共查询到20条相似文献,搜索用时 46 毫秒
1.
SERGEY SHABALA JIAYIN PANG MEIXUE ZHOU LANA SHABALA TRACEY A. CUIN PETER NICK & LARS H. WEGNER 《Plant, cell & environment》2009,32(2):194-207
Nutrient acquisition in the mature root zone is under systemic control by the shoot and the root tip. In maize, exposure of the shoot to light induces short-term (within 1–2 min) effects on net K+ and H+ transport at the root surface. H+ efflux decreased (from −18 to −12 nmol m−2 s−1 ) and K+ uptake (∼2 nmol m−2 s−1 ) reverted to efflux (∼−3 nmol m−2 s−1 ). Xylem probing revealed that the trans-root (electrical) potential drop between xylem vessels and an external electrode responded within seconds to a stepwise increase in light intensity; xylem pressure started to decrease after a ∼3 min delay, favouring electrical as opposed to hydraulic signalling. Cutting of maize and barley roots at the base reduced H+ efflux and stopped K+ influx in low-salt medium; xylem pressure rapidly increased to atmospheric levels. With 100 m m NaCl added to the bath, the pressure jump upon cutting was more dramatic, but fluxes remained unaffected, providing further evidence against hydraulic regulation of ion uptake. Following excision of the apical part of barley roots, influx changed to large efflux (−50 nmol m−2 s−1 ). Kinetin (2–4 µ m ), a synthetic cytokinin, reversed this effect. Regulation of ion transport by root-tip-synthesized cytokinins is discussed. 相似文献
2.
As water and nutrient uptake should be related in the response of plants to salinity, the aim of this paper is to establish whether or not aquaporin functionality is related to H+ -ATPase activity in root cells of pepper ( Capsicum annuum L.) plants. Thus, H+ -ATPase activity was measured in plasma membrane vesicles isolated from roots and aquaporin functionality was measured using a cell pressure probe in intact roots. Salinity was applied as 60 m M NaCl or 60 m M KCl, to determine which ion (Na+ , K+ or Cl− ) is producing the effects. We also investigated whether the effects of both salts were ameliorated by Ca2+ . Similar results were obtained for cell hydraulic conductivity, Lpc , and H+ -ATPase activity, large reductions in the presence at NaCl or KCl and an ameliorative effect of Ca2+ . However, fusicoccin (an activator of H+ -ATPase) did not alter osmotic water permeability of protoplasts isolated from roots. Addition of Hg2+ inhibited both ATPase and aquaporins, but ATPase also contains Hg-binding sites. Therefore, the results indicate that H+ -ATPase and aquaporin activities may not be related in pepper plants. 相似文献
3.
Calcium transport and ATPase activity in a microsomal vesicle fraction from corn roots 总被引:2,自引:2,他引:0
Abstract. An investigation has been made of methods for isolating membrane vesicles from corn ( Zea mays L.) roots active in calcium transport and K+ -stimulated ATPase. Pretreating and grinding the roots at room temperature with EGTA and fusicoccin increases basal ATPase activity. Improvement in Ca2+ uptake requires isolation of a scaled vesicle fraction by the method of Sze(1980). Sorbitol is superior to sucrose as an osmoticant. The pH optimum for Ca2+ uptake is 7.5. whereas that for associated ATPase activity is 6.5. Calmodulin strongly stimulates Ca2+ uptake in a process little affected by uncouplers and ATPase inhibitors, but blocked by chlorpromazine. Fusicoccin gives less stimulation of Ca2+ uptake which is sensitive to uncouplers, and is dependent upon isolation with fusicoccin present. It appears that the sealed vesicle fraction may possess two Ca2+ transport systems: a calmodulin-activated Ca2+ -transporting ATPase, and a Ca2+ /H+ antiport coupled through the protonmotive force to a fusicoccin-stimulated H+ -ATPase. 相似文献
4.
The uptake of the auxin type herbicide 2,4-D into rice seedlings ( Oryza sativa L. cv. Dunghan Shali) and its effects on the K+ , NH+ 4 and NO3 ion uptake and the K+ content were investigated at different pH values. A short incubation of the roots in 0.01 m M 2,4-D caused a marked ion uptake inhibition only at low pH. The non-auxin type herbicide benthiocarb did not produce such an inhibitory effect. Lowering of the pH in the external medium led to an increased 2,4-D uptake by the roots. These results can be explained by the increased H+ permeability of the membranes, allowing a more rapid entrance of 2,4-D into the root cells, thereby inhibiting the active ion uptake. Rice roots not subjected to 2,4-D treatment responded to H+ stress with an increased anomalous K+ uptake and a decreased K+ content. With reference to the effects of pH changes on the ion and 2,4-D uptake, possible transport mechanism of NH+ 4 and 2,4-D are briefly discussed. 相似文献
5.
