植物与病原菌互作的蛋白质组学研究进展

蛋白质组学作为功能基因组学研究的主要内容之一,在阐述基因功能、了解生命现象和本质的分子机制等方面发挥着重要作用。植物蛋白质组学作为蛋白质组学的一个分支,研究应用也越来越广泛,尤其是探索植物与病原菌互作机制是其中的一个研究热点。本文就多年来植物与真菌、病毒、细菌互作的蛋白质组学研究做一综述,并对当前该领域今后的研究方向进行展望,以期为相关研究提供一些参考和理论基础。     

Priming in plant-pathogen interactions

Plants can acquire enhanced resistance to pathogens after treatment with necrotizing attackers, nonpathogenic root-colonizing pseudomonads, salicylic acid, beta-aminobutyric acid and many other natural or synthetic compounds. The induced resistance is often associated with an enhanced capacity to mobilize infection-induced cellular defence responses - a process called 'priming'. Although the phenomenon has been known for years, most progress in our understanding of priming has been made only recently. These studies show that priming often depends on the induced disease resistance key regulator NPR1 (also known as NIM1 or SAI1) and that priming has a major effect on the regulation of cellular plant defence responses.     

Recognition and response in plant-pathogen interactions

Most plants are resistant to the majority of pathogens. Susceptibility is the exception to the more common state of resistance, i.e., being refractory to infection. However, plant pathogens cause serious economic losses by reducing crop yield and quality. Although such organisms are relatively simple genetic entities, in plants, the mechanisms underlying the generation of disease symptoms and resistance responses are complex and, often, unknown. The study of genes associated with plant-pathogen resistance addresses fundamental questions about the molecular, biochemical, cellular, and physiological means of these interactions. Over the past 10 years, the cloning and analysis of numerous plant resistance genes has led researchers to formulate unifying theories about resistance and susceptibility, and the co-evolution of plant pathogens and their hosts. In this review, we discuss the identification of response genes that have been characterized at the molecular level, as well as their putative links to various signaling pathways. We also summarize the knowledge regarding crosstalk among signaling pathways and plant resistance genes.     

Protein acetylation and deacetylation in plant-pathogen interactions

Protein acetylation and deacetylation catalysed by lysine acetyltransferases (KATs) and deacetylases (KDACs), respectively, are major mechanisms regulating various cellular processes. During the fight between microbial pathogens and host plants, both apply a set of measures, including acetylation interference, to strengthen themselves while suppressing the other. In this review, we first summarize KATs and KDACs in plants and their pathogens. Next, we introduce diverse acetylation and deacetylation mechanisms affecting protein functions, including the regulation of enzyme activity and specificity, protein–protein or protein-DNA interactions, subcellular localization and protein stability. We then focus on the current understanding of acetylation and deacetylation in plant–pathogen interactions. Additionally, we also discuss potential acetylation-related approaches for controlling plant diseases.     

Respiratory protein interactions in Dehalobacter sp. strain 8M revealed through genomic and native proteomic analyses

Dehalobacter (Firmicutes) encompass obligate organohalide-respiring bacteria used for bioremediation of groundwater contaminated with halogenated organics. Various aspects of their biochemistry remain unknown, including the identities and interactions of respiratory proteins. Here, we sequenced the genome of Dehalobacter sp. strain 8M and analysed its protein expression. Strain 8M encodes 22 reductive dehalogenase homologous (RdhA) proteins. RdhA D8M_v2_40029 (TmrA) was among the two most abundant proteins during growth with trichloromethane and 1,1,2-trichloroethane. To examine interactions of respiratory proteins, we used blue native gel electrophoresis together with dehalogenation activity tests and mass spectrometry. The highest activities were found in gel slices with the highest abundance of TmrA. Protein distributions across gel lanes provided biochemical evidence that the large and small subunits of the membrane-bound [NiFe] uptake hydrogenase (HupL and HupS) interacted strongly and that HupL/S interacted weakly with RdhA. Moreover, the interaction of RdhB and membrane-bound b-type cytochrome HupC was detected. RdhC proteins, often encoded in rdh operons but without described function, migrated in a protein complex not associated with HupL/S or RdhA. This study provides the first biochemical evidence of respiratory protein interactions in Dehalobacter, discusses implications for the respiratory architecture and advances the molecular comprehension of this unique respiratory chain.     

Nitric oxide signaling in plant-pathogen interactions

Nitric oxide (NO), first characterized as an endothelium-derived relaxation factor, is involved in diverse cellular processes including neuronal signaling, blood pressure homeostasis, and immune response. Recent studies have also revealed a role for NO as a signaling molecule in plants. As a developmental regulator, NO promotes germination, leaf extension and root growth, and delays leaf senescence and fruit maturation. Moreover, NO acts as a key signal in plant resistance to incompatible pathogens by triggering resistance-associated hypersensitive cell death. In addition, NO activates the expression of several defense genes (e.g. pathogenesis-related genes, phenylalanine ammonialyase, chalcone synthase) and could play a role in pathways leading to systemic acquired resistance.     

