植物的超越补偿反应

阐述了植物的超越补偿反应,并根据前人分散的研究资料总结得出植物超越补偿反应的生理学机制是植物光合活性提高和因减少生长冗余引起植物运集中心改变及其调节下的植物体内同化产物运转的最优化分配。细胞分裂素在该调控系统中承担重要作用。     

植物铵态氮同化及其调控机制的研究进展

氮是维持植物生长发育最重要的矿质营养元素之一,在植物整个生命进程中发挥着重要作用。在植物体内,氮同化既是植物利用氮素的一个中心环节,也是导致植物氮利用效率不高的因素之一。氮同化主要分为硝态氮(NO3–)和铵态氮(NH4+)同化,其中铵态氮同化是氮同化中最为关键的一步。按照不同来源,植物体内铵态氮同化又可分为一次同化和二次同化,但两者都是通过谷氨酰胺/谷氨酸合成酶(GS/GOGAT)途径进行。植物铵态氮同化不仅需要大量的能量,而且需要大量的碳源,所以其在转录、转录后以及翻译后等各个水平上都受到严格调控。该文综述了目前关于植物铵态氮同化及其调控机制的最新研究进展。     

C_3和C_4植物的氮素利用机制

提高植物的氮素利用效率(NUE)不仅有利于保障全球粮食安全,也是实现农业可持续发展的重要途径。近半个世纪以来,植物氮素利用机理研究已取得重要进展,但NUE的调控机制仍不明确, NUE的提高仍然十分有限。高等植物集光合碳素同化和氮素同化于一体,只有碳氮代谢相互协调,才能维持植物体内的碳氮平衡,保证植物正常生长发育。由于C_3和C_4植物的光合氮素利用率(PNUE)存在差异,对氮素的利用效率也会存在差异。为了更有效地提高作物的NUE,须更全面地了解C_3和C_4植物对氮素吸收、转运、同化和信号转导等关键因子的功能和调控机制。此外,面对大气CO_2浓度增高和全球气候变暖条件下的植物碳氮同化及其机理的研究也不容忽视。该文综述了C_3和C_4植物氮素利用关键因素的差异及其调控机制,并对提高C_3禾本科作物氮素利用效率的遗传改良途径进行了展望。     

C3和C4植物的氮素利用机制

提高植物的氮素利用效率(NUE)不仅有利于保障全球粮食安全, 也是实现农业可持续发展的重要途径。近半个世纪以来, 植物氮素利用机理研究已取得重要进展, 但NUE的调控机制仍不明确, NUE的提高仍然十分有限。高等植物集光合碳素同化和氮素同化于一体, 只有碳氮代谢相互协调, 才能维持植物体内的碳氮平衡, 保证植物正常生长发育。由于C₃和C₄植物的光合氮素利用率(PNUE)存在差异, 对氮素的利用效率也会存在差异。为了更有效地提高作物的NUE, 须更全面地了解C₃和C₄植物对氮素吸收、转运、同化和信号转导等关键因子的功能和调控机制。此外, 面对大气CO₂浓度增高和全球气候变暖条件下的植物碳氮同化及其机理的研究也不容忽视。该文综述了C₃和C₄植物氮素利用关键因素的差异及其调控机制, 并对提高C₃禾本科作物氮素利用效率的遗传改良途径进行了展望。     

植物氮代谢及其环境调节研究进展

氮代谢是植物的基本生理过程之一,也是参与地球化学循环的重要组成部分,植物氮素同化的主要途径是经过硝酸盐还原为铵后直接参与氨基酸的合成与转化,期间硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酰胺合酶(GOGAT)、天冬酰胺转氨酶(AspAT)等关键酶参与了催化和调节,以氨基酸为主要底物在细胞中合成蛋白质,再经过对蛋白质的修饰、分类、转运及储存等,成为植物有机体的组成部分,同时与植物的碳代谢等协调统一,共同成为植物生命活动的基本过程,文中概述了植物氮素同化的途径、几种关键酶的特性和调控机制,简述了氮素代谢的信号传导、植物细胞蛋白质的形成、转运、储存和降解过程,基于水分胁迫等关键生态因子对氮代谢的影响及其调节机制的评述,强调了未来需加强研究的7个方面。     

