寄主——病原物互作

 植物病理学是研究两种生命形式之间关系的科学。所谓寄主——病原物互作,就是在一定条件下,植物发病过程中寄主和病原物相互作用,从而决定发病表型的生理、生化和遗传调控过程。它主要是从寄主——病原物相互关系的角度研究病理过程机制。     

植物-病原菌识别

 按Sequeira(1978)的定义,"植物一病原物识别(recognition)是发生在植物与病原物相互作用早期的一种特定事件(specific event),可以启动(trigger)寄主多方面的快速反应,其后果或是促进、或是抑制病原物的进一步生长(即互作的进一步发展)"。这一定义规定了"识别"的3个主要特征:(1)"制动"作用,识别相当于互作的"开关"或"制动器".     

《植物保护》2011年第1期各栏目最受读者关注的文章

专论与综述1.傅本重.植物与病原物互作中的生物膜研究2.罗沙,余柳青,刘都才,等.稻田稗草对二氯喹啉酸的抗药性研究进展研究报告     

植物抗病基因研究进展

 植物抗病基因的研究是目前植物病理学科的热点及难点之一。R基因的克隆与鉴定促进了寄主与病原物互作分子机制研究的深入。本文就近几年来对植物R基因的克隆、结构与功能,R基因信号传导途径和R基因的进化等方面的研究进展作一评述。     

植物与病原物互作中的生物膜研究

生物膜是一种附着于生命或非生命物体表面的有特殊结构和功能的微生物群落。它广泛地存在于自然界和人工环境中。本文对细菌生物膜的定义、形成过程、影响因素、抗性机制以及在植物与病原物互作中的研究作了简要综述。     

植物抗病过程中的活性氧代谢(二)——植物抗病过程中活性氧的作用与引起活性氧产生的信号传导

植物在抵御外来病原物侵染的过程中能产生大量活性氧 ,特别是过氧化氢 (H2 O2 )与超氧化物阴离子自由基 (O· - 2 )。在病原物与寄主植物发生亲和互作与非亲和互作的过程中 ,活性氧的产生与累积表现出不同的特点 ,亲和互作中活性氧产生与累积的速度与程度都明显强于非亲和互作 ;同时寄主植物体内与活性氧代谢相关的酶类活性也发生相应的变化。研究表明 ,植物抗病过程中产生的活性氧具有重要的作用。本文将从活性氧在植物抗病过程中的作用及引起活性氧产生的信号传导等方面介绍植物抗病过程中的活性氧代谢。1　活性氧在植物抗病过程中的作…     

植物防卫基因研究进展

植物在与病原微生物共同进化的过程中，发展了一系列拮抗病原物侵染的复杂的防御反应体系。在植物与病原互作中，有大量的基因诱导表达，它们编码的蛋白质参与植物对病原物的防卫生反应，这类基因称之为防卫相关基因（defense related genes)，或简称为防卫基因（defense genes)。根据防卫基因表达产物及其功能，可大致分为次生物质合成基因、水解酶和病程相关基因、细胞壁修饰有关基因和清除活性氧的细胞内防卫酶系统基因四大类。从1902年人们发现病原物侵染而引起植物过敏反应起，人们对防卫反应进行了广泛深入的研究，到目前为止，防卫基因仍然是植保和遗传学家们研究的前沿和重点。     

拟南芥BOI 基因在抗氧化胁迫和细胞死亡中的功能分析

 本文利用BOI(Botrytis Susceptible 1 Interactor)基因敲减(knock-down) 株系、过量表达株系以及烟草瞬时表达系统,研究了BOI 基因在细胞程序化死亡(PCD)中的作用以及BOI 蛋白中RING 和WRD 结构域的功能。结果表明,BOI 基因的表达下调导致抗氧化胁迫能力下降,弱化了对活性氧介导的PCD 抑制作用;BOI 过量表达或瞬间表达可以增强对活性氧介导和α-吡啶甲酸诱导的PCD 的抑制作用。进一步研究发现,BOI 蛋白中的RING 结构域是BOI 抑制PCD 所必需的,WRD 结构域与BOI 对PCD 的抑制作用关系不大。     

植物受病原物诱导启动子概述

植物受病原物诱导启动子是一类能对病原物的侵染作出响应的启动子,其活性主要局限于被侵染之时及被侵染的位点。植物受病原物诱导启动子的这一特性赋予其在抗病基因工程中潜在的应用价值。相比植物庞大的启动子组,已发现的植物受病原物诱导启动子仍是少数,关于其作用机制的研究仍有待加强和深入,而其调控的基因与植物抗病性关系还需要引起足够的重视。作者在对植物受病原物诱导启动子进行归类的基础上,重点关注了病原物诱导启动子调控基因的编码产物与植物抗病性的关系,对植物受病原物诱导启动子的顺式调控元件作了简要分析,并对该领域的发展动向进行了讨论。     

