RESUMO
The rhizosphere hosts complex and abundant microbiomes whose structure and composition are now well described by metagenomic studies. However, the dynamic mechanisms that enable micro-organisms to establish along a growing plant root are poorly characterized. Here, we studied how a motile bacterium utilizes the microhabitats created by soil pore space to establish in the proximity of plant roots. We have established a model system consisting of Bacillus subtilis and lettuce seedlings co-inoculated in transparent soil microcosms. We carried out live imaging experiments and developed image analysis pipelines to quantify the abundance of the bacterium as a function of time and position in the pore space. Results showed that the establishment of the bacterium in the rhizosphere follows a precise sequence of events where small islands of mobile bacteria were first seen forming near the root tip within the first 12-24 h of inoculation. Biofilm was then seen forming on the root epidermis at distances of about 700-1000 µm from the tip. Bacteria accumulated predominantly in confined pore spaces within 200 µm from the root or the surface of a particle. Using probabilistic models, we could map the complete sequence of events and propose a conceptual model of bacterial establishment in the pore space. This study therefore advances our understanding of the respective role of growth and mobility in the efficient colonization of bacteria in the rhizosphere.
Assuntos
Bacillus subtilis , Lactuca , Raízes de Plantas , Rizosfera , Microbiologia do Solo , Bacillus subtilis/crescimento & desenvolvimento , Bacillus subtilis/metabolismo , Bacillus subtilis/fisiologia , Raízes de Plantas/microbiologia , Lactuca/microbiologia , Biofilmes/crescimento & desenvolvimento , Plântula/microbiologia , Plântula/crescimento & desenvolvimentoRESUMO
Public sector data associated with health is a highly valuable resource with multiple potential end-users, from health practitioners, researchers, public bodies, policy makers and industry. Data for infectious disease agents is used for epidemiological investigations, disease tracking and assessing emerging biological threats. Yet, there are challenges in collating and re-using it. Data may be derived from multiple sources, generated and collected for different purposes. While public sector data should be open access, providers from public health settings or from agriculture, food or environment sources have sensitivity criteria to meet with ethical restrictions in how the data can be reused. Yet, sharable datasets need to describe the pathogens with sufficient contextual metadata for maximal utility, e.g. associated disease or disease potential and the pathogen source. As data comprises the physical resources of pathogen collections and potentially associated sequences, there is an added emerging technical issue of integration of 'omics 'big data'. Thus, there is a need to identify suitable means to integrate and safely access diverse data for pathogens. Established genomics alliances and platforms interpret and meet the challenges in different ways depending on their own context. Nonetheless, their templates and frameworks provide a solution for adaption to pathogen datasets.
RESUMO
Our understanding of plant-microbe interactions in soil is limited by the difficulty of observing processes at the microscopic scale throughout plants' large volume of influence. Here, we present the development of three-dimensional live microscopy for resolving plant-microbe interactions across the environment of an entire seedling growing in a transparent soil in tailor-made mesocosms, maintaining physical conditions for the culture of both plants and microorganisms. A tailor-made, dual-illumination light sheet system acquired photons scattered from the plant while fluorescence emissions were simultaneously captured from transparent soil particles and labeled microorganisms, allowing the generation of quantitative data on samples â¼3,600 mm3 in size, with as good as 5 µm resolution at a rate of up to one scan every 30 min. The system tracked the movement of Bacillus subtilis populations in the rhizosphere of lettuce plants in real time, revealing previously unseen patterns of activity. Motile bacteria favored small pore spaces over the surface of soil particles, colonizing the root in a pulsatile manner. Migrations appeared to be directed toward the root cap, the point of "first contact," before the subsequent colonization of mature epidermis cells. Our findings show that microscopes dedicated to live environmental studies present an invaluable tool to understand plant-microbe interactions.
