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1.
Diapause-specific peptide (DSP) is an insect antimicrobial peptide, composed of 41 amino acid residues including six cysteines and isolated from diapausing adults of the leaf beetle Gastrophysa atrocyaneais. Recent research results have been demonstrated that in vitro, DSP has selective antifungal activity against the higher animal pathogenic fungus Trichophyton rubrum and the plant phytopathogenic fungus Fusarium solani. To elucidate the effect of DSP on other phytopathogenic fungi, we respectively introduced a Cht1SP-DSP-FLAG fusion gene and Cht1SP-FLAG fusion gene into Arabidopsis ecotype col-0. Transgenic plants expressing Cht1SP-DSP-FLAG fusion gene showed significant resistance to Golovinomyces cichoracearum (biotrophic fungus), Botrytis cinerea (necrotrophic fungus) and Hyaloperonospora arabidopsidis (H. a.) Noco2 (oomycete), whilst transgenic plants expressing Cht1SP-FLAG fusion gene showed no resistance to these pathogens. These results indicated that for many plant pathogenic fungi, DSP has high antimicrobial activity, which suggests that DSP has a huge potential in protecting crops from damage from phytopathogenic fungi.  相似文献   

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3.
ROPs (also called RACs) are RHO-like monomeric G-proteins of plants, well-known as molecular switches in plant signal transduction processes, which are involved in plant development and a variety of biotic and abiotic stress responses. The barley (Hordeum vulgare) ROPs RACB, RAC1 and RAC3 have been shown to be involved in cellular growth, polarity and in susceptibility to the biotrophic barley powdery mildew fungus Blumeria graminis f.sp. hordei. We produced transgenic tobacco (Nicotiana tabacum) plants expressing constitutively activated (CA) mutants of the barley ROPs RACB and RAC3 to monitor the impact of heterologous ROP expression on cell polarity and disease susceptibility of tobacco. CA HvROPs influenced leaf texture, disturbed root hair polarity and induced cell expansion in tobacco. Both barley ROPs induced super-susceptibility to the compatible powdery mildew fungus Golovinomyces cichoracearum but only CA HvRAC3 induced super-susceptibility to the bacterial leaf pathogen Pseudomonas syringae pv. tabaci. Data suggest involvements of ROPs in tobacco cell expansion, polar growth and in response to bacterial and fungal leaf pathogens.  相似文献   

4.
Plant innate immunity relies on specialised immune receptors that can detect and defend against a wide variety of microbes. The first group of receptors comprises the transmembrane pathogen- or pattern-recognition receptors (PRRs), which respond to slowly evolving pathogen- or microbe-associated molecular patterns (PAMPs/MAMPs). The second group of immune receptors is formed by the polymorphic disease resistance (R) proteins that detect microbe-derived effector proteins. Most R proteins are members of the nucleotide binding leucine-rich repeat (NB-LRR) class. Although this class comprises one of the biggest protein families in plants, relatively few have been functionally characterised to date. The question rises whether all NB-LRRs function as immune receptors, or that they might have alternative functions. The answer is: yes, they do have alternative functions that are different from the immune receptor function. This review summarises the current knowledge about non-immune receptor signal transduction functions of NB-LRRs in plants.  相似文献   

5.
As plants mature it has been observed that some become more resistant to normally virulent pathogens. The ability to manifest the Age-Related Resistance (ARR) response in Arabidopsis to Pseudomonas syringae pathovars tomato (Pst) coincided with the transition to flowering in plants both delayed and accelerated in the transition to flowering. ARR was also associated with a change in PR-1 gene expression, such that young plants expressed PR-1 abundantly at 3 days post inoculation (dpi) while mature plants expressed much less. The Arabidopsis ARR response requires SA accumulation via isochorismate synthase (ICS1) [24]. ICS1 was expressed one dpi with virulent and avirulent Pst in both young and mature plants. The ARR response was also effective versus avirulent Pst providing an additional 4-fold limitation in bacterial growth. Arabidopsis ARR was found to be ineffective against two necrotrophs, Erwinia carotovora subspecies carotovora (bacterium) and Botrytis cinerea (fungus) and one obligate biotroph, Erysiphe cichoracearum (fungus). However, mature wild type, SA-deficient sid2 and NahG plants supported little growth of the obligate biotrophic oomycete, Peronospora parasitica. Therefore ARR to P. parasitica appears to be SA-independent, however the level of ARR resistance was somewhat reduced in these mutants in some experiments. Thus, there may be numerous defence pathways that contribute to adult plant resistance in Arabidopsis.  相似文献   

