Plant-pathogenic
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Plant pathogenic bacteria can have devastating effects on plant productivity and yield. Nevertheless, because these often soil-dwelling bacteria have evolved to interact with eukaryotes, they generally exhibit a strong adaptivity, a versatile metabolism, and ingenious mechanisms tailored to modify the development of their hosts. Consequently, besides being a threat for agricultural practices, phytopathogens may also represent opportunities for plant production or be useful for specific biotechnological applications. Here, we illustrate this idea by reviewing the pathogenic strategies and the (potential) uses of five very different (hemi)biotrophic plant pathogenic bacteria: Agrobacterium tumefaciens, A. rhizogenes, Rhodococcus fascians, scab-inducing Streptomyces spp., and Pseudomonas syringae.
- MeSH
- Bacteria * růst a vývoj patogenita MeSH
- biotechnologie MeSH
- genetické inženýrství MeSH
- geneticky modifikované rostliny genetika mikrobiologie fyziologie MeSH
- nemoci rostlin mikrobiologie MeSH
- techniky tkáňových kultur MeSH
- zemědělské plodiny * genetika mikrobiologie fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
As the number of biogas plants has grown rapidly in the last decade, the amount of potentially contaminated wastes with pathogenic Clostridium spp. has increased as well. This study reports the results from examining 203 biogas plant wastes (BGWs). The following Clostridium spp. with different frequencies could be isolated via a new enrichment medium (Krüne medium) and detected by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS): Clostridium perfringens (58 %) then Clostridium bifermentans (27 %), Clostridium tertium (23 %) and Clostridium butyricum (19 %), Clostridium cadaveris (15 %), Clostridium parapurificum (6 %), Clostridium glycolicum (5 %), Clostridium baratii (4 %), Clostridium sporogenes (2 %), Clostridium sordellii (1 %) and Clostridium subterminale (0.5 %). The mean most probable number (MPN) count of sulfite reducing bacteria was between 10(3) and 10(4)/mL, and the higher the MPN, the more pathogenic Clostridium spp. were present. Also, real-time PCR was used to be compared with culture method for C. perfringens, C. bifermentans, C. butyricum, C. sporogenes/Clostridium botulinum and C. sordellii. Although real-time PCR was more sensitive than the culture method, both systems improve the recovery rate but in different ways and are useful to determine pathogenic clostridia in biogas plants. In conclusion, BGWs could present a biohazard risk of clostridia for humans and animals.
Cytokinins are adenine and non-adenine derived heterogeneous class of regulatory molecules that participate in almost every aspect of plant biology. They also affect plant defense responses as well as help microbial pathogens to establish pathogenesis. The functional approaches that ensure desired and subtle modulations in the levels of plant cytokinins are highly instrumental in assessing their functions in plant immunity. Here, we describe a detailed working protocol regarding the enhanced production of cytokinins from plants that harbor isopentenyltransferase (IPT) enzyme gene under the control of 4xJERE (jasmonic acid and elicitor-responsive element) pathogen-inducible promoter. Our devised expression system is a context-dependent solution when it comes to investigating host-pathogen interactions under the modulated conditions of plant cytokinins.
- MeSH
- cytokininy metabolismus MeSH
- fenotyp MeSH
- geneticky modifikované rostliny MeSH
- imunita rostlin MeSH
- interakce hostitele a patogenu * imunologie MeSH
- nemoci rostlin genetika imunologie mikrobiologie MeSH
- regulace genové exprese u rostlin MeSH
- regulátory růstu rostlin metabolismus MeSH
- signální transdukce MeSH
- transformace genetická MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- Ascophyllum chemie imunologie MeSH
- betain * chemie MeSH
- hlístice chemie patogenita růst a vývoj MeSH
- hmyz chemie patogenita růst a vývoj MeSH
- houby chemie patogenita růst a vývoj MeSH
- imunita rostlin * imunologie účinky léků MeSH
- interakce hostitele a patogenu * imunologie účinky léků MeSH
- paraziti chemie růst a vývoj účinky léků MeSH
- rostlinné extrakty MeSH
- rostliny MeSH
- sloučeniny draslíku MeSH
- statistika jako téma MeSH
- Tylenchoidea růst a vývoj účinky léků MeSH
BACKGROUND: Soil microorganisms are key determinants of soil fertility and plant health. Soil phytopathogenic fungi are one of the most important causes of crop losses worldwide. Microbial biocontrol agents have been extensively studied as alternatives for controlling phytopathogenic soil microorganisms, but molecular interactions between them have mainly been characterised in dual cultures, without taking into account the soil microbial community. We used an RNA sequencing approach to elucidate the molecular interplay of a soil microbial community in response to a plant pathogen and its biocontrol agent, in order to examine the molecular patterns activated by the microorganisms. RESULTS: A simplified soil microcosm containing 11 soil microorganisms was incubated with a plant root pathogen (Armillaria mellea) and its biocontrol agent (Trichoderma atroviride) for 24 h under controlled conditions. More than 46 million paired-end reads were obtained for each replicate and 28,309 differentially expressed genes were identified in total. Pathway analysis revealed complex adaptations of soil microorganisms to the harsh conditions of the soil matrix and to reciprocal microbial competition/cooperation relationships. Both the phytopathogen and its biocontrol agent were specifically recognised by the simplified soil microcosm: defence reaction mechanisms and neutral adaptation processes were activated in response to competitive (T. atroviride) or non-competitive (A. mellea) microorganisms, respectively. Moreover, activation of resistance mechanisms dominated in the simplified soil microcosm in the presence of both A. mellea and T. atroviride. Biocontrol processes of T. atroviride were already activated during incubation in the simplified soil microcosm, possibly to occupy niches in a competitive ecosystem, and they were not further enhanced by the introduction of A. mellea. CONCLUSIONS: This work represents an additional step towards understanding molecular interactions between plant pathogens and biocontrol agents within a soil ecosystem. Global transcriptional analysis of the simplified soil microcosm revealed complex metabolic adaptation in the soil environment and specific responses to antagonistic or neutral intruders.
