植物一氧化氮生物学的研究进展

一氧化氮 (NO) 是植物中的一种关键的信号分子。在植物中, NO的潜在来源包括一氧化氮合成酶、硝酸还原酶、黄嘌呤氧化还原酶和非酶促途径。NO能促进植物生长, 延缓叶片、花和果实衰老, 促进休眠和需光种子的萌发, 能与植物激素相互作用调节气孔运动, 诱导程序性细胞死亡和防御相关基因的表达, 并在逆境中作为一种抗氧化剂起作用。 NO的细胞内信号反应包括环鸟苷酸、环腺苷二磷酸核糖的产生和细胞质Ca2+浓度的增加, 其信号转导途径及其生物化学和细胞学本质还不十分清楚。     

植物体内一氧化氮合成途径研究进展

一氧化氮(NO)作为一种气体信号分子,在植物生理过程中发挥重要作用,它参与调节植物的生长、发育及对外界环境的应激反应.植物体内主要通过酶催化途径和非酶催化途径合成NO.酶催化途径合成NO的主要酶包括一氧化氮合酶(nitric oxide synthase,NOS)和硝酸还原酶(nitrate reductase,NR),以及在某些植物的特定组织或器官或在特殊环境条件下存在的一氧化氮氧化还原酶(nitric oxide oxidoreductase,Ni-NOR)和黄嘌呤氧化还原酶(xanthine oxidoreductase,XOR).非酶催化合成途径主要是在酸性和还原剂存在条件下将亚硝酸盐还原成NO.该文主要结合研究方法,综述了植物体内NO合成途径的研究进展,为植物体内NO信号的作用机理的深入研究提供信息资料.     

植物一氧化氮信号分子的研究进展

一氧化氮(NO)作为一种重要的信号分子,不仅参与植物的种子休眠和萌发以及根的形态建成等生长发育过程,还参与调节植物细胞的气孔运动以及植物抗逆应答反应。该文结合最新研究成果,总结了植物NO信号调控机理的研究进展,主要包括NO合成途径、信号转导途径及其与其它信号分子之间的交叉反应和对植物抗逆的调控作用等。     

NO在植物中的调控作用

一氧化氮(NO)是一种易扩散的生物活性分子,是生物体内重要的信号分子.植物细胞通过NO合酶、硝酸还原酶、或非生化反应途径产生NO.NO参与植物生长发育调控和对生物与非生物环境胁迫的应答反应,大量证据表明NO是植物防御反应中的关键信使,其信号转导机制也受到越来越多的关注.本文主要通过讨论NO的产生、对植物生长周期的影响、在植物代谢中的信号调节以及参与细胞凋亡来阐述NO在植物中的作用.     

一氧化氮对植物细胞基因表达和代谢产物合成的影响机制

一氧化氮(NO)作为一种气体信号分子,在植物体内具有多种生理功能,许多研究逐步揭示了NO在植物发育、新陈代谢和疾病响应等方面的分子机制。内源和外源NO都可以使植物组织或悬浮细胞基因表达发生变化,高通量的基因表达的研究,如转录分析等,为信号网络通路分析提供了有力的证据。我们简要综述了NO的合成途径,并讨论了次生代谢产物及细胞程序性死亡过程中依赖NO调控的相应基因及蛋白的变化,揭示了NO是一种重要的植物信号分子,有较高的研究价值。     

NO在植物中的调控作用

一氧化氮（NO）是一种易扩散的生物活性分子,是生物体内重要的信号分子。植物细胞通过NO合酶、硝酸还原酶、或非生化反应途径产生NO。NO参与植物生长发育调控和对生物与非生物环境胁迫的应答反应,大量证据表明NO是植物防御反应中的关键信使,其信号转导机制也受到越来越多的关注。本文主要通过讨论NO的产生、对植物生长周期的影响、在植物代谢中的信号调节以及参与细胞凋亡来阐述NO在植物中的作用。     

