of melafen on the function of endoplasmic reticulum and plasmalemmal H+ -ATPase in the regulation of growth processes in potato tubers

The mechanism of the stimulatory effect of melafen on potato tuber sprouting was studied. The treatment with 10(-8) M melafen intensified division and stretching and activated granular endoplasmic reticulum of apical meristem cells. An increase in the activity of membrane-bound H+-ATPase in the plasmalemma of parenchymal cells of melafen-treated potato tubers and enhancement of passive proton permeability of the plasmalemma was observed. In vitro studies showed that melafen at concentrations of 10(-5-10-12) M stimulated the activity of plasmalemmal H+-ATPase in a concentration-dependent manner.     

Effect of salicylic acid on the proton translocation activity of plasmalemma of potato tuber cells

Action of salicylic acid (SA) on the activity of membrane bound H⁺-ATPase and passive proton permeability of plasmalemma membrane vesicles (PMV) from parenchyma cells of potato tubers was detected. A correlation between SA action on germination of tubers and activity of plasmalemma H⁺-ATPase was revealed: the application of growth-stimulating concentrations of SA (10⁻¹⁰–10⁻⁸ M) in the system in vitro resulted in activation of plasmalemma H⁺-ATPase, while the use of growth-inhibiting concentrations (10⁻⁴, 10⁻⁵ M) provoked inhibition of the enzyme activity. Addition of jasmonic acid (JA) to the incubation mix resulted in increase of SA effect on the accumulation of H⁺ in PMV.     

Alteration of plasmalemma H<Superscript>+</Superscript>-ATPase activity in maize coleoptile cells at different age of seedlings

An irregular alteration of the activity and character of the distribution of plasmalemma H⁺-ATPase has been shown in parenchymal cells of the coleoptile subapical zone within the period from the third to fifth day of ethiolated maize seedling development. The study was carried out by the cytochemical method. The highest enzyme activity was determined in the cells of four-day-old coleoptiles. The revealed change in H⁺-ATPase activity does not correspond to the dynamics of the growth intensity of the elongation of coleoptile cells within the studied period of seedling development.     

The effect of melamine salt of bis(oxymethyl)phosphinic acid (melafen) on the growth processes and cytoplasmic membrane function in potato tuber cells

The effects of a new synthetic growth regulator, preparation melafen, on the growth processes in potato plant tubers and the H+ -ATPase activity in cell plasmalemma were studied. It was demonstrated that melafen could both stimulate and inhibit the growth of potato tubers depending on its concentration and the physiological state of the tubers. It is likely that one of the manifestations of melafen action is its influence on the division and extension of apical meristem cells. The growth stimulation caused by melafen is connected with modifications of the plasmalemma of potato tuber cells, namely, the activation of H+ -ATPase and increase in the membrane proton permeability.     

Indolacetic and humic acids induce lateral root development through a concerted plasmalemma and tonoplast H<Superscript>+</Superscript> pumps activation

Increasing evidences have indicated that humic substances can induce plant growth and productivity by functioning as an environmental source of auxinic activity. Here we comparatively evaluate the effects of indole-3-acetic acid (IAA) and humic acids (HA) isolated from two different soils (Inseptsol and Ultisol) and two different organic residues (vermicompost and sewage sludge) on root development and on activities of plasmalemma and tonoplast H⁺ pumps from maize roots. The data show that HA isolated from these different sources as well as low IAA concentrations (10⁻¹⁰ and 10⁻¹⁵ M) improve root growth through a markedly proliferation of lateral roots along with a differential activation not only of the plasmalemma but also of vacuolar H⁺-ATPases and H⁺-pyrophosphatase. Further, the vacuolar H⁺-ATPase had a peak of stimulation in a range from 10⁻⁸ to 10⁻¹⁰ M IAA, whereas the H⁺-pyrophosphatase was sensitive to a much broader range of IAA concentrations from 10⁻³ to 10⁻¹⁵ M. It is proposed a complementary view of the acid growth mechanism in which a concerted activation of the plasmalemma and tonoplast H⁺ pumps plays a key role in the root cell expansion process driven by environment-derived molecules endowed with auxinic activity, such as that of humic substances.     