水稻与白叶枯病菌互作的功能基因组学研究

水稻白叶枯病是水稻生产上重要的细菌病害之一。随着水稻和白叶枯病菌(Xanthomonas oryzaepv.oryzae,Xoo)全基因组序列的完成,该病害己成为植物-病原物互作研究的模式。水稻-Xoo互作涉及到寄主与病原菌因子的时空表达和严密调控。因此,阐明互作基因的表达调控机理,对于全面解析水稻-Xoo互作机制具有重要的科学意义。本文介绍了近年相关工作的研究进展。1Xoo基因鉴别和功能分析1.1Xoo侵染的基因表达谱和分子量化根据Xoo基因组序列信息,自主研制了载有调控基因、致病基因、特有基因以及保守基因特异片段的基因芯片,成功地用于在离体培养、…     

番茄细菌性斑点病菌无毒基因研究进展

番茄细菌性斑点病是影响番茄产量和品质的重要病害,Pseudomonas syringaepv.tomato(Pst)为其病原菌,其与番茄的互作系统是研究植物抗感病机理的典型模式系统。Pst存在2种无毒基因:avrPto和avrPtoB,它们编码的蛋白质均能与番茄抗性基因Pto编码的Ser-Thr蛋白激酶互作,符合Flor"基因对基因"学说。AvrPto和AvrPtoB在表达Pto的抗性植物中,与Pto互作,表现无毒功能,引发植物防御反应;而在缺失Pto的感病植物中,它们具有毒性,促进细菌的生长。本文综述了番茄细菌性斑点病菌无毒基因avrPto及avrPtoB的结构特点及其功能,这有助于了解病原物与植物的互作机制,对认识植物的感病性、抗病性以及植物防御反应都具有重要意义。     

Differential effects of phenylalanine ammonia lyase, cinnamyl alcohol dehydrogenase, and energetic metabolism inhibition on resistance of appropriate host and nonhost cereal-rust interactions

ABSTRACT Effects of phenylpropanoid and energetic metabolism inhibition on resistance were studied during appropriate host and nonhost cereal-rust interactions. In the appropriate barley-Puccinia hordei interaction, phenylalanine ammonia lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD) inhibition reduced penetration resistance in two genotypes, suggesting a role for phenolics and lignins in resistance. Interestingly, penetration resistance of the barley genotype 17.5.16 was not affected by phenylpropanoid biosynthesis but penetration resistance was almost completely inhibited by D-mannose, which reduces the energy available in plant host cells. This suggests a parallel in the cellular basis of penetration resistance between 17.5.16 rust and mlo barleys powdery mildew interaction. Results revealed differing patterns of programmed cell death (PCD) in appropriate versus nonhost rust interactions. PAL and CAD inhibitors reduced PCD (hypersensitivity) in appropriate interactions. Conversely, they had no effect in PCD of wheat to P. hordei; whereas D-mannose dramatically reduced nonhost resistance and allowed colony establishment. The differential effects of inhibitors in the expression of the different resistances and the commonalities with the cereal-powdery mildew interaction is analyzed and discussed.     

Two phases of intracellular reactive oxygen species production during victorin-induced cell death in oats

Reactive oxygen species (ROS) are thought to be involved in various forms of programmed cell death (PCD) in animal and plant cells. PCD, along with the production of ROS, occurs during plant–pathogen interactions. Here we show that victorin, a host-specific toxin produced by Cochliobolus victoriae, which causes victoria blight of oats, induces two phases of intracellular ROS production in victorin-sensitive oat mesophyll cells. The initial production of ROS is restricted at mitochondria and not accompanied with cellular oxidative damage. Later production of ROS is dispersed into cells concomitant with lipid peroxidation, chloroplast dysfunction, and cell death. Superoxide dismutase can clearly suppress the initial ROS production and delay the progression of cell death. These data indicate that the initial ROS production may be involved in the cell death induction process, and the later ROS production may play important roles in events leading to cellular disruption.     

Pathogenicity and infectivity of Phytophthora ramorum vary depending on host species,infected plant part,inoculum potential,pathogen genotype,and temperature

A total of 25 ornamental plant species representing 10 families were inoculated using three genotypes, each representing one of the genetic lineages NA1, NA2, and EU1 of the pathogen Phytophthora ramorum. Leaves were inoculated using suspensions with two zoospore concentrations and exposure at three temperatures, while stems were inoculated using agar plugs colonized by mycelia. Susceptibility was determined by measuring either the success of pathogen reisolation or lesion length caused by the pathogen. Infectivity was determined by counting sporangia in washes of inoculated leaves or stems. Results from all three pathogen genotypes combined were used to rank each of the 25 plant species for susceptibility and infectivity, while pooled results per genotype from all 25 hosts combined were employed for a preliminary comparison of pathogenicity and infectivity among genotypes. Statistical analyses showed that leaf results were affected by the concentration of zoospores, temperature, plant host, pathogen genotype, and by the interaction between host and pathogen genotype. Stem results were mostly affected by host and by the interaction between host and pathogen genotype. Hosts ranked differently when looking at the various parameters, and differences in rankings were also significant when comparing stem and leaf results. Differences were identified among the 25 hosts and the three pathogen genotypes for all parameters: results can be used for decision-making regarding regulations or selection of plants to be grown where infestations by P. ramorum are an issue.     

