Rhizosphere immunity: targeting the underground for sustainable plant health management

Managing plant health is a great challenge for modern food production and is further complicated by the lack of common ground between the many disciplines involved in disease control. Here we present the concept of rhizosphere immunity, in which plant health is considered as an ecosystem level property emerging from networks of interactions between plants, microbiota and the surrounding soil matrix. These interactions can potentially extend the innate plant immune system to a point where the rhizosphere immunity can fulfil all four core functions of a full immune system: pathogen prevention, recognition, response and homeostasis. We suggest that considering plant health from a meta-organism perspective will help in developing multidisciplinary pathogen management strategies that focus on steering the whole plant-microbe-soil networks instead of individual components. This might be achieved by bringing together the latest discoveries in phytopathology, microbiome research, soil science and agronomy to pave the way toward more sustainable and productive agriculture.     

A bacterial virulence protein suppresses host innate immunity to cause plant disease

Plants have evolved a powerful immune system to defend against infection by most microbial organisms. However, successful pathogens, such as Pseudomonas syringae, have developed countermeasures and inject virulence proteins into the host plant cell to suppress immunity and cause devastating diseases. Despite intensive research efforts, the molecular targets of bacterial virulence proteins that are important for plant disease development have remained obscure. Here, we show that a conserved P. syringae virulence protein, HopM1, targets an immunity-associated protein, AtMIN7, in Arabidopsis thaliana. HopM1 mediates the destruction of AtMIN7 via the host proteasome. Our results illustrate a strategy by which a bacterial pathogen exploits the host proteasome to subvert host immunity and causes infection in plants.     

园艺植物 WRKY 基因功能研究进展

WRKY 转录因子是植物中特有的一类反式作用因子。WRKY 基因家族成员众多,是植物中最大的转录因子家族之一。目前,已在多种园艺植物中对该家族进行了全基因组鉴定。大量研究表明,WRKY 转录因子参与了植物中多种生物学过程,如营养剥夺、胚胎发生、种子发育、毛状体发育、叶片衰老及其他发育和激素调节的过程,是许多调控信号网络的重要组成部分。WRKY 转录因子还可参与植物适应各种逆境的转录调控,已被证明其在生物应激反应中发挥重要作用并参与植物的防御机制,其在植物防御病菌、病毒和虫害调控过程中的重要作用正被逐步揭示。此外,WRKY 转录因子在植物响应环境中非生物胁迫方面的作用也被不断解析,其可参与调控植物对干旱、温度、盐及渗透的响应,并在此过程中发挥正向或负向调节作用。本文基于近年来的相关研究成果,重点综述了 WRKY 转录因子在园艺植物生长发育、胁迫响应和代谢合成方面所发挥的作用和调控机理,进一步明确园艺植物 WRKY 转录因子的重要生物学功能,阐明 WRKY 转录因子介导的转录调控网络,为园艺植物优良性状相关的遗传资源挖掘和分子育种提供理论支撑。     

Herpesviral protein networks and their interaction with the human proteome

The comprehensive yeast two-hybrid analysis of intraviral protein interactions in two members of the herpesvirus family, Kaposi sarcoma-associated herpesvirus (KSHV) and varicella-zoster virus (VZV), revealed 123 and 173 interactions, respectively. Viral protein interaction networks resemble single, highly coupled modules, whereas cellular networks are organized in separate functional submodules. Predicted and experimentally verified interactions between KSHV and human proteins were used to connect the viral interactome into a prototypical human interactome and to simulate infection. The analysis of the combined system showed that the viral network adopts cellular network features and that protein networks of herpesviruses and possibly other intracellular pathogens have distinguishing topologies.     

蛋白质互作组学技术及其在植物 研究中的应用进展

蛋白质互作组学技术是一门鉴定和量化蛋白质与其他代谢物或蛋白质等分子相互作用的前沿技 术,已成为研究植物系统生物学和多组学研究的重要组成部分。近年来,基于质谱的组学技术迅速发展,也促 进蛋白质 - 代谢物相互作用（Protein-metabolite interaction, PMI）、蛋白质 - 蛋白质相互作用（ Protein-protein interaction, PPI）的发现和验证方法取得巨大进步 , 这些蛋白质互作组学技术在功能基因组和功能代谢组研究中 逐渐展示出巨大的应用潜力。系统总结了过去 10 年不同蛋白质互作组学技术（主要包括 PMI 和 PPI）的分析策略, 并详细分析了它们各自的优缺点和适用的相互作用类型,综述了蛋白质互作组学技术在植物研究领域的应用进 展,对植物蛋白质互作组学技术的应用策略和需要攻克的关键技术瓶颈进行了总结。蛋白质互作组学技术的不 断发展将进一步推动植物胞内信号转导及代谢调控通路的解析,而精准解析信号网络中关键相互作用将为植物 自身生长发育以及适应外界环境等机制研究提供重要的信息。     

