H2O2-NOX系统: 一种植物体内重要的发育调控与胁迫响应机制

以H₂O₂为中心的活性氧(reactive oxygen species, ROS)的产生是动植物发育与响应外界生物与非生物胁迫的普遍 特征, 其在生理和分子2个水平上调控植物的发育和对外界胁迫的响应, 并与一系列信号转导过程相关联。作为关键的ROS产生酶, 质膜NADPH氧化酶(plasma membrane NADPH oxidase, PM-NOX)在植物应对各种生物和非生物胁迫中具有重要作用, 被广泛认为是胁迫条件下植物细胞ROS产生并积累的主要来源。该文简要综述了近年来人们在植物细胞ROS产生、清除、生理功能以及PM-NOX酶的结构特征与功能等方面的研究进展, 并认为H₂O₂-NOX系统是一种植物体内普遍存在的重要发育调控与胁迫响应机制。     

植物类LORELEI糖基磷脂酰肌醇锚定蛋白研究进展

类LORELEI糖基磷脂酰肌醇锚定蛋白(LLG)定位于细胞质膜外表面, 作为CrRLK1L家族类受体激酶的分子伴侣, 参与其转运和胞外信号转导, 从而调控植物生殖发育以及免疫与逆境应答等过程。LLG2/3与ANX和BUPS互作, 调控花粉管顶端生长与爆裂。LLG1与FER (FERONIA)互作, 调控下游的NADPH氧化酶产生活性氧(ROS), 促进根部细胞伸长和根毛生长。此外, LLG1作为FER的共受体, 与快速碱化因子(RALFs)互作, 调节G蛋白β亚基(AGB1)和质膜H ⁺-ATPase功能、胞内ROS稳态以及Ca ²⁺瞬变, 引起根部和气孔的盐应答反应。LLG1与FLS2和EFR互作激活下游RbohD, 调节ROS产生, 调控植物免疫应答。该文综述了植物LLG的相关研究进展, 可为深入理解LLG的生物学功能提供重要信息。     

H2S信号参与SDH调控能量和活性氧代谢过程的作用机制

作为新兴的气体信号分子，硫化氢(hydrogen sulfide, H₂S)能够调节植物生长发育，广泛参与植物抵御生物及非生物胁迫的过程。琥珀酸脱氢酶(succinate dehydrogenase, SDH)结合于线粒体内膜，既是参与三羧酸循环的关键酶，也是氧化磷酸化过程的重要电子载体，在植物响应各类胁迫中发挥着重要作用。鉴于H₂S与SDH参与调控的生理过程有很大相关性，本文以模式植物拟南芥为实验材料，对H₂S与SDH之间的关系进行了探索。结果表明，在AtSDH1-1-OE中，H₂S的关键生成酶编码基因LCD和DES1大量表达，且H₂S产率和含量较WT显著升高。SDH抑制剂TTFA处理导致活性氧(ROS)大量产生，幼苗根的伸长受到极显著抑制，根发育生长基因RHD2、TRH和SCN1表达下调；而同时进行生理浓度的NaHS(H₂S供体)熏蒸，能够清除过量ROS,幼苗生长有所恢复。但在AtSDH1-1-OE中，施加HT(H₂S清除剂)后的...     

保卫细胞中ABA信号调控机制研究进展

脱落酸(ABA)具有调节植物快速响应逆境的重要功能。植物细胞中ABA核心信号通路由ABA受体PYR1/PYLs/ RCARs、A类碱性蛋白磷酸酶PP2Cs和Snf1相关蛋白激酶SnRK2s组成。活性氧(ROS)和Ca²⁺是保卫细胞中的重要第二信使, 调控ABA诱导的气孔关闭。该文对保卫细胞中核心ABA信号蛋白的调控以及ROS和Ca²⁺介导的ABA信号转导等最新研究成果进行综述, 旨在阐明保卫细胞中ABA信号调控机制。     

过氧化氢酶在植物生长发育和胁迫响应中的功能研究进展

过氧化氢酶(catalase, CAT)作为过氧化氢(hydrogen peroxide, H₂O₂)的清除酶在植物生长发育和胁迫响应中扮演着十分重要的角色。CAT的功能受到严格调控,其在正常条件下维持适当浓度的H₂O₂作为信号分子以保证植物的生长发育;在胁迫下保持H₂O₂稳态以增强植物耐逆性。本文对近年来CAT在植物生长发育和胁迫响应中的功能研究进展予以综述,特别是翻译后修饰和亚细胞定位对CAT功能的调控,并对植物CAT的调控机理研究进行了展望。     

