拟南芥CEO1基因在氯化镉诱导的氧化胁迫中的作用

以拟南芥ceo1、突变体为材料,研究CEO1（clone eight-one）在镉胁迫条件下作用的结果表明,与野生型植株相比,150μmol·L^-1的CdCl2处理10d后,拟南芥ceo1突变体表现为植株生长矮小,叶片卷曲发黄,根系短小。镉处理后,拟南芥突变体幼苗叶中H2O2的积累较多;镉处理1h后的突变体中抗坏血酸过氧化物酶（APX）活性明显上升,至2h时又开始下降,而镉处理2h后,野生型APX活性才开始增加。镉处理2h后的野生型的谷胱甘肽还原酶（GR）显著增加,而突变体无明显变化。两种类型拟南芥的超氧化物歧化酶（SOD）与过氧化氢酶（CAT）的活性没有明显差异。     

H2O2和ABA对干旱高温复合胁迫诱导的玉米叶片sHSPs表达的影响

以玉米脱落酸(ABA)缺失突变体vp5及其野生型Vp5的叶片为材料,分别采用ABA、碘化钾(H2O2清除剂)、钨酸钠(ABA抑制剂)预先处理,对干旱+高温复合胁迫下玉米叶片小热休克蛋白(sHSPs)基因表达进行研究,以确定H2O2和ABA对干旱+高温复合胁迫诱导的玉米叶片sHSPs基因表达的影响。结果显示:(1)与对照和干旱相比,高温、干旱+高温复合胁迫显著诱导了sHSP16.9、sHSP17.2、sHSP17.4、sHSP17.5、sHSP22和sHSP26等6种sHSPs的表达。(2)H2O2清除剂KI和ABA抑制剂钨酸钠预处理,仅略微抑制高温、干旱+高温复合胁迫诱导的6种sHSPs表达。(3)与未用100μmol/L ABA预处理的vp5相比,100μmol/L ABA预处理仅略微提高了高温、干旱+高温复合胁迫诱导的6种sHSPs的表达水平。研究表明,在干旱+高温复合胁迫条件下H2O2和ABA参与了干旱+高温复合胁迫诱导的玉米叶片sHSPs表达,但并无显著影响,暗示了H2O2和ABA不是干旱+高温复合胁迫诱导sHSPs表达的重要调控因子。     

干旱高温胁迫下转基因水稻的生理变化

用PEG-6000、38℃及PEG-6000+38℃胁迫处理携带谷胱甘肽转移酶(GST)和过氧化氢酶(CAT1)的转基因水稻和非转基因水稻(Oryza sativa L.cv中花11), 并比较分析了二者在胁迫下的生理指标和抗氧化酶活性变化.结果显示,在单一PEG及PEG和高温复合胁迫下,植株生长、光合参数和相对含水量的降低幅度及H2O2和MDA(malon dialdehyde)的积累量在非转基因水稻与转基因水稻之间都有显著差异.在这2种胁迫下,转基因水稻的可溶性糖含量及CAT和POD (Peroxidase) 活性与非转基因水稻也有显著差异.这些结果表明,谷胱甘肽转移酶(GST)和过氧化氢酶(CAT1)的表达减轻了转基因水稻在单一干旱及干旱+高温复合胁迫下的伤害.     

油桃花芽破眠过程中H2O2代谢与Ca2+转运的关系

利用化学测定法分析高温、单氰胺和TDZ 3种破眠处理对"曙光"油桃休眠花芽H2O2代谢的主要影响,利用非损伤微测技术检测H2O2对休眠芽Ca2+转运的影响,研究H2O2在芽休眠解除过程中的调控作用.结果表明:在深休眠时期,高温和单氰胺处理均能诱导芽内H2O2含量升高和过氧化氢酶(CAT)活性降低,并具有显著的破眠作用;TDZ对H2O2含量及CAT、过氧化物酶(POD)活性影响不大,破眠效果较差.休眠花芽原基组织钙通道活跃,对外源Ca2+呈吸收状态.外源H2O2可诱导休眠花芽原基组织Ca2+转运发生变化,低浓度H2O2降低Ca2+吸收速率,高浓度H2O2使组织对Ca2+的转运由吸收转变为释放.这表明休眠芽内H2O2信号和Ca2+信号相关联,通过诱导H2O2积累调控Ca2+信号可能在高温和单氰胺打破休眠的信号转导过程中起重要作用.     