Novel understanding of Trichoderma interaction mechanisms

Trichoderma- based biofungicides are a reality in commercial agriculture, with more than 50 formulations registered worldwide as biopesticides or biofertilizers. Several research strategies have been applied to identify the main genes and compounds involved in the complex, three-way interactions between fungal antagonists, plants and microbial pathogens. Proteome and genome analyses have greatly enhanced our ability to conduct targeted and genome-based functional studies. We have obtained repr…     

几丁质触发植物免疫的研究现状与展望

真菌病害是植物病害中最为严重的一种,世界上70%—80%的植物病害都是由真菌引起。几丁质是病原真菌细胞壁的重要组成成分,是一种典型的病原相关分子模式（pathogen-associated molecular pattern,PAMP）。当植物受到病原真菌入侵,位于细胞膜上的模式识别受体（pattern recognition receptor,PRR）能够直接与几丁质及其寡糖相互作用并触发植物的免疫反应。近几年,随着植物几丁质受体的成功鉴定,其与几丁质的相互作用机制以及几丁质触发植物免疫的分子机理被广泛研究,并取得了许多重要进展。为了较全面、系统地反应几丁质触发免疫研究的历史沿革、研究现状和发展趋势,笔者就植物对几丁质的识别机制、信号转导以及病原真菌对几丁质触发的免疫反应的抑制机制这3方面进行了综述,并对未来研究的发展方向进行了探讨。     

RNA interference directs innate immunity against viruses in adult Drosophila

Innate immunity against bacterial and fungal pathogens is mediated by Toll and immune deficiency (Imd) pathways, but little is known about the antiviral response in Drosophila. Here, we demonstrate that an RNA interference pathway protects adult flies from infection by two evolutionarily diverse viruses. Our work also describes a molecular framework for the viral immunity, in which viral double-stranded RNA produced during infection acts as the pathogen trigger whereas Drosophila Dicer-2 and Argonaute-2 act as host sensor and effector, respectively. These findings establish a Drosophila model for studying the innate immunity against viruses in animals.     

Disease tolerance as a defense strategy

The immune system protects from infections primarily by detecting and eliminating the invading pathogens; however, the host organism can also protect itself from infectious diseases by reducing the negative impact of infections on host fitness. This ability to tolerate a pathogen's presence is a distinct host defense strategy, which has been largely overlooked in animal and human studies. Introduction of the notion of "disease tolerance" into the conceptual tool kit of immunology will expand our understanding of infectious diseases and host pathogen interactions. Analysis of disease tolerance mechanisms should provide new approaches for the treatment of infections and other diseases.     

Deciphering the rhizosphere microbiome for disease-suppressive bacteria

Disease-suppressive soils are exceptional ecosystems in which crop plants suffer less from specific soil-borne pathogens than expected owing to the activities of other soil microorganisms. For most disease-suppressive soils, the microbes and mechanisms involved in pathogen control are unknown. By coupling PhyloChip-based metagenomics of the rhizosphere microbiome with culture-dependent functional analyses, we identified key bacterial taxa and genes involved in suppression of a fungal root pathogen. More than 33,000 bacterial and archaeal species were detected, with Proteobacteria, Firmicutes, and Actinobacteria consistently associated with disease suppression. Members of the γ-Proteobacteria were shown to have disease-suppressive activity governed by nonribosomal peptide synthetases. Our data indicate that upon attack by a fungal root pathogen, plants can exploit microbial consortia from soil for protection against infections.     

Expression Comparisons of Pathogenesis-Related (PR) Genes in Wheat in Response to Infection/Infestation by Fusarium,Yellow dwarf virus (YDV) Aphid-Transmitted and Hessian Fly

Expression profiles of ten pathogenesis-related (PR) genes during plant defense against Fusarium, Yellow dwarf virus (YDV) aphid-transmitted and Hessian fly (Hf) were compared temporally in both resistant and susceptible genotypes following pathogen infection or insect infestation. Quantitative real-time PCR (qRT-PCR) revealed that PR1, PR2, PR3, PR5, PR6, PR8, PR9, and PR15 appeared to be induced or suppressed independently in response to Fusarium, YDV aphid-transmitted or Hf during the interactions. The PR gene(s) essential to defense against one organism may play little or no role in defense against another pathogen or pest, suggesting the alternative mechanisms may be involved in different interactions of wheat-Fusarium, wheat-YDV aphid-transmitted and wheat-Hf. However, strong up- or down-regulation of PR12 and PR14 encoding low molecular membrane acting protein, defensin and lipid transfer protein (LTP), respectively, had been detected after either pathogen infection or insect infestation, therefore showed broad responses to pathogens and insects. It was postulated that low molecular proteins such as defensins and LTPs might play a role in the early stages of pathogenesis in the signaling process that informs plants about the attack from biotic stresses. In addition, a synergistic action between different PR genes might exist in plants to defense certain pathogens and insects on the basis of comprehensive expression profiling of various pathogenesis-related genes revealed by qRT-PCR in this study.     

