NaCl胁迫对嫁接番茄根系质膜和液泡膜ATP酶活性的影响

在NaCl胁迫下,对番茄嫁接苗和自根苗的根系活力、根系质膜H+-ATPase、液泡膜H+-ATPase和H+-PPase、质膜和液泡膜Ca2+-ATPase、质膜氧化还原系统活性进行了比较。结果表明,胁迫条件下,嫁接苗根系活力显著高于自根苗。胁迫前期,嫁接苗根系质膜H+-ATPase活性、液泡膜H+-ATPase和H+-PPase活性、质膜和液泡膜Ca2+-ATPase活性、质膜NADH氧化速率和Fe (CN)63- 还原速率被显著诱导;自根苗根系液泡膜H+-ATPase、H+-PPase和Ca2+-ATPase活性、质膜NADH氧化速率和Fe (CN)63- 还原速率被显著诱导。胁迫后期,嫁接苗和自根苗根系各项指标均被显著抑制,但嫁接苗各指标受抑制时间较自根苗晚,且数值上均显著高于自根苗。表明嫁接苗比自根苗具有较强的耐盐性。     

镉对玉米苗中钙调蛋白含量和Ca2+-ATPase活性的影响

试验采用营养液培养的方法,以玉米为试材,研究了不同供镉浓度（0﹑5﹑20和100 µmol/L）和处理时间（12﹑24﹑48﹑96、168 h）对植株体内钙调蛋白（CaM）含量及生物膜上的Ca²⁺-ATPase活性的影响。结果表明,植株可溶性Ca²⁺含量在镉胁迫后较不加镉处理增加,镉处理在叶和根中分别在48和24 h后达最高,然后随镉处理浓度和处理时间的增加逐步下降;同时镉诱导了植株CaM的合成,其含量随镉处理浓度和处理时间增加逐步增加,但20 µmol/L和100 µmol/L镉处理在168 h后有所下降;与不加镉处理相比,镉胁迫导致植株生物膜上的Ca²⁺-ATPase活性迅速升高,但随镉处理浓度提高和时间延长,镉胁迫植株的Ca²⁺-ATPase活性在48 h（质膜、液泡膜和内质网膜）和24 h（线粒体膜）后逐步降低。各膜上的Ca²⁺-ATPase活性依次为质膜> 液泡膜> 内质网膜> 线粒体膜,且同一微囊膜,根中的活性大于叶中。     

镉对玉米苗中钙调蛋白含量和Ca2+-ATPase 活性的影响

试验采用营养液培养的方法,以玉米为试材,研究了不同供镉浓度（0、5、20和100μmol／L）和处理时间（12、2,4、48、96、168h）对植株体内钙调蛋白（CaM）含量及生物膜上的Ca^2＋＋ATPase活性的影响。结果表明,植株可溶性Ca^2＋含量在镉胁迫后较不加镉处理增加,镉处理在叶和根中分别在48和24h后达最高,然后随镉处理浓度和处理时间的增加逐步下降;同时镉诱导了植株CaM的合成,其含量随镉处理浓度和处理时间增加逐步增加,但20μmol／L和100μmol／L镉处理在168h后有所下降;与不加镉处理相比,镉胁迫导致植株生物膜上的Ca^2＋-ATPase活性迅速升高,但随镉处理浓度提高和时间延长,镉胁迫植株的Ca^2＋-ATPase活性在48h（质膜、液泡膜和内质网膜）和24h（线粒体膜）后逐步降低。各膜上的Ca^2＋-ATPase活性依次为质膜〉液泡膜〉内质网膜〉线粒体膜,且同一微囊膜,根中的活性大于叶中。     