丛枝菌根真菌提高植物抗病性的作用机制*

近年来, 人们越来越重视丛枝菌根（AM）真菌对植物病原物的影响和提高植物抗病性的效应。当前建立在分子生物学、免疫学和组织化学技术上的基础研究, 可以从分子水平上深入了解AM真菌提高植物抗病性的作用机制。本文主要探讨AM真菌拮抗植物土传病原物、提高抗病性的可能机制和研究途径。1 AM真菌对植物土传病原物的拮抗作用自然条件下,绝大多数植物都能形成菌根。菌根围（Mycorrhizosphere）内的主要成员：根系、细菌、真菌、线虫等之间往往通过协同和/或拮抗作用达到动态平衡。其中植物—植物间、植物—微生物间、微生物—微生物间、…     

茉莉酸及其甲酯在植物诱导抗病性中的作用

茉莉酸类物质被认为是植物抗病防卫反应的内源及中间信号分子。本文介绍了茉莉酸及其甲酯在植物抗病性中的作用,从它们在体内激活的代谢途径及相关基因表达探讨有关作用机制以及有可能在农业上应用的前景。     

一氧化氮与植物耐盐性

盐胁迫是制约植物生长发育的主要环境因子之一,信号分子一氧化氮（NO）参与调节植物的耐盐性,本文介绍近年来NO合成及其与植物耐盐性关系的研究进展,并讨论了NO可能的作用机制。     

植物的硫同化及其相关酶活性在镉胁迫下的调节

植物对土壤中硫的利用包括根系对硫酸盐的吸收、转运、同化、分配等过程,也是由一系列酶和蛋白质参与和调节的代谢过程。近年来的研究表明,在植物体内,硫同化与植物对镉等重金属元素的胁迫反应机制有着密切关系。镉胁迫能调节植物对硫酸盐的吸收、转运、同化,以及半胱氨酸、谷胱甘肽（glutathione,GSH）和植物螯合肽（Dhytochelatins,pc）的合成。植物在镉胁迫下通过多种调节机制,增强对硫酸盐的吸收和还原,迅速合成半胱氨酸和谷胱甘肽等代谢物,从而合成足够的PC,以满足植物生理的需要。     

转录后基因沉默及其在植物中的应用

本文综述了转录后基因沉默的特点、发生机制和传导途径,及其作为一种抗病毒防卫机制,在植物基因调控表达、改良植物抗病性和植物功能基因组学等方面的应用和进展。     

Chitosan Treatment: An Emerging Strategy for Enhancing Resistance of Greenhouse Tomato Plants to Infection by Fusarium oxysporum f.sp. radicis-lycopersici

The potential of chitosan, a non-toxic and biodegradable polymer of beta -1,4-glucosamine, for controlling fusarium crown and root rot of greenhouse-grown tomato caused by Fusarium oxysporum f.sp. radicis-lycopersici (FORL) was investigated. The amendment of plant growth substratum with chitosan at concentrations of 12.5 or 37.5 mg l-1 significantly reduced plant mortality, root rot symptoms and yield loss attributed to FORL. Maximum disease control was achieved with chitosan at 37.5 mg l-1, when plant mortality was reduced by more than 90% and fruit yield was comparable with that of non-infected plants. In the absence of FORL, chitosan did not adversely affect plant growth and fruit yield. Cytological observations on root samples from FORL-inoculated plants revealed that the beneficial effect of chitosan in reducing disease was associated with increased plant resistance to fungal colonization. In chitosan-treated plants, fungal growth was restricted to the epidermis and the cortex. Invading hyphae showed marked cellular disorganization, characterized by increased vacuolation and even complete loss of the protoplast. The main host reactions included the formation of structural barriers at sites of attempted fungal penetration, the deposition of an opaque material (probably enriched with phenolics according to its electron density) in intercellular spaces and the occlusion of xylem vessels with tyloses, polymorphic bubbles and osmiophilic substances. Although chitosan may also have antifungal properties, the ultrastructural observations provide evidence that chitosan sensitizes tomato plants to respond more rapidly and efficiently to FORL attack. Chitosan has the potential to become a useful agent for controlling greenhouse diseases caused by soil-borne pathogens.     