YIYONG ZHU TINGJUN DI GUOHUA XU XI CHEN HOUQING ZENG FENG YAN & QIRONG SHEN 《Plant, cell & environment》2009,32(10):1428-1440
The preference of paddy rice for NH4 + rather than NO3 - is associated with its tolerance to low pH since a rhizosphere acidification occurs during NH4 + absorption. However, the adaptation of rice root to low pH has not been fully elucidated. This study investigated the acclimation of plasma membrane H+ -ATPase of rice root to low pH. Rice seedlings were grown either with NH4 + or NO3 - . For both nitrogen forms, the pH value of nutrient solutions was gradually adjusted to pH 6.5 or 3.0. After 4 d cultivation, hydrolytic H+ -ATPase activity, V max , K m , H+ -pumping activity, H+ permeability and pH gradient across the plasma membrane were significantly higher in rice roots grown at pH 3.0 than at 6.5, irrespective of the nitrogen forms supplied. The higher activity of plasma membrane H+ -ATPase of adapted rice roots was attributed to the increase in expression of OSA1, OSA3, OSA7, OSA8 and OSA9 genes, which resulted in an increase of H+ -ATPase protein concentration. In conclusion, a high regulation of various plasma membrane H+ -ATPase genes is responsible for the adaptation of rice roots to low pH. This mechanism may be partly responsible for the preference of rice plants to NH4 + nutrition. 相似文献
6.
The roles of phytohormones and fusicoccin in H+ extrusion by isolated protoplasts from rape leaves ( Brassica napus L. cv. Belinda) were investigated and compared to results obtained with leaf segments of the same plants. Net H+ release by protoplasts, which was at least partly due to ATPase activity, was enhanced by 10 μ M indole-3-acetic acid and reduced by 20 μ M abscisic acid, whereas fusicoccin (10 μ M ), brassinosteroid (3 μ M ), kinetin (20 μ M ) and gibberellic acid (10 μ M ) had no effect. Hormone effects and H+ release were not detectable with leaf segments from the same plants. However, using field-grown plants, indole-3-acetic acid and especially fusicoccin stimulated the acidification of the external medium by leaf segments. Hormonecontrolled H+ release by leaf cells is interpreted as the first step in acid-triggered and turgor-regulated cell growth. 相似文献
7.
Bert P. Stok Otto Gy. Tànczos Monika Kähr C. E. E. Stuiver ers Kylin Pieter J. C. Kuiper 《Physiologia plantarum》1981,52(1):115-123
Mg2+ - and Ca2+ -uptake was measured in dark-grown oat seedlings ( Avena sativa L. cv. Brighton) cultivated at two levels of mineral nutrition. In addition the stimulation of the ATPase activity of the microsomal fraction of the roots by Mg2+ was measured. Ca2+ -uptake by the roots was mainly passive. Mg2+ -uptake mainly active; the passive component of Mg2+ -uptake was accompanied by Ca2+ -efflux up to 60% of the Ca2+ present in the roots.
In general Mg2+ -uptake of oat roots was biphasic. The affinity of the second phase correspond well with that of the Mg2+ -stimulation of the ATPase activity, in low-salt roots as well as in high-salt roots and in roots of plants switched to the other nutritional condition. Linear relationships were observed when [phase 2] Mg2+ -uptake was plotted against Mg2+ -stimulation of the ATPase activity of the microsomal fraction of the roots. In 5 days old high-salt plants 1 ATP (hydrolysed in the presence of Mg2+ J corresponded with active uptake of a single Mg2+ ion, but in older high-salt roots and in low-salt roots more ATP was hydrolysed per net uptake of a Mg2+ ion. The results are discussed against the background of regulation of the Mg2+ -level of the cytoplasm of root cells by transport of Mg2+ by a Mg2+ -ATPase to the vacuole, to the xylem vessels, and possibly outwards. 相似文献
In general Mg
8.