6.
What we know about the life history of fungi that cause disease in plants is commonly based on studies of the pathogen’s interaction with a susceptible host: how and when infection occurs, growth and reproduction within the host, and survival during the interval when a growing host is not available. This focus is appropriate, given the need for information that will facilitate management of disease affecting an economically important crop, but it can limit recognition of the full range of resources that may be utilized by fungi that we classify as plant pathogens. This was certainly the case for Fusarium circinatum, which causes a destructive disease of pines known as pitch canker. Although F. circinatum was initially known only as a necrotrophic, wound-infecting pathogen of coniferous trees, recent research has revealed that an isolate of this fungus that will kill shoot tissue when inoculated into a wound can also have a biotrophic relationship with roots of pine seedlings, infect and grow within grasses without causing symptoms, and cause ear rot of corn. Thus, although F. circinatum became known to science because it induced visible symptoms on pines, it has the capacity for a much broader range of ecological activities than is captured by its designation as a necrotrophic pathogen. The physiological plasticity manifested by F. circinatum illustrates the challenge of obtaining a comprehensive understanding of the life history of a plant pathogenic fungus.  相似文献   

7.
Apoptosis, programmed cell death and the hypersensitive response   总被引：13，自引：0，他引：13  
Apoptosis is typically a morphologically identifiable form of programmed cell death in mammals that is regulated by genes with homologues in other animal Phyla. Although both plants and fungal plant pathogens exhibit forms of developmental programmed cell death, demonstrated morphological or genetic homologies with mammalian apoptosis are still generally lacking. Because of its ubiquity and the involvement of signal transduction pathways in its induction, a strong case is developing that the hypersensitive response is a specific form of plant programmed cell death evolved as a defense against microbial parasites. Data suggest that separate signalling pathways may lead to the cell death and the defense gene activation that characterize this response and that parasite-specific resistance genes represent only one of many types of genes involved in response regulation. However, despite some biochemical similarities between the hypersensitive response, forms of developmental programmed cell death in plants, and animal apoptosis, no unique and consistent markers for the hypersensitive response (or plant programmed cell death in general) have yet been found. Whether any of these forms of plant cell death should be called apoptosis depends on how the term is defined. Assuming the hypersensitive response is a form of programmed cell death and is the default state upon pathogen entry into a cell, it seems likely that intracellular biotrophic plant pathogens resemble some animal viruses in being able to suppress this response in susceptible hosts.  相似文献   

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9.
In 1994, Oku reported that plant pathogens, mainly fungal pathogens, require three essential abilities to infect plants: to enter plants, to overcome host resistance, and to evoke disease. Because the infectious process of phytopathogenic bacteria differs from that of fungal pathogens, we have attempted to characterize pathogenicity, the ability of a pathogen to cause disease, using the phytopathogenic bacterium Pseudomonas syringae as a representative pathogen. To establish infection and incite disease development, bacteria first have to enter a plant. This process requires flagella- and type IV pili-mediated motility, and active taxis is probably necessary for effective infection. After bacteria enter a plant’s apoplastic spaces, they need to overcome host plant resistance. To do this, they secrete a wide variety of hypersensitive response and pathogenicity (Hrp) effector proteins into the plant cytoplasm to interfere with pathogen/microbe-associated molecular pattern- and effector-triggered immunity, produce phytohormones and/or phytotoxins to suppress plant defense responses and extracellular polysaccharides to prevent access by antibiotics and to chelate Ca2+, and activate the multidrug resistance efflux pump to extrude antimicrobial compounds for successful colonization. Furthermore, to evoke disease, bacteria produce toxins and Hrp effectors that compromise a plant’s homeostasis and injure plant cells. The expression of these virulence factors depends on the infection processes and environmental conditions. Thus, the expression and function of virulence factors interact with each other, creating complex networks in the regulation of bacterial virulence-related genes.  相似文献   