The effect of thaumatin gene overexpression on the properties of H+-ATPase from the plasmalemma of potato tuber cells

The introduction of the thaumatin gene into potato plants was accompanied by a decrease in the activity of H⁺-ATPase in the plasmalemma (PL) of tuber cells. When tubers were released from dormancy, the enzyme was activated in the tuber cells of both the original and transgenic plants. Experiments performed in vitro demonstrated that sensitivities to ambiol (AM) and jasmonic acid (JA) of H⁺-ATPase in the PL of tubers from the original plants were lower after the release from a period of deep dormancy. In preparations from the tubers of transgenic plants, the situation was reversed. The differences between the activities of H⁺-ATPase in the PL preparations produced from the original and transgenic tubers that sprouted under the action of AM and JA were detected. Thus, the overexpression of the thaumatin gene in potato plants changed the properties of H⁺-ATPase from PL.     

Melafen effect on ATP-dependent accumulation of calcium in plasma membrane vesicles from cells of potato tubers

Synthetic growth regulator melafen (10⁻⁵–10⁻¹⁰ M) was tested for aneffect on the Ca²⁺ accumulation in plasma membrane vesicles (PMVs) isolated from potato Solanum tuberosum L. tubers at forced rest and sprouting. Melafen proved to regulate the Ca²⁺ accumulation in PMVs by changing the activity of Ca²⁺, Mg²⁺-ATPase of the plasma membrane, while no effect was observed with respect to Ca²⁺ outflow from vesicles. The melafen effect on Ca²⁺, Mg²⁺-ATPase activity depended on the physiological condition of tubers and the melafen concentration.     

Activity of Plasma Membrane H<Superscript>+</Superscript>-ATPase in Coleoptile Cells during Development of Maize Seedlings

Hydrolytic activities of the H⁺-ATPase were compared for plasma membrane fractions isolated from coleoptile cells of 3-, 4-, and 5-day-old etiolated maize seedlings. The membrane preparations obtained by differential centrifugation were additionally purified in the gradient of sucrose density and in the polyethylene glycol-dextran system. The highest level of ATP-hydrolyzing activity was observed in the plasmalemma fraction obtained from 4-day-old seedlings. The pattern of age-dependent changes in H⁺-ATPase activity of the plasma membranes was clearly different from the monotonic deceleration of coleoptile cell elongation in the period examined. It is supposed that changes in ATPase activity reflect different regulatory roles of this principal ion-transporting enzyme of the plasma membrane at the stage of cell elongation and at a later developmental stage when the coleoptile has completed its physiological function.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 566–572.Original Russian Text Copyright © 2005 by Rudashevskaya, Kirpichnikova, Shishova.     

Cell physiological aspects of the plasma membrane electrogenic H<Superscript>+</Superscript> pump

This article deals with cell physiological aspects of the plasma membrane electrogenic proton (H⁺) pump and emphasizes the contribution of the giant algal cells of the Characeae in elucidating the mechanism of the pump. First, a history of the development of intracellular perfusion techniques in characean internodal cells is described, including preparation of tonoplast-free cells. Then, an outline of the hypothesis of the electrogenic H⁺ pump proposed by Kitasato is introduced, who prophesied the existence of an electric potential generated by an active H⁺ efflux. Subsequently, a history of finding ATP as the direct energy source of the electrogenic ion pump is presented. Quantitative agreement between the pump current and the ATP-dependent H⁺ efflux supports the notion that the ion carried by the electrogenic ion pump is H⁺. The role of the H⁺ pump in regulation of the cytosolic pH is discussed. Mechanisms of light-induced potential change through photosynthesis-controlled activation of the H⁺ pump are discussed in terms of changes in the levels of adenine nucleotides and in modulation of the K_m value for the ATP of H⁺-ATPase. Recent progress in the molecular mechanism of the blue-light-induced activation of the H⁺-ATPase in guard cells is presented. However, there are cases where H⁺-ATPase activity is inhibited by blue light, indicating the flexibility of the control mechanisms of H⁺-ATPase activity. Finally, modulation of H⁺-pumping or H⁺-ATPase activities in response to environmental factors, such as anoxia, membrane excitation, osmotic and salt stresses, nutrient deficiencies and aluminum toxicity are described. Discussions are presented on the regulation of the electrogenic H⁺ pump.     