Assuntos
Bacillus subtilis/metabolismo , Microscopia/métodos , Raízes de Plantas/microbiologia , Rizosfera , Plântula/microbiologia , Calibragem , Meio Ambiente , Desenho de Equipamento , Fluorescência , Processamento de Imagem Assistida por Computador , Lactuca , Raízes de Plantas/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Silício , Solo , Microbiologia do Solo , TemperaturaRESUMO
The success of conventional cancer therapeutics is hindered by associated dreadful side-effects of antibiotic resistance and the dearth of antitumor drugs' selectivity and specificity. Hence, the conceptual evolution of anti-cancerous therapeutic agents that selectively target cancer cells without impacting the healthy cells or tissues, has led to a new wave of scientific interest in microbial-derived bioactive molecules. Such strategic solutions may pave the way to surmount the shortcomings of conventional therapies and raise the potential and hope for the cure of wide range of cancer in a selective manner. This review aims to provide a comprehensive summary of anti-carcinogenic properties and underlying mechanisms of bioactive molecules of microbial origin, and discuss the current challenges and effective therapeutic application of combinatorial strategies to attain minimal systemic side-effects.
Assuntos
Antineoplásicos , Neoplasias , Humanos , Neoplasias/tratamento farmacológico , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêuticoRESUMO
Microgreens, the immature plants harvested after a few weeks of growth, are perceived as a heathy, nutritious food ingredient but may be susceptible to colonisation by human pathogens including Shiga-toxigenic Escherichia coli (STEC). Some microgreen cultivars accumulate anthocyanins or secrete essential oils which, when extracted or purified, have been reported to inhibit bacterial growth. Therefore, the impact of anthocyanins on bacterial colonisation by STEC (Sakai) was compared for three species that have pigmented cultivars: basil (Ocimum basilicum L.), cabbage (Brassica oleracea L.) and mustard greens (Brassica juncea L.). Inoculation with low concentrations of STEC (Sakai) (3 log10 colony forming units/ml (CFU/ml)) during seed germination resulted in extensive colonisation at the point of harvest, accumulating to â¼ 8 log10 CFU/g FW in all cultivars. Bacterial colonies frequently aligned with anticlinal walls on the surface of epidermal cells of the cotyledons and, in basil, associated with peltate and capitate gland cells. Crude lysates of pigmented and non-pigmented basil cultivars had no impact on STEC (Sakai) growth rates, viability status or biofilm formation. Anthocyanins are located within plant vacuoles of these microgreen cultivars and did not affect colonisation by STEC (Sakai) and pigmentation therefore cannot be considered as a controlling factor in bacterial interactions.
Assuntos
Antocianinas , Ocimum basilicum , Humanos , Mostardeira , Cotilédone , PigmentaçãoRESUMO
Arabinose is a major plant aldopentose in the form of arabinans complexed in cell wall polysaccharides or glycoproteins (AGP), but comparatively rare as a monosaccharide. l-arabinose is an important bacterial metabolite, accessed by pectolytic micro-organisms such as Pectobacterium atrosepticum via pectin and hemicellulose degrading enzymes. However, not all plant-associated microbes encode cell-wall-degrading enzymes, yet can metabolize l-arabinose, raising questions about their use of and access to the glycan in plants. Therefore, we examined l-arabinose metabolism in the food-borne pathogen Escherichia coli O157:H7 (isolate Sakai) during its colonization of plants. l-arabinose metabolism (araBA) and transport (araF) genes were activated at 18 °C in vitro by l-arabinose and expressed over prolonged periods in planta. Although deletion of araBAD did not impact the colonization ability of E. coli O157:H7 (Sakai) on spinach and lettuce plants (both associated with STEC outbreaks), araA was induced on exposure to spinach cell-wall polysaccharides. Furthermore, debranched and arabinan oligosaccharides induced ara metabolism gene expression in vitro, and stimulated modest proliferation, while immobilized pectin did not. Thus, E. coli O157:H7 (Sakai) can utilize pectin/AGP-derived l-arabinose as a metabolite. Furthermore, it differs fundamentally in ara gene organization, transport and regulation from the related pectinolytic species P. atrosepticum, reflective of distinct plant-associated lifestyles.
