大气臭氧浓度升高对银杏叶片活性氧代谢及相关基因表达的影响

采用开顶式气室熏蒸法,设置自然条件下臭氧(O₃)浓度(对照,约40 nmol·mol^-1)、80、160及200 nmol·mol^-14个臭氧浓度,观测了不同浓度臭氧条件下银杏叶片可见伤害、活性氧生成量、抗氧化酶活性及相关基因表达变化情况,分析大气臭氧浓度升高对植物活性氧代谢的影响.结果表明: 160和200 nmol·mol^-1 O₃熏蒸明显伤害银杏叶片,80 nmol·mol^-1与对照无差异,无可见伤害.O₃处理20 d后,160和200 nmol·mol^-1条件下银杏叶片的超氧自由基(O₂^-·)产生速率显著高于80 nmol·mol^-1和对照,而80 nmol·mol^-1与对照无差异;O₃处理40 d后,160和200 nmol·mol^-1熏蒸下叶片过氧化氢(H₂O₂)含量显著高于80 nmol·mol^-1和对照,而过氧化氢酶(CAT)活性显著高于80 nmol·mol^-1和对照,各臭氧处理抗坏血酸过氧化物酶(APX)活性均低于对照.熏蒸40 d后,CAT、APX基因的转录表达持续加强;防御素(GbD)的表达强度则随着臭氧浓度的增加及熏蒸时间的延长而呈显著加强.高浓度臭氧胁迫可使银杏叶片活性氧生成量增加、抗氧化酶活性下降、相关基因表达水平上调,有明显可见叶片伤害.     

外源表油菜素内酯对NaHCO3胁迫下黄瓜幼苗生长及氧化还原平衡的影响

以‘津研四号’黄瓜为试材,以30 mmol·L^-1NaHCO_3模拟盐碱环境,采用水培法研究了0.2μmol·L^-1外源2,4表油菜素内酯(2,4-epibrassinolide,EBR)对盐碱胁迫下黄瓜幼苗生长和活性氧代谢的影响.结果表明:NaHCO_3胁迫显著诱导了叶片及根系中O2-·的产生和H_2O_2的积累,导致丙二醛含量和电解质渗透率提高.NaHCO_3胁迫下,超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶、脱氢抗坏血酸还原酶、单脱氢抗坏血酸还原酶、谷胱甘肽还原酶活性及还原型抗坏血酸、还原型谷胱甘肽含量随胁迫时间延长呈现先升后降的趋势.外源EBR显著提高了NaHCO_3胁迫下黄瓜叶片和根系中抗氧化酶活性、抗氧化物质的含量以及As A/DHA(双脱氢抗坏血酸)和GSH/GSSG(氧化型谷胱甘肽)比值,维持了植株内的氧化还原平衡,降低了活性氧积累水平,缓解了膜脂过氧化,从而提高了黄瓜幼苗的盐碱耐受性.     

Molecular markers for ozone stress isolated by suppression subtractive hybridization: specificity of gene expression and identification of a novel stress-regulated gene

Suppression subtractive hybridization was used to identify genes regulated by ozone (100 nmol mol ^{? 1}) in Pisum sativum. One novel gene (named PsUod1) was found. In addition, mRNA levels for four genes (encoding lipid transfer protein, pre‐hevein‐like protein, leucine‐rich repeat protein, and disease‐resistance response protein 230), which previously were shown to be regulated by biotic stress, increased. Finally, mRNA species for two genes (encoding extensin and pathogenesis‐related protein 4A), previously shown to be regulated by ozone in other species, were found to increase in abundance. The ozone‐specificity of the expression of these genes was studied by using UV‐B radiation. PsUod1 and the genes encoding extensin, leucine‐rich repeat protein, and disease‐resistance response protein 230, were differentially regulated when comparing ozone and UV‐B. Moreover, the mRNA levels for extensin, leucine‐rich repeat protein and disease‐resistance response protein 230 all increased under NaCl and aluminium stress and after wounding, whereas the message abundance for PsUod1 was unchanged under these stresses. Thus, in general, ozone caused changes similar to wounding, salt stress and aluminium stress, whereas UV‐B radiation regulated gene expression differently.     