Electrogenic activity of plasma membrane H<Superscript>+</Superscript>-ATPase in germinating male gametophyte of petunia and its stimulation by exogenous auxin: Mediatory role of calcium and reactive oxygen species

A lipophilic potential-sensitive cationic dye, safranin O was employed to examine the influence of exogenous IAA on plasma membrane electric potential in germinating pollen grains of petunia (Petunia hybrida L.) with the aim of elucidating whether the electrogenic H⁺-ATPase activity of the plasma membrane is sensitive to this phytohormone. The addition of IAA to pollen grains suspended in a K⁺-free medium was found to induce significant hyperpolarization of the plasmalemma. This effect was fully blocked by orthovanadate, Ca²⁺-active reagents (EGTA and verapamil), and by the inhibitor of NADPH oxidase of plasmalemma, diphenyleneiodonium (DPI). It was also strongly inhibited by the presence of K⁺ at centimolar concentrations in the medium. The hyperpolarizing influence of IAA was mimicked by application of hydrogen peroxide; furthermore, the H₂O₂-induced shift of the membrane potential was inhibited by the same agents that suppressed the IAA-induced hyperpolarization of the pollen plasmalemma. It is concluded that the IAAinduced hyperpolarization of the plasma membrane in male gametophytes of petunia is caused by the enhanced electrogenic activity of ATP-dependent proton pump in the presence of this phytohormone. It is supposed that the effect of IAA is mediated by the transient increase in cytosolic Ca²⁺ level and by generation of reactive oxygen species (ROS). Possible mechanisms underlying the mediatory role of calcium and ROS in the auxin signal transduction and the resulting stimulation of electrogenic activity of the plasma membrane H⁺-ATPase are discussed.     

Effects of salt-adaptation and salt-stress on extracellular acidification and microsome phosphohydrolase activities in tomato cell suspensions

The effects of NaCl-adaptation and NaCl-stress on in vivo H⁺ extrusion and microsomal vanadate- and bafilomycin-sensitive ATPase and PPase activities were studied in tomato cell suspensions. Acidification of the external medium by 50 mM NaCl-adapted and non-adapted (control) tomato cells was similar. Extracellular acidification by both types of cells during the first hour of incubation with 2 μM fusicoccin (FC) in the presence of 100 mM NaCl was lightly increased while in the presence of 100 mM KCl it was increased by 3 (control)- and 6.5 (adapted)-fold. Extracellular alkalinization after 2 h of cell incubation in 100 mM NaCl indicated the possibility that a Na⁺/H⁺ exchange activity could be operating in both types of cells. Moreover, acidification induced by adding 100 mM NaCl + FC to non-adapted cells was relatively less affected by vanadate than that induced by 5 mM KCl + FC, which suggested that salt stress could induce some component other than H⁺ extrusion by H⁺-ATPase. In addition, no differences were observed in microsomal vanadate-sensitive ATPase activity among control, NaCl-adapted and NaCl-stressed cells, while K⁺-stimulated H⁺-PPase and bafilomycin-sensitive H⁺-ATPase activities were higher in microsomes from NaCl-adapted than in those from control cells. Likewise, the stimulation of in vivo H⁺ extrusion in NaCl adapted cells under NaCl or KCl stress in the presence of FC occurred with an inhibition of H⁺-PPase and bafilomycin-sensitive H⁺-ATPase activities and without changes in the vanadate-sensitive H⁺-ATPase activity. These results suggest that the stimulation of tonoplast proton pumps in NaCl-adapted cells, without changes in plasmalemma H⁺-ATPase, could serve to energize Na⁺ efflux across the plasmalemma and Na⁺ fluxes into vacuoles catalyzed by the Na⁺/H⁺ antiports. This revised version was published online in June 2006 with corrections to the Cover Date.     