Assuntos
Arabinose/metabolismo , Escherichia coli O157/metabolismo , Plantas Comestíveis/microbiologia , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Contagem de Colônia Microbiana , Escherichia coli O157/genética , Escherichia coli O157/crescimento & desenvolvimento , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Microbiologia de Alimentos , Lactuca/microbiologia , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Spinacia oleracea/microbiologiaRESUMO
Current crop protection strategies against the fungal pathogen Botrytis cinerea rely on a combination of conventional fungicides and host genetic resistance. However, due to pathogen evolution and legislation in the use of fungicides, these strategies are not sufficient to protect plants against this pathogen. Defence elicitors can stimulate plant defence mechanisms through a phenomenon known as defence priming. Priming results in a faster and/or stronger expression of resistance upon pathogen recognition by the host. This work aims to study defence priming by a commercial formulation of the elicitor chitosan. Treatments with chitosan result in induced resistance (IR) in solanaceous and brassicaceous plants. In tomato plants, enhanced resistance has been linked with priming of callose deposition and accumulation of the plant hormone jasmonic acid (JA). Large-scale transcriptomic analysis revealed that chitosan primes gene expression at early time-points after infection. In addition, two novel tomato genes with a characteristic priming profile were identified, Avr9/Cf-9 rapidly elicited protein 75 (ACRE75) and 180 (ACRE180). Transient and stable over-expression of ACRE75, ACRE180 and their Nicotiana benthamiana homologs, revealed that they are positive regulators of plant resistance against B. cinerea. This provides valuable information in the search for strategies to protect Solanaceae plants against B. cinerea.
Assuntos
Botrytis , Quitosana/metabolismo , Resistência à Doença , Doenças das Plantas/imunologia , Solanum lycopersicum/microbiologia , Arabidopsis , Western Blotting , Clonagem Molecular , Perfilação da Expressão Gênica , Glucanos/metabolismo , Solanum lycopersicum/imunologia , Solanum lycopersicum/fisiologia , Microscopia Confocal , Doenças das Plantas/microbiologia , Plantas Geneticamente Modificadas , Nicotiana/imunologia , Nicotiana/metabolismo , Nicotiana/microbiologiaRESUMO
Shiga-toxigenic Escherichia coli (STEC) is often transmitted into food via fresh produce plants, where it can cause disease. To identify early interaction factors for STEC on spinach, a high-throughput positive-selection system was used. A bacterial artificial chromosome (BAC) clone library for isolate Sakai was screened in four successive rounds of short-term (2 h) interaction with spinach roots, and enriched loci identified by microarray. A Bayesian hierarchical model produced 115 CDS credible candidates, comprising seven contiguous genomic regions. Of the two candidate regions selected for functional assessment, the pO157 plasmid-encoded type two secretion system (T2SS) promoted interactions, while a chaperone-usher fimbrial gene cluster (loc6) did not. The T2SS promoted bacterial binding to spinach and appeared to involve the EtpD secretin protein. Furthermore, the T2SS genes, etpD and etpC, were expressed at a plant-relevant temperature of 18 °C, and etpD was expressed in planta by E. coli Sakai on spinach plants.
Assuntos
Escherichia coli O157/genética , Interações entre Hospedeiro e Microrganismos/genética , Sistemas de Secreção Tipo II/genética , Adesinas Bacterianas/genética , Aderência Bacteriana , Cromossomos Artificiais Bacterianos , Escherichia coli O157/isolamento & purificação , Escherichia coli O157/metabolismo , Genes Bacterianos , Genômica , Mutação , Raízes de Plantas/microbiologia , Plasmídeos/genética , Spinacia oleracea/microbiologia , Sistemas de Secreção Tipo II/metabolismoRESUMO
Fresh produce is often a source of enterohaemorrhagic Escherichia coli (EHEC) outbreaks. Fimbriae are extracellular structures involved in cell-to-cell attachment and surface colonisation. F9 (Fml) fimbriae have been shown to be expressed at temperatures lower than 37 °C, implying a function beyond the mammalian host. We demonstrate that F9 fimbriae recognize plant cell wall hemicellulose, specifically galactosylated side chains of xyloglucan, using glycan arrays. E. coli expressing F9 fimbriae had a positive advantage for adherence to spinach hemicellulose extract and tissues, which have galactosylated oligosaccharides as recognized by LM24 and LM25 antibodies. As fimbriae are multimeric structures with a molecular pattern, we investigated whether F9 fimbriae could induce a transcriptional response in model plant Arabidopsis thaliana, compared with flagella and another fimbrial type, E. coli common pilus (ECP), using DNA microarrays. F9 induced the differential expression of 435 genes, including genes involved in the plant defence response. The expression of F9 at environmentally relevant temperatures and its recognition of plant xyloglucan adds to the suite of adhesins EHEC has available to exploit the plant niche.