Morphological and histochemical investigation of the response of Olea europaea leaves to fungal attack by Spilocaea oleagina

This study investigated the response of Olea europaea (cv. Conservolea) leaves to attack by the fungal pathogen Spilocaea oleagina. Cryostat and semithin sections of healthy and S. oleagina‐infected olive leaves were analysed histochemically for polyphenol oxidase (PPO) activity and tested for programmed cell death (PCD) induction by means of terminal deoxynucleotidyl transferase‐mediated dUTP nick end labelling (TUNEL). At all stages of infection, the fungus remained localized between the external and internal layers of cuticle without crossing the pectocellulosic layer. No PCD phenomena could be detected in plant cells at any stage of the disease. However, extensive degeneration of palisade parenchyma cells was observed in advanced infections, with massive loss of cytoplasmic contents and disappearance of cell compartments. Polyphenol oxidases are enzymes that, in olive, oxidize o‐diphenols (principally oleuropein and rutin) to produce o‐diquinones and melanins, substances that are toxic to many pathogens. No significant increase in overall PPO activity was found in infected leaves; on the contrary, enzyme activity was gradually lost as infection progressed, most probably due to degradation of plastids within mesophyll cells, in which such enzymes are normally confined. Only a limited local PPO activation occurred in a few upper epidermal cells of the leaf, indicating a feeble induction of a plant response.     

绿色荧光蛋白在植物病理学研究中的应用

绿色荧光蛋白（green fluorescent protein, GFP）是生命科学研究中的一种重要报告基因,本文在论述GFP的发现、结构和发光原理的基础上,从抗病基因的亚细胞定位、启动子活性分析、病原菌 植物互作研究和基因表达分析等方面讨论GFP在植物病理学研究中的应用。     

Techniques for the treatment, removal and disposal of host material during programmes for plant pathogen eradication

Eradication of plant pathogen incursions is very important for the protection of plant industries, managed gardens and natural environments worldwide. The consequence of a pathogen becoming endemic can be serious, in some cases having an impact on the national economy. The current strategy for eradication of a pathogen relies on techniques for the treatment, removal and disposal of affected host plants. There are many examples where these techniques have been successful but many where they have not. Success relies on a sound understanding of the biology and epidemiology of the pathogen and its interaction with the host. Removal and disposal of infected plant material for eradication and containment of plant and soil inhabiting fungal, bacterial and viral pathogens are reviewed by considering black Sigatoka of banana, apple scab, maize smut, fireblight, citrus canker and sharka disease of stone-fruit crops. In examining examples of dealing with plant pathogens and diseased host material around the world, particularly Australasia, various techniques including burning, burying, pruning, composting, soil- and biofumigation, solarization, steam sterilization and biological vector control are discussed. Gaps in the literature are identified and emphasize the insufficient detail of information available from past eradications. More effort is required to produce and publish scientific evidence to support the success or otherwise of techniques and suggestions for future research are proposed.     

Temporal dynamics of pathogenesis-related metabolites and their plausible pathways of induction in potato leaves following inoculation with <Emphasis Type="Italic">Phytophthora infestans</Emphasis>

Metabolite profiles based on GC/MS were used to study the temporal dynamics of metabolites in potato leaves following pathogen inoculation. In the polar and non-polar plant extracts a total of 106 consistent peaks were detected, of which 95 metabolites were tentatively identified. Following pathogen inoculation, the abundances of 42 metabolites were significantly increased or decreased, and these metabolites were designated as Pathogenesis-Related (PR) Metabolites. Factor analysis of the abundance of 106 metabolites identified four plant–pathogen interaction functions: (i) homeostasis; (ii) primary defence; (iii) secondary defence; (iv) collapse of primary and secondary defence responses. During the primary and secondary defence phases, dramatic changes in the amino acids, known precursors of several plant defence-related metabolites, were observed. Plausible satellite-networks of metabolic pathways leading to the up-regulation of these families of amino acids and other secondary metabolites, and their potential application for the evaluation of horizontal resistance in potato against the late blight pathogen is discussed.     

Neue Erkenntnisse zur Biodiversität des Apfelmehltau-Erregers

Apple powdery mildew is one of the main fungal diseases in commercial apple production. High amounts of fungicides are applied to reduce the damage caused by the pathogen. The main objective in the extension of integrated fruit production is the reduction of the amount of applied pesticides in order to minimize adverse effects on the environment and consumers. To develop successful alternatives to the chemical plant protection a detailed knowledge about the host-pathogen-interaction is required. In the interaction of the host plant apple and the powdery mildew pathogen much research has been carried out on the plant side. Within the framework of an EU-funded project the apple powdery mildew pathogen has now been characterised by molecular analyses and in pathogenicity tests. The objective was to determine the variability between mildew samples of European and Asian origin. The results show a high level of variability regarding the pathogenicity of the tested isolates. On the molecular level it was possible to distinguish between two separate major groups of isolates. The relevance of these results for apple breeding is discussed.