Nitric oxide and reactive oxygen species are two important signal molecules that play key roles in plant defense responses. Nitric oxide generation and oxidative burst and accumulation of reactive oxygen species are t...Nitric oxide and reactive oxygen species are two important signal molecules that play key roles in plant defense responses. Nitric oxide generation and oxidative burst and accumulation of reactive oxygen species are the early reactions of Taxus chinensis suspension cells to fungal elicitor prepared from the cell walls of Penicillium citrinum. In order to investigate the relationship and/or interactions of ni- tric oxide and reactive oxygen species in the elici- tor-induced Taxol biosynthesis of T. chinensis sus- pension cells, we treated the cells with nitric oxide specific scavenger 2-4-carboxyphenyl-4,4,5,5-tetra- methylimidazoline-1-oxyl-3-oxide (cPITO), nitric ox- ide synthase inhibitor S,S′-1,3-phenylene-bis(1,2-eth- anediyl)-bis-isothiourea (PBITU), membrane NAD(P) H oxidase inhibitor diphenylene iodonium (DPI), su- peroxide dismutases (SOD) and catalase. The results show that pretreatment of T. chinensis cells with cPITO and DPI inhibited not only the elicitor-induced nitric oxide biosynthesis and oxidative burst, but also the elicitor-induced Taxol production, suggesting that both nitric oxide and reactive oxygen species are involved in elicitor-induced Taxol biosynthesis. Fur- thermore, pretreatment of the cells with cPITO and PBITU suppressed the elicitor-induced oxidative burst, indicating that the oxidative burst might be dependent on NO. Application of nitric oxide via its donor sodium nitroprusside (SNP) triggered Taxol biosynthesis of T. chinensis cells. The nitric ox-ide-induced Taxol production was suppressed by DPI, showing that the oxidative burst is involved in NO-triggered Taxol biosynthesis. However, nitric ox- ide and the fungal elicitor induced Taxol biosynthesis even though the accumulation of reactive oxygen species wass completely abolished in T. chinensis cells. Our data show that nitric oxide may mediate the elicitor-induced Taxol biosynthesis of T. chinensis suspension cells through both reactive oxygen spe- cies-dependent and -independent signal pathways. Moreover, the results of 展开更多
A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaC...A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaCl3 and CdCl3 ） were added to tobacco （ Nicotiana tabacum） cell suspension culture. Addition of superoxide dismutase （480 U·ml^-1） and Tiron （5 μmol·L^-1） to cell culture suspension decreases the level of lanthanide cation-induced ·O2^- generation, suggesting that ·O2^- generation is extra-cellular. Pretreatment of the cell culture suspension with diphenyleneiodonium （10 and 50 μmol·L^-1 ）, quinacrine （ 1 and 5 mmol· L^-1 ） and imidazol （ 10 mmol· L^-1 ）, inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase. In addition, addition of SHAM （1 and 5 mmol· L^-1）, azide （0.2 and 1 mmol· L^-1 ）, inhibitor of peroxidase, has no influence on ·O2^- generation.展开更多
Sphinganine or dihydrosphingosine （d18：0, DHS）, one of the most abundant free sphingoid Long Chain Base （LCB） in plants, has been recently shown to induce both cytosolic and nuclear calcium transient increases an...Sphinganine or dihydrosphingosine （d18：0, DHS）, one of the most abundant free sphingoid Long Chain Base （LCB） in plants, has been recently shown to induce both cytosolic and nuclear calcium transient increases and a correlated Programmed Cell Death （PCD） in tobacco BY-2 cells. In this study, in order to get deeper insight into the LCB signaling pathway leading to cell death, the putative role of Reactive Oxygen Species （ROS） has been investigated. We show that DHS triggers a rapid dose-dependent production of H2O2 that is blocked by diphenyleniodonium （DPI）, indicating the involvement of NADPH oxidase（s） in the process. In addition, while DPI does not block DHS-induced calcium increases, the ROS production is inhibited by the broad spectrum calcium channel blocker lanthanum （La^3＋）. Therefore, ROS production occurs downstream of DHS-induced Ca^2＋ transients. Interestingly, DHS activates expression of defense-related genes that is inhibited by both La^3＋ and DPI. Since DPI does not prevent DHS-induced cell death, these results strongly indicate that DHS-induced H2O2 production is not implicated in PCD mechanisms but rather would be associated to basal cell defense mechanisms.展开更多