外源表油菜素内酯对NaHCO3胁迫下黄瓜幼苗生长及氧化还原平衡的影响

以‘津研四号’黄瓜为试材,以30 mmol·L^-1 NaHCO₃模拟盐碱环境,采用水培法研究了0.2 μmol·L^-1外源2,4表油菜素内酯(2,4-epibrassinolide,EBR)对盐碱胁迫下黄瓜幼苗生长和活性氧代谢的影响.结果表明: NaHCO₃胁迫显著诱导了叶片及根系中O₂^-·的产生和H₂O₂的积累,导致丙二醛含量和电解质渗透率提高.NaHCO₃胁迫下,超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶、脱氢抗坏血酸还原酶、单脱氢抗坏血酸还原酶、谷胱甘肽还原酶活性及还原型抗坏血酸、还原型谷胱甘肽含量随胁迫时间延长呈现先升后降的趋势.外源EBR显著提高了NaHCO₃胁迫下黄瓜叶片和根系中抗氧化酶活性、抗氧化物质的含量以及AsA/DHA(双脱氢抗坏血酸)和GSH/GSSG(氧化型谷胱甘肽)比值,维持了植株内的氧化还原平衡,降低了活性氧积累水平,缓解了膜脂过氧化,从而提高了黄瓜幼苗的盐碱耐受性.     

Impact of chloroplastic- and extracellular-sourced ROS on high light-responsive gene expression in Arabidopsis

The expression of 28 high light (HL)-responsive genes of Arabidopsiswas analysed in response to environmental and physiologicalfactors known to influence the expression of the HL-responsivegene, ASCORBATE PEROXIDASE2 (APX2). Most (81%) of the HL-responsivegenes, including APX2, required photosynthetic electron transportfor their expression, and were responsive to abscisic acid (ABA;68%), strengthening the impression that these two signals arecrucial in the expression of HL-responsive genes. Further, fromthe use of mutants altered in reactive oxygen species (ROS)metabolism, it was shown that 61% of these genes, includingAPX2, may be responsive to chloroplast-sourced ROS. In contrast,apoplastic/plasma membrane-sourced H₂O₂, in part directed bythe respiratory burst NADPH oxidases AtrbohD and AtrbohF, wasshown to be important only for APX2 expression. APX2 expressionin leaves is limited to bundle sheath parenchyma; however, forthe other genes in this study, information on their tissue specificityof expression is sparse. An analysis of expression in petioles,enriched for bundle sheath tissue compared with distal leafblade, in HL and control leaves showed that 25% of them had>10-fold higher expression in the petiole than in the leafblade. However, this did not mean that these petiole expressiongenes followed a pattern of regulation observed for APX2. Key words: Arabidopsis, chloroplast, excess light, gene expression, plasma membrane, reactive oxygen species, signalling     

Effects of H2O2 on the growth, secretion, and metabolism of hybridoma cells in culture

Summary The effect of low concentrations of hydrogen peroxide (H₂O₂) (5 × 10⁻⁷−9.5 × 10⁻⁷ M) on cell growth and antibody production was investigated with murine hybridoma cells (Mark 3 and anti-hPL) in culture. Cell growth, measured by flow cytometry with morphological parameters, was significantly stimulated by H₂O₂ (8 × 10⁻⁷ M) but H₂O₂ concentration of 7 × 10⁻⁶ M and above increased cell death. H₂O₂ stimulation of antibody production was nonsignificant. The metabolism of cells treated with 8 × 10⁻⁷ or 1 × 10⁻⁵ M H₂O₂ was similar to that of the control in terms of glucose and glutamine consumption, lactate and ammonia production, and amino acid concentrations in the medium. The concentrations of lactate dehydrogenase, a marker of cell death, in test and control cells were similar. However, concentrations of intracellular free radicals measured by flow cytometry with dihydrorhodamine 123 (DHR 123) and dichlorofluorescein diacetate (DCFH-DA) as fluorochromes were different. The reactive oxygen species content of cells in 8 × 10⁻⁷ M H₂O₂ was similar to that of the controls, but there was a sudden, marked production of superoxide anions (detected with DHR 123) and H₂O₂ or peroxides (detected with DCFH-DA) by cells incubated with 1 × 10⁻⁵ M H₂O₂ which increased with increasing H₂O₂ until cell death.     

盐胁迫下外源Ca2+对花生生长发育、生理及产量的影响

以‘花育22’为试验材料,使用外源钙[0、6、12 mmol·L^-1的Ca(NO₃)₂]处理盐胁迫(100 mmol·L^-1 NaCl)及正常条件下生长的花生,以盆栽方式研究了不同Ca²⁺浓度处理对盐胁迫条件下花生整个生育期的相关生理与产量指标的影响.结果表明: 在100 mmol·L^-1 NaCl条件下,施加不同浓度外源钙均可提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性以及叶绿素含量,降低丙二醛(MDA)含量和电解质外渗,增加根系活力,改善植株的农艺性状,增加生物积累量,最终提高花生产量,并且12 mmol·L^-1 Ca²⁺处理的效果最显著.通过增强活性氧的清除能力、维持细胞膜的稳定性以及完整性,是外源钙有效缓解花生植株的盐胁迫伤害并最终提高荚果产量的重要原因.     