死亡信号传递: 叶绿体与线粒体间信号交流调控植物程序性细胞死亡

程序性细胞死亡(PCD)是生物体受遗传调控的自主细胞死亡现象, 在植物生长发育和抵抗环境胁迫中起重要作用。PCD的发生可受线粒体中活性氧(ROS)诱导。中国科学院遗传与发育生物学研究所李家洋研究组早期的研究发现了1个拟南芥(Arabidopsis thaliana)细胞死亡突变体mod1, 并暗示植物细胞中存在叶绿体与线粒体之间的信号交流调控PCD, 但其中的具体作用机制尚不清楚。最近, 他们通过大规模筛选mod1突变体的抑制突变体, 克隆了3个新的抑制基因plNAD- MDH、DiT1和mMDH1。此3个基因分别编码质体定位的NAD依赖的苹果酸脱氢酶、叶绿体被膜定位的二羧酸转运蛋白1和线粒体定位的苹果酸脱氢酶1, 突变后都可抑制mod1中ROS的积累及PCD的发生。通过对这些基因进行深入的功能分析, 他们论证了苹果酸从叶绿体到线粒体的转运对线粒体中ROS的产生及随后PCD的诱导起重要作用。该研究拓展了我们对植物细胞中细胞器间交流的认识, 为我们深入理解植物PCD发生机制提供了新线索, 是该领域的一项突破性进展。     

植物中的细胞程序性死亡

细胞程序性死亡(PCD)对于维持植物的正常生长发育非常重要,目前已成为植物学研究的一个热点。本文综合评述了近年来植物PCD研究的某些进展,包括植物PCD的特征,植物的营养生长、生殖生长以及与环境互作过程中存在的各种PCD及其证据,植物PCD发生的分子机制及其调控等等。对植物PCD研究中有待进一步解决的问题和可能意义提出了自己的见解。     

miR172-AP2模块调控植物生长发育及逆境响应的研究进展

MicroRNA (miRNA)是一类具有调控能力的非编码小分子RNA, 通过与靶基因mRNA特异或非特异性结合, 诱导靶基因mRNA降解或抑制其翻译, 从而调控植物的生长发育。其中, miR172的靶基因AP2所编码的转录因子为植物所特有, miR172在转录后或翻译水平对AP2进行表达调控, 进而调控植物的花发育、时序转换、小穗形态、块茎和果实发育、结瘤(豆科)以及逆境响应等过程。该文综述了近年来miR172-AP2模块在植物生长发育调控方面的最新研究进展。     

ROS信号对植物抗性的调控作用研究进展

活性氧(reactive oxygen species,ROS)是植物体代谢所产生的小分子化合物,既是生长发育和防御途径的关键调节因子,又是需氧代谢的有毒副产物。植物细胞的生理过程受一个被活性氧调节的氧化还原网状途径的调控,本文从植物体内ROS产生的部位与时空特异性、ROS信号与NO和Ca2+波信号的互作等方面综述了ROS信号对植物抗性的调控作用研究进展。     

气孔运动中的活性氧信号

大量研究证明活性氧(ROS)在气孔运动中起信号分子的作用。保卫细胞中ROS的产生依赖于特定的酶,其中NADPH氧化酶组分RBOH已得到深入研究,并已证实其参与生物与非生物胁迫反应。植物激素包括脱落酸(ABA)、水杨酸(SA)、乙烯、生长素及细胞分裂素等,它们均通过ROS的介导来调控气孔运动。生物胁迫(如毒性细菌和真菌)也会调控气孔运动。ROS参与这些调控过程。保卫细胞中存在多层次对ROS产生及其作用的调节,抗氧化活性物质和ROS敏感蛋白(如蛋白激酶和磷酸酶)均可传递ROS信号并调节气孔运动。ROS对离子通道调节的证据也越来越多。保卫细胞由于可通过ROS整合复杂的信号途径,已成为研究植物ROS信号转导过程的良好模式系统。     

The role of reactive oxygen species in cell growth: lessons from root hairs

Reactive oxygen species (ROS) play a diversity of roles in plants. In recent years, a role for NADPH oxidase-derived ROS during cell growth and development has been discovered in a number of plant model systems. These studies indicate that ROS are required for cell expansion during the morphogenesis of organs such as roots and leaves. Furthermore, there is evidence that ROS are required for root hair growth where they control the activity of calcium channels required for polar growth. The role of ROS in the control of root hair growth is reviewed here and results are highlighted that may provide insight into the mechanism of plant cell growth in general.     