Rhizobia interact with host legumes to induce the formation of nitrogen-fixing nodules,which is very important in agriculture and ecology.The development of nitrogen-fixing nodules is stringently regulated by host pla...Rhizobia interact with host legumes to induce the formation of nitrogen-fixing nodules,which is very important in agriculture and ecology.The development of nitrogen-fixing nodules is stringently regulated by host plants and rhizobial symbionts.In our previous work,a new Sinorhizobium meliloti LysR regulator gene(lsrB)was identified to be essential for alfalfa nodulation.However,how this gene is involved in alfalfa nodulation was not yet understood.Here,we found that this gene was associated with prevention of premature nodule senescence and abortive bacteroid formation.Heterogeneous deficient alfalfa root nodules were induced by the in-frame deletion mutant of lsrB(lsrB1-2),which was similar to the plasmid-insertion mutant,lsrB1.Irregular senescence zones earlier appeared in these nodules where bacteroid differentiation was blocked at different stages from microscopy observations.Interestingly,oxidative bursts were observed in these nodules by DAB staining.The decreased expression of lipopolysaccharide core genes(lpsCDE)was correspondingly determined in these nodules.S.meliloti lipopolysaccharide is required for suppression of oxidative bursts or host cell defense.These findings demonstrate that the S.meliloti lsrB gene is involved in alfalfa root nodule development and bacteroid differentiation by suppressing oxidative bursts or defense responses in host cells.展开更多
Objective:To evaluate in vitro immunomodulating properties and potential cytotoxicity of six tropical medicinal herbs and food plants namely Antidesma madagascariense(Euphorbiaceae) (AM),Erylhroxylum macrocarpum(Eryth...Objective:To evaluate in vitro immunomodulating properties and potential cytotoxicity of six tropical medicinal herbs and food plants namely Antidesma madagascariense(Euphorbiaceae) (AM),Erylhroxylum macrocarpum(Erythroxylaceae)(EM),Faujasiopsis flexuosa(Asteraceae) (FF),Pittosporum senacia(Pittosporaceae)(PS),Momordica charantia(Cucurbitaceae)(MC) and Orimum tenuiflorum(Lamiaceae)(Of).Methods:Initially,the crude water and methanol extracts were probed for their capacity to trigger immune cells’ NADPH oxidase and MPO-dependent activities as measured by lucigenin- and luminol-amplified chemiluminescence,respectively; as compared to receptor-dependent(serum opsonised zymosan- OPZ) or receptor-independent phorbol myristerate acetate(PMA).Results:Preliminary screening on whole human blood oxidative buret activity showed significant and concentration-dependent immunomodulating properties of three plants AM,FF and OT.Further investigations of the fractions on isolated human polymorphonuclear cells(PMNs) and mice monocytes using two different pathways for activation of phagocytic oxidative burst showed that ethyl acetate fraction was the most potent extract. None of the active samples had cell-death effects on human PMNs,under the assay conditions as determined by the trypan-blue exclusion assay.Since PMA and OPZ NADPH oxidase complex is activated via different transduction pathways,these results suggest that AM,FF and OT does not affect a specific transductional pathway,but rather directly inhibit a final common biochemical target such as the NADPH oxidase enzyme and/or scavenges ROS.Conclusions:Our findings suggest that some of these plants extracts/fractions were able to modulate significantly immune response of phagocytes and monocytes at different steps,emphasizing their potential as a source of new natural alternative immunomodulatory agents.展开更多
激发植物本身的天然免疫系统可作为防控植物病害的新途径。以50株分离自繁茂膜海绵的真菌为受试菌株筛选具有诱导植物抗性活性的菌株及其代谢产物。采用基于H2DCF-DA的荧光酶标法考察这些真菌的粗代谢物诱导烟草悬浮细胞产生氧爆发的活...激发植物本身的天然免疫系统可作为防控植物病害的新途径。以50株分离自繁茂膜海绵的真菌为受试菌株筛选具有诱导植物抗性活性的菌株及其代谢产物。采用基于H2DCF-DA的荧光酶标法考察这些真菌的粗代谢物诱导烟草悬浮细胞产生氧爆发的活性,最终筛选到一株真菌HMP-F66能够显著诱导烟草悬浮细胞产生活性氧。根据其形态学特征、培养特征、特征性生理生化反应以及基于r DNA ITS的分子生物学分析,推测该菌株为米曲霉(Aspergillus oryzae)。展开更多
基金This work was supported by the Natural National Science Foundation of China （Grant No. 30572331） the Natural Science Foundation of Zhejiang Province （Grant No. 302785）.