Net fluxes of NH4 + and NO3 – along adventitious roots of rice ( Oryza sativa L.) and the primary seminal root of maize ( Zea mays L.) were investigated under nonperturbing conditions using ion-selective microelectrodes. The roots of rice contained a layer of sclerenchymatous fibres on the external side of the cortex, whereas this structure was absent in maize. Net uptake of NH4 + was faster than that of NO3 – at 1 mm behind the apex of both rice and maize roots when these ions were supplied together, each at 0·1 mol m–3 . In rice, NH4 + net uptake declined in the more basal regions, whereas NO3 – net uptake increased to a maximum at 21 mm behind the apex and then it also declined. Similar patterns of net uptake were observed when NH4 + or NO3 – was the sole nitrogen source, although the rates of NO3 – net uptake were faster in the absence of NH4 + . In contrast to rice, rates of NH4 + and NO3 – net uptake in the more basal regions of maize roots were similar to those near the root apex. Hence, the layer of sclerenchymatous fibres may have limited ion absorption in the older regions of rice roots. 相似文献
9.
Protons pumps of the tonoplast may be involved in the regulation of cytosolic pH, but the effects of pH on the coupled activities of these transporters are poorly understood. The effects of pH on the activities of the H+ -translocating pyrophosphatase (PPi ase) and vacuolar-type H+ -translocating adenosine triphosphatase (H+ -ATPase) from maize ( Zea mays L. cv. FRB 73) root membranes were assessed by model that simultaneously considers proton transport by the pump and those processes that reduce net transport. The addition of either pyrophosphate or ATP to either microsomal or tonoplast membranes generated a pH gradient. The pH gradient generated in the presence of both substrates was not the sum of the gradients produced by the two substrates added separately. When membranes were separated by sucrose density gradient centrifugation, pyrophosphate (PPi )-dependent proton transport was associated with light density membranes having tonoplast H+ -ATPase activity. These results indicate that some portion of the PPi ase was located on the same membrane system as the tonoplast ATPase; however, tonoplast vesicles may be heterogeneous, differing slightly in the ratio of ATP- to PPi -dependent transport. Proton transport by both the PPi ase and ATPase had maximal activity at pH 7.0 to 8.0 Decreases in proton transport by the ATPase at pH above the optimum were associated with increases in the processes that reduce net transport. Such an association was not observed at pH values below the optimum. These results are discussed in terms of in situ regulation of cytoplasmic pH by the two pumps. 相似文献
10.
In embryos of the sea urchin, Hemicentrotus pulcherrimus , as well as in cultured cells derived from isolated micromeres, spicule formation was inhibited by allylisothiocyanate, an inhibitor of H+ , K+ -ATPase, at above 0.5 μM and was almost completely blocked at above 10 μM. Amiloride, an inhibitor of Na+ , H+ antiporter, at above 100 μM exerted only slight inhibitory effect, if any, on spicule formation. Intravesicular acidification, determined using [ dimethylamine -14 C]-aminopyrine as a pH probe, was observed in the presence of ATP and 200 mM KCl in microsome fraction obtained from embryos at the post gastrula stage, at which embryos underwent spicule calcification. Intravesicular acidification and K+ -dependent ATPase activity were almost completely inhibited by allylisothiocyanate at 10 μM. Allylisothiocyanate-sensitive ATPase activity was found mainly in the mesenchyme cells with spicules isolated from prisms. H+ , K+ -ATPase, an H+ pump, probably mediates H+ release to accelerate CaCO3 deposition from Ca2+ , CO2 and H2 O in the primary mesenchyme cells. Intravesicular acidification was stimulated by valinomycin at the late gastrula and the prism stages but not at the pluteus stage. K+ permeability probably increases after the prism stage to activate H+ release. 相似文献
11.
12.
Thomas Jahn Frantisek Baluska Wolfgang Michalke Jeffrey F. Harper Dieter Volkmann 《Physiologia plantarum》1998,104(3):311-316
The cell and subcellular localization of plasma membrane P‐type H+ ‐ATPase in root apices from Zea mays L. (maize) seedlings was investigated by immunofluorescence microscopy. H+ ‐ATPase was highly abundant in cells of epidermal and endodermal tissues as well as in phloem companion cells. Strong immunodecoration was also observed in a subset of xylem parenchyma cells forming a connection between the endodermis and metaxylem. Evidence that these cells are equipped for active membrane transport raises the potential that they play a special role in xylem loading. Significant amounts of H+ ‐ATPase were also observed in outer cortical cells. Progressively less H+ ‐ATPase was seen in cortical cells further away from the root‐soil interface. The H+ ‐ATPase was asymmetrically localized within both epidermal and outer cortical cells, with higher levels detected on cell surfaces closest to the root‐soil interface. This asymmetric localization of H+ ‐ATPase is consistent with the hypothesis that transport systems for uptake of nutrients from the soil are selectively targeted to cell surfaces most exposed to nutrients. 相似文献
13.