Signal recognition and transduction mediated by the tomato Pto kinase: a paradigm of innate immunity in plants

Plant disease resistance is the result of an innate host defense mechanism, which relies on the ability of the plant to recognize pathogen invasion and to efficiently mount defense responses. In tomato, resistance to the pathogen Pseudomonas syringae is mediated by the specific interaction between the plant serine/threonine kinase Pto and the bacterial protein AvrPto. This article reviews molecular and biochemical properties that confer to Pto the capability to function as an intracellular receptor and to activate a signaling cascade leading to the induction of defense responses.     

Early events induced by chitosan on plant cells

Chitosan (a polymer of beta-1,4-glucosamine residues) is a deacetylated derivative of chitin which presents antifungal properties and acts as a potent elicitor of plant resistance against fungal pathogens. Attention was focused in this study on the chitosan-induced early events in the elicitation chain. Thus, it was shown that chitosan triggered in a dose-dependent manner rapid membrane transient depolarization of Mimosa pudica motor cells and, correlatively, a transient rise of pH in the incubation medium of pulvinar tissues. By using plasma membrane vesicles (PMVs), it was specified that a primary site of action of the compound is the plasma membrane H(+)-ATPase as shown by its inhibitory effect on the proton pumping and the catalytic activity of the enzyme up to 250 microg ml(-1). As a consequence, chitosan treatment modified H(+)-mediated processes, in particular it inhibited the uptake of the H(+)-substrate co-transported sucrose and valine, and inhibited the light-induced H(+)/K(+)-mediated turgor reaction of motor cells. The present data also allowed the limit of the cytotoxicity of the compound to be established close to a concentration of 100 microg ml(-1) at the plasma membrane level. As a consequence, chitosan could be preferably used in plant disease control as a powerful elicitor rather than a direct antifungal agent.     

蛋白磷酸化修饰在植物-病原微生物互作中的作用研究进展

蛋白磷酸化修饰是植物细胞信号调控的普遍机制。植物-病原微生物互作过程中, 关键调控蛋白的磷酸化状态影响免疫信号的激活。多种病原微生物通过干扰宿主蛋白的磷酸化状态攻击免疫系统, 以提高致病性。该文对植物免疫调控过程中关键元件的磷酸化修饰及其在免疫信号中的调控作用进行了综述。研究植物-病原菌互作过程中关键蛋白的磷酸化修饰, 有助于深入探讨植物-病原微生物互作的分子机理。该文将为寻找广谱抗病的新途径提供理论依据。     

Solution structure of the plant disease resistance-triggering protein NIP1 from the fungus Rhynchosporium secalis shows a novel beta-sheet fold

Activation of the disease resistance response in a host plant frequently requires the interaction of a plant resistance gene product with a corresponding, pathogenderived signal encoded by an avirulence gene. The products of resistance genes from diverse plant species show remarkable structural similarity. However, due to the general paucity of information on pathogen avirulence genes the recognition process remains in most cases poorly understood. NIP1, a small protein secreted by the fungal barley pathogen Rhynchosporium secalis, is one of only a few fungal avirulence proteins identified and characterized to date. The defense-activating activity of NIP1 is mediated by barley resistance gene Rrs1. In addition, a role of the protein in fungal virulence is suggested by its nonspecific toxicity in leaf tissues of host and non-host cereals as well as its resistance gene-independent stimulatory effect on the plant plasma membrane H+-ATPase. Four naturally occurring NIP1 isoforms are characterized by single amino acid alterations that affect the different activities in a similar way. As a step toward unraveling the signal perception/transduction mechanism, the solution structure of NIP1 was determined. The protein structure is characterized by a novel fold. It consists of two parts containing beta-sheets of two and three anti-parallel strands, respectively. Five intramolecular disulfide bonds, comprising a novel disulfide bond pattern, stabilize these parts and their position with respect to each other. A comparative analysis of the protein structure with the properties of the NIP1 isoforms suggests two loop regions to be crucial for the resistance-triggering activity of NIP1.     