外源一氧化氮对镉胁迫下长春花质膜过氧化、ATPase及矿质营养吸收的影响

重金属污染已成为全球范围的主要问题之一,其中土壤镉（Cd）污染已成为当今社会普遍关注的问题。镉是植物生长发育的非必需元素,极小浓度即可产生较大危害。一氧化氮（NO）是一种氧化还原信号分子和活性氮（RNS）, 参与植物对重金属镉胁迫的应答。长春花（Catharanthus roseus）是我国广泛栽培的兼具园林绿化和抗癌药源等有重要价值的多年生草本花卉植物。为了解镉胁迫下外源NO 对园林地被植物生理响应的调控机制,采用盆栽试验研究了外源NO（硝普钠SNP）对镉胁迫下长春花幼苗生长、 活性氧代谢、 质膜ATPase酶和5'-核苷酸酶活性以及矿质营养元素吸收的影响。结果表明, 25 mg/kg 镉胁迫严重抑制长春花幼苗的生长,显著增加地上部和根系镉的富集量,抑制对大量元素和微量元素的吸收。施加0.45、 0.90、 1.80 mg/kg 的SNP显著降低镉从根系向地上部的转运,缓解因镉胁迫对钾（K）、 钙（Ca）、 镁（Mg） 和 铁（Fe）、 铜（Cu）、 锌（Zn） 吸收产生的抑制效应,降低镉胁迫的毒害作用,促进植物生长。镉胁迫下,丙二醛（MDA）含量和活性氧（O2和H2O2）水平显著升高。施加低浓度 SNP 能够显著缓解细胞质膜过氧化,降低硫代巴比妥酸反应产物（TBARS）堆积,且对抗氧化酶和ATPase酶具有相同作用。添加0.45、 0.90、 1.80 mg/kg 的SNP 可提高镉胁迫下长春花地上部和根系的抗氧化酶［过氧化氢酶（CAT）、 超氧化物歧化酶（SOD）、 过氧化物酶（POD）］活性与抗氧化物（还原型谷胱甘肽GSH）含量,诱导质膜H+-ATPase、 Ca2+-ATPase和 5-AMPase 活性提升到正常水平（对照CK）。添加1.80 mg/kg 的SNP对镉毒害的缓解作用最有效,而添加3.60、 7.20 mg/kg 的SNP的处理则无明显效果。     

钙对苹果果实钙调蛋白含量和Ca2+ -ATPase活性及其基因表达的影响

研究不同浓度钙（0、1和10 mmo1/L CaCl2 ;5 mmo1/L EGTA）对苹果果实钙调蛋白（CaM）含量和Ca2+-ATPase活性及其基因表达的影响。利用同源克隆方法分离CaM和Ca2+-ATPase基因,采用荧光定量PCR方法研究它们表达特征。结果表明,果实切片外源补钙,可溶性Ca2+及CaM含量在高钙处理12 h达到高峰;高钙处理12 h质膜Ca2+-ATPase活性显著增加,与胞内CaM含量增加时间一致;高钙处理24 h液泡膜Ca2+-ATPase活性显著增加;随着质膜和液泡膜Ca2+-ATPase活性显著增加,可溶性Ca2+含量在加钙处理48 h显著下降。研究基因表达发现,加钙处理6 h苹果CaM基因的表达量显著增加;加钙处理12 h苹果Ca2+-ATPase基因的表达量显著增加,与CaM含量及质膜Ca2 +-ATPase活性变化一致。果实缺钙处理显著增加CaM基因表达量,而苹果Ca2 +-ATPase基因的表达量没有显著变化。上述研究表明,苹果补钙可以提高细胞内可溶性Ca2+和CaM含量以及CaM基因的表达量,有效启动钙信使系统;质膜及液泡膜Ca2+-ATPase是调控胞内Ca2+关键的酶,通过提高质膜及液泡膜Ca2+-ATPase的活性及Ca2+-ATPase基因的表达量,维持胞内Ca2+的稳态水平。     