- MeSH
- anotace sekvence MeSH
- ekosystém * MeSH
- exprese genu MeSH
- interakce hostitele a patogenu genetika MeSH
- kořeny rostlin genetika mikrobiologie MeSH
- metagenom MeSH
- metagenomika metody MeSH
- půdní mikrobiologie * MeSH
- shluková analýza MeSH
- stanovení celkové genové exprese MeSH
- transkriptom * MeSH
- výpočetní biologie metody MeSH
- vysoce účinné nukleotidové sekvenování MeSH
- Publikační typ
- časopisecké články MeSH
Background and Aims: Pisum sativum L. (pea) seed is a source of carbohydrate and protein for the developing plant. By studying pea seeds inoculated by the cytokinin-producing bacterium, Rhodococcus fascians , we sought to determine the impact of both an epiphytic (avirulent) strain and a pathogenic strain on source-sink activity within the cotyledons during and following germination. Methods: Bacterial spread was monitored microscopically, and real-time reverse transcription-quantitative PCR was used to determine the expression of cytokinin biosynthesis, degradation and response regulator gene family members, along with expression of family members of SWEET , SUT , CWINV and AAP genes - gene families identified initially in pea by transcriptomic analysis. The endogenous cytokinin content was also determined. Key Results: The cotyledons infected by the virulent strain remained intact and turned green, while multiple shoots were formed and root growth was reduced. The epiphytic strain had no such marked impact. Isopentenyl adenine was elevated in the cotyledons infected by the virulent strain. Strong expression of RfIPT , RfLOG and RfCKX was detected in the cotyledons infected by the virulent strain throughout the experiment, with elevated expression also observed for PsSWEET , PsSUT and PsINV gene family members. The epiphytic strain had some impact on the expression of these genes, especially at the later stages of reserve mobilization from the cotyledons. Conclusions: The pathogenic strain retained the cotyledons as a sink tissue for the pathogen rather than the cotyledon converting completely to a source tissue for the germinating plant. We suggest that the interaction of cytokinins, CWINVs and SWEETs may lead to the loss of apical dominance and the appearance of multiple shoots.
- MeSH
- cytokininy metabolismus MeSH
- hrách setý genetika mikrobiologie MeSH
- interakce hostitele a patogenu MeSH
- klíčení MeSH
- kotyledon růst a vývoj mikrobiologie MeSH
- nemoci rostlin mikrobiologie MeSH
- polymerázová řetězová reakce MeSH
- Rhodococcus fyziologie MeSH
- semena rostlinná mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
Classical virulence analysis is based on discovering virulence phenotypes of isolates with regard to a composition of resistance genes in a differential set of host genotypes. With such a vision, virulence phenotypes are usually treated in a genetic manner as one of two possible alleles, either virulence or avirulence in a binary locus. Therefore, population genetics metrics and methods have become prevailing tools for analyzing virulence data at multiple loci. However, a basis for resolving binary virulence phenotypes is infection type (IT) data of host-pathogen interaction that express functional traits of each specific isolate in a given situation (particular host, environmental conditions, cultivation practice, and so on). IT is determined by symptoms and signs observed (e.g., lesion type, lesion size, coverage of leaf or leaf segments by mycelium, spore production and so on), and assessed by IT scores at a generally accepted scale for each plant-pathogen system. Thus, multiple IT profiles of isolates are obtained and can be subjected to analysis of functional variation within and among operational units of a pathogen. Such an approach may allow better utilization of the information available in the raw data, and reveal a functional (e.g., environmental) component of pathogen variation in addition to the genetic one. New methods for measuring functional variation of plant-pathogen interaction with IT data were developed. The methods need an appropriate assessment scale and expert estimations of dissimilarity between IT scores for each plant-pathogen system (an example is presented). Analyses of a few data sets at different hierarchical levels demonstrated discrepancies in results obtained with IT phenotypes versus binary virulence phenotypes. The ability to measure functional IT-based variation offers promise as an effective tool in the study of epidemics caused by plant pathogens.
