不同生境两种生态型芦苇叶片质膜H~ -ATPase的比较(英文)

利用两相法纯化质膜微囊,研究了分布于西北沙漠地区的两种生态型芦苇(Phragmites communis Trin.)(水生芦苇和重度盐化草甸芦苇,分别简称为水芦和盐芦)叶片质膜H -ATPase的部分性质。结果显示,与水芦相比,盐芦质膜H -ATPase的ATP水解活性升高,Km值由1.27 mmol/L降至0.30 mmol/L,但Vmax没有显著差异。并且该酶活性对温度的敏感性和pH谱型也发生了变化。以对硝基苯磷酸盐为底物,低浓度时盐芦的质膜H -ATPase水解活性高于水芦,高浓度时则没有差异。Km在水芦和盐芦中分别为3.61 mmol/L和1.92 mmol/L,但Vmax在两种生态型中没有差异。钒酸盐抑制实验表明,两种生态型的质膜H -ATPase磷酸-酶区的催化性质不同。胰酶对质膜H -ATPase活性的活化谱型也存在差异,说明该酶C末端的结构或性质发生了变化。此外,与水芦相比,盐芦质膜H -ATPase的质子泵活性及与水解活性的耦联程度也升高了。以上结果说明,当芦苇从水生环境向盐渍环境过渡时,质膜H -ATPase的催化性质发生了变化,这些变化可能是由酶结构的修饰和不同的同工酶谱引起的。H -ATPase催化性质的变化可能是对盐渍生境的适应性反应。     

两种生态型芦苇叶绿体的光合电子传递和抗氧保护体系

分布于甘肃省河西走廊的两种不同生态型芦苇-水生芦苇(水芦,生长在深约1m的水滩里)和沙丘芦苇(沙芦,生长在高约5m的沙丘上)在其离体叶绿体的光化学活性上表现为前者高于后者。其中,沙芦全链电子传递速率及光系统Ⅱ(PSⅡ)电子传递速率明显低于水芦,而光系统Ⅰ(PSⅠ)电子传递速率却与水芦接近。沙芦叶片和叶绿体中抗氧化酶活性及叶片抗坏血酸含量均高于水芦。综合结果表明,喜水植物芦苇登陆后,在自然选择压力下,为适应长期的自然干旱胁迫环境,其抗氧保护系统在保护PSⅠ免受水分胁迫诱导的氧化伤害中可能发挥着重要作用。     

两种生态型芦苇叶绿体的光合电子传递和抗氧保护体系

分布于甘肃省河西走廓的两种不同生态型芦苇－水生芦苇（水芦,生长在深约１ｍ的水滩里）和沙丘芦苇（沙芦,生长在高约５ｍ的沙丘上）在其离体叶绿体的光化学活性上表现为前者高于后者。其中,沙芦全链电子传递速率及光系统Ⅱ（ＰＳⅡ）电子传递速率明显低于水芦,而光系统Ⅰ（ＰＳⅠ）电子传递速率却与水芦接近。沙芦叶片和叶绿体中抗氧化酶活性及叶片抗坏血酸含量均高于水芦。综合结果表明,喜水植物芦苇登陆后,在自然选择压力下     

不同生境两种生态型芦苇叶片质膜H+-ATPase的比较

利用两相法化纯化质膜微囊,研究了分布西北沙地区的两种生态型芦苇(Phragmites communis trih.)水生芦苇和重度盐化草甸芦苇,分别简称为水芒和盐芦)叶片质膜H - ATPase的部分性质.结果显示,与水芦相比,盐芦质膜H -ATPase的ATP水解活性升高,Km值由1.27mmol\l降至Vmax没有显著差异.并且该酶活性对温度的敏感必玫PH谱型也发生了变化.以对硝基苯磷酸盐为底物,低浓度时盐芦的的质膜H -ATPase水解活性有差异.钡酸盐抑制实验表明,两种生态的质膜H -ATPase磷酸-酶区的催化性质不同.胰酶对质膜H -ATPase活性的活化谱型也存在差异,说明该酶C末端的结构或性质发生了变化.此外,与水芦相比,盐芦质膜H -ATPase的质子泵活性的耦联程度也升高了.以上结果明,当芦苇从水生环境向盐渍环境过渡时,质膜H -ATPase的催化性质发生了变化,这些变化可能是由酶结构的修饰和不同的同工酬酶谱引起的.H -ATPase催化性质的变化可能是对盐渍生境的适应性反应.     