外源一氧化氮介导铜胁迫下番茄幼苗中铁、锌、锰的累积及亚细胞分布

采用营养液培养方法,以改良毛粉802F1番茄为材料, 研究外源一氧化氮（NO,SNP为供体）对铜（Cu）胁迫下番茄幼苗铁（Fe）、 锌（Zn）、 锰（Mn）吸收分配的影响。结果显示, 50 mol/ L的 Cu2+ 胁迫下,番茄幼苗的生物量和株高显著降低了33.7% 和23.1%,外施100 mol/L SNP可显著缓解这种抑制作用, 提高Cu 胁迫下番茄幼苗根系、 茎中Fe、 Mn含量及叶柄、 叶片中Fe、 Zn含量,降低茎中Zn含量及叶柄、 叶片中Mn含量; 根系、 茎、 叶柄、 叶片Fe、 Zn及根系和茎中Mn的累积相应增加; 根系吸收的Fe、 Zn、 Mn向地上部的转运降低。Cu 胁迫下, 外源NO可显著提高番茄液泡、 细胞器的Fe、 Zn 含量, 降低根系和叶片细胞壁Fe、 Zn、 Mn含量。在作为转运组织的茎和叶柄中,Mn主要分布在细胞壁上,而在叶柄和叶片液泡、 细胞器中也有增加。表明外源NO可以调控番茄幼苗各部位及亚细胞中Fe、 Zn、 Mn的合理分布,维持胞质离子稳态和矿质营养元素平衡,缓解铜胁迫,保证番茄幼苗正常的生理代谢。     

外源NO对镉胁迫下长春花质膜过氧化ATP酶活性及光合特性的影响

为了解镉胁迫下外源NO对地被植物生理响应的调控机制,采用盆栽试验研究了外源NO（SNP）对镉胁迫下长春花幼苗生长、活性氧代谢、质膜ATP酶活性及光合特性的影响。结果表明,外施100μmol·L^-1SNP能缓解25mg·kg一镉胁迫对长春花幼苗生长的抑制,增加叶长、叶宽、株高、基径和生物量。与镉胁迫相比,施用SNP能够降低叶片和根系中丙二醛（MDA）、过氧化氢（H2O2）含量和过氧根离子自由基（O2^-·）产生速率,提高过氧化氢酶（CAT）、过氧化物酶（POD）、超氧化物歧化酶（SOD）活性及还原型谷胱甘肽（GSH）含量。SNP能显著缓解镉胁迫对叶绿素a（Chla）、叶绿素b（Chlb）和总叶绿素的抑制,提高叶片净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和气孔限制值（Ls）,降低胞间CO2浓度（G）和瞬时光能利用效率（LUE）。同时,外源NO能诱导叶片和根系中质膜H＋-ATPase和Ca2＋-ATPase活性提升到正常水平（对照）。但外施100μmol·L-1 NO分解产物NaNOx或SNP相似物Na3Fe（CN）6对镉胁迫则无明显缓解作用。因此,外源NO可通过提高活性氧清除能力,增加叶绿素含量,增强质膜ATP酶活性,从而提高叶肉细胞光合能力,加强离子跨膜运输和信号转导,缓解镉胁迫对细胞质膜的损伤。     

外源NO对铜胁迫下番茄光合、生物发光特性及矿质元素吸收的影响

采用营养液培养,研究了外源一氧化氮（NO）供体硝普钠(Sodium nitroprusside, SNP)对50 μmol/L铜（Cu）胁迫下番茄叶片叶绿素含量、光合特性、生物发光强度和矿质营养元素的影响。结果表明,在Cu胁迫下,外施100 μmol/L SNP显著提高番茄叶片叶绿素a、叶绿素b、叶绿素a+b含量、叶绿素a/b比值、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和叶片中Cu、Ca、Fe、Zn、Mn以及根系中Cu、K、Fe、Zn的含量; 显著降低叶片超微弱发光强度、荧光强度、磷光强度、胞间CO2浓度(Ci)和根系中Ca的含量。然而,SNP对Cu胁迫下的缓解效应可被NO的清除剂血红蛋白所抑制。在Cu处理液中加入100 μmol/L NO-x（NO的分解产物）或100 μmol/L亚铁氰化钠（SNP的相似物或分解产物）,与Cu胁迫处理差异不显著。表明外源NO可以通过改善Cu胁迫下番茄叶片光合特性,降低超微弱发光、荧光、磷光强度,维持矿质营养元素平衡,缓解Cu胁迫对番茄的抑制作用。     