Assuntos
Adesinas de Escherichia coli/metabolismo , Arabidopsis/microbiologia , Escherichia coli O157/fisiologia , Fímbrias Bacterianas/fisiologia , Glucanos/metabolismo , Xilanos/metabolismo , Arabidopsis/metabolismoRESUMO
Metabolism is the underpinning force that sustains life. Within the rhizosphere it is a cyclic process, with substrates flowing between different compartments of the complete soil-plant-microbe system. The physiochemical and structural environment of the rhizosphere is shaped by a combination of plant genotype and soil type, both of which strongly impact the microbial community structure. External influences such as seasonality, the degree of water saturation and anthropomorphic inputs also play a role. Together these factors influence the flux of metabolites through the rhizosphere community, which in turn impacts on plant growth, development and disease. In this review, the focus is on metabolism within the bacterial population of the rhizosphere, since this group covers every type of plant-microbe interaction: from obligately symbiotic to destructively pathogenic, and includes those have little or no direct impact on plant hosts. The focus of the review is on metabolic functions that occur in the rhizosphere either during bacteria-plant interactions or bacteria-bacteria interactions and mainly covers heterotrophic metabolism of organic substrates. As such, many of the autotrophic (and phototrophic) reactions of inorganic compounds are not included.
Assuntos
Bactérias/metabolismo , Fenômenos Fisiológicos Bacterianos , Metabolismo Energético , Fenômenos Fisiológicos Vegetais , Raízes de Plantas/microbiologia , Rizosfera , Redes e Vias Metabólicas , SimbioseRESUMO
Contamination of fresh produce with pathogenic Escherichia coli, including Shiga-toxigenic E. coli (STEC), represents a serious risk to human health. Colonization is governed by multiple bacterial and plant factors that can impact the probability and suitability of bacterial growth. Thus, we aimed to determine whether the growth potential of STEC for plants associated with foodborne outbreaks (two leafy vegetables and two sprouted seed species) is predictive of the colonization of living plants, as assessed from growth kinetics and biofilm formation in plant extracts. The fitness of STEC isolates was compared to that of environmental E. coli isolates at temperatures relevant to plant growth. Growth kinetics in plant extracts varied in a plant-dependent and isolate-dependent manner for all isolates, with spinach leaf lysates supporting the highest rates of growth. Spinach extracts also supported the highest levels of biofilm formation. Saccharides were identified to be the major driver of bacterial growth, although no single metabolite could be correlated with growth kinetics. The highest level of in planta colonization occurred on alfalfa sprouts, though internalization was 10 times more prevalent in the leafy vegetables than in sprouted seeds. Marked differences in in planta growth meant that the growth potential of STEC could be inferred only for sprouted seeds. In contrast, biofilm formation in extracts related to spinach colonization. Overall, the capacity of E. coli to colonize, grow, and be internalized within plants or plant-derived matrices was influenced by the isolate type, plant species, plant tissue type, and temperature, complicating any straightforward relationship between in vitro and in planta behaviors.IMPORTANCE Fresh produce is an important vehicle for STEC transmission, and experimental evidence shows that STEC can colonize plants as secondary hosts, but differences in the capacity to colonize occur between different plant species and tissues. Therefore, an understanding of the impact that these plant factors have on the ability of STEC to grow and establish is required for food safety considerations and risk assessment. Here, we determined whether growth and the ability of STEC to form biofilms in plant extracts could be related to specific plant metabolites or could predict the ability of the bacteria to colonize living plants. Growth rates for sprouted seeds (alfalfa and fenugreek) but not those for leafy vegetables (lettuce and spinach) exhibited a positive relationship between plant extracts and living plants. Therefore, the detailed variations at the level of the bacterial isolate, plant species, and tissue type all need to be considered in risk assessment.