Lone Baunsgaard Kees Venema Kristian B. Axelsen José Manuel Villalba Annikki Welling Bernd Wollenweber Michael G. Palmgren 《The Plant journal : for cell and molecular biology》1996,10(3):451-458
Transport across the plasma membrane is driven by an electrochemical gradient of H+ ions generated by the plasma membrane proton pump (H+ -ATPase). Random mutants of Arabidopsis H+ -ATPase AHA1 were isolated by phenotypic selection of growth of transformed yeast cells in the absence of endogenous yeast H+ -ATPase (PMA1). A Trp-874-Leu substitution as well as a Trp-874 to Lys-935 deletion in the hydrophilic C-terminal domain of AHA1 conferred growth of yeast cells devoid of PMA1. A Trp-874-Phe substitution in AHA1 was produced by site-directed mutagenesis. The modified enzymes hydrolyzed ATP at 200–500% of wild-type level, had a sixfold increase in affinity for ATP (from 1.2 to 0.2 mM; pH 7.0), and had the acidic pH optimum shifted towards neutral pH. AHA1 did not contribute significantly to H+ extrusion by transformed yeast cells. The different species of aha1, however, displayed marked differences in initial rates of net H+ extrusion and in their ability to sustain an electrochemical H+ gradient. These results provide evidence that Trp-874 plays an important role in auto-inhibition of the plant H+ -ATPase and may be involved in controlling the degree of coupling between ATP hydrolysis and H+ pumping. Finally, these results demonstrate the usefulness of yeast as a generalized screening tool for isolating regulatory mutants of plants transporters. 相似文献
14.
15.
Abstract. Rates of proton extrusion and potassium (86 Rb) influx by intact roots of barley ( Hordeum vulgare cvs . Fergus, Conquest and Betzes) plants were simultaneously measured in short-term (15min) experiments. The nature and extent of apparent coupling between these ion fluxes was explored by manipulating conditions of temperature, pH and cation composition and concentration during flux determinations. In addition, the influence of salt status upon these fluxes was examined. At low K+ concentrations (0.01 to 1 mol m−3 ), H+ efflux and K+ influx were strongly correlated in both low- and high-K+ roots, although K+ : H+ exchange stoichiometries were almost consistently greater than 2:1. At higher concentrations (1 to 5 mol m−3 ), H+ efflux was either reduced or remained unchanged while K+ influxes increased. In the presence of Na2 SO4 , rates of H+ extrusion demonstrated similar cation dependence, although below 10 mol m−3 Na2 SO4 , H+ fluxes were generally 50% lower than in equivalent concentrations of K2 SO4 . These observations are considered in the context of current hypotheses regarding the mechanisms of k+ /H+ exchange. 相似文献
16.
Influence of aluminium on phosphorus and calcium localization in roots of beech (Fagus sylvatica) 总被引:2,自引:0,他引:2
Beech plants ( Fagus sylvatica L. provenance Maramures) were grown in nutrient solution at low pH (4.2) and exposed to different concentrations of AlCl3 . Uptake and leakage of Ca2+ (45 Ca2+ ) and H2 PO4 -(32 P) were studied. A high external aluminium concentration (1.0m M ) reduced the uptake and export to the shoot of both calcium and phosphate, while 0.1 m M Al increased the phosphorus level in the roots. To determine the impact of aluminium on the localization of calcium and phosphate, leakage of the elements from both intact plants and plants frozen prior to the leakage experiment was studied. The leakage of Ca2+ from intact plants was not affected by prior exposure to 0.1 m M Al. Freezing of the beech plants before the leakage experiment increased leakage of calcium slightly more from roots of control plants than for roots exposed to 0.1 m M Al, indicating that even low concentrations of alminium may impede the influx of calcium across the plasma membrane in the roots. The patterns of Ca2+ leakage from roots previously exposed to 1.0 m M Al indicated that very little Ca2+ was located extracellularly. The extracellular fraction of phosphate increased with increasing Al concentration in the nutrient solution. Low Al concentration (0.1 m M ) only reduced the intracellular phosphate concentration to a minor extent, while 1.0 m M Al profoundly decreased it. It is concluded that 0.1 m M AlCl3 has a limited effect upon the localization of Ca2+ and phosphate in the roots. At higher levels of Al, 0.1–1.0 m M , there is a more dramatic change in nutrient localization in the free space and uptake over the plasma membrane. 相似文献
17.