Effects of nitrogen on the activity of antioxidant enzymes and gene expression in leaves of Populus plants subjected to cadmium stress

The research aimed to verify the important physiological effect of nitrogen (N) on plants exposed to cadmium (Cd). The poplar plants were grown in a Hoagland nutrient solution and treated with extra N, Cd, and N + Cd. After treatment, plant growth and chlorophyll content were recorded. The oxidative stress, the activity of antioxidant enzymes, and the expression of related genes were also examined. The results indicated the plants treated with sole Cd presented obvious toxicity symptoms, i.e. growth inhibition, reactive oxygen species accumulation, and chlorophyll content decrement. However, when N was added to the plants under Cd stress, plant growth was enhanced, chlorophyll synthesis was promoted, and the oxidative stress was alleviated. Further, the expression of antioxidant enzymes genes was upregulated by N. The results indicated that N partially reversed the toxic effect of Cd on poplar plants, which can provide new methodology to enhance the phytoremediation technology for heavy metal pollution soil.     

不同时期喷施NaHS对盐碱胁迫下裸燕麦H2S产生和活性氧代谢的影响

为了解气体信号硫化氢（H₂S）对盐碱胁迫下裸燕麦（Avena nuda）活性氧（ROS）代谢的调节效应,筛选和确定H₂S最佳的施用时期和适宜浓度。采用盆栽土培试验,研究了在裸燕麦不同时期（幼苗期、拔节期、抽穗期、开花期和灌浆期）喷施0、25、50、100、200、400 μmol·L^-1 H₂S供体硫氢化钠（NaHS）对3.0 g·kg^-1盐碱混合 （NaCl∶Na₂SO₄∶NaHCO₃∶Na₂CO₃摩尔比为12∶8∶9∶1）胁迫下裸燕麦叶片H₂S含量、H₂S生成关键酶L-半胱氨酸脱巯基酶（LCD）活性和ROS代谢相关物质含量和酶活性的影响。结果表明：喷施时期和NaHS浓度及其交互作用对盐碱胁迫下裸燕麦叶片中H₂S、超氧阴离子（）、过氧化氢（H₂O₂）、丙二醛（MDA）、抗坏血酸（AsA）和谷胱甘肽（GSH）含量及LCD、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）、抗坏血酸过氧化物酶（APX）和谷胱甘肽还原酶（GR）活性存在显著影响。与喷施0 μmol?L^-1 NaHS相比,喷施一定浓度NaHS能够提高H₂S、AsA、GSH含量和LCD、SOD、CAT、POD、APX和GR活性,减少、H₂O₂和MDA积累,但以上各指标最佳的喷施时期和NaHS浓度存在差异。隶属函数综合分析显示,在幼苗期和拔节期喷施25~200 μmol?L^-1 NaHS的综合评价值（D）最高,表明在幼苗—拔节期喷施25~200 μmol?L^-1 NaHS能更好提高ROS清除能力,从而缓解盐碱胁迫诱导ROS对裸燕麦的氧化伤害。     

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.     

CO2加富对盐胁迫下黄瓜幼苗叶片光合特性及活性氧代谢的影响

以‘津优35号’黄瓜(Cucumis sativus L.)水培苗为试材,采用裂区设计,主区因素为CO_2浓度处理,设大气CO_2浓度(Symbol{B@400μmol/mol)和CO_2加富[(800±40)μmol/mol]2个CO_2浓度水平,裂区因素为盐胁迫处理,用NaCl模拟盐胁迫,设对照(0 mmol/L NaCl)、盐胁迫(80 mmol/L NaCl)2个盐分水平,研究了CO_2加富对盐胁迫下黄瓜幼苗生长、光合特性及活性氧代谢的影响。结果表明:盐胁迫显著抑制黄瓜幼苗的生长,并降低了叶绿素含量、ETR、Φ_(PSII)、核酮糖-1,5-二磷酸羧化酶(RuBPCase)活性及净光合速率;盐胁迫增加了丙二醛及活性氧的累积,与此同时也提高了脯氨酸含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性,但降低了过氧化物酶(POD)活性。CO_2加富显著提高了盐胁迫下黄瓜幼苗的株高、茎粗、叶面积及地上部鲜重,降低了叶绿素a、叶绿素b、类胡萝卜素及叶绿素(a+b)含量,但显著提高了净光合速率和RuBPCase活性,同时降低了气孔导度及蒸腾速率,并且使其具有较高的表观电子传递速率及PSII实际光化学效率;CO_2加富显著提高了盐胁迫下黄瓜幼苗叶片脯氨酸含量及SOD、POD、CAT活性,丙二醛、过氧化氢含量和超氧阴离子产生速率显著降低。综上所述,CO_2加富可通过提高幼苗叶片净光合速率、脯氨酸含量及抗氧化酶活性,降低蒸腾速率、减少丙二醛含量及活性氧的积累,从而缓解盐胁迫对黄瓜植株造成的伤害。