Nitric oxide signalling functions in plant-pathogen interactions

Nitric oxide (NO) is a highly reactive molecule that rapidly diffuses and permeates cell membranes. During the last few years NO has been detected in several plant species, and the increasing number of reports on its function in plants have implicated NO as a key molecular signal that participates in the regulation of several physiological processes; in particular, it has a significant role in plant resistance to pathogens by triggering resistance-associated cell death and by contributing to the local and systemic induction of defence genes. NO stimulates signal transduction pathways through protein kinases, cytosolic Ca2+ mobilization and protein modification (i.e. nitrosylation and nitration). In this review we will examine the synthesis of NO, its effects, functions and signalling giving rise to the hypersensitive response and systemic acquired resistance during plant-pathogen interactions.     

植物与病原微生物互作分子基础的研究进展

植物在与病原微生物共同进化过程中形成了复杂的免疫防卫体系。植物的先天免疫系统可大致分为两个层面。第一个层面的免疫基于细胞表面的模式识别受体对病原物相关分子模式的识别, 该免疫过程被称为病原物相关分子模式触发的免疫(PAMP-triggered immunity, PTI), 能帮助植物抵抗大部分病原微生物; 第二个层面的免疫起始于细胞内部, 主要依靠抗病基因编码的蛋白产物直接或间接识别病原微生物分泌的效应子并且激发防卫反应, 来抵抗那些能够利用效应子抑制第一层面免疫的病原微生物, 这一过程被称为效应子触发的免疫(Effector-triggered immunity, ETI)。这两个层面的免疫都是基于植物对“自我”及“非我”的识别, 依靠MAPK级联等信号网络, 将识别结果传递到细胞核内, 调控相应基因的表达, 做出适当的免疫应答。本文着重阐述了植物与病原微生物互作过程中不同层面的免疫反应所发生主要事件的分子基础及研究进展。     

The role of abscisic acid in plant-pathogen interactions

The effect of the abiotic stress hormone abscisic acid on plant disease resistance is a neglected field of research. With few exceptions, abscisic acid has been considered a negative regulator of disease resistance. This negative effect appears to be due to the interference of abscisic acid with biotic stress signaling that is regulated by salicylic acid, jasmonic acid and ethylene, and to an additional effect of ABA on shared components of stress signaling. However, recent research shows that abscisic acid can also be implicated in increasing the resistance of plants towards pathogens via its positive effect on callose deposition.     

Predicting co-complexed protein pairs using genomic and proteomic data integration

Background  

Identifying all protein-protein interactions in an organism is a major objective of proteomics. A related goal is to know which protein pairs are present in the same protein complex. High-throughput methods such as yeast two-hybrid (Y2H) and affinity purification coupled with mass spectrometry (APMS) have been used to detect interacting proteins on a genomic scale. However, both Y2H and APMS methods have substantial false-positive rates. Aside from high-throughput interaction screens, other gene- or protein-pair characteristics may also be informative of physical interaction. Therefore it is desirable to integrate multiple datasets and utilize their different predictive value for more accurate prediction of co-complexed relationship.     

植物与病原微生物互作分子基础的研究进展

植物在与病原微生物共同进化过程中形成了复杂的免疫防卫体系。植物的先天免疫系统可大致分为两个层面。第一个层面的免疫基于细胞表面的模式识别受体对病原物相关分子模式的识别,该免疫过程被称为病原物相关分子模式触发的免疫(PAMP-triggered immunity,PTI),能帮助植物抵抗大部分病原微生物;第二个层面的免疫起始于细胞内部,主要依靠抗病基因编码的蛋白产物直接或间接识别病原微生物分泌的效应子并且激发防卫反应,来抵抗那些能够利用效应子抑制第一层面免疫的病原微生物,这一过程被称为效应子触发的免疫(Effector-triggered immunity,ETI)。这两个层面的免疫都是基于植物对"自我"及"非我"的识别,依靠MAPK级联等信号网络,将识别结果传递到细胞核内,调控相应基因的表达,做出适当的免疫应答。本文着重阐述了植物与病原微生物互作过程中不同层面的免疫反应所发生主要事件的分子基础及研究进展。     

Cytokinins and auxins in plant-pathogen interactions – An overview

Alterations in plant development are frequently observed following pathogen infection. Infection by virus frequently results in stunting of growth, and the chlorosis and abscission of leaves; infection by fungi is often notable for green island formation and growth malformations; and infection by some bacteria results in the formation of galls. While the area of plant-pathogen interactions is currently receiving considerable attention and some plant-pathogen interactions are well characterised with both cytokinins and auxins being implicated (infection by Agrobacterium tumefaciens being the obvious example), there has been relatively little published in the recent literature pertaining to the involvement of cytokinins and auxins in viral, fungal and other forms of bacterial pathogenesis. This overview focuses on what is known concerning the strategies utilised by gall-forming bacteria, and fungal and viral phytopathogens to manipulate the endogenous cytokinin and/or auxin content of their host plant.     