外源硝酸钙对盐胁迫下黄瓜幼苗叶片抗氧化系统及膜质子泵活性的影响

采用营养液水培法,以较耐盐黄瓜品种"新泰密刺"为试验材料,研究了叶面喷施硝酸钙对盐胁迫(NaCl65mmol·L-1)下黄瓜幼苗活性氧、谷胱甘肽-抗坏血酸循环(GluAsA)中抗氧化酶和抗氧化物质及膜质子泵活性的影响。结果表明:叶面喷施硝酸钙能够显著降低盐胁迫下黄瓜幼苗叶片超氧阴离子(O.2-)产生速率和丙二醛(MDA)含量;显著提高盐胁迫下黄瓜幼苗叶片抗坏血酸过氧化物酶(APX)和脱氢抗坏血酸还原酶(DHAR)等酶活性、抗氧化物质抗坏血酸(AsA)含量、AsA/DHA和GSH/GSSG比值及质膜和液泡膜H+-ATPase和H+-PPase活性。表明外源硝酸钙通过提高Glu-AsA抗氧化系统和膜质子泵活性,降低活性氧对叶片的伤害,增强了植株抗氧化能力和对离子的区域化,进而提高植株盐胁迫耐性。     

NaCl胁迫对螺旋藻生长及抗氧化酶活性的影响

在0.1％～5.0％NaCl浓度范围的培养基中培养极大螺旋藻(Spirulina maxima),发现NaCl浓度高于2.0％时螺旋藻生长受到明显抑制。培养7天后测定超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(ASA-POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量。结果表明：在盐胁迫下,SOD酶活性升高;抗坏血酸过氧化物酶和过氧化氢酶活性在低盐胁迫下活性升高,高盐胁迫下抗坏血酸过氧化物酶活性迅速降低,过氧化物酶则完全失活;MDA含量先随盐胁迫程度增加而降低,后随盐胁迫的进一步增强恢复至对照水平。     

外源α-萘乙酸对花期长期干旱大豆叶片抗氧化系统的影响

以不同耐旱型品种‘南农99-6’和‘科丰1号’大豆为材料,2012年在南京农业大学牌楼试验站进行为期110 d的盆栽试验,研究大豆花期叶面喷施α-萘乙酸(NAA)对长期干旱条件下大豆植株抗氧化系统的影响.结果表明:干旱胁迫显著降低了大豆地上部干物质量,叶片中丙二醛(MDA)含量及活性氧(ROS)水平显著升高,同时,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDHAR)、谷胱甘肽还原酶(GR)和谷胱甘肽过氧化物酶(GPX)活性,还原型抗坏血酸(AsA)、还原型谷胱甘肽(GSH)含量及AsA/DHA(双脱氢抗坏血酸)和GSH/GSSG(氧化型谷胱甘肽)比值显著升高,其中‘科丰1号’大豆的抗氧化能力更高,从而维持较低的ROS水平和MDA含量.NAA可显著提高叶片中的APX、POD、CAT、MDHAR活性及AsA/DHA、GSH/GSSG比值,其中‘科丰1号’大豆叶片的脱氢抗坏血栓还原酶(DHAR)活性和AsA含量极显著增加.     

NaCl胁迫对海滨木槿抗氧化系统和渗透调节的影响

以盐生植物海滨木槿为材料,不同浓度NaCl胁迫对其抗氧化酶活性、抗氧化物质和渗透调节物质含量的影响进行分析。结果显示:随着NaCl浓度的升高,海滨木槿叶片中超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)和谷胱甘肽转硫酶(GST)的活性先升高后降低,而过氧化氢酶(CAT)的活性呈持续下降趋势,但它们达到最高活性时的NaCl浓度不同;各处理的丙二醛(MDA)含量先下降后升高,但始终低于对照;抗氧化物质抗坏血酸(AsA)和谷胱甘肽(GSH)的含量均高于对照,且在200 mmol.L-1时达到最高;各处理渗透调节物质可溶性糖和脯氨酸(Pro)的含量均较对照增加且升幅较大。研究表明,海滨木槿在NaCl胁迫下具有较强的活性氧清除能力和渗透调节能力,从而表现出较强的耐盐性。     

NaCI胁迫对海滨木槿抗氧化系统和渗透调节的影响

以盐生植物海滨木槿为材料,不同浓度NaCl胁迫对其抗氧化酶活性、抗氧化物质和渗透调节物质含量的影响进行分析.结果显示随着NaCl浓度的升高,海滨木槿叶片中超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)和谷胱甘肽转硫酶(GST)的活性先升高后降低,而过氧化氢酶(CAT)的活性呈持续下降趋势,但它们达到最高活性时的NaCl浓度不同;各处理的丙二醛(MDA)含量先下降后升高,但始终低于对照;抗氧化物质抗坏血酸(AsA)和谷胱甘肽(GSH)的含量均高于对照,且在200 mmol·L-1时达到最高;各处理渗透调节物质可溶性糖和脯氨酸(Pro)的含量均较对照增加且升幅较大.研究表明,海滨木槿在NaCl胁迫下具有较强的活性氧清除能力和渗透调节能力,从而表现出较强的耐盐性.     