铵态氮营养下水稻根系分泌氢离子与细胞膜电位及质子泵的关系

为了研究水稻在铵态氮营养下分泌氢离子的机理,采用不同浓度的铵态氮（0.1～1.0 mol/L）处理水稻幼苗根系,4h后用1 mol/L NaOH滴定培养液,计算氢离子的分泌量;同时,将水稻根系用多聚糖PEG-DEXTRAN两相系统分离出细胞膜囊体,并测定细胞膜H+-ATPase的水解活性和质子泵活性。另外,利用毛细管微电极测定水稻根细胞在上述不同铵浓度下膜电位的变化,以阐明水稻根系吸收铵态氮后分泌氢离子与细胞膜电位及细胞膜质子泵之间的关系。结果表明,随着培养液中铵离子浓度的升高,根系分泌氢离子的量随之增加;分离细胞膜后,离体细胞膜囊体H+-ATPase的水解活性和质子泵活性也相应增强。原位测定细胞膜电位时,膜电位去极化程度亦随NH4+浓度的升高而升高;氢离子分泌量与细胞膜电位、细胞膜H+-ATPase水解活性及质子泵活性之间的均具有一定的相关性。说明根系在NH4+-N营养下分泌氢离子是由于细胞膜上H+-ATPase主动泵出氢离子造成的,这与根系吸收NH4+后引起细胞膜去极化,需要通过提高质子泵活性来维持膜电位有关。     

在铝胁迫下黑麦根系分泌的柠檬酸和苹果酸的解毒机制的研究

在我国普遍种植的黑麦(冬牧70),在铝胁迫下其根系能分泌柠檬酸-苹果酸复合有机酸。为了揭示在铝胁迫下黑麦根系分泌的复合有机酸(柠檬酸-苹果酸)的解毒机理,研究了上述复合有机酸对铝胁迫下小麦幼根细胞膜透性、过氧化物酶(POD)、过氧化氢酶(CAT)、H -ATPase活性和根伸长的影响。结果显示,复合有机酸使小麦幼根电解质渗漏率下降,根尖过氧化物酶、过氧化氢酶、H -ATPase活性提高,幼根伸长量增加,并且复合有机酸的效果随其浓度(25~200μm ol/L)的增加而增强。在50或100μm ol/L苹果酸的基础上,柠檬酸与苹果酸比值(C¨M)从1¨2增加到1¨1,复合有机酸的解毒效果更显著;而在相同柠檬酸浓度下,苹果酸浓度增加一倍对小麦铝毒害无显著影响。可以推断,在铝胁迫环境下,黑麦根系分泌的柠檬酸-苹果酸复合有机酸可以维持细胞膜结构的完整性,减轻自由基伤害和铝对根生长的毒害,并且复合有机酸中柠檬酸的作用强于苹果酸。铝胁迫下根系分泌复合有机酸是黑麦抵御铝毒害的有效机制。     

Saline and alkaline stress genotypic tolerance in sweet sorghum is linked to sodium distribution