植物非寄主抗性研究进展

非寄主抗性是植物对大多数病原微生物最普遍的抗病形式, 由于它具有广谱持久的特性, 因此在农业上有着广阔的应用前景。尽管近年来对植物抗病的分子机理研究取得了很大进展, 但对植物非寄主抗性分子机制仍不十分了解。文章对目前研究的非寄主抗性产生分子机理、植物与病原物的互作系统、PEN1编码的SNARE蛋白参与非寄主抗性、非寄主抗性研究所面临的困难以及今后的发展前景进行了概述。     

壳聚糖对植物病害的抑制作用研究进展

本文综述了甲壳素的重要衍生物－－壳聚糖对植物病害的抑制作用及作用方式,并对壳聚糖对植物病害的抑制作用机制及壳聚糖在农业方面的应用前景作了介绍。     

生物炭介导植物病害抗性及作用机理

生物炭是生物有机材料在缺氧或限氧条件下经高温热裂解后生成的固体产物，在固碳减排、污染修复、土壤改良等方面具有较大的应用潜力。研究表明，生物炭在植物病害胁迫中也起重要的抗性作用。综述了国内外关于生物炭缓解植物病害的相关研究，重点介绍了生物炭在降低病害和提高植物抗性方面的作用机理。生物炭通过诱导植物增强系统抗性，改良土壤理化特性，改变土壤微生物群落结构，增加土壤有益微生物类群的丰度和活性，吸附病原菌及其产生的有毒物质等来降低病原菌对寄主植物的侵害作用，从而促进植物生长和增强植株抗病性。生物炭对病害的抗病效果与生物炭的原料类型、用量、土壤及病害类型等有关。未来的研究应重点应围绕"生物炭-土壤-植物病害"体系，借助组学手段，深入研究生物炭介导植物病害的分子机理。     

Antifungal effect and mechanism of chitosan against the rice sheath blight pathogen, Rhizoctonia solani

The antifungal properties and mechanism of three types of chitosan against the rice sheath blight pathogen, Rhizoctonia solani, were evaluated. Each chitosan had strong antifungal activity against R. solani and protected rice seedlings from sheath blight, in particular, two types of acid-soluble chitosan caused a 60–91?% inhibition in mycelial growth, 31–84?% inhibition of disease incidence, and 66–91?% inhibition in lesion length. The mechanism of chitosan in protection of rice from R. solani pathogen was attributed to direct destruction of the mycelium, evidenced by scanning and transmission electron microscopic observations and pathogenicity testing; indirect induced resistance was evidenced by the changes in the activities of the defense-related phenylalanine ammonia lyase, peroxidase and polyphenol oxidase in rice seedling. To our knowledge, this is the first report on the antifungal activity of chitosan against rice R. solani.     

植物抗病分子机制研究进展

近十年来,植物抗病分子机制研究取得显著进展。综述了植物抗病基因的克隆及其结构分析、病原菌无毒基因及其相关致病因子的克隆与研究、信号传导相关因子的克隆及其结构分析以及植物-病原菌的相互作用研究,重点介绍了以植物特异抗病基因为介导的诱导防卫作用机制(包括抗病基因编码毒素蛋白,进而抑制病原菌的繁殖;显性基因编码病原菌致病性的靶标物;抗病基因表达产物直接引发抗病反应和基因对基因的抗病作用机制等)的研究进展,以期为植物抗病育种提供有益的信息。