Marten Staal Frans J. M. Maathuis J. Theo M. Elzenga J. Hans M. Overbeek Hidde B. A. Prins 《Physiologia plantarum》1991,82(2):179-184
Plantago species differ in their strategy towards salt stress, a major difference being the uptake and distribution of Na+ ions. A salt-sensitive ( Plantago media L.) and a salt-tolerant ( P. maritima L.) species were compared with respect to Na+ /H+ antiport activities at the tonoplast. After exposure of the plants to 50 m M NaCl for 6 days isolated tonoplast vesicles of P. maritima showed Na+ /H+ antiport activity with saturation kinetics and a Km of 2.4 m M Na+ , NaCl-grown P. media and the control plants of both species showed no antiport activity. Selectivity of the antiport system for Na+ was high and was determined by adding different chloride salts after formation of a Δ pH in the vesicles. Specific tonoplast ATPase activities were similar in the two species and did not alter after exposure to NaCl stress. 相似文献
18.
Lobão FA Façanha AR Okorokov LA Dutra KR Okorokova-Façanha AL 《FEMS microbiology letters》2007,274(1):17-23
The effect of aluminum on dimorphic fungi Yarrowia lipolytica was investigated. High aluminum (0.5–1.0 mM AlK(SO4 )2 ) inhibits yeast–hypha transition. Both vanadate-sensitive H+ transport and ATPase activities were increased in total membranes isolated from aluminum-treated cells, indicating that a plasma membrane H+ pump was stimulated by aluminum. Furthermore, Al-treated cells showed a stronger H+ efflux in solid medium. The present results suggest that alterations in the plasma membrane H+ transport might underline a pH signaling required for yeast/hyphal development. The data point to the cell surface pH as a determinant of morphogenesis of Y. lipolytica and the plasma membrane H+ -ATPase as a key factor of this process. 相似文献
19.
Abstract Washed cells of Rhodopseudomonas sphaeroides forma sp. denitrificans , grown under photodenitrifying conditions, exhibited K+ uptake dependent on the transmembrane proton gradient (Δ pH). These cells also acidified the suspension medium in response to K+ pulses both aerobically and anaerobically in light and in the dark. The results indicate that the photodenitrifier has a reversible K+ /H+ exchange activity which reflects its role in regulating the intracellular K+ concentration, as well as intracellular pH. The acidification of the external medium resulting from K+ pulses was inhibited by carbonyl cyanide- m -chlorophenylhydrazone (CCCP) indicating that the antiporter is energy-dependent. Addition of KCl to washed cells depolarized the membrane potential (Δψ) with a concomitant increase in ΔpH, indicating that the K+ /H+ antiporter was electrogenic. 相似文献
20.
Marco Zancani Valentino Casolo Angelo Vianello Francesco Macrí 《Physiologia plantarum》1998,103(3):304-311
The H+ /PPi stoichiometry of the mitochondrial H+ ‐PPi ase from pea ( Pisum sativum L.) stem was determined by two kinetic approaches, and compared with the H+ /substrate stoichiometries of the mitochondrial H+ ‐ATPase, and the vacuolar H+ ‐PPi ase and H+ ‐ATPase. Using sub‐mitochondrial particles or preparations enriched in vacuolar membranes, the rates of substrate‐dependent H+ ‐transport were evaluated: by a mathematical model, describing the time‐course of H+ ‐gradient (ΔpH) formation; or by determining the rate of H+ ‐leakage following H+ ‐pumping inhibition by EDTA at the steady‐state ΔpH. When the H+ ‐transport rates were divided by those of PPi or ATP hydrolysis, measured under identical conditions, apparent stoichiometries of ca 2 were determined for the mitochondrial H+ ‐PPi ase and H+ ‐ATPase, and for the vacuolar H+ ‐ATPase. The stoichiometry of the vacuolar H+ ‐PPi ase was found to be ca 1. From these results, it is suggested that the mitochondrial H+ ‐PPi ase may, in theory, function as a primary H+ ‐pump poised towards synthesis of PPi and, therefore, acting in parallel with the main H+ ‐ATPase. 相似文献