镉胁迫对萝卜幼苗活性氧产生、脂质过氧化和抗氧化酶活性的影响

镉胁迫使萝卜幼苗超氧阴离子(O2)、过氧化氢(H2O2)和丙二醛(MDA)含量增加;随着镉浓度提高,超氧化物歧化酶(SOD)活性首先明显上升,然后逐渐下降,甚至低于对照;叶片过氧化氢酶(CAT)活性明显增加,根系CAT活性则减少;根系以及较高浓度镉处理后期叶片的谷胱甘肽还原酶(GR)活性均显著增加.由此推测:在胁迫初期可能主要由SOD和CAT发挥抗氧化作用,而在胁迫后期由于抗坏血酸-谷胱甘肽(AsA-GsH)循环途径的激活,还原型谷胱甘肽和植物络合素含量的提高可能在清除活性氧或者直接螯合镉中起作用.     

转GST和CAT1基因水稻根系抗氧化系统对干旱高温胁迫的响应(英文)

以携带谷胱甘肽转移酶(GST)和过氧化氢酶(CAT1)的转基因水稻和非转基因水稻(Oryza sativa L.) 品种'中花11'的根系为材料, 比较分析了二者在PEG 6000、38℃及PEG 6000和38℃复合胁迫下抗氧化系统特别是抗坏血酸-谷胱甘肽循环系统的变化.结果显示, 6% PEG处理时,转基因水稻的CAT、GST、超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)和脱氢抗坏血酸还原酶(DHAR)的活性都显著高于非转基因水稻;38℃处理时,前者的CAT、GST、SOD和GR的活性则显著低于后者;6% PEG和38℃复合处理时,前者的CAT、GST、抗坏血酸过氧化物酶(APX)和DHAR的活性也都显著高于后者,但前者的SOD和GR活性则显著低于后者.6%PEG 诱导的转基因水稻根系的抗坏血酸氧还状态显著低于非转基因水稻,但二者的谷胱甘肽氧还状态无显著差异; 而6% PEG和38℃同时处理时,转基因水稻的谷胱甘肽氧还状态则显著高于非转基因水稻,但二者的抗坏血酸氧还状态差异不显著.研究发现,干旱和高温复合胁迫时,转基因水稻和非转基因水稻的抗氧化组分的变化均不等于这2种单一胁迫的叠加;GST和CAT1基因的转入对水稻抗氧化系统内源功能相关组分尤其是抗坏血酸-谷胱甘肽循环系统产生了一定的影响,两种水稻的根系可能利用不同的抗氧化组分调节机制对这些胁迫做出应答.     

逆境胁迫对油菜谷胱甘肽还原酶基因表达及其酶活性的影响

利用cDNA末端快速分离(RACE)技术从陇油6号油菜中克隆得到一个新的谷胱甘肽还原酶基因GR2,全长2073 bp,开放阅读框1692 bp,编码563个氨基酸,预测蛋白质分子量为60.7 kDa,等电点7.9.实时荧光定量PCR分析表明:GR2基因在油菜根、茎、叶中均有表达,其中在叶中表达量最高.GR1和GR2基因的转录以及谷胱甘肽还原酶(GR)活性受到低温、高温、干旱、高盐胁迫的诱导,表明油菜谷胱甘肽还原酶在抵御低温、高温、干旱、高盐胁迫过程中发挥重要作用.脱落酸(ABA)预处理后再进行上述胁迫处理,与单独上述胁迫相比,GR1和GR2基因的转录以及GR活性水平明显上升,表明ABA可以诱导GR1和GR2基因表达和GR酶活性.MAPKK抑制剂U0126预处理后再进行上述胁迫处理,与单独上述胁迫相比,GR1和GR2基因的转录以及GR活性水平明显下降,表明U0126对GR1、GR2基因表达以及GR酶活性有抑制作用.     

