TheRelati磷饥饿时番茄幼苗根系质膜H~ - ATP酶活性的变化与磷吸收的关系(英文)

磷饥饿提高了番茄幼苗质膜H ATP酶活性并促进了番茄幼苗根部的H 分泌。动力学分析表明 ,磷饥饿使番茄幼苗根部质膜H ATP酶的Km 值明显降低 ,亦即提高了该酶对其底物的亲和力 ,但对该酶的Vmax影响不大。另外 ,磷饥饿并不改变ATP酶的最适 pH值 (最适 pH值为 6.5)。钒酸盐显著抑制番茄幼苗根部质膜ATP酶的活性以及H 分泌 ,也显著抑制番茄幼苗的Pi吸收。与对照相比 ,上述抑制作用在饥饿处理的植物中表现得更强。以上结果表明 ,磷饥饿时高亲和性Pi传递系统的诱导很可能包含质膜H ATP酶的参与。     

磷饥饿时番茄幼苗根系质膜H^＋—ATP酶活性的变化与磷吸收的关系

磷饥饿提高了番茄幼苗质膜H^ -ATP酶活性并促进了番茄幼苗根部的H^＋分泌和。动力学分析表明,磷饥饿使番茄功苗根部质膜H^ -ATP酶的K m值明显降低,亦即提高了该酶对其底物的亲和力,但对该酶的Vmax影响不大。另外,磷饥饿并不改变ATP酶的最适pH值（最适pH值为6.5）。钡酸盐显著抑制番茄幼苗根部质膜ATP酶的活性以及H^＋分泌,也显著抑制番茄幼苗的Pi吸收。与对照相比,上述抑制作用在饥饿处理的植物中表现得更强,以上结果表明,磷饥饿时高亲和性Pi传递系统的诱导很可能包含质膜H^ -ATP酶的参与。     

磷饥饿时番茄幼苗根系质膜H+-ATP酶活性 的变化与磷吸收的关系

磷饥饿提高了番茄幼苗质膜H     

磷饥饿对番茄幼苗H+分泌及Pi吸收的影响

磷饥饿条件下番茄幼苗的H⁺分泌速率明显提高。质膜质子泵专一性抑制剂钒酸盐能显著抑制番茄幼苗的H⁺分泌,也能显著抑制其Pi吸收。此结果表明,磷饥饿时番茄幼苗Pi吸收速率的变化与H⁺分泌速率的变化之间可能具有一定的相关性,并进一步暗示质膜H⁺-ATPase可能参与其中。本文结果还表明,Pi/H⁺的准量关系约为1:1。     

磷饥饿下番茄幼苗根系液泡膜H+-ATPase活性的适应性变化

以‘世纪星’番茄为材料。研究了磷饥饿下番茄幼苗的生长状况及其根部液泡膜H^＋-ATPase活性的适应性变化。结果表明：磷饥饿下番茄幼苗的平均高度均低于对照苗,而主根长度均显著长于对照。磷饥饿提高了番茄幼苗根部液泡膜H^＋-ATPase的水解活性,随着磷胁迫时间的延长,该酶的活性逐渐增大,在磷饥饿7d时达到最大,后又略有降低;而对照番茄幼苗根部该酶的活性变化很小。动力学分析表明：磷饥饿使番茄幼苗根部液泡膜H^＋-ATPase的Km值明显降低,但对该酶的Kmax影响不大。这说明磷饥饿提高了该酶对其底物的亲和力。此外,磷饥饿并不改变液泡膜H^＋-ATPase酶的最适pH值（仍为7．5）。     

磷酸饥饿对番茄幼苗生长状况及其磷吸收的影响

本文就磷酸饥饿对番茄幼苗生长状况及共磷吸收的影响进行了研究。结果表明,磷酸饥饿时,番茄幼苗的平均高度下降,而主根的长度却明显长于对照。磷酸饥饿初期对番茄幼苗鲜重累积影响不大,但随着饥饿的继续,受胁迫苗的鲜重累积与对照间的差异加大并且变得明显低于对照。     