文摘Nitric oxide and reactive oxygen species are two important signal molecules that play key roles in plant defense responses. Nitric oxide generation and oxidative burst and accumulation of reactive oxygen species are the early reactions of Taxus chinensis suspension cells to fungal elicitor prepared from the cell walls of Penicillium citrinum. In order to investigate the relationship and/or interactions of ni- tric oxide and reactive oxygen species in the elici- tor-induced Taxol biosynthesis of T. chinensis sus- pension cells, we treated the cells with nitric oxide specific scavenger 2-4-carboxyphenyl-4,4,5,5-tetra- methylimidazoline-1-oxyl-3-oxide (cPITO), nitric ox- ide synthase inhibitor S,S′-1,3-phenylene-bis(1,2-eth- anediyl)-bis-isothiourea (PBITU), membrane NAD(P) H oxidase inhibitor diphenylene iodonium (DPI), su- peroxide dismutases (SOD) and catalase. The results show that pretreatment of T. chinensis cells with cPITO and DPI inhibited not only the elicitor-induced nitric oxide biosynthesis and oxidative burst, but also the elicitor-induced Taxol production, suggesting that both nitric oxide and reactive oxygen species are involved in elicitor-induced Taxol biosynthesis. Fur- thermore, pretreatment of the cells with cPITO and PBITU suppressed the elicitor-induced oxidative burst, indicating that the oxidative burst might be dependent on NO. Application of nitric oxide via its donor sodium nitroprusside (SNP) triggered Taxol biosynthesis of T. chinensis cells. The nitric ox-ide-induced Taxol production was suppressed by DPI, showing that the oxidative burst is involved in NO-triggered Taxol biosynthesis. However, nitric ox- ide and the fungal elicitor induced Taxol biosynthesis even though the accumulation of reactive oxygen species wass completely abolished in T. chinensis cells. Our data show that nitric oxide may mediate the elicitor-induced Taxol biosynthesis of T. chinensis suspension cells through both reactive oxygen spe- cies-dependent and -independent signal pathways. Moreover, the results of
文摘A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaCl3 and CdCl3 ） were added to tobacco （ Nicotiana tabacum） cell suspension culture. Addition of superoxide dismutase （480 U·ml^-1） and Tiron （5 μmol·L^-1） to cell culture suspension decreases the level of lanthanide cation-induced ·O2^- generation, suggesting that ·O2^- generation is extra-cellular. Pretreatment of the cell culture suspension with diphenyleneiodonium （10 and 50 μmol·L^-1 ）, quinacrine （ 1 and 5 mmol· L^-1 ） and imidazol （ 10 mmol· L^-1 ）, inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase. In addition, addition of SHAM （1 and 5 mmol· L^-1）, azide （0.2 and 1 mmol· L^-1 ）, inhibitor of peroxidase, has no influence on ·O2^- generation.
文摘Sphinganine or dihydrosphingosine （d18：0, DHS）, one of the most abundant free sphingoid Long Chain Base （LCB） in plants, has been recently shown to induce both cytosolic and nuclear calcium transient increases and a correlated Programmed Cell Death （PCD） in tobacco BY-2 cells. In this study, in order to get deeper insight into the LCB signaling pathway leading to cell death, the putative role of Reactive Oxygen Species （ROS） has been investigated. We show that DHS triggers a rapid dose-dependent production of H2O2 that is blocked by diphenyleniodonium （DPI）, indicating the involvement of NADPH oxidase（s） in the process. In addition, while DPI does not block DHS-induced calcium increases, the ROS production is inhibited by the broad spectrum calcium channel blocker lanthanum （La^3＋）. Therefore, ROS production occurs downstream of DHS-induced Ca^2＋ transients. Interestingly, DHS activates expression of defense-related genes that is inhibited by both La^3＋ and DPI. Since DPI does not prevent DHS-induced cell death, these results strongly indicate that DHS-induced H2O2 production is not implicated in PCD mechanisms but rather would be associated to basal cell defense mechanisms.