低温处理对北美冬青叶片抗氧化能力的影响

为了解低温对北美冬青(Ilex verticillata)生长的影响,对2年生扦插苗经低温处理(-6℃)后的生长和抗氧化能力进行了研究。结果表明,随着低温处理时间的延长,北美冬青叶片的叶绿素/类胡萝卜素比值和叶绿素b含量增加,而其他色素含量都呈下降趋势;相对电导率(REC)和H_2O_2含量(72 h除外)显著增加。低温处理对超氧化物歧化酶(SOD)活性影响不大,却显著降低CAT的活性。低温处理过氧化物酶(POD)活性显著提高,48 h活性达到最高;而抗坏血酸过氧化物酶(APX)活性在处理12 h达最高,然后下降。还原型抗坏血酸(As A)、还原型谷胱甘肽(GSH)含量均呈先升高再下降的趋势。因此,北美冬青在短时间内(≤24 h)能够忍受低温(-6℃),抗氧化防御系统在低温初期起关键的作用,但随时间延长(72 h)其抗氧化能力减弱。     

Antioxidant defense system in <Emphasis Type="Italic">Phragmites communis</Emphasis> Trin. ecotypes

The antioxidant defense system in three ecotypes of reed (Phragmites communis Trin.), swamp reed (SR), dune reed (DR), and heavy salt meadow reed (HSMR), from northwest China were investigated. The HSMR possessed the highest ratio of ascorbate (ASC)/dehydroascorbate (DHA) and activities of superoxide dismutase (SOD) and catalase among the three reed ecotypes, whereas, the DR exhibited the highest ratio of glutathione/glutathione disulfide and activities of ASC peroxidase (APX) and DHA reductase. Malondialdehyde and hydrogen peroxide contents were highest in HSMR, intermediate in SR, and lowest in DR. In addition, different isoenzymes of glutathion reductase, APX, SOD and DHA were also observed in three reed ecotypes.     

Anatomical and chemical characteristics of foliar vascular bundles in four reed ecotypes adapted to different habitats

We investigated the anatomical and chemical characteristics of the foliar vascular bundles in four ecotypes of common reed (Phragmites communis Trin.) inhabiting the desert region of northwest China: swamp reed (SR), low-salt meadow reed (LSMR), high-salt meadow reed (HSMR), and dune reed (DR). The cell walls of the vascular systems of all four ecotypes exhibited bright autofluorescence. Compared to SR, the three terrestrial ecotypes, LSMR, HSMR and DR, had higher percentages of bundle sheath cell areas, lower percentages of xylem and phloem areas, lower xylem/phloem ratios, and higher frequencies of leaf veins. In addition to differences in the autofluorescence intensity and the morphology of the detached cell walls of the vascular bundle sheath, the three terrestrial ecotypes also exhibited anatomical differences in the outerface tangential walls of the bundle sheath and higher frequencies of pit fields in the walls in comparison to SR. The Fourier transform infrared (FTIR) microspectroscopy spectra of the vascular bundle cell walls differed greatly among the tissues of the different ecotypes as well as within different tissues within each ecotype. Histochemical methods revealed that although pectins were present in all bundle tissue cell walls, large amounts of unesterified pectin were present in the phloem cell walls, especially in the salt reed ecotypes LSMR and HSMR, and large quantities of highly methyl-esterified pectin were present in the xylem and sclerenchyma cell walls of the SR and DR ecotypes. Differences were observed in the lignification and suberization of the xylem and sclerenchyma cell walls of the four ecotypes, but the phloem and bundle sheath cell walls were generally similar. These results suggest that the adaptation of common reed, a hydrophytic species, to saline or drought-prone dunes triggers changes in the anatomical and chemical characteristics of the foliar vascular bundle tissues. These alterations, including higher percentages of bundle sheath areas and lower percentages of xylem and phloem areas and their ratios, changes in the chemical compositions and modifications of the cell walls of different vascular bundle tissues, and differences in the deposition of major cell wall components in the walls of different vascular bundle tissues, could contribute to the high resistance of reeds to extreme habitats such as saline and drought-prone dunes.     