外源γ-氨基丁酸对低氧胁迫下甜瓜幼苗活性氧代谢的影响

以甜瓜品种‘西域一号’幼苗为材料,采用营养液水培方法,设置正常通气(对照)、正常通气+GABA(5mmol.L-1)、低氧胁迫、低氧胁迫+GABA(5mmol.L-1)4个处理,研究了外源γ-氨基丁酸(GABA)对正常通气和低氧胁迫下甜瓜幼苗活性氧代谢的影响。结果表明:与正常通气处理相比,低氧胁迫处理导致甜瓜幼苗体内O2.-产生速率和H2O2、MDA含量显著增加,同时SOD、POD、CAT、APX、GR等抗氧化酶活性和抗氧化物质AsA、GSH含量显著提高。低氧胁迫下外源GABA能显著提高甜瓜幼苗叶片SOD、CAT、APX、GR等酶活性和AsA、GSH含量,降低了植株体内O2.-产生速率和H2O2、MDA含量;而正常通气条件下添加外源GABA处理对甜瓜幼苗活性氧代谢的影响较小,仅CAT、GR活性和AsA、GSH含量显著提高,而H2O2、MDA含量显著降低。结果证明,添加外源GABA可以通过显著提高低氧胁迫下抗氧化酶活性和抗氧化物质含量来降低甜瓜幼苗活性氧积累,维持其细胞膜结构稳定性,从而有效减轻低氧胁迫对甜瓜幼苗的伤害。     

外源H2O2对盐胁迫下小麦幼苗生理指标的影响

以‘郑麦-004’小麦幼苗为供试材料,采用Hoagland营养液培养方法,通过添加H2O2的清除剂过氧化氢酶(CAT)和抗坏血酸(ASA),研究0.05μmol/L外源H2O2处理对150mmol/L NaCl胁迫下小麦幼苗生长和抗氧化系统活性的影响,探讨低浓度外源H2O2对盐胁迫下小麦幼苗伤害的防护作用及其生理机制。结果显示:外源H2O2能缓解盐胁迫对小麦幼苗生长的抑制效应,降低丙二醛(MDA)含量和超氧自由基(O2.-)的产生速率,使小麦幼苗的株高、根长和干重均显著增加,并能提高超氧化物歧化酶(SOD)、过氧化物酶(POD)、CAT、抗坏血酸氧化酶(APX)等保护酶活性和抗氧化物质谷胱甘肽(GSH)的含量;而H2O2清除剂(CAT和AsA)能够逆转外源H2O2对盐胁迫下小麦幼苗生长的促进作用。研究表明,低浓度外源H2O2处理能促进小麦幼苗中的酶类和非酶类抗氧化剂的产生,减少脂质过氧化物的含量,提高小麦幼苗的耐盐性。     

水分胁迫下苹果叶片的H2O2代谢

轻度水分胁迫下苹果叶片Pr迅速升高,CAT活性变化不大,NaHSO3处理能显著降低叶内H2O2含量,表明光呼吸的加强促进了H2O2产生可能是叶内H2O2大量积累的主要原因;中度水分胁迫下叶片AsA含量的下降和Mehler反应的增强都非常明显,DDTC和AsA处理都能有效降低叶内H2O2积累,但MV处理的作用不大,说明叶片H2O2主要来源于Mehler反应,AsA降解造成叶片对H2O2清除能力的下降是其积累的根本原因;严重水分胁迫时,NaHSO3和DDTC都不能有效地减轻叶内H2O2积累,光呼吸和Mehler反应都可能不是H2O2的主要来源。     

