RESUMO
In this study, two hundred and forty bacterial strains were isolated from inner tissue of potato tubers collected from DaTong, TaiYuan and Inner Mongolia Autonomous regions. On the basis of antagonistic examination in vitro, fifty and five bacteria strains were characterized for antagonistic bacteria to ring rot of potato. It was 22.9 percentage of all bacteria strains. The biggest radius of suppression circle was 13 mm. Nine strains were chosen for their suppression of bacterial ring rot, blackleg and dry rot of potato. These strains were bacteriologically ideatified. Strain 118 was Pseudomonas fluorescens biovar V. Strain 110 was Bacillus pumilus. Strain 085 was Bacillus stearothermophilus. Strain 069 was Erwinia herbicola. Strain 043 was Xanthomomas fragariae. Strain 116 was Curtobacterium. Strains A-10' and T3 were Bacillus. Strain H1-6 was Pseudomonas fluorescens.
Assuntos
Bactérias/isolamento & purificação , Erwinia/fisiologia , Doenças das Plantas/microbiologia , Solanum tuberosum/microbiologia , Bacillus/isolamento & purificação , Bacillus/fisiologia , Erwinia/isolamento & purificação , Controle Biológico de Vetores/métodos , Doenças das Plantas/prevenção & controle , Pseudomonas fluorescens/isolamento & purificação , Pseudomonas fluorescens/fisiologia , Xanthomonas/isolamento & purificação , Xanthomonas/fisiologiaRESUMO
One hundred and thirty-three bacterial strains were isolated from inner tissue of potato tubers collected from Datong, Taiyuan and Inner Mongolia Autonomous regions. On the basis of antagonistic examination in vitro, greenhouse and field tests, five strains named as 069, 085, 110, 116 and 118 were chosen for their suppression of bacterial ring rot or their growth promotion. Strain 118 is an endophytic bacterium with three effects of colonization, growth promotion and suppression of the pathogenic bacteria, showing good prospects for commercial use.
Assuntos
Antibiose , Bactérias/isolamento & purificação , Doenças das Plantas/microbiologia , Solanum tuberosum/microbiologia , Actinomycetales/crescimento & desenvolvimento , Actinomycetales/isolamento & purificação , Contagem de Colônia Microbiana , Erwinia/isolamento & purificação , Erwinia/fisiologia , Geobacillus stearothermophilus/isolamento & purificação , Geobacillus stearothermophilus/fisiologia , Pseudomonas fluorescens/isolamento & purificação , Pseudomonas fluorescens/fisiologia , Solanum tuberosum/crescimento & desenvolvimentoRESUMO
Bacterial cells sense their population density through a sophisticated cell-cell communication system and trigger expression of particular genes when the density reaches a threshold. This type of gene regulation, which controls diverse biological functions including virulence, is known as quorum sensing. Quorum-sensing signals, such as acyl-homoserine lactones (AHLs), are the essential components of the communication system. AHLs regulate virulence gene expression in a range of plant and animal (including human) bacterial pathogens. AHL-producing tobacco restored the pathogenicity of an AHL-negative mutant of Erwinia carotovora. Different bacterial species may produce different AHLs, which vary in the length and substitution of the acyl chain but contain the same homoserine lactone moiety. Here we show that the acyl-homoserine lactonase (AHL-lactonase), a new enzyme from Bacillus sp., inactivates AHL activity by hydrolysing the lactone bond of AHLs. Plants expressing AHL-lactonase quenched pathogen quorum-sensing signalling and showed significantly enhanced resistance to E. carotovora infection. Our results highlight a promising potential to use quorum-sensing signals as molecular targets for disease control, thereby broadening current approaches for prevention of bacterial infections.
Assuntos
4-Butirolactona/análogos & derivados , Proteínas de Bactérias , Hidrolases de Éster Carboxílico/metabolismo , Erwinia/fisiologia , Homosserina/metabolismo , 4-Butirolactona/metabolismo , Bacillus/enzimologia , Erwinia/patogenicidade , Estudos de Viabilidade , Regulação Bacteriana da Expressão Gênica , Homosserina/análogos & derivados , Hidrólise , Lactonas/metabolismo , Metaloendopeptidases/genética , Metaloendopeptidases/metabolismo , Dados de Sequência Molecular , Doenças das Plantas/microbiologia , Plantas Geneticamente Modificadas , Plantas Tóxicas , Transdução de Sinais , Solanum tuberosum/microbiologia , Nicotiana/microbiologia , VirulênciaRESUMO
Erwinia carotovora subsp. atroseptica was mutagenized and assayed for virulence in planta. Those mutants which exhibited reduced virulence (Rvi-) were assayed for growth rate, auxotrophy and extracellular enzyme secretion and seven mutants were found to be wild type for all of these phenotypes. When screened for other phenotypes, two were found to be non-motile. One mutant was complemented for motility by a heterologous gene library. A 2.7kb XmaIII-ClaI complementing fragment was sequenced and the gene products were found to have similarity to flagella biosynthesis gene products from several bacteria. Further similarity was found to a pathogenicity protein from the plant pathogen Xanthomonas campestris pv. glycines and to the Spa pathogenicity proteins of the human pathogen Shigella flexneri, which are involved in the surface presentation of antigens. These studies highlight the emergence of common themes in the molecular strategies employed by both plant and animal bacterial pathogens for the targeting of proteins involved in the elaboration of disease.