Leaf anatomy and C4 photosynthetic enzymes in three reed ecotypes

Differences in leaf interveinal distances, chloroplasts distribution in bundle sheath cells (BSC) and activities of C₄ photosynthetic enzymes in the leaves of three ecotypes of Phragmites communis Trinius, namely swamp reed (SR), heavy salt meadow reed (HSMR) and dune reed (DR), occurring in the desert region of northwest China were investigated. The two terrestrial ecotypes, DR and HSMR, had denser vascular system, more and longer BSC chloroplasts and higher capacity of CO₂ concentrating mechanism of NAD-ME subtype as compared with the SR ecotype. The enhanced NADP-ME pathway in the HSMR might contribute to its adaptation to the salinity habitat.     

Up-regulation of glutathione metabolism and changes in redox status involved in adaptation of reed (Phragmites communis) ecotypes to drought-prone and saline habitats

The glutathione (GSH) metabolic characteristics and redox balance in three ecotypes of reed (Phragmites communis), swamp reed (SR), dune reed (DR), and heavy salt meadow reed (HSMR), from different habitats in desert regions of northwest China were investigated. The DR possessed the highest rate of GSH biosynthesis and metabolism with the lowest levels of total and reduced GSH and its biosynthetic precursors, gamma-glutamylcysteine (gamma-EC) and cysteine (Cys), of the three reed ecotypes. This suggests that a higher rate of GSH biosynthesis and metabolism, but not GSH accumulation, might be involved in the adaptation of this terrestrial reed ecotype to its dry habitat. The HSMR shared this profile although it exhibited the highest reduced thiol levels of the three ecotypes. Two key enzymes in the Calvin-cycle possessing exposed sulfhydryl groups, NADP(+)-dependent glyceraldehydes-3-phosphate dehydrogenase (G3PD) and fructose-1,6-bisphosphatase (FBPase), and other two key enzymes in the pentose-phosphate pathway (PPP), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6-PGD), had very similar activities in the three reed ecotypes. Compared to the SR, the DR and HSMR had higher ratios of NADPH/NADP+ and NADH/NAD+, indicating that a more reduced redox status in the plant cells might be involved in the survival and adaptation of the two terrestrial reed ecotypes to long-term drought and salinity, respectively. These results suggest that changes of GSH metabolism and redox balance were important components of the adaptation of reed, a hydrophilic plant, to more extreme dune and saline habitats. The coordinated up-regulations of the rate of GSH biosynthesis and metabolism and reduction state of redox status of plant cells, conferred on the plant high resistance or tolerance to long-term drought and salinity.     

Differential expression of photosynthesis-related genes of reed ecotypes in response to drought and saline habitats

Three ecotypes of reed (Phragmites communis Trinius), swamp reed (SR), dune reed (DR), and heavy salt meadow reed (HSMR), growing in desert regions of northwest China were simultaneously investigated in their natural state for gas exchange patterns and the expression of three photosynthesis-related genes, cab (the gene for the light-harvesting chlorophyll a/b binding protein, LHC), psbA (the gene for the reaction centre D1 protein of photosystem 2, PS2), and 16S rDNA (the gene for plastid 16S rRNA). Stomatal conductance (gs) and intercellular CO2 concentration (ci) were markedly lower in the two terrestrial ecotypes (DR and HSMR) as compared to SR, paralleling a similar observed depression in net photosynthetic rate (PN). However, DR with the lowest measured gs and ci still exhibited a higher PN compared to HSMR. These results suggest that both stomatal and non-stomatal factors account for the comparatively low carbon assimilation in the terrestrial ecotypes. An increase in the expression of photosynthesis-related genes was observed in DR compared to SR, whereas the reverse situation was true in HSMR. The expression of photosynthesis-related genes may contribute to reed plants' photosynthetic capacity per leaf area under natural water deficits, but the levels of photosynthesis-related gene expression are not directly correlated with reed plants' general ability for survival and adaptation under water deficient conditions.     

Comparison of Plasma Membrane H^＋-ATPase Activity in Two Ecotypes of Reed （Phragmites communis） Leaves from Different Habitats

