K S Bell

Publications (3)14.11 Total impact

• Article: Novel quorum-sensing-controlled genes in Erwinia carotovora subsp. carotovora: identification of a fungal elicitor homologue in a soft-rotting bacterium.

  C L Pemberton, N A Whitehead, M Sebaihia, K S Bell, L J Hyman, S J Harris, A J Matlin, N D Robson, P R J Birch, J P Carr, I K Toth, G P C Salmond
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  ABSTRACT: Seven new genes controlled by the quorum-sensing signal molecule N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) have been identified in Erwinia carotovora subsp. carotovora. Using TnphoA as a mutagen, we enriched for mutants defective in proteins that could play a role in the interaction between E. carotovora subsp. carotovora and its plant hosts, and identified NipEcc and its counterpart in E. carotovora subsp. atroseptica. These are members of a growing family of proteins related to Nep1 from Fusarium oxysporum which can induce necrotic responses in a variety of dicotyledonous plants. NipEcc produced necrosis in tobacco, NipEca affected potato stem rot, and both affected virulence in potato tubers. In E. carotovora subsp. carotovora, nip was shown to be subject to weak repression by the LuxR family regulator, EccR, and may be regulated by the negative global regulator RsmA.
  Molecular Plant-Microbe Interactions 05/2005; 18(4):343-53. · 4.43 Impact Factor
• Source

  Available from: ncbi.nlm.nih.gov

  Article: Genome sequence of the enterobacterial phytopathogen Erwinia carotovora subsp. atroseptica and characterization of virulence factors.

  K S Bell, M Sebaihia, L Pritchard, M T G Holden, L J Hyman, M C Holeva, N R Thomson, S D Bentley, L J C Churcher, K Mungall, [......], D Ormond, C Price, M A Quail, M Sanders, D Walker, S Whitehead, G P C Salmond, P R J Birch, J Parkhill, I K Toth
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  ABSTRACT: The bacterial family Enterobacteriaceae is notable for its well studied human pathogens, including Salmonella, Yersinia, Shigella, and Escherichia spp. However, it also contains several plant pathogens. We report the genome sequence of a plant pathogenic enterobacterium, Erwinia carotovora subsp. atroseptica (Eca) strain SCRI1043, the causative agent of soft rot and blackleg potato diseases. Approximately 33% of Eca genes are not shared with sequenced enterobacterial human pathogens, including some predicted to facilitate unexpected metabolic traits, such as nitrogen fixation and opine catabolism. This proportion of genes also contains an overrepresentation of pathogenicity determinants, including possible horizontally acquired gene clusters for putative type IV secretion and polyketide phytotoxin synthesis. To investigate whether these gene clusters play a role in the disease process, an arrayed set of insertional mutants was generated, and mutations were identified. Plant bioassays showed that these mutants were significantly reduced in virulence, demonstrating both the presence of novel pathogenicity determinants in Eca, and the impact of functional genomics in expanding our understanding of phytopathogenicity in the Enterobacteriaceae.
  Proceedings of the National Academy of Sciences 08/2004; 101(30):11105-10. · 9.68 Impact Factor
• Article: Detection and quantification of fungal and bacterial potato pathogens in plants and soil*

  D. W. Cullen, A. K. Lees, I. K. Toth, K. S. Bell, J. M. Duncan
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  ABSTRACT: We have developed polymerase chain reaction (PCR)-based diagnostic assays for fungal and bacterial diseases of potato together with rapid methods of DNA extraction and purification from soil and plant samples. Pathogen detection and quantification is a crucial step in the control of crop diseases. PCR primers were designed to unique sequences for specific detection of the potato blemish complex of pathogens: Spongospora subterranea (powdery scab), Streptomyces scabies (common scab), Helminthosporium solani (silver scurf), Rhizoctonia solani AG-3 (black scurf) and Colletotrichum coccodes (black dot). A multiplex PCR test was designed with a high level of sensitivity to detect H. solani, C. coccodes, and S. scabies simultaneously in one reaction, and individual quantitative PCR assays were also developed to detect these pathogens and S. subterranea in soil and tubers. PCR-based detection systems for the major storage-rot pathogens of potato (Fusarium spp., Phoma foveata, Pythium ultimum and Phytophthora erythroseptica) are also under development. The potential of these techniques to detect and monitor these pathogen populations in soil and potato tubers for epidemiological studies is discussed.
  Bulletin OEPP/EPPO Bulletin 08/2000; 30(3‐4):485 - 488.