Three Sclerotinia species as the cause of white mold on pea in Chongqing and Sichuan of China

White mold of pea caused by Sclerotinia sclerotiorum is a common disease in China. However, we discovered that the diverse Sclerotinia species could cause white mold on pea plants in Chongqing and Sichuan of China during recent disease surveys. Thus, the objective of this study was to confirm the causal agents from diseased pea plants. The obtained isolates of white mold from Chongqing and Sichuan were identified by morphological characters and molecular characterization to determine the pathogen species, and their pathogenicity was confirmed on pea through completing Koch's postulates. Fungal isolates of Sclerotinia-like were obtained from diseased plants or sclerotia. Based on morphological characteristics and molecular characterization, 30 isolates were identified to three species, six isolates as S. minor, seven as S. sclerotiorum, and 17 as S. trifoliorum. In pathogenicity tests on pea cultivars Zhongwan 4 and Longwan 1, all 30 isolates caused typical symptoms of white mold on the inoculated plants, and the inoculated pathogens were re-isolated from the diseased plants. This study confirmed that white mold of pea was caused by three Sclerotinia species, S. sclerotiorum, S. minor and S. trifoliorum in Chongqing and Sichuan. It is the first report that S. minor and S. trifoliorum cause white mold of pea in Southwest China.     

番茄SlβCA3在防御丁香假单胞菌番茄致病变种中的功能

【背景】在全球气候变化的背景下,大气CO₂浓度的升高会影响植物病害的发生,进而影响农业生产。β型碳酸酐酶（β- carbonic anhydrase,βCA）是植物CO₂感应和浓缩系统中的重要组成元件,参与拟南芥和烟草的植物免疫过程,但在番茄（Solanum lycopersicum）等园艺作物中的研究较少。【目的】通过探究番茄SlβCA3在抵御植物病害中的作用及机制,为番茄生产中的抗性调控提供科学依据。【方法】以拟南芥AtβCA氨基酸系列为参考序列,在番茄Sol genomics network 数据库中鉴定到4个SlβCA。进一步以野生型（wild-type,WT）番茄‘Ailsa Craig’（AC）为材料接种丁香假单胞菌番茄致病变种（Pseudomonas syringae pv. tomato DC3000,Pst DC3000）,利用qRT-PCR技术测定叶片中SlβCA的表达量,筛选出受Pst DC3000诱导表达的基因SlβCA3。在此基础上,以AC为背景,利用农杆菌介导法进行番茄遗传转化,构建SlβCA3稳定过表达植株（OE-SlβCA3）。通过观察OE-SlβCA3植株接种Pst DC3000后的抗性表型,明确SlβCA3在番茄抵御Pst DC3000过程中的作用。为了研究SlβCA3调控植物抗病性的内在机制,比较WT和OE-SlβCA3植株接种Pst DC3000与对照条件下转录组的变化,并利用KEGG数据库对差异基因进行功能分析,推测糖代谢与SlβCA3介导的免疫反应有关。最后,通过测定WT和OE-SlβCA3植株糖代谢及其信号途径相关基因表达量以及葡萄糖、果糖和蔗糖含量,对转录组结果进行验证及分析。【结果】OE-SlβCA3植株对Pst DC3000的抗性增强,接种Pst DC3000后,叶片中的细菌生长量、病斑数以及死细胞积累量明显减少。转录组测序结果显示,正常条件下,OE-SlβCA3植株转录谱没有发生明显变化;接种Pst DC3000后,在WT和OE-SlβCA3植株中检测到2 100个Pst DC3000诱导基因,其中有63.3%的基因在OE-SlβCA3植株中表达量更高。KEGG分析结果显示,依赖于SlβCA3过表达的Pst DC3000诱导基因富集在糖代谢相关路径中,包括淀粉和蔗糖代谢,内质网中的蛋白质加工（糖基化）,氨基糖和核苷酸糖代谢,真核生物中的核糖体生物合成以及光合作用等路径。糖代谢与糖信号密不可分,qRT-PCR及糖含量测定结果显示,接种Pst DC3000后,OE-SlβCA3植株叶片中糖代谢及其信号传导途径相关基因表达量与葡萄糖、果糖和蔗糖的含量较WT更高。【结论】番茄SlβCA3的过表达增强了植株对Pst DC3000的抗性,该过程可能与糖代谢及其信号通路在植物免疫中的作用有关。     