Assuntos
Meios de Cultura/química , Extratos Vegetais/química , Plantas/microbiologia , Escherichia coli Shiga Toxigênica/crescimento & desenvolvimento , Temperatura , Biofilmes/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Inocuidade dos Alimentos , Especificidade de Hospedeiro , Cinética , Lactuca/microbiologia , Medicago sativa/microbiologia , Folhas de Planta/microbiologia , Plântula/microbiologia , Escherichia coli Shiga Toxigênica/isolamento & purificação , Spinacia oleracea/microbiologia , Trigonella/microbiologia , Verduras/microbiologiaRESUMO
The flagellum organelle is an intricate multiprotein assembly best known for its rotational propulsion of bacteria. However, recent studies have expanded our knowledge of other functions in pathogenic contexts, particularly adherence and immune modulation, e.g., for Salmonella enterica, Campylobacter jejuni, Pseudomonas aeruginosa, and Escherichia coli. Flagella-mediated adherence is important in host colonisation for several plant and animal pathogens, but the specific interactions that promote flagella binding to such diverse host tissues has remained elusive. Recent work has shown that the organelles act like probes that find favourable surface topologies to initiate binding. An emerging theme is that more general properties, such as ionic charge of repetitive binding epitopes and rotational force, allow interactions with plasma membrane components. At the same time, flagellin monomers are important inducers of plant and animal innate immunity: variation in their recognition impacts the course and outcome of infections in hosts from both kingdoms. Bacteria have evolved different strategies to evade or even promote this specific recognition, with some important differences shown for phytopathogens. These studies have provided a wider appreciation of the functions of bacterial flagella in the context of both plant and animal reservoirs.
Assuntos
Bactérias/ultraestrutura , Evolução Biológica , Flagelos/fisiologia , Animais , Aderência Bacteriana/fisiologia , Quimiotaxia/fisiologia , Flagelos/química , Interações Hospedeiro-Patógeno , Humanos , Evasão da Resposta Imune/fisiologia , Mamíferos/microbiologia , Movimento , Plantas/microbiologiaRESUMO
Outbreaks of verotoxigenic Escherichia coli are often associated with fresh produce. However, the molecular basis to adherence is unknown beyond ionic lipid-flagellum interactions in plant cell membranes. We demonstrate that arabinans present in different constituents of plant cell walls are targeted for adherence by E. coli common pilus (ECP; or meningitis-associated and temperature-regulated (Mat) fimbriae) for E. coli serotypes O157:H7 and O18:K1:H7. l-Arabinose is a common constituent of plant cell wall that is rarely found in other organisms, whereas ECP is widespread in E. coli and other environmental enteric species. ECP bound to oligosaccharides of at least arabinotriose or longer in a glycan array, plant cell wall pectic polysaccharides, and plant glycoproteins. Recognition overlapped with the antibody LM13, which binds arabinanase-sensitive pectic epitopes, and showed a preferential affinity for (1â5)-α-linked l-arabinosyl residues and longer chains of arabinan as demonstrated with the use of arabinan-degrading enzymes. Functional adherence in planta was mediated by the adhesin EcpD in combination with the structural subunit, EcpA, and expression was demonstrated with an ecpR-GFP fusion and ECP antibodies. Spinach was found to be enriched for ECP/LM13 targets compared with lettuce. Specific recognition of arabinosyl residues may help explain the persistence of E. coli in the wider environment and association of verotoxigenic E. coli with some fresh produce plants by exploitation of a glycan found only in plant, not animal, cells.
Assuntos
Adesinas Bacterianas/genética , Arabinose/química , Parede Celular/química , Escherichia coli O157/genética , Fímbrias Bacterianas/genética , Regulação Bacteriana da Expressão Gênica , Polissacarídeos/química , Adesinas Bacterianas/química , Adesinas Bacterianas/metabolismo , Anticorpos Monoclonais/química , Especificidade de Anticorpos , Arabinose/metabolismo , Aderência Bacteriana , Parede Celular/metabolismo , Parede Celular/microbiologia , Escherichia coli O157/química , Escherichia coli O157/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas de Fímbrias/química , Proteínas de Fímbrias/genética , Proteínas de Fímbrias/metabolismo , Fímbrias Bacterianas/química , Fímbrias Bacterianas/metabolismo , Interações Hospedeiro-Patógeno , Chaperonas Moleculares/química , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Células Vegetais/química , Células Vegetais/metabolismo , Células Vegetais/microbiologia , Polissacarídeos/metabolismo , Ligação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Spinacia oleracea/química , Spinacia oleracea/metabolismo , Spinacia oleracea/microbiologiaRESUMO
Bacterial attachment to plant and animal surfaces is generally thought to constitute the initial step in colonization, requiring adherence factors such as flagella and fimbriae. We describe the molecular mechanism underpinning flagella-mediated adherence to plant tissue for the foodborne pathogen, enterohaemorrhagic Escherichia coli. Escherichia coliâ H7 flagella interacted with a sulphated carbohydrate (carrageenan) on a glycan array, which occurred in a dose-dependent manner. Adherence of E. coli O157 : H-expressing flagella of serotype H7, H6 or H48 to plants associated with outbreaks from fresh produce and to Arabidopsis thaliana, was dependent on flagella interactions with phospholipids and sulpholipids in plasma membranes. Adherence of purified H7 and H48 flagella to carrageenan was reduced at higher concentrations of KH2 PO4 or KCl, showing an ionic basis to the interactions. Purified H7 flagella were observed to physically interact with plasma membranes in spinach plants and in A.thaliana. The results show a specific interaction between E. coliâ H7, H6 and H48 flagella and ionic lipids in plant plasma membranes. The work extends our understanding of the molecular mechanisms underpinning E.coli flagella targeting of plant hosts and suggests a generic mechanism of recognition common in eukaryotic hosts belonging to different biological kingdoms.