基金supported by National Basic Research Program of China (2010CB126501, 2011CB100702)the National Natural Science Foundation of China (31070218)
文摘Rhizobia interact with host legumes to induce the formation of nitrogen-fixing nodules,which is very important in agriculture and ecology.The development of nitrogen-fixing nodules is stringently regulated by host plants and rhizobial symbionts.In our previous work,a new Sinorhizobium meliloti LysR regulator gene(lsrB)was identified to be essential for alfalfa nodulation.However,how this gene is involved in alfalfa nodulation was not yet understood.Here,we found that this gene was associated with prevention of premature nodule senescence and abortive bacteroid formation.Heterogeneous deficient alfalfa root nodules were induced by the in-frame deletion mutant of lsrB(lsrB1-2),which was similar to the plasmid-insertion mutant,lsrB1.Irregular senescence zones earlier appeared in these nodules where bacteroid differentiation was blocked at different stages from microscopy observations.Interestingly,oxidative bursts were observed in these nodules by DAB staining.The decreased expression of lipopolysaccharide core genes(lpsCDE)was correspondingly determined in these nodules.S.meliloti lipopolysaccharide is required for suppression of oxidative bursts or host cell defense.These findings demonstrate that the S.meliloti lsrB gene is involved in alfalfa root nodule development and bacteroid differentiation by suppressing oxidative bursts or defense responses in host cells.
基金the Tertiary Education Commission,the University of Mauritius,H.E.J.Research Institute of Chemistry,ICCBS,and Dr Panjwani Center for Molecular Medicines and Drug Research,University of Karachi,Pakistan,for financial support
文摘Objective:To evaluate in vitro immunomodulating properties and potential cytotoxicity of six tropical medicinal herbs and food plants namely Antidesma madagascariense(Euphorbiaceae) (AM),Erylhroxylum macrocarpum(Erythroxylaceae)(EM),Faujasiopsis flexuosa(Asteraceae) (FF),Pittosporum senacia(Pittosporaceae)(PS),Momordica charantia(Cucurbitaceae)(MC) and Orimum tenuiflorum(Lamiaceae)(Of).Methods:Initially,the crude water and methanol extracts were probed for their capacity to trigger immune cells’ NADPH oxidase and MPO-dependent activities as measured by lucigenin- and luminol-amplified chemiluminescence,respectively; as compared to receptor-dependent(serum opsonised zymosan- OPZ) or receptor-independent phorbol myristerate acetate(PMA).Results:Preliminary screening on whole human blood oxidative buret activity showed significant and concentration-dependent immunomodulating properties of three plants AM,FF and OT.Further investigations of the fractions on isolated human polymorphonuclear cells(PMNs) and mice monocytes using two different pathways for activation of phagocytic oxidative burst showed that ethyl acetate fraction was the most potent extract. None of the active samples had cell-death effects on human PMNs,under the assay conditions as determined by the trypan-blue exclusion assay.Since PMA and OPZ NADPH oxidase complex is activated via different transduction pathways,these results suggest that AM,FF and OT does not affect a specific transductional pathway,but rather directly inhibit a final common biochemical target such as the NADPH oxidase enzyme and/or scavenges ROS.Conclusions:Our findings suggest that some of these plants extracts/fractions were able to modulate significantly immune response of phagocytes and monocytes at different steps,emphasizing their potential as a source of new natural alternative immunomodulatory agents.
文摘激发植物本身的天然免疫系统可作为防控植物病害的新途径。以50株分离自繁茂膜海绵的真菌为受试菌株筛选具有诱导植物抗性活性的菌株及其代谢产物。采用基于H2DCF-DA的荧光酶标法考察这些真菌的粗代谢物诱导烟草悬浮细胞产生氧爆发的活性,最终筛选到一株真菌HMP-F66能够显著诱导烟草悬浮细胞产生活性氧。根据其形态学特征、培养特征、特征性生理生化反应以及基于r DNA ITS的分子生物学分析,推测该菌株为米曲霉(Aspergillus oryzae)。