Background and Aims: Selected beneficial Pseudomonas spp. strains have the ability to influence root architecture in Arabidopsis thaliana by inhibiting primary root elongation and promoting lateral root and root hair formation. A crucial role for auxin in this long-term (1week), long-distance plant-microbe interaction has been demonstrated. Methods: Arabidopsis seedlings were cultivated in vitro on vertical plates and inoculated with pathogenic strains Pseudomonas syringae pv. maculicola (Psm) and P. syringae pv. tomato DC3000 (Pst), as well as Agrobacterium tumefaciens (Atu) and Escherichia coli (Eco). Root hair lengths were measured after 24 and 48h of direct exposure to each bacterial strain. Several Arabidopsis mutants with impaired responses to pathogens, impaired ethylene perception and defects in the exocyst vesicle tethering complex that is involved in secretion were also analysed. Key Results: Arabidopsis seedling roots infected with Psm or Pst responded similarly to when infected with plant growth-promoting rhizobacteria; root hair growth was stimulated and primary root growth was inhibited. Other plant- and soil-adapted bacteria induced similar root hair responses. The most compromised root hair growth stimulation response was found for the knockout mutants exo70A1 and ein2. The single immune pathways dependent on salicylic acid, jasmonic acid and PAD4 are not directly involved in root hair growth stimulation; however, in the mutual cross-talk with ethylene, they indirectly modify the extent of the stimulation of root hair growth. The Flg22 peptide does not initiate root hair stimulation as intact bacteria do, but pretreatment with Flg22 prior to Psm inoculation abolished root hair growth stimulation in an FLS2 receptor kinase-dependent manner. These early response phenomena are not associated with changes in auxin levels, as monitored with the pDR5::GUS auxin reporter. Conclusions: Early stimulation of root hair growth is an effect of an unidentified component of living plant pathogenic bacteria. The root hair growth response is triggered in the range of hours after bacterial contact with roots and can be modulated by FLS2 signalling. Bacterial stimulation of root hair growth requires functional ethylene signalling and an efficient exocyst-dependent secretory machinery.
- MeSH
- Arabidopsis genetika růst a vývoj mikrobiologie MeSH
- genový knockout MeSH
- interakce hostitele a patogenu * MeSH
- kořeny rostlin růst a vývoj mikrobiologie MeSH
- mutace MeSH
- proteinkinasy genetika MeSH
- proteiny huseníčku genetika MeSH
- Pseudomonas syringae * MeSH
- receptory buněčného povrchu genetika MeSH
- regulace genové exprese u rostlin MeSH
- signální transdukce MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Conventional chemical antiseptics used for treatment of oral infections often produce side-effects, which restrict their long-term use. Plants are considered as perspective sources of novel natural antiseptics. However, little is still known about their inhibitory properties against oral pathogens. The objective of this study was to test in vitro antimicrobial activities of generally recognized as safe (GRAS) species against planktonic cultures of cariogenic, periodontal and candidal microorganisms and identify active compounds of the most active extracts. Growth-inhibitory effects of ethanol extracts from 109 GRAS plant species, six Humulus lupulus cultivars and two hop supercritical CO2 extracts were evaluated using broth microdilution method. The chemical analysis was done through high-performance liquid chromatography. Best results were obtained for supercritical CO2 and ethanol extracts of H. lupulus with minimum inhibitory concentrations (MIC) ≥8 μg/mL and ≥16 μg/mL, respectively. The chemical analysis of supercritical CO2H. lupulus extracts revealed that α- and β-acids were their main constituents. Capsicum annuum and Capsicum frutescens showed antibacterial effect against Streptococcus sobrinus and Streptococcus salivarius (MIC=64-128 μg/mL). These strains were further inhibited by Zanthoxylum clava-herculis (MIC=64-128 μg/mL) and Myristica fragrans (both MIC≥128 μg/mL). The latter also exhibited antimicrobial activity against Fusobacterium nucleatum (MIC=64 μg/mL). Punica granatum possessed inhibitory effects against Candida albicans (MIC=128 μg/mL) and F. nucleatum (MIC=64 μg/mL). The results indicate that supercritical CO2H. lupulus extracts together with ethanol extracts of C. annuum, C. frutescens, M. fragrans, P. granatum and Z. clava-herculis are promising materials for further investigation on new antiseptic agents of oral care products.
- MeSH
- antibakteriální látky chemie MeSH
- Candida albicans účinky léků MeSH
- Capsicum chemie MeSH
- ethanol MeSH
- Fusobacterium nucleatum účinky léků MeSH
- Humulus chemie MeSH
- mikrobiální testy citlivosti MeSH
- Myristica chemie MeSH
- rostlinné extrakty chemie MeSH
- Streptococcus sobrinus účinky léků MeSH
- Zanthoxylum chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