一氧化氮调控植物缺铁响应的研究进展

一氧化氮(nitric oxide,NO)是植物体内一种重要的信号分子,不仅对植物的生长发育具有重要的调控作用,而且在植物应答缺铁胁迫中同样扮演着关键角色。近年来,有关NO介导的植物缺铁响应调控机制研究取得了一系列重要进展。本文重点针对植物体内NO的合成及其信号转导途径在缺铁胁迫应答中的作用和NO与其他信号分子互作介导植物缺铁响应调控研究进行系统综述与展望,以加深NO在植物缺铁响应调控功能的认识。     

一氧化氮在植物对病原物反应中的信号作用

一氧化氮(NO)作为一种新型的细胞间和细胞内信息传递的信使分子,在人体与动物的神经、心血管和免疫等系统中的作用已引起人们的普遍关注,它广泛存在于生物界包括植物和微生物中[1]。已证明植物中也存在与哺乳动物类似的一氧化氮合成酶(ni-tric oxide synthase,NOS)[2,3],它摧化合成的NO可影响叶和根的生长、植保素的形成[3,4],在植物生长、发育和抗病反应中起作用。Durner等[2]和Delledonne等[3]最近证明,NO在植物抗病的过敏反应(hypersensi-tive response)中也可作为信号物与活性氧协同作用,激活植物抗病基因表达,参与植物的抗病反应,是过敏反应所必须的。但植物中NO的作用研究还刚开始,前景诱人。本文简要介绍NO在植物抗病反应中的作用及其模式。1 NO作为气体信号分子的作用1.1 NO生物学活性的发现 19世纪医学上就开始用NO的生成剂有机硝酸酯和硝酸甘油治疗心脏缺血,但一直未认识到其本质就是NO在起作用,更未意识到内源NO的存在所起的重要的生物学意义。70年代由于对亚硝胺的致癌作用的研究,人们发现巨噬细胞能被L-精氨酸及NO所激活,而增强巨噬细胞的杀菌和杀肿瘤作用。80年代,Furchgott等发现促进血管扩张的内皮衍生因子就是NO,硝酸甘油的扩血管作用是源于这一功能的活性代谢产物NO。随后,Garth-waite等发现NO在中枢神经系统中起作用,并证实脑细胞中存在一氧化氮合成酶[1,4]。80年代以来,人们通过对血管内皮衍生因子化学本质(即NO的揭示),以及NO在巨噬     

一氧化氮在植物抗病反应中的信号作用

近年来的研究发现,一氧化氮(nitricoxide,NO)在植物抗病反应中具有重要作用,本文概述了植物中NO的来源、NO在植物抗病反应中的信号传导作用、NO与植物中其它信号分子之间的相互作用以及NO的研究进展。     

植物中硫化氢和一氧化氮信号的交互作用

植物在整个生长、发育和响应环境胁迫过程中,涉及多种信号分子如钙(Ca2+)、活性氧(ROS)、硫化氢(H2S)和一氧化氮(NO)等的交互作用。近年来,H2S和NO都被认为是植物中重要的第二信使,参与种子的萌发、植物的生长与发育和对环境胁迫的响应和适应,并且在这些生理过程中,存在H2S和NO信号的交互作用。基于H2S和NO信号的最新研究进展,对H2S和NO信号在植物中的合成和分解代谢,以及它们在植物细胞中的动态平衡进行了讨论,并对植物中H2S和NO信号的交互作用,即二者的化学反应、作用于共同的靶分子、调节彼此代谢酶和其他信号途径等方面进行了归纳和总结。     

Nitric oxide accelerates seed germination in warm-season grasses

The nitric oxide (NO) donor sodium nitroprusside (SNP) significantly promoted germination of switchgrass (Panicum virgatum L. cv Kanlow) in the light and in the dark at 25°C, across a broad range of concentrations. SNP also promoted seed germination in two other warm-season grasses. A chemical scavenger of NO inhibited germination and blocked SNP stimulation of seed germination. The phenolic (+)-catechin acted synergistically with SNP and nitrite in promoting seed germination. Acidified nitrite, an alternate NO donor also significantly stimulated seed germination. Interestingly, sodium cyanide, potassium ferricyanide and potassium ferrocyanide at 200 μM strongly enhanced seed germination as well, whereas potassium chloride was without effect. Ferrocyanide and cyanide stimulation of seed germination was blocked by an NO scavenger. Incubation of seeds with a fluorescent NO-specific probe provided evidence for NO production in germinating switchgrass seeds. Abscisic acid (ABA) at 10 μM depressed germination, inhibited root elongation and essentially abolished coleoptile emergence. SNP partially overcame ABA effects on radicle emergence but did not overcome the effects of ABA on coleoptile elongation. Light microscopy indicated extension of the radicle and coleoptiles in seeds maintained on water or on SNP after 2 days. In contrast, there was minimal growth of the radicle and coleoptile in ABA-treated seeds even after 3–4 days. These data indicate that seed germination of warm-season grasses is significantly influenced by NO signaling pathways and document that NO could be an endogenous trigger for release from dormancy in these species.     