Time‐course analysis of salicylic acid effects on ROS regulation and antioxidant defense in roots of hulled and hulless barley under combined stress of drought,heat and salinity

Greater crop losses can result from simultaneous exposure to a combination of drought, heat and salinity in the field. Salicylic acid (SA), a phenolic phytohormone, can affect a range of physiological and biochemical processes in plants and significantly impacts their resistance to these abiotic stresses. Despite numerous reports involving the positive effects of SA by applying each abiotic stress separately, the mechanism of SA‐mediated adaptation to combined stresses remains elusive. This study, via a time‐course analysis, investigated the role of SA on the roots of hulled and hulless (naked) barley (Hordeum vulgare L. ‘Tarm’ and ‘Özen’, respectively), which differed in salt tolerance, under the combined stress of drought, heat and salt. The combined stress caused marked reductions in root length and increases in proline content in both genotypes; however, Tarm exhibited better adaptation to the triple stress. Under the first 24 h of stress, superoxide dismutase (SOD; EC.1.15.1.1) and peroxidase (POX; EC.1.11.1.7) activity in the Tarm roots increased remarkably, while decreasing in the Özen roots. Furthermore, the Tarm roots showed higher catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11) and glutathione reductase (GR; EC 1.6.4.2) activity than the Özen during the combined stresses. The sensitivity of hulless barley roots may be related to decreasing SOD, POX, CAT and GR activity under stress. Over 72 h of stress, the SA pretreatment improved the APX and GR activity in Tarm and that of POX and CAT in Özen, demonstrating that exogenously applied SA regulates antioxidant defense enzymes in order to detoxify reactive oxygen species. The results of this study suggest that SA treatment may improve the triple‐stress combination tolerance in hulled and hulless barley cultivars by increasing the level of antioxidant enzyme activity and promoting the accumulation of proline. Thus, SA alleviated the damaging effects of the triple stress by improving the antioxidant system, although these effects differed depending on characteristic of the hull of the grain.     

Nickel elicits a fast antioxidant response in Coffea arabica cells.

The antioxidant responses of coffee (Coffea arabica L.) cell suspension cultures to nickel (Ni) were investigated. Ni was very rapidly accumulated in the cells and the accumulation could be directly correlated with the increase of NiCl(2) concentration in the medium. At 0.05 mM NiCl(2) growth was stimulated, but at 0.5 mM NiCl(2), the growth rate was reduced. An indication of alterations in the presence of reactive oxygen species was detected by an increase in lipid peroxidation at 0.5 mM NiCl(2). Catalase (CAT; EC 1.11.1.6), glutathione reductase (GR; EC 1.6.4.2), ascorbate peroxidase (APX; EC 1.11.1.11), guaiacol peroxidase (GOPX; EC 1.11.1.7) and superoxide dismutase (SOD; EC 1.15.1.1) activities were increased, particularly at earlier NiCl(2) exposure times and the activities were higher at 0.5 mM NiCl(2) for most of exposure times tested. Non-denaturing PAGE revealed one CAT isoenzyme, nine SOD isoenzymes and four GR isoenzymes. The SOD isoenzymes were differentially affected by NiCl(2) treatment and one GR isoenzyme was increased by NiCl(2). NiCl(2) at 0.05 mM did not induce lipid peroxidation and the main response appeared to be via the induction of SOD, CAT, GOPX and APX activities for the removal of the reactive oxygen species and through the induction of GR to ensure the availability of reduced glutathione.     