磷酸饥饿时番茄幼苗酸性磷酸酶活性的变化与Pi吸收的关系

磷酸饥饿时,番茄幼苗根部及地上部酸性磷酸酶活性均显著增强,根部细胞表面酸性磷酸酶及根部外泌的酸性磷酸酶活性亦明显提高。动力学分析表明,磷酸饥饿提高了番茄幼苗根部的酸性磷酸酶对其底物的亲和力。另外,磷酸饥饿对番茄幼苗根部酸性磷酸酶活性的最适ｐＨ值没有影响。钼酸对番茄幼苗根部酸性磷酸酶活性有强烈的抑制作用,对番茄幼苗Ｐｉ吸收速率也有十分明显的抑制效果。以上结果表明,磷酸饥饿时,番茄幼苗Ｐｉ吸收的适应性变化可能与根部酸性磷酸酶特别是根部细胞表面酸性磷酸酶及其外泌酸性磷酸酶的参与密切关联。     

低温、高pH胁迫对水稻幼苗根系质膜、液泡膜ATP酶活性的影响

以耐冷性不同的两个水稻品种为材料,比较研究了幼苗根系质膜、液泡膜ATP酶对低温(8℃)及高pH(8.0)胁迫的反应。结果表明水稻根细胞质膜和液泡膜上均存在Ca3+-ATP酶,但活性远低于H+-ATP酶。耐冷品种武育粳3号经低温(8℃)处理2d,根系质膜和液泡膜H+-ATP酶、Ca2+-ATP酶活性均明显升高,至冷处理12d,H+-ATP酶、Ca2+-ATP酶活性有所下降,但仍与对照相近;而冷敏感品种汕优63经低温(8℃)处理2d,根系质膜H+-ATP酶活性略有升高,而质膜Ca2+-ATP酶以及液泡膜H+-ATP酶、Ca2+-ATP酶活性已明显下降;至冷处理12d,4种酶活性均明显低于对照。高pH胁迫使质膜和液泡膜H+-ATP酶活性下降,而使Ca2+-ATP酶活性上升。高pH胁迫会加剧低温冷害。结果表明,耐冷品种质膜、液泡膜ATP酶比冷敏感品种对低温胁迫有更强的适应能力。     

磷饥饿对番茄幼苗H^＋分泌及Pi吸收的影响

磷饥饿条件下番茄幼苗的Ｈ＾＋分泌速率明显提高,质膜质子泵专一性抑制剂钒酸盐能显著抑制番茄幼苗的Ｈ＾＋分泌,也能显著抑制其Ｐｉ吸收。此结果表明,磷饥饿时番茄幼苗Ｐｉ吸收速率的变化与Ｈ＾＋分泌速率的变化之间可能具有一定的相关性,并进一步暗示质膜Ｈ＾＋－ＡＴＰａｓｅ可能参与其中,本文结果还表明,Ｐｉ／Ｈ＾＋的准量关系约为１：１。     

磷酸盐饥饿时番茄幼苗根部质膜蛋白组分的变化

对处于磷酸盐饥饿条件下的番茄幼苗根部质膜以及去除质膜的其他膜部分的蛋白质含量及组分的变化进行了检测。结果显示,磷酸盐饥饿第７ｄ时,受胁迫苗根部质膜及去除质膜的其他膜蛋白质含量与各自的对照相当。而ＳＤＳ－ＰＡＧＥ的结果表明,磷酸盐饥饿第７ｄ时受胁迫苗根部质膜蛋白质中出现４条对照中所没有的新的多肽（分子量分别为３４ｋＤ,３６ｋＤ,４６ｋＤ和４９ｋＤ）。该结果经浓度梯度电泳得到进一步的证实。本文推测在受     

NaCl胁迫下大麦根液泡膜H+-ATPase活性、离子吸收与钙的关系

NaCl胁迫2 d,耐盐大麦(Hordeum vulgare L.cv) ("滩引2号")根系液泡膜H+-ATPase活性增强,H+-PPase活性下降.以质膜Ca2+通道抑制剂La3+ (1 mmol/L)或Ca2+螯合剂EGTA (5 mmol/L)处理大麦幼苗,抑制了NaCl诱导的液泡膜H+-ATPase活性的增强,但提高了H+-PPase活性;用CaM拮抗剂三氟拉嗪(TFP,20 μmol/L)处理,也抑制了液泡膜H+-ATPase活性的增强.NaCl胁迫下,外加La3+,TFP或La3++TFP处理,使Na+吸收增加,K+和Ca2+吸收降低.结果表明,NaCl胁迫下,液泡膜H+-ATPase活性提高和离子吸收的变化可能与Ca-CaM系统有关.     