10.
Triterpenoid saponins are sugar-modified triterpene derivatives. Cereals and other grasses are generally deficient in these secondary metabolites with the exception of oat. Oat accumulates antimicrobial triterpenoid saponins in its roots. These oat-root-derived compounds, called avenacins, confer broad-spectrum resistance to soil-borne pathogens. Here, we tested the effect of avenacins on the development of infection structures of fungal pathogens Blumeria graminis f. sp. hordei and Bipolaris oryzae and Magnaporthe oryzae. We show that avenacins are able to inhibit the infection process of these phytopathogens on plant hosts.  相似文献   

11.
Sclerotinia sclerotiorum is a necrotrophic fungus that causes a devastating disease called white mould, infecting more than 450 plant species worldwide. Control of this disease with fungicides is limited, so host plant resistance is the preferred alternative for disease management. However, due to the nature of the disease, breeding programmes have had limited success. A potential alternative to developing necrotrophic fungal resistance is the use of host‐induced gene silencing (HIGS) methods, which involves host expression of dsRNA‐generating constructs directed against genes in the pathogen. In this study, the target gene chosen was chitin synthase (chs), which commands the synthesis of chitin, the polysaccharide that is a crucial structural component of the cell walls of many fungi. Tobacco plants were transformed with an interfering intron‐containing hairpin RNA construct for silencing the fungal chs gene. Seventy‐two hours after inoculation, five transgenic lines showed a reduction in disease severity ranging from 55·5 to 86·7% compared with the non‐transgenic lines. The lesion area did not show extensive progress over this time (up to 120 h). Disease resistance and silencing of the fungal chs gene was positively correlated with the presence of detectable siRNA in the transgenic lines. It was demonstrated that expression of endogenous genes from the very aggressive necrotrophic fungus S. sclerotiorum could be prevented by host induced silencing. HIGS of the fungal chitin synthase gene can generate white mould‐tolerant plants. From a biotechnological perspective, these results open new prospects for the development of transgenic plants resistant to necrotrophic fungal pathogens.  相似文献   

12.
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13.
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14.
Fungal phytopathogens have evolved efficient mechanisms that enable them to exploit the plant nutrient reservoir for the purpose of growth and propagation. These are counteracted by the plants to arrest fungal development. Two general principles control the specificity of host/fungus interactions. In several cases, the interplay between fungus-produced toxins and either plant toxin targets or detoxification mechanisms determine the outcome of the interaction. An analogous principle appears to be operative in the opposite direction; deposition by plants of fungitoxic compounds that can be detoxified by pathogenic fungi. Presumably of more general importance is the recognition-based plant defense system. The ensuing resistance is frequently controlled by single genes in both interacting organisms. Originally observed in many crop plants at the sub-species level, it has recently also been described in wild plants and at the species level. The structures of disease resistance genes cloned to date from different plants allow the conclusion that the plant protective system against pathogens is based on a general principle that appears to be as effective as the animal disease protection system.  相似文献   

15.
Disease resistance is without argument the best technological approach to control diseases in plants since no management input is required by the grower once the resistant variety has been planted. The biggest problems in using disease resistance lie in the facts that effective sources of resistance are not available for many important diseases, especially those caused by necrotrophic pathogens; and that pathogen populations adapt to the utilisation of novel sources of resistance, most notably for air-borne biotrophic pathogens. Several biotechnological approaches have been developed to produce disease resistant plants, the most recent known as NBT – New Breeding Technologies. This review focuses on recent advances in those technologies which adapt the knowledge obtained using molecular genetic approaches for the study of plant-microbe interactions to combat plant diseases.  相似文献   

16.
Vascular plants have various inducible resistance mechanisms as defense against pathogens. Mosses, small nonvascular plants (subkingdom Bryophyta), have been little studied in regard to their pathogens or modes of defense. Data here show that Erwinia carotovora, a bacterial plant pathogen that causes softrot in many dicotyledonous plants, can also cause soft rot symptoms in the moss Physcomitrella patens. Infection of moss by E. carotovora required pathogenicity factors similar to those required to infect vascular plants and, again as in vascular plants, salicylic acid (SA) induced moss to inhibit tissue maceration by Erwinia. These data reveal that SA-dependent defense pathways may have evolved before differentiation of vascular and nonvascular plants.  相似文献   