Assuntos
Arabidopsis/microbiologia , Membrana Celular/microbiologia , Escherichia coli O157/metabolismo , Flagelos/metabolismo , Lipídeos de Membrana/metabolismo , Spinacia oleracea/microbiologia , Arabidopsis/química , Aderência Bacteriana , Carragenina/metabolismo , Membrana Celular/química , Contagem de Colônia Microbiana , Escherichia coli O157/química , Flagelos/química , Especificidade de Hospedeiro , Interações Hospedeiro-Patógeno , Lipídeos de Membrana/química , Concentração Osmolar , Spinacia oleracea/químicaRESUMO
The foodborne pathogen Escherichia coli O157:H7 is increasingly associated with fresh produce (fruit and vegetables). Bacterial colonization of fresh produce plants can occur to high levels on the external tissue but bacteria have also been detected within plant tissue. However, questions remain about the extent of internalization, its molecular basis, and internal location of the bacteria. We have determined the extent of internalization of E. coli O157:H7 in live spinach and lettuce plants and used high-resolution microscopy to examine colony formation in roots and pathways to internalization. E. coli O157:H7 was found within internal tissue of both produce species. Colonization occurred within the apoplast between plant cells. Furthermore, colonies were detected inside the cell wall of epidermal and cortical cells of spinach and Nicotiana benthamiana roots. Internal colonization of epidermal cells resembled that of the phytopathogen Pectobacterium atrosepticum on potato. In contrast, only sporadic cells of the laboratory strain of E. coli K-12 were found on spinach, with no internal bacteria evident. The data extend previous findings that internal colonization of plants appears to be limited to a specific group of plant-interacting bacteria, including E. coli O157:H7, and demonstrates its ability to invade the cells of living plants.
Assuntos
Escherichia coli O157/fisiologia , Escherichia coli/fisiologia , Lactuca/microbiologia , Raízes de Plantas/microbiologia , Spinacia oleracea/microbiologia , Verduras/microbiologia , Contagem de Colônia Microbiana , Endófitos , Escherichia coli/citologia , Escherichia coli/crescimento & desenvolvimento , Escherichia coli O157/citologia , Escherichia coli O157/crescimento & desenvolvimento , Contaminação de Alimentos , Microbiologia de Alimentos , Interações Hospedeiro-Patógeno , Humanos , Lactuca/citologia , Microscopia Eletrônica de Transmissão , Pectobacterium/citologia , Pectobacterium/crescimento & desenvolvimento , Pectobacterium/fisiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Plantas Geneticamente Modificadas , Rizosfera , Microbiologia do Solo , Solanum tuberosum/citologia , Solanum tuberosum/microbiologia , Spinacia oleracea/citologia , Nicotiana/citologia , Nicotiana/microbiologiaRESUMO
Plant microbiomes are the microbial communities essential to the functioning of the phytobiome-the system that consist of plants, their environment, and their associated communities of organisms. A healthy, functional phytobiome is critical to crop health, improved yields and quality food. However, crop microbiomes are relatively under-researched, and this is associated with a fundamental need to underpin phytobiome research through the provision of a supporting infrastructure. The UK Crop Microbiome Cryobank (UKCMC) project is developing a unique, integrated and open-access resource to enable the development of solutions to improve soil and crop health. Six economically important crops (Barley, Fava Bean, Oats, Oil Seed Rape, Sugar Beet and Wheat) are targeted, and the methods as well as data outputs will underpin research activity both in the UK and internationally. This manuscript describes the approaches being taken, from characterisation, cryopreservation and analysis of the crop microbiome through to potential applications. We believe that the model research framework proposed is transferable to different crop and soil systems, acting not only as a mechanism to conserve biodiversity, but as a potential facilitator of sustainable agriculture systems.