灵武长枣果实质膜和液泡膜H~+-ATPase和H~+-PPase活性与果实糖分积累

以不同发育时期灵武长枣(Ziziphus jujuba cv.Lingwuchangzao)的果实为材料,通过测定与分析果肉组织中细胞质膜、液泡膜H+-ATPase和H+-PPase活性、果实糖分含量变化,研究了灵武长枣果实质膜、液泡膜H+-ATPase和H+-PPase活性与糖积累特性的关系。结果表明:(1)果实第二次快速生长期之前主要积累葡萄糖和果糖,之后果实迅速积累蔗糖,葡萄糖和果糖含量则逐渐下降,成熟期果实主要积累蔗糖。(2)在果实发育的缓慢生长期S1,质膜H+-ATPase活性最低;第一次快速生长期,质膜H+-ATPase活性最高;缓慢生长期S2,其活性降低;第二次快速生长期,质膜H+-ATPase活性升至次高;完熟期,质膜H+-ATPase活性下降幅度较大。(3)在果实发育过程中,液泡膜H+-ATPase和H+-PPase活性的变化趋势相似。缓慢生长期S1,液泡膜H+-ATPase和H+-PPase活性较低;从缓慢生长期S1至第一次快速生长期缓慢下降至最低;从第一次快速生长期开始,液泡膜H+-ATPase和H+-PPase活性呈现为逐渐增高的变化趋势;除第二次快速生长期以外,液泡膜H+-PPase活性始终高于H+-ATPase。由此推测,质膜H+-ATPase和液泡膜H+-ATPase、H+-PPase对灵武长枣果实糖分的跨膜次级转运起到重要的调控作用。     

Congruence between PM H<Superscript>+</Superscript>-ATPase and NADPH oxidase during root growth: a necessary probability

Plasma membrane (PM) H⁺-ATPase and NADPH oxidase (NOX) are two key enzymes responsible for cell wall relaxation during elongation growth through apoplastic acidification and production of ˙OH radical via O₂˙^?, respectively. Our experiments revealed a putative feed-forward loop between these enzymes in growing roots of Vigna radiata (L.) Wilczek seedlings. Thus, NOX activity was found to be dependent on proton gradient generated across PM by H⁺-ATPase as evident from pharmacological experiments using carbonyl cyanide m-chlorophenylhydrazone (CCCP; protonophore) and sodium ortho-vanadate (PM H⁺-ATPase inhibitor). Conversely, H⁺-ATPase activity retarded in response to different ROS scavengers [CuCl₂, N, N’ –dimethylthiourea (DMTU) and catalase] and NOX inhibitors [ZnCl₂ and diphenyleneiodonium (DPI)], while H₂O₂ promoted PM H⁺-ATPase activity at lower concentrations. Repressing effects of Ca⁺² antagonists (La⁺³ and EGTA) on the activity of both the enzymes indicate its possible mediation. Since, unlike animal NOX, the plant versions do not possess proton channel activity, harmonized functioning of PM H⁺-ATPase and NOX appears to be justified. Plasma membrane NADPH oxidase and H⁺-ATPase are functionally synchronized and they work cooperatively to maintain the membrane electrical balance while mediating plant cell growth through wall relaxation.     

Alteration of transport activity of proton pumps in coleoptile cells during early development stages of maize seedlings

Comparative analysis of the transport activity of proton pumps (plasmalemma H⁺-ATPase, vacuolar H⁺-ATPase, and vacuolar H⁺-pyrophosphatase) in the membrane preparations obtained from coleoptile cells of etiolated maize seedlings (Zea mays L.) was carried out. The highest level of vacuolar pyrophosphatase activity was observed during the early development of coleoptile cells under growth intensification through the elongation. The role of ATPase pumps of tonoplast and plasmalemma in the transport of hydrogen ions increases during further development. The plasmalemma activity in this process is higher. When the growth stops, the activity of proton pumps becomes significantly lower. Nevertheless, their substrate specificity and sensitivity to proton pump inhibitors do not change, which can be an evidence of physiological significance of pumps in the maintenance of cell homeostasis.     

Possible Regulatory Effect of Lipid Peroxidation on the H+-ATPase Activity of the Plasmalemma under Stress Conditions

We studied the effects of high temperature and paraquat on the rate of lipid peroxidation and activity of the H⁺-ATPase in the plasmalemma fraction isolated from pea leaves. We demonstrated a heat-induced increase in both indices. When lipid-peroxidation was inhibited by pretreatment with butylated hydroxytoluene, a synthetic antioxidant, the H⁺-ATPase activity increased to a lesser extent than after heat shock without pretreatment. Treatment of plants with paraquat, a prooxidant causing an oxidative stress, resulted in a dramatic increase in lipid peroxidation and H⁺-ATPase activity. We suggested that the enhanced lipid peroxidation could be one of the causes for the H⁺-ATPase activation in the plasmalemma under stress conditions.