The Relationship Between Growth and Oxygen Uptake in Hypoxic Rice Seedlings

Atwell, B. J. and Green way, H. 1987. The relationship betweengrowth and oxygen uptake in hypoxic rice seedlings.—J.exp. Bot. 38: 454–465. Rice seedlings (Oryza saliva L.) were grown in the dark forup to 4 d in solutions containing various concentrations ofO₂. Compared with seedlings grown at 0·250 mol O₂ m^–3,the dry weight of the growing seedling was 14% lower at 0·110mol O₂ m^–3 and 60% lower at 0 mol O₂ m^–3. Decreasesin fresh weight were similar but not identical to decreasesin dry weight, possibly because leaf growth was suppressed evenabove 0·110 mol O₂ m^–3. Oxygen deficiency inhibitedroot growth more severely than coleoptile growth. Coleoptiles from seedlings grown in aerated solution were exposedto an atmosphere of pure N₂ for 30 min. Anoxia caused a declinein ATP content and energy charge, suggestive of decreased oxidativephosphorylation. It is not clear whether the decline in oxidativephosphorylation was solely responsible for impaired growth inhypoxia. In seedlings growing at O₂ concentrations less than 0·110mol O₂ m^–3, significant amounts of ethanol were synthesized.The rate of O₂ uptake decreased markedly below 0·06 molO₂ m^–3; this was presumably near the external O₂ concentrationat which oxidative phosphorylation became limited by the supplyof O₂. The stage of development of the seedlings appeared toinfluence O₂ uptake, possibly through changes in conductanceof the tissue to O₂. Uncouplers were used to confirm that thecritical O₂ concentration was dependent on O₂ diffusion ratherthan enzyme kinetics. Impaired growth above 0·110 molO₂ m^–3 may have been due to a decreased activity of oxygenasesof relatively low affinity for O₂, which in turn altered cellmetabolism. Key words: Growth, oxygen uptake, rice seedlings, hypoxia     

Repression of the K+ Uptake and Cation-Stimulated ATPase Activity Associated with the Plasma Membrane-Enriched Fraction of Cucumber Roots Due to Ca2+ Starvation

The uptake of K⁺ by cucumber plants decreased markedly duringCa²⁺ starvation. A plasma membrane-enriched fraction, judgedfrom the distribution of marker enzymes, was prepared from controland Ca²⁺-starved roots. The Mg²⁺- and K⁺-Mg²⁺-ATPase activitiesassociated with the plasma membrane-enriched fraction of controlroots were maxima at pH 6.5. Various monovalent cations andpotassium salts of monovalent anions stimulated Mg²⁺-ATPaseactivity. Vanadate, DES and DCCD inhibited K⁺- Mg²⁺-ATPase activity.Of the divalent cations and phosphate esters tested, Mg²⁺ andATP were most effective for the stimulation of ATPase by K⁺,whereas Ca²⁺ was ineffective in replacing Mg²⁺. Mg²⁺- and K⁺-Mg²⁺-ATPase activities associated with the plasmamembrane enriched fraction of Ca²⁺-starved roots were much lowerthan those of control roots. K_m values of K⁺-Mg²⁺-ATPase forATP were comparable for control and Ca²⁺-starved roots. The K⁺-stimulated activity of Mg²⁺-ATPase in Ca²⁺-starved rootswas approximately one fourth that of the control, whereas therate of stimulation was only slightly lower in Ca²⁺-starvedroots. (Received May 9, 1984; Accepted September 17, 1984)     

Changes of Some Membrane-Associated Enzyme Activities Degradation of Membrane Phospholipids in Cucumber Roots Due to Ca2+ Starvation