Nitric oxide has dual opposite roles during early and late phases of apoptosis in cerebellar granule neurons

The involvement and the role of nitric oxide (NO) as a signaling molecule in the course of neuronal apoptosis, whether unique or modulated during the progression of the apoptotic program, has been investigated in a cellular system consisting of cerebellar granule cells (CGCs) where apoptosis can be induced by lowering extracellular potassium. Several parameters involved in NO signaling pathway, such as NO production, neuronal nitric oxide synthase (nNOS) expression, and cyclic GMP (cGMP) production were examined in the presence or absence of different inhibitors. We provide evidence that nitric oxide has dual and opposite effects depending on time after induction of apoptosis. In an early phase, up to 3 h of apoptosis, nitric oxide supports survival of CGCs through a cGMP-dependent mechanism. After 3 h, nNOS expression and activity decreased resulting in shut down of NO and cGMP production. Residual NO then contributes to the apoptotic process by reacting with rising superoxide anions leading to peroxynitrite production and protein inactivation. We conclude that whilst NO over-production protects neurons from death in the early phase of neuronal damage, its subsequent reduction may contribute to neuronal degeneration and ultimate cell death.     

植物细胞一氧化氮信号转导研究进展

一氧化氮（nitric oxide,NO）作为重要的信号分子,调控植物的种子萌发、根形态建成和花器官发生等许多生长发育过程,并参与气孔运动的调节以及植物对多种非生物胁迫和病原体侵染的应答过程。已经知道,精氨酸依赖的NOS途径和亚硝酸盐依赖的NR途径是植物细胞NO产生的主要酶促合成途径。NO及其衍生物能够直接修饰底物蛋白的金属基团、半胱氨酸和酪氨酸残基,通过金属亚硝基化、巯基亚硝基化和Tyr．硝基化等化学修饰方式,调节靶蛋白的活性,并影响cGMP和Ca2＋信使系统等下游信号途径,调控相应的生理过程。最新的一些研究结果也显示,MAPK级联系统与NO信号转导途径之间存在复杂的交叉调控。此外,作为活跃的小分子信号,NO和活性氧相互依赖并相互影响,共同介导了植物的胁迫应答和激素响应过程。文章综述了植物NO信号转导研究领域中一些新的研究进展,对NO与活性氧信号途径间的交叉作用等也作了简要介绍。     

植物一氧化氮(NO)研究进展

一氧化氮（NO）是植物的重要生物活性分子,它参与植物生长发育的许多过程,如种子萌发、下胚轴伸长、叶扩展、根生长、侧根形成、细胞凋亡以及植物抗逆反应等。大量的证据表明,植物可以通过与动物NO合酶类似的酶产生NO。此外,植物还可通过硝酸还原酶产生NO。NO在植物中的信号传递途径仍不十分清楚,植物有可能采用与动物相类似的机制。由于植物的大多数生长发育现象都受到植物激素的调节和控制,NO与植物激素之间的关系也受到越来越多的关注。通过激素起作用可能是植物内源NO作用的机理之一。     

Nitric oxide gas stimulates germination of dormant Arabidopsis seeds: use of a flow-through apparatus for delivery of nitric oxide