Abscisic acid-regulated responses of aba2-1 under osmotic stress: the abscisic acid-inducible antioxidant defence system and reactive oxygen species production

We investigated the interaction among abscisic acid (ABA), reactive oxygen species (ROS) and antioxidant defence system in the transduction of osmotic stress signalling using Arabidopsis thaliana WT (Columbia ecotype, WT) and an ABA-deficient mutant (aba2-1). For this, 50 μm ABA and osmotic stress, induced with 40% (w/v) polyethylene glycol (PEG8000; -0.7 MPa), were applied to WT and aba2-1 for 6, 12 or 24 h. Time course analysis was undertaken for determination of total/isoenzyme activity of the antioxidant enzymes, superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11), NADPH oxidase (NOX; EC 1.6.3.1) activity; scavenging activity of the hydroxyl radical (OH˙), hydrogen peroxide (H(2) O(2) ); endogenous ABA and malondialdehyde (MDA). The highest H(2) O(2) and MDA content was found in PEG-treated groups of both genotypes, but with more in aba2-1. ABA treatment under stress reduced the accumulation of H(2) O(2) and MDA, while it promoted activity of SOD, CAT and APX. APX activity was higher than CAT activity in ABA-treated WT and aba2-1, indicating a protective role of APX rather than CAT during osmotic stress-induced oxidative damage. Treatment with ABA also significantly induced increased NOX activity. Oxidative damage was lower in ABA-treated seedlings of both genotypes, which was associated with greater activity of SOD (Mn-SOD1 and 2 and Fe-SOD isoenzymes), CAT and APX in these seedlings after 24 h of stress. These results suggest that osmotic stress effects were overcome by ABA treatment because of increased SOD, CAT, APX and NOX.     

Involvement of hydrogen peroxide in heat shock- and cadmium-induced expression of ascorbate peroxidase and glutathione reductase in leaves of rice seedlings

Hydrogen peroxide (H2O2) is considered a signal molecule inducing cellular stress. Both heat shock (HS) and Cd can increase H2O2 content. We investigated the involvement of H2O2 in HS- and Cd-mediated changes in the expression of ascorbate peroxidase (APX) and glutathione reductase (GR) in leaves of rice seedlings. HS treatment increased the content of H2O2 before it increased activities of APX and GR in rice leaves. Moreover, HS-induced H2O2 production and APX and GR activities could be counteracted by the NADPH oxidase inhibitors dipehenylene iodonium (DPI) and imidazole (IMD). HS-induced OsAPX2 gene expression was associated with HS-induced APX activity but was not regulated by H2O2. Cd-increased H2O2 content and APX and GR activities were lower with than without HS. Cd did not increase the expression of OsAPX and OsGR without HS treatment. Cd increased H2O2 content by Cd before it increased APX and GR activities without HS. Treatment with DPI and IMD effectively inhibited Cd-induced H2O2 production and APX and GR activities. Moreover, the effects of DPI and IMD could be rescued with H2O2 treatment. H2O2 may be involved in the regulation of HS- and Cd-increased APX and GR activities in leaves of rice seedlings.     

镉诱导的菊芋幼苗膜脂过氧化和抗氧化酶活性及过氧化物酶同工酶的改变

用含有不同浓度(0~400μmol/L)Cd(NO3)2的Hoagland营养液处理砂培的菊芋。处理50d后,测定植物体内镉积累量以及过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性,并对POD同工酶进行电泳分析。发现在Cd50~100μmol/L浓度内,随着镉浓度的升高,菊芋根和叶中镉的积累量显著增加,而随后积累量的增加有所减少。根和叶中MDA含量显著上升,说明镉引起了膜脂过氧化。0~100μmol/LCd处理,根和叶中POD活性随Cd浓度增加而增强,而在200~400μmol/LCd处理下有所减弱。根和叶SOD活性在50~200μmol/LCd处理下随Cd浓度增加而增强,而在400μmol/LCd处理下SOD活性明显受到抑制。根和叶CAT活性随Cd浓度升高而增强。电泳结果显示,POD同工酶变化明显,镉诱导出一条新酶带LP10。菊芋POD同工酶可以作为镉污染的土壤的生物指示剂。