Deprivation of Ca²⁺ from a complete culture medium affectedthe enzyme activities associated with five membrane fractionsof cucmber roots obtained by discontinuous sucrose density gradientcentrifugation. The total activity of K⁺-ATPase, Cyt. c oxidaseand NADPH-Cyt. c reductase of Ca²⁺-deficient roots, starvedfor only 4 days, had decreased to 14, 38 and 60% of the activityof the control roots. In general, loss of enzyme activitieswas accompanied by a shift of activity distribution from theheavier density fractions to lighter ones. The amounts of Ca²⁺ associated with membranes from Ca²⁺-starvedroots decreased to 50–60% of those of the control roots.Both phospholipid and neutral lipid contents in the membranesdecreased markedly while the protein content was not changedby Ca²⁺ deficiency. Phospholipid analysis indicated a drasticdrop in the percent composition of phosphatidylinositol butan increase of phosphatidic acid. Also, phospholipase D activityincreased remarkably during Ca²⁺ starvation, paralleling theappearance of Ca²⁺-deficiency symptoms. Thus, the major effects of Ca²⁺ deficiency appear to be to stimulatephospholipase D activity and a reduction in membrane bound Ca²⁺.These effect may be involved in disorganization of the membranestructure and the changes of enzyme activities associated withthe altered membranes. ¹Rubber Research Institute of Sri Lanka, Dartonfield, Agalwatta,Sri Lanka. (Received July 15, 1985; Accepted November 21, 1985)     

Plasma Membrane H+-ATPase in Maize Roots Induced for NO3- Uptake

Plasma membrane H+-ATPase was studied in maize (Zea mays L.) roots induced for NO3- uptake. Membrane vesicles were isolated by means of Suc density gradient from roots exposed for 24 h either to 1.5 mM NO3- or 1.5 mM SO4-. The two populations of vesicles had similar composition as shown by diagnostic inhibitors of membrane-associated ATPases. However, both ATP-dependent intravesicular H+ accumulation and ATP hydrolysis were considerably enhanced (60-100%) in vesicles isolated from NO3--induced roots. Km for Mg:ATP and pH dependency were not influenced by NO3- treatment of the roots. ATP hydrolysis in plasma membrane vesicles for both control and NO3--induced roots was not affected by 10 to 150 mM NO3- or Cl-. On the other hand, kinetics of NO3-- or Cl--stimulated ATP-dependent intravesicular H+ accumulation were modified in plasma membrane vesicles isolated from NO3-- induced roots. Immunoassays carried out with polyclonal antibodies against plasma membrane H+-ATPase revealed an increased steady-state level of the enzyme in plasma membrane vesicles isolated from NO3--induced roots. Results are consistent with the idea of an involvement of plasma membrane H+-ATPase in the overall response of roots to NO3-.     

盐胁迫下大麦根系多胺代谢与其耐盐性的关系

研究了0～300mmol/LNaCl对大麦(Hordeum-vulgare-L.)幼苗生长速率、根系游离和结合态多胺含量以及多胺生物合成关键酶活性的影响。结果表明,在0～200mmol/L NaCl处理下精氨酸脱羧酶（ADC）、多胺氧化酶(PAO)以及转谷酰胺酶(Tgase)活性明显提高,而在300 mmol/L NaCl处理下活性下降。与之对应,游离腐胺（Put）含量随处理盐浓度的提高一直呈上升趋势,亚精胺(Spd)和在根系内检测到的未知多胺(Pax)在低浓度盐处理时含量上升,随盐浓度的提高含量下降。盐处理前后精胺(Spm)含量变化不明显。低浓度盐处理时游离态（Spd+Pax）/Put上升,随盐浓度的提高比值明显下降。结合态Put、Spd和Pax含量以及结合态多胺总量均在低浓度盐处理时上升,随盐浓度的提高含量明显下降。统计分析显示,大麦相对生长速率与游离态（Spd+Pax）/Put和结合态多胺含量间均呈极显著正相关关系,与游离态多胺和结合态多胺的比值间均呈显著负相关关系,上述结果说明盐胁迫下大麦体内游离态Spd、Pax与Put以及结合态形式之间的平衡与大麦耐盐性关系密切,游离态Put向Spd 、Pax以及结合态形式转化均有利于大麦耐盐性的提高.