Nitric oxide (NO) is a gaseous free radical that reacts with O₂ in air and aqueous solution. NO donors have been widely used to circumvent the difficulties inherent in working with a reactive gas, but NO donors do not deliver NO at a constant rate for prolonged periods of time. Furthermore, some of the most commonly used NO donors produce additional, bioactive decomposition products. We designed and built an apparatus that allowed for the precise mixing of gaseous NO with air and the delivery of gas through sample vials at fixed rates. This experimental setup has the added advantage that continuous flow of gas over the sample reduces the buildup of volatile breakdown products. To show that this experimental setup was suitable for studies on the dormancy and germination of Arabidopsis thaliana seeds, we introduced vapors from water or sodium nitroprusside (SNP) into the gas stream. Seeds remained dormant when treated with water vapor, but gases generated by SNP increased germination to 90%. When pure NO was mixed with air and passed over dormant seeds, ∼ ∼30% of the seeds germinated. Because nitrite accumulates in aqueous solutions exposed to NO gas, we measured the accumulation of nitrite under our experimental conditions and found that it did not exceed 100 µM. Nitrite or nitrate at concentrations of up to 500 µM did not increase germination of C24 ecotype Arabidopsis seeds to more than 10%. These data support the hypothesis that NO participates in the loss of Arabidopsis seed dormancy, and they show that for some dormant seeds, exposure to exogenous NO is sufficient to trigger germination.     

Nitric oxide inhibits larval settlement in Amphibalanus amphitrite cyprids by repressing muscle locomotion and molting

Nitric oxide (NO) is a universal signaling molecule and plays a negative role in the metamorphosis of many biphasic organisms. Recently, the NO/cGMP (cyclic guanosine monophosphate) signaling pathway was reported to repress larval settlement in the barnacle Amphibalanus amphitrite. To understand the underlying molecular mechanism, we analyzed changes in the proteome of A. amphitrite cyprids in response to different concentrations of the NO donor sodium nitroprusside (SNP; 62.5, 250, and 1000 μM) using a label‐free proteomics method. Compared with the control, the expression of 106 proteins differed in all three treatments. These differentially expressed proteins were assigned to 13 pathways based on KEGG pathway enrichment analysis. SNP treatment stimulated the expression of heat shock proteins and arginine kinase, which are functionally related to NO synthases, increased the expression levels of glutathione transferases for detoxification, and activated the iron‐mediated fatty acid degradation pathway and the citrate cycle through ferritin. Moreover, NO repressed the level of myosins and cuticular proteins, which indicated that NO might inhibit larval settlement in A. amphitrite by modulating the process of muscle locomotion and molting.     

Dormancy of<Emphasis Type="Italic"> Arabidopsis</Emphasis> seeds and barley grains can be broken by nitric oxide

Seeds of Arabidopsis thaliana (L.) Heynh. and grains of barley (Hordeum vulgare L.) were used to characterize the affects of nitric oxide (NO) on seed dormancy. Seeds of the C24 and Col-1 ecotypes of Arabidopsis are almost completely dormant when freshly harvested, but dormancy was broken by stratification for 3 days at 4°C or by imbibition of seeds with the NO donor sodium nitroprusside (SNP). This effect of SNP on dormancy of Arabidopsis seeds was concentration dependent. SNP concentrations as low as 25 M reduced dormancy and stimulated germination, but SNP at 250 M or more impaired seedling development, including root growth, and inhibited germination. Dormancy was also reduced when Arabidopsis seeds were exposed to gasses that are generated by solutions of SNP. Nitrate and nitrite, two other oxides of nitrogen, reduced the dormancy of Arabidopsis seeds, but much higher concentrations of these were required compared to SNP. Furthermore, the kinetics of germination were slower for seeds imbibed with either nitrate or nitrite than for seeds imbibed with SNP. Although seeds imbibed with SNP had reduced dormancy, seeds imbibed with SNP and abscisic acid (ABA) remained strongly dormant. This may indicate that the effects of ABA action on germination are downstream of NO action. The NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3 oxide (cPTIO) strengthened dormancy of unstratified and briefly stratified Arabidopsis seeds. Dormancy of three cultivars of barley was also reduced by SNP. Furthermore, dormancy in barley grain was strengthened by imbibition of grain with cPTIO. The data presented here support the conclusion that NO is a potent dormancy breaking agent for seeds and grains. Experiments with the NO scavenger suggest that NO is an endogenous regulator of seed dormancy.Abbreviations ABA Abscisic acid - cPTIO 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3 oxide - GA Gibberellin - SNP Sodium nitroprusside - NO_x Gaseous oxides of nitrogen