Reactive oxygen species as signals that modulate plant stress responses and programmed cell death

Reactive oxygen species (ROS) are known as toxic metabolic products in plants and other aerobic organisms. An elaborate and highly redundant plant ROS network, composed of antioxidant enzymes, antioxidants and ROS-producing enzymes, is responsible for maintaining ROS levels under tight control. This allows ROS to serve as signaling molecules that coordinate an astonishing range of diverse plant processes. The specificity of the biological response to ROS depends on the chemical identity of ROS, intensity of the signal, sites of production, plant developmental stage, previous stresses encountered and interactions with other signaling molecules such as nitric oxide, lipid messengers and plant hormones. Although many components of the ROS signaling network have recently been identified, the challenge remains to understand how ROS-derived signals are integrated to eventually regulate such biological processes as plant growth, development, stress adaptation and programmed cell death.     

Oxygen and reactive oxygen species-dependent regulation of plant growth and development

Oxygen and reactive oxygen species (ROS) have been co-opted during evolution into the regulation of plant growth, development, and differentiation. ROS and oxidative signals arising from metabolism or phytohormone-mediated processes control almost every aspect of plant development from seed and bud dormancy, liberation of meristematic cells from the quiescent state, root and shoot growth, and architecture, to flowering and seed production. Moreover, the phytochrome and phytohormone-dependent transmissions of ROS waves are central to the systemic whole plant signaling pathways that integrate root and shoot growth. The sensing of oxygen availability through the PROTEOLYSIS 6 (PRT6) N-degron pathway functions alongside ROS production and signaling but how these pathways interact in developing organs remains poorly understood. Considerable progress has been made in our understanding of the nature of hydrogen peroxide sensors and the role of thiol-dependent signaling networks in the transmission of ROS signals. Reduction/oxidation (redox) changes in the glutathione (GSH) pool, glutaredoxins (GRXs), and thioredoxins (TRXs) are important in the control of growth mediated by phytohormone pathways. Although, it is clear that the redox states of proteins involved in plant growth and development are controlled by the NAD(P)H thioredoxin reductase (NTR)/TRX and reduced GSH/GRX systems of the cytosol, chloroplasts, mitochondria, and nucleus, we have only scratched the surface of this multilayered control and how redox-regulated processes interact with other cell signaling systems.

Oxygen and reactive oxygen species regulate plant growth, development, and differentiation through multiple interlinked signaling pathways.

Advances

• Developmentally regulated hypoxia and reactive oxygen species (ROS) production are key features of the stem cell niches, providing information about stem cell position, the environment, and metabolic state.
• Protein cysteine oxidation is central to oxygen and ROS signaling. However, S-nitrosylation, S-glutathionylation, S-sulfhydration, and S-sulfenylation modifications can occur on the same cysteine. The influence of each modification on stability, localization, and function remains unknown.
• Numerous intersecting ROS signaling pathways are probable and likely depend on the site of ROS production and the nature of the oxidized receptor protein. ROS sensors such as the hydrogen peroxide (H₂O₂)-INDUCED Ca²⁺ INCREASES 1 (HPCA1) leucine rich receptor kinase translate redox signals into protein modifications to regulate signaling cascades. H₂O₂ perception/transduction is dependent on thiol-dependent mechanisms policed by the ferredoxin/thioredoxin (TRX), NAD(P)H TRX reductase C (NTRC), reduced glutathione (GSH), and glutaredoxin (GRX) systems.
• ROS waves transmit redox signals from cell to cell in the apoplast, and probably through plasmodesmata. Long-distance transport of H₂O₂ and other ROS, therefore, appears to be unnecessary. Similarly, contact sites between organelles allow ROS transfer.
• Convergence points for oxygen and ROS signaling occur on proteins such as ROH OF PLANT 2 (ROP2) GTPase,RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD), and TRX-h to regulate meristematic activity via TARGET OF RAPAMYCIN (TOR) kinase activity.