Salt and alkali stress limit crop growth and reduce agricultural productivity worldwide, which have led to increased interest in enhancing salt tolerance in crop plants. Sweet sorghum (Sorghum bicolor (Linn.) Moench) is a monocotyledonous crop species that shows greater tolerance to salt–alkali stress than most other crops, although the underlying mechanisms behind this tolerance remain unclear. Therefore, we investigated the effects of salt and alkali stresses on two sweet sorghum varieties M-81E, which is stress tolerant, and 314B, which is stress sensitive. Namely, we surveyed plant growth parameters, measured Na⁺ and K⁺ distributions at the level of the whole plant as well as in three specific tissues, and then determined the activities of H⁺-ATPase, H⁺-PPase and Na⁺/H⁺ exchange in root vacuole membranes under stress conditions. Following treatment of the seedlings for 3 days with salt or alkali solutions, the plant growth was inhibited and Na⁺ levels in the whole plant, leaves, sheath, and roots were increased in both genotypes. Under alkali stress, K⁺ levels in the whole plant, leaves, sheath, and roots were decreased in both genotypes. M-81E roots accumulated significantly higher levels of Na⁺ than leaves, whereas the opposite was true for 314B. Under salt stress, both the hydrolytic and proton-transporting activities of V-H⁺-ATPase were enhanced and Na⁺/H⁺ exchange activity was dramatically upregulated, whereas V-H⁺-PPase activity was decreased. M-81E showed a greater capacity to compartmentalize Na⁺ within root cell vacuoles and maintain higher levels of K⁺ uptake compared with 314B, resulting in higher K⁺/Na⁺ transport selectivity in this genotype. These results also demonstrated that H⁺-ATPase activity and ionic homeostasis (Na⁺/K⁺) were likely important contributors to the tolerance of saline-alkali stress and crucially important for understanding alkaline stress in both crops and wild plants.     

Aluminum-Enhanced Proton Release Associated with Plasma Membrane H+-Adenosine Triphosphatase Activity and Excess Cation Uptake in Tea (Camellia sinensis) Plant Roots

Cultivated tea (Camellia sinensis) plants acidify the rhizosphere, and Aluminum (Al) toxicity is recognized as a major limiting factor for plant growth in acidic soils. However, the mechanisms responsible for rhizosphere acidification associated with Al have not been fully elucidated. The present study examined the effect of Al on root-induced rhizosphere acidification, plasma membrane H⁺-adenosine triphosphatase (H⁺-ATPase) activity, and cation-anion balance in tea plant roots. The exudation of H⁺ from tea plant roots with or without Al treatment was visualized using an agar sheet with bromocresol purple. The H⁺-ATPase activity of plasma membranes isolated from the roots was measured after hydrolysis using the two-phase partition system. The Al treatment strongly enhanced the exudation of H⁺, and the acidification of tea plant roots by Al was closely associated with plasma membrane H⁺-ATPase activity. The root plasma membrane H⁺-ATPase activity increased with Al concentration. The Al content, amount of protons released, and H⁺-ATPase activity were significantly higher in roots treated with Al than in those untreated. The results of the cation-anion balance in roots showed an excess of cations relative to anions, with the amount of excess cation uptake increasing with increasing Al concentrations. These suggest that Al-enhanced proton release is associated with plasma membrane H⁺-ATPase activity and excess cation uptake. Findings of this study would provide insights into the contributing factors of soil acidification in tea plantations.     

The role of root plasma membrane ATPase and rhizosphere acidification in zinc uptake by two different Zn-deficiency-tolerant wheat cultivars in response to zinc and histidine availability

ABSTRACT

We investigated the effect of histidine (His) and Zn deficiency on H⁺-ATPase activity and H⁺ release from wheat roots. Two bread wheat (Triticum aestivum L. cvs. Kavir and Back Cross Roshan) were grown in a nutrient solution for four weeks before being transferred to treatment solutions consisting of two concentrations of His (0 and 50 µM) and two concentrations of Zn (0 and 10 μM). The Zn-only and the Zn+His treatments were observed to release more H⁺ in the root media than did the control ones, with the highest achieved under the Zn+His treatment which was roughly 2.1 times higher than that under the control conditions. The H⁺ release from wheat roots increased slightly but significantly in the presence of only His when compared with the control solutions. The hydrolytic and transport activities of H⁺-ATPase were affected by both Zn deficiency and His supply. In both cultivars, application of Zn and His resulted in a higher hydrolytic activity of H⁺-ATPase when compared with the control solutions. The highest hydrolytic activity of H⁺-ATPase in the root plasma membrane vesicles was achieved with the Zn+His treatment. The ‘Back Cross Roshan’ exhibited a higher (PM) H⁺-ATPase activity and H⁺ pumping than did ‘Kavir’.     