Evolution of resistance and virulence in plant-herbivore and plant-pathogen interactions

Herbivores and pathogens often attack or infect the same plant parts, and the same plant traits can affect the likelihood and degree of damage. Research on plant-herbivore and plant-pathogen interactions in natural systems have, however, proceeded largely independently of each other. Our understanding of both types of plant-enemy interaction would be enhanced by greater exposure of researchers to developments in both disciplines and by more studies of interactions between pathogen and herbivore species associated with the same hosts.     

Network analysis of epidermal growth factor signaling using integrated genomic, proteomic and phosphorylation data

To understand how integration of multiple data types can help decipher cellular responses at the systems level, we analyzed the mitogenic response of human mammary epithelial cells to epidermal growth factor (EGF) using whole genome microarrays, mass spectrometry-based proteomics and large-scale western blots with over 1000 antibodies. A time course analysis revealed significant differences in the expression of 3172 genes and 596 proteins, including protein phosphorylation changes measured by western blot. Integration of these disparate data types showed that each contributed qualitatively different components to the observed cell response to EGF and that varying degrees of concordance in gene expression and protein abundance measurements could be linked to specific biological processes. Networks inferred from individual data types were relatively limited, whereas networks derived from the integrated data recapitulated the known major cellular responses to EGF and exhibited more highly connected signaling nodes than networks derived from any individual dataset. While cell cycle regulatory pathways were altered as anticipated, we found the most robust response to mitogenic concentrations of EGF was induction of matrix metalloprotease cascades, highlighting the importance of the EGFR system as a regulator of the extracellular environment. These results demonstrate the value of integrating multiple levels of biological information to more accurately reconstruct networks of cellular response.     

Towards the molecular dissection of fertilization signaling: Our functional genomic/proteomic strategies

Recent advances in DNA sequencing techniques and automated informatics has led to clarification of all genome sequence of some model organisms in a very short period. The demonstration of the first draft sequence of the human genome has prompted us to elaborate new approaches in biology, pharmacology and medicine. Such new research will focus on high throughput methods to function on collections of genes, and hopefully, on a genome-wide, quantitative modeling of the cell system as a whole. In this review article, we discuss the present status of "post genome sequencing" approaches in line with our strategies for understanding the molecular mechanism of fertilization and activation of development using the African clawed frog, Xenopus laevis, as a model system.     

Polygalacturonases, polygalacturonase-inhibiting proteins and pectic oligomers in plant-pathogen interactions

Polygalacturonases (PGs) are produced by fungal pathogens during early plant infection and are believed to be important pathogenicity factors. Polygalacturonase-inhibiting proteins (PGIPs) are plant defense proteins which reduce the hydrolytic activity of endoPGs and favor the accumulation of long-chain oligogalacturonides (OGs) which are elicitors of a variety of defense responses. PGIPs belong to the superfamily of leucine reach repeat (LRR) proteins which also include the products of several plant resistance genes. A number of evidence demonstrates that PGIPs efficiently inhibit fungal invasion.     

The role and regulation of programmed cell death in plant-pathogen interactions

It is commonly known that animal pathogens often target and suppress programmed cell death (pcd) pathway components to manipulate their hosts. In contrast, plant pathogens often trigger pcd. In cases in which plant pcd accompanies disease resistance, an event called the hypersensitive response, the plant surveillance system has learned to detect pathogen-secreted molecules in order to mount a defence response. In plants without genetic disease resistance, these secreted molecules serve as virulence factors that act through largely unknown mechanisms. Recent studies suggest that plant bacterial pathogens also secrete antiapoptotic proteins to promote their virulence. In contrast, a number of fungal pathogens secrete pcd-promoting molecules that are critical virulence factors. Here, we review recent progress in determining the role and regulation of plant pcd responses that accompany both resistance and susceptible interactions. We also review progress in discerning the mechanisms by which plant pcd occurs during these different interactions.     

Plant integrity: An important factor in plant-pathogen interactions

The effect of plant integrity and of aboveground-belowground defense signaling on plant resistance against pathogens and herbivores is emerging as a subject of scientific research. There is increasing evidence that plant defense responses to pathogen infection differ between whole intact plants and detached leaves. Studies have revealed the importance of aboveground-belowground defense signaling for plant defenses against herbivores, while our studies have uncovered that the roots as well as the plant integrity are important for the resistance of the potato cultivar Sarpo Mira against the hemibiotrophic oomycete pathogen Phytophthora infestans. Furthermore, in the Sarpo Mira–P. infestans interactions, the plant’s meristems, the stalks or both, seem to be associated with the development of the hypersensitive response and both the plant’s roots and shoots contain antimicrobial compounds when the aerial parts of the plants are infected. Here, we present a short overview of the evidence indicating the importance of plant integrity on plant defense responses.