     

Endophyte-mediated adjustments in host morphology and physiology and effects on host fitness traits in grasses

Endophytic fungi have been shown to increase tolerance of hosts to biotic and abiotic stresses and in some cases alter growth and development of plants. In this article we evaluate some effects that clavicipitaceous endophytes have on development and physiology of plant tissues. We postulate that oxidative stress protection is the fundamental underlying benefit conferred by many endophytes, accounting for frequently observed enhanced disease resistance, drought tolerance, heavy metal tolerance and tolerance to numerous additional oxidative stresses. We hypothesize that endophyte-mediated oxidative stress protection of the host is the result of at least two processes, including: (1) secretion of reactive oxygen species (ROS) from endophytic mycelia into plant cells; and (2) secretion of auxin from endophytic mycelia into plant cells. Both processes result in an increase in ROS in plant tissues; and stimulate plant tissues to increase activities of antioxidant systems. Auxin is suggested to function in suppression of plant cell death and may be important in maintaining the endophyte–plant symbiosis.     

Reactive oxygen and nitrogen species and glutathione: key players in the legume-Rhizobium symbiosis

Several reactive oxygen and nitrogen species (ROS/RNS) are continuously produced in plants as by-products of aerobic metabolism or in response to stresses. Depending on the nature of the ROS and RNS, some of them are highly toxic and rapidly detoxified by various cellular enzymatic and non-enzymatic mechanisms. Whereas plants have many mechanisms with which to combat increased ROS/RNS levels produced during stress conditions, under other circumstances plants appear to generate ROS/RNS as signalling molecules to control various processes encompassing the whole lifespan of the plant such as normal growth and development stages. This review aims to summarize recent studies highlighting the involvement of ROS/RNS, as well as the low molecular weight thiols, glutathione and homoglutathione, during the symbiosis between rhizobia and leguminous plants. This compatible interaction initiated by a molecular dialogue between the plant and bacterial partners, leads to the formation of a novel root organ capable of fixing atmospheric nitrogen under nitrogen-limiting conditions. On the one hand, ROS/RNS detection during the symbiotic process highlights the similarity of the early response to infection by pathogenic and symbiotic bacteria, addressing the question as to which mechanism rhizobia use to counteract the plant defence response. Moreover, there is increasing evidence that ROS are needed to establish the symbiosis fully. On the other hand, GSH synthesis appears to be essential for proper development of the root nodules during the symbiotic interaction. Elucidating the mechanisms that control ROS/RNS signalling during symbiosis could therefore contribute in defining a powerful strategy to enhance the efficiency of the symbiotic interaction.     

Unravelling how plants benefit from ROS and NO reactions,while resisting oxidative stress

Background and Aims Reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as nitric oxide (NO), play crucial roles in the signal transduction pathways that regulate plant growth, development and defence responses, providing a nexus of reduction/oxidation (redox) control that impacts on nearly every aspect of plant biology. Here we summarize current knowledge and concepts that lay the foundations of a new vision for ROS/RNS functions – particularly through signalling hubs – for the next decade.Scope Plants have mastered the art of redox control using ROS and RNS as secondary messengers to regulate a diverse range of protein functions through redox-based, post-translational modifications that act as regulators of molecular master-switches. Much current focus concerns the impact of this regulation on local and systemic signalling pathways, as well as understanding how such reactive molecules can be effectively used in the control of plant growth and stress responses.Conclusions The spectre of oxidative stress still overshadows much of our current philosophy and understanding of ROS and RNS functions. While many questions remain to be addressed – for example regarding inter-organellar regulation and communication, the control of hypoxia and how ROS/RNS signalling is used in plant cells, not only to trigger acclimation responses but also to create molecular memories of stress – it is clear that ROS and RNS function as vital signals of living cells.     