植物与有益微生物互作的分子基础及其应用的研究进展

植物与微生物在长期的侵染和抗侵染过程中逐渐形成了复杂的互作关系,二者相互利用、协同进化。一些病原微生物致病能力的变化或增强迫使植物提高抗病性,同时改进了植物的农艺性状、产量性状和品质性状。植物与微生物互作关系的分子生物学研究促进了植物基因工程育种途径的创立和生产潜力的提高,尤其微生物介导的基因转移已成为改良植物的重要工具。本文概括性综述了植物与一些主要有益微生物互作的应答反应、信号传导和分子基础,以及利用有益微生物对改良植物性状和生产水平的研究进展。描述了植物对主要有益微生物的应答途径,以及植物和农杆菌、根瘤菌、真菌及植物病毒互作的分子信号系统,并介绍了它们在基因工程、遗传育种和生产实践中的应用。对于人们正确认识有益微生物的两面性,改变传统观念,进一步利用有益微生物的正向作用提高植物抗病性、抗逆性、品质和生产潜力,培育优良作物品种等,具有一定参考价值。     

Has the microbiota played a critical role in the evolution of the adaptive immune system?

Although microbes have been classically viewed as pathogens, it is now well established that the majority of host-bacterial interactions are symbiotic. During development and into adulthood, gut bacteria shape the tissues, cells, and molecular profile of our gastrointestinal immune system. This partnership, forged over many millennia of coevolution, is based on a molecular exchange involving bacterial signals that are recognized by host receptors to mediate beneficial outcomes for both microbes and humans. We explore how specific aspects of the adaptive immune system are influenced by intestinal commensal bacteria. Understanding the molecular mechanisms that mediate symbiosis between commensal bacteria and humans may redefine how we view the evolution of adaptive immunity and consequently how we approach the treatment of numerous immunologic disorders.     

常见病原菌MAMPs在植物天然免疫中的作用

MAMPs又称病原相关分子模式,在植物的抗病性中发挥着重要作用。在充满潜在致病微生物的环境中,植物能够很好地存活下来,主要功劳在于其具有强大的病原体识别体系和快速的免疫应答系统。植物可以从寄生病原菌和非寄生病原菌中识别几种通用的MAMPs。MAMPs对于病原菌微生物来说,经常是序列高度保守且组成结构不可缺少的。在植物中,MAMPs被其相对应的PRRs识别的过程称为微生物或病原菌引起的免疫。主要介绍了几种常见的MAMPs及其在植物天然免疫研究中的作用。     

Genome-wide RNAi screen for host factors required for intracellular bacterial infection

Most studies of host-pathogen interactions have focused on pathogen-specific virulence determinants. Here, we report a genome-wide RNA interference screen to identify host factors required for intracellular bacterial pathogenesis. Using Drosophila cells and the cytosolic pathogen Listeria monocytogenes, we identified 305 double-stranded RNAs targeting a wide range of cellular functions that altered L. monocytogenes infection. Comparison to a similar screen with Mycobacterium fortuitum, a vacuolar pathogen, identified host factors that may play a general role in intracellular pathogenesis and factors that specifically affect access to the cytosol by L. monocytogenes.     

碱蓬属植物耐盐机理研究进展

碱蓬属(Suaeda)植物是一类典型的真盐生植物,属于重要的盐生植物资源,全球广泛分布.人们已经对20种碱蓬属植物进行了观察和盐胁迫实验,研究了不同器官或组织的生理生化特征及其对盐胁迫的反应,并基于这些研究分析了盐胁迫的应答机制.叶片肉质化、细胞内离子区域化、渗透调节物质增加和抗氧化系统能力增强是碱蓬属植物响应和适应盐胁迫的重要方式和途径.但迄今为止的研究工作尚有一定的局限性,主要包括:研究工作主要集中在植物地上部分,而对植物地下部分的研究较少;多是少数生物学指标或生理学现象的单独观察,而缺乏对生理代谢过程的整体和综合分析;针对某种碱蓬的独立分析较多,而与近缘种的比较研究较少;植物对中性盐胁迫的反应研究较多,而对碱性盐的研究较少.为进一步系统阐明碱蓬属植物的耐盐机制,今后的工作应注重碱蓬属植物响应和适应盐胁迫的信号网络和调控机制研究,基于系统生物学研究思路,采用现代组学技术探索该属植物响应盐胁迫的由复杂信号网络调控的特殊生理特征和特异代谢途径.     

核盘菌（Sclerotinia sclerotiorum）致病分子机理研究进展

核盘菌[Sclerotinia sclerotiorum (Lib.) de Bary]可以侵染包括油菜、大豆、向日葵等多种重要农作物在内的400多种植物,引致严重病害,对植物生产危害极大,越来越引起人们的重视.随着分子生物学技术在核盘菌研究中的应用,人们对其致病机理的研究也越来越深入.作者从细胞壁降解酶类、草酸毒素、侵染垫的形成和菌核形成的影响因素以及其与寄主的互作等方面,对核盘菌的分子致病机理研究进行了综述.