Plasma membrane (PM) vesicles of the leaves of two ecotypes of reed (Phragrnites communis Trin.), swamp reed (SR) and heavy salt meadow reed (HSMR) growing in the desert region of Northwest China, were purified by two-phase partitioning and the properties of their PM H^ -ATPases (EC 3.6.1.35) were compared. The specific activity of this enzyme was greater in HSMR than in SR and the Km lower (1.27mmol/L in SR and 0.30mmol/L in HSMR), and the Vmax of ATP hydrolysis activity showed no significant difference between the two ecotypes. The PM H^ -ATPase was more sensitive to denaturing temperatures in HSMR than in SR, and the pH profile also showed a slight difference, suggesting that the catalytic mechanism of this enzyme was different in HSMR compared with that in SR. The p-nitrophenyl phosphate (PNPP) hydrolysis activity of H^ -ATPase was higher in HSMR than in SR at low concentrations of PNPP, but showed no difference at high PNPP concentration. The Km for PNPP hydrolysis was 3.61mmol/L and 1.92mmol/L in SR and HSMR, respectively. And the Vmax of PNPP hydrolysis showed no significant difference in the two reed ecotypes. An experiment with the inhibitor vanadate showed that the catalytic mechanisms of the phosphatase domain of the ATPase were different in the two ecotypes. The data obtained following trypsin treatment showed a difference in the enzyme activity pattern, suggesting that there existed a possible change in the C-terminus of the ATPase, either in the structure or in the property or both of them. In addition, compared with SR, the ATP-dependent H^ pumping activity of ATPase and the coupling between proton transport and ATP hydrolysis in HSMR were increased. These results indicated that the properties of PM H^ -ATPase were changed in HSMR with compared to those in SR, which might include enzyme modifications and different isoforms expressed. The alterations of the properties of this enzyme might be an adaptive response to the habitat.     

Effect of abscisic acid on heat stress tolerance in the calli from two ecotypes of <Emphasis Type="Italic">Phragmites communis</Emphasis>

Dune reed (DR) and swamp reed (SR) are two ecotypes of reed (Phragmites communis Trin.) that displayed differences in stress tolerance. To uncover the molecular basis for such difference, the effects of heat stress were studied using the calli derived from the two ecotypes. Heat stress caused increased ion leakage, inhibited growth, decreased cell viability, and elevated hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents in the calli of both ecotypes, but DR callus showed better heat tolerance than SR callus. In DR callus, heat stress caused significant increase in the endogenous ABA content but not in SR callus. Application of fluridone (an ABA synthesis inhibitor) aggravated the heat stress damages on the DR callus whereas it had only minimal impact on the SR callus. Exogenous application of ABA alleviated the heat stress symptoms in the calli of both ecotypes. ABA treatment increased the activities of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase, and also decreased H₂O₂ and MDA contents. These results indicate that the ability of ABA synthesis under heat stress is a key factor attributing to the higher heat tolerance of DR than SR.     

Comparative study on calli from two reed ecotypes under heat stress

The different physiological responses to heat stress in calli from two ecotypes of common reed (Phragmites communis Trin.) plants (dune reed (DR) and swamp reed (SR)) were studied. The relative water content, the relative growth rate, cell viability, membrane permeability (MP), H₂O₂ content, MDA content, proline level, and the activities of enzymes, such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR), and lipoxygenase (LOX) were assayed. Results showed that under heat stress, DR callus could maintain the higher relative growth rate and cell viability than SR callus, while H₂O₂ content, MDA content, and MP in SR callus increased more than in DR callus. The activities of antioxidant enzymes, such as SOD, CAT, POD, APX, and GR in two calli were enhanced by high temperature. However, antioxidant enzymes in DR callus showed the higher thermal stability than those in SR callus. LOX activity increased more in SR callus than in DR callus under heat stress. High temperature markedly elevated proline content in DR callus whereas had no effect on that in SR callus. Taken together, DR callus is more thermotolerant than SR callus, which might be due to the higher activity of antioxidant enzymes and proline level compared with SR callus under heat stress.     

Nitric oxide protects against polyethylene glycol-induced oxidative damage in two ecotypes of reed suspension cultures

Dune reed (DR) is the more tolerant ecotype of reed to environmental stresses than swamp reed (SR). Under osmotic stress mediated by polyethylene glycol (PEG-6000), the suspension culture of SR showed higher ion leakage, and more oxidative damage to the membrane lipids and proteins was observed compared with the relatively tolerant DR suspension culture. Treatment with sodium nitroprusside (SNP) can significantly alleviated PEG-induced ion leakage, thiobarbituric acid reactive substances (TBARS) and carbonyl contents increase in SR suspension culture. The levels of H(2)O(2) and O(2)(-) were reduced, and the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were increased in both suspension cultures in the presence of SNP under osmotic stress, but lipoxygenase (LOX) activity was inhibited. 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific Nitric oxide (NO) scavenger, blocked the SNP-mediated protection. Depletion of endogenous NO with PTIO strongly enhanced oxidative damage in DR compared with that of PEG treatment alone, whereas had no effect on SR. Moreover, NO production increased significantly in DR while kept stable in SR under osmotic stress. Taken together, these results suggest that PEG induced NO release in DR but not SR can effectively protect against oxidative damage and confer an increased tolerance to osmotic stress in DR suspension culture.