Extracellular ATP in plants. Visualization, localization, and analysis of physiological significance in growth and signaling

Extracellular ATP (eATP) in animals is well documented and known to play an important role in cellular signaling (e.g. at the nerve synapse). The existence of eATP has been postulated in plants; however, there is no definitive experimental evidence for its presence or an explanation as to how such a polar molecule could exit the plant cell and what physiological role it may play in plant growth and development. The presence of eATP in plants (Medicago truncatula) was detected by constructing a novel reporter; i.e. fusing a cellulose-binding domain peptide to the ATP-requiring enzyme luciferase. Application of this reporter to plant roots allowed visualization of eATP in the presence of the substrate luciferin. Luciferase activity could be detected in the interstitial spaces between plant epidermal cells and predominantly at the regions of actively growing cells. The levels of eATP were closely correlated with regions of active growth and cell expansion. Pharmacological compounds known to alter cytoplasmic calcium levels revealed that ATP release is a calcium-dependent process and may occur through vesicular fusion, an important step in the polar growth of actively growing root hairs. Reactive oxygen species (ROS) activity at the root hair tip is not only essential for root hair growth, but also dependent on the cytoplasmic calcium levels. Whereas application of exogenous ATP and a chitin mixture increased ROS activity in root hairs, no changes were observed in response to adenosine, AMP, ADP, and nonhydrolyzable ATP (betagammameATP). However, application of exogenous potato (Solanum tuberosum) apyrase (ATPase) decreased ROS activity, suggesting that cytoplasmic calcium gradients and ROS activity are closely associated with eATP release.     

NO and ROS implications in the organization of root system architecture

Over the past decades the role of nitric oxide (NO) and reactive oxygen species (ROS) in signaling and cellular responses to stress has witnessed an exponential trend line. Despite advances in the subject, our knowledge of the role of NO and ROS as regulators of stress and plant growth and their implication in signaling pathways is still partial. The crosstalk between NO and ROS during root formation offers new domains to be explored, as it regulates several plant functions. Previous findings indicate that plants utilize these signaling molecules for regulating physiological responses and development. Depending upon cellular concentration, NO either can stimulate or impede root system architecture (RSA) by modulating enzymes through post-translational modifications. Similarly, the ROS signaling molecule network, in association with other hormonal signaling pathways, control the RSA. The spatial regulation of ROS controls cell growth and ROS determine primary root and act in concert with NO to promote lateral root primordia. NO and ROS are two central messenger molecules which act differentially to upregulate or downregulate the expression of genes pertaining to auxin synthesis and to the configuration of root architecture. The investigation concerning the contribution of donors and inhibitors of NO and ROS can further aid in deciphering their role in root development. With this background, this review provides comprehensive details about the effect and function of NO and ROS in the development of RSA.     

活性氧对植物自噬调控的研究进展

自噬是一种在真核生物中高度保守的降解细胞组分的生物过程, 在饥饿、衰老和病菌感染等过程中起关键作用。而活性氧是有氧生物在正常或胁迫条件下产生的一种代谢副产物, 在植物的生长发育、胁迫适应和程序性细胞死亡过程中起重要作用。最新研究结果表明, 当植物受到病菌感染产生超敏反应时活性氧和自噬在程序性细胞死亡、生长发育和胁迫适应过程中起重要调控作用。因此, 该文结合最新的研究进展, 从活性氧的种类及特点、自噬的分子基础以及活性氧在植物自噬中的作用等方面, 探讨了活性氧与植物自噬之间的信号转导关系。     

Regulation of plant reactive oxygen species (ROS) in stress responses: learning from AtRBOHD

Reactive oxygen species (ROS) are constantly produced in plants, as the metabolic by-products or as the signaling components in stress responses. High levels of ROS are harmful to plants. In contrast, ROS play important roles in plant physiology, including abiotic and biotic tolerance, development, and cellular signaling. Therefore, ROS production needs to be tightly regulated to balance their function. Respiratory burst oxidase homologue (RBOH) proteins, also known as plant nicotinamide adenine dinucleotide phosphate oxidases, are well studied enzymatic ROS-generating systems in plants. The regulatory mechanisms of RBOH-dependent ROS production in stress responses have been intensively studied. This has greatly advanced our knowledge of the mechanisms that regulate plant ROS production. This review attempts to integrate the regulatory mechanisms of RBOHD-dependent ROS production by discussing the recent advance. AtRBOHD-dependent ROS production could provide a valuable reference for studying ROS production in plant stress responses.