La(NO3)3 对盐胁迫下黑麦草幼苗生长及抗逆生理特性的影响

为探讨稀土元素镧(La)对牧草盐胁迫伤害的缓解作用, 采用水培法研究了叶面喷施20 mg·L^-1La(NO₃)₃ 对NaCl 胁迫下黑麦草幼苗生长及其抗逆生理特性的影响。结果表明: 盐胁迫显著抑制黑麦草幼苗的生长, 提高叶片电解质渗漏率及丙二醛(MDA)、O₂^- 和H₂O₂ 含量, 其作用随盐浓度的增大而增强。超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性蛋白质、脯氨酸含量随盐浓度增大呈先升后降趋势, 可溶性糖和Na⁺/K⁺比逐渐增大, 质膜H⁺-ATP 酶活性逐渐降低, 过氧化物酶(POD)活性及POD 同功酶数量表达增强。喷施La(NO₃)₃ 处理可降低盐胁迫下黑麦草幼苗叶片的O₂^- 和H₂O₂ 含量, 提高SOD、CAT、POD、APX 和质膜H⁺-ATP 酶的活性及POD 同功酶的表达, 使AsA、GSH、可溶性蛋白质、可溶性糖和游离脯氨酸含量及幼苗生物量增加, Na⁺/K⁺比降低。表明La(NO₃)₃ 可通过提高抗氧化系统的活性和积累渗透溶质减轻盐胁迫伤害, 从而提高黑麦草的耐盐性。     

H+‐atpase and H+‐transport activities in tonoplast vesicles from barley roots under salt stress and influence of calcium and abscisic acid 1

Seedlings of two barley cultivars differing in NaCl sensitivity were treated with low (100 mM) or high (400 mM) concentration of NaCl for 6 days. Tonoplast vesicles were prepared from roots, and H⁺‐ATPase and H⁺‐transport activities associated with tonoplast were assayed. Both H⁺‐ATPase and H⁺‐transport activities in the two cultivars were increased at 100 mM NaCl. These activities also increased in the salt‐tolerant cultivar at 400 mM NaCl, but in salt‐sensitive cultivar were decreased. In vivo treatment with 10 mM Ca²⁺ stimulated H⁺‐ATPase and H⁺‐transport activities at two levels of NaCl, however, treatment with 10⁵M (±) abscisic acid (ABA) inhibited these activities. From these results we propose that the increase of the vacuolar H⁺ pumps in barley roots reflects an adaptation to salt stress. The stimulation of HVATPase and H⁺‐transport activities by calcium (Ca) depends mainly on its effect in maintaining stability of membrane under salt stress.     

Effect of sodium chloride stress on the plasma membrane ATPase of barley roots: Probable cause for decrease in ATPase activity

The regulation of plasma membrane ATPase activity by salt stress was investigated in barley roots. The plasma membrane fractions were prepared from the roots treated with or without 200 mM sodium chloride (NaCl) for one day. After salt treatment, ATPase activity reduced by 20 to 30% as compared with that of control roots. No significant changes in the content of total phospholipid and sterol were detected in the plasma membrane fraction by salt stress. After extraction of most of the phospholipids in the plasma membrane vesicles with a solution containing 1% (W/V) octylglucoside and 1% (W/V) Triton X‐100, the ATPase activity in salt‐stressed roots was lower than that of control roots. After reconstitution of detergent‐extracted protein into liposome, the reduction of ATPase activity by salt stress did not recover. Based on immunoblott analysis, the relative amount of H⁺‐ATPase in plasma membrane fraction prepared, from NaCl‐stressed roots was smaller than that of control roots. These results indicate that the reduction of H⁺‐ATPase activity by salt stress was caused by the decrease in the amount of H⁺‐ATPase rather than the modification of ATPase.