RESUMO
Most reviews of climate change are epidemiological, focusing on impact assessment and risk mapping. However, there are many reports of the effects of environmental stress factors on defense mechanisms in plants against pathogens. We review those representative of key climate change-related stresses to determine whether there are any patterns or trends in adaptation responses. We recognize the complexity of climate change itself and the multitrophic nature of the complex biological interactions of plants, microbes, soil, and the environment and, therefore, the difficulty of reductionist dissection approaches to resolving the problems. We review host defense genes, germplasm, and environmental interactions in different types of organisms but find no significant group-specific trends. Similarly, we review by host defense mechanism type and by host-pathogen trophic relationship but identify no dominating mechanism for stress response. However, we do identify core stress response mechanisms playing key roles in multiple response pathways whether to biotic or abiotic stress. We suggest that these should be central to mechanistic climate change plant defense research. We also recognize biodiversity, heterogeneity, and the need for understanding stress in a true systems biology approach as being essential components of progressing our understanding of and response to climate change.
Assuntos
Mudança Climática , Plantas , Biodiversidade , Clima , Ecossistema , Plantas/metabolismo , SoloRESUMO
The colonization of six edible plant species: alfalfa, broccoli, coriander, lettuce, parsley and rocket, by the human pathogen Shigatoxigenic Escherichia coli was investigated following two modes of artificial inoculation of seeds, by soaking or watering. The frequency and extent of colonization of cotyledons depended on the mode of inoculation, with three, rapidly germinating species being successfully colonized after overnight soaking, but slower germinating species requiring prolonged exposure to bacteria by watering of the surrounding growth media. Separate analysis of the cotyledons and leaves from individual plants highlighted that successful colonization of the true leaves was also species dependent. For three species, failure of transfer, or lack of nutrients or suitable microhabitat on the leaf surface resulted in infrequent bacterial colonization. Colonization of leaves was lower and generally in proportion to that in cotyledons, if present. The potential risks associated with consumption of leafy produce are discussed.
Assuntos
Escherichia coli O157 , Humanos , Cotilédone , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Folhas de Planta/microbiologia , Plantas , Contaminação de Alimentos/análiseRESUMO
Analysis of Escherichia coli taxonomy has expanded into a species-complex with the identification of divergent cryptic clades. A key question is the evolutionary trajectory of these clades and their relationship to isolates of clinical or veterinary importance. Since they have some environmental association, we screened a collection of E. coli isolated from a long-term spring barley field trial for their presence. While most isolates clustered into the enteric-clade, four of them clustered into Clade-V, and one in Clade-IV. The Clade -V isolates shared >96% intra-clade average nucleotide sequence identity but <91% with other clades. Although pan-genomics analysis confirmed their taxonomy as Clade -V (E. marmotae), retrospective phylogroup PCR did not discriminate them correctly. Differences in metabolic and adherence gene alleles occurred in the Clade -V isolates compared to E. coli sensu scricto. They also encoded the bacteriophage phage-associated cyto-lethal distending toxin (CDT) and antimicrobial resistance (AMR) genes, including an ESBL, blaOXA-453. Thus, the isolate collection encompassed a genetic diversity, and included cryptic clade isolates that encode potential virulence factors. The analysis has determined the phylogenetic relationship of cryptic clade isolates with E. coli sensu scricto and indicates a potential for horizontal transfer of virulence factors.
RESUMO
Escherichia coli species exhibits a high genomic diversification from evolution, mobile genetic elements and recombination. An environmental E. coli isolate, 'JHI_5025' from a crop trial appeared to be clonally related to the historical reference isolate E. coli K-12 strain 'MG1655', warranting further genomic analysis. Their genomes share an average nucleotide identity of 99.74% and whole genome alignment showed little rearrangement of the JHI_5025 sequence compared to the reference. Five genomic islands not in the reference aligned to other sequences in the Enterobacteriaceae. Isolate JHI_5025 contained E. coli K-12 F plasmid sequence and at least one complete prophage sequence. The genome and comparison dataset provides utility of E. coli JHI_5025 as a representative contemporary genetic mimic of a well-known and much used workhorse strain.