17.
Cucumber Fusarium wilt (CFW), caused by the soil-borne fungus Fusarium oxysporum f. sp. cucumerium, is a serious disease in cucumber (Cucumis sativus) production worldwide. For the efficient control of the pathogenic fungi, a better understanding of its interaction and associated resistance mechanisms at the molecular level is required. Here, we report a comparative proteomics analysis of total root protein isolated from infected cucumber root of susceptible bulk (SB) and resistant bulk (RB) of cucumber generation F2. Two-dimensional gel electrophoresis (2-DE) coupled with MS/MS approaches identified 15 over-accumulated proteins from the RB plants. Identified proteins are mainly involved in defense and stress responses, oxidation reduction, metabolism and transport and other process. These proteins are likely to be a part of resistance-related protein network, playing different roles in cucumber disease resistance. Three vital clues regarding wilt resistance of C. sativus are gained from this study. First, jasmonic acid and redox signaling components were found in response to F. oxysporum infection in resistant plants. Second, the LRR family protein may play an important role in the defense reaction against CFW. Third, biotic and abiotic stress-related proteins were induced by the CFW fungus F. oxysporum, indicating the activation of common stress pathway.  相似文献   

18.
木寡糖是一种植物源寡糖,对动物体的生理功能多且显著,而其是否作为寡糖素诱发植物防卫尚不明确.本文分析了不同浓度木寡糖诱导拟南芥植株对不同营养型病原的抗性.结果表明,木寡糖能诱发拟南芥对半活体病原细菌丁香假单胞菌番茄致病变种、活体病原烟草花叶病毒和死体病原真菌核盘菌的抗性,且具有剂量依赖效应,随着木寡糖浓度的提高到100...  相似文献   

19.
Rice blast disease, caused by the fungus Magnaporthe oryzae, is a major threat to worldwide rice production. Plant basal resistance is activated by virulent pathogens in susceptible host plants. OsNPR1/NH1, a rice homolog of NPR1 that is the key regulator of systemic acquired resistance in Arabidopsis thaliana, was shown to be involved in the resistance of rice to bacterial blight disease caused by Xanthomonas oryzae pv. oryzae and benzothiadiazole (BTH)-induced blast resistance. However, the role of OsNPR1/NH1 in rice basal resistance to blast fungus M. oryzae remains uncertain. In this study, the OsNPR1 gene was isolated and identified from rice cultivar Gui99. Transgenic Gui99 rice plants harbouring OsNPR1-RNAi were generated, and the OsNPR1-RNAi plants were significantly more susceptible to M. oryzae infection. Northern hybridization analysis showed that the expression of pathogenesis-related (PR) genes, such as PR-1a, PBZ1, CHI, GLU, and PAL, was significantly suppressed in the OsNPR1-RNAi plants. Consistently, overexpression of OsNPR1 in rice cultivars Gui99 and TP309 conferred significantly enhanced resistance to M. oryzae and increased expression of the above-mentioned PR genes. These results revealed that OsNPR1 is involved in rice basal resistance to the blast pathogen M. oryzae, thus providing new insights into the role of OsNPR1 in rice disease resistance.  相似文献   

20.
Plants recognize conserved molecular structures from microorganisms, which triggers active immune responses. Successful pathogens have to overcome this level of immunity; however, plants in turn can adapt their immune system, thus plants and pathogens are in an evolutionary arms race. As being sessile organisms, plants need to integrate and adapt to changing environmental conditions such as light, temperature, drought, or microorganisms. Plants protect themselves against diseases through sensitive recognition of potential pathogens and effective defense systems. The first level of the plant immune system provides recognition of a broad spectrum of microorganisms leading to defense activation (Bittel and Robatzek 2007). The second level of the plant immunity allows certain plant cultivars to detect of specific pathogen strains??a phenomenon also referred to as ??gene-for-gene resistance?? (Jones and Dangl 2006). The first level of immunity occurs rapidly and triggers active defenses normally without harm to the plant cell. The second level of plant immunity develops over days and deploys a local cell death, which prevents pathogens from further spread into tissues. In addition to these cell-autonomous defense systems, plants have also evolved strategies of systemic immunity.  相似文献   

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