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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #160774
Title: GENOMIC DIVERSITY OF ERWINIA CAROTOVORA SUBSP. CAROTOVORA AND ITS CORRELATION WITH VIRULENCE.

Author
item YAP, MEE-NGAN - UNIV. OF WISC. MADISON
item Barak Cunningham, Jeri
item CHARKOWSKI, AMY - UNIV. OF WISC. MADISON

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2004
Publication Date: 5/1/2004
Citation: Yap, M., Barak Cunningham, J.D., Charkowski, A. 2004. Genomic diversity of erwinia carotovora subsp. carotovora and its correlation with virulence.. Applied and Environmental Microbiology. 70(5):3013-3023

Interpretive Summary: The diversity of Erwinia carotovora subsp. carotovora (Ecc) potato isolates representing multiple serogroups was assessed by fingerprinting in combination with phenotypic analysis. All the Ecc strains examined, except one, contained seven fingerprint fragments and at least 26 distinct fingerprints were identified among the strains tested. Significant differences were observed in all Ecc strains. Intraspecies variation of Ecc was also evaluated by sequencing of two housekeeping genes, mdh and acnA. We found the average pairwise variation in mdh and acnA sequences was 2.13% and 8.97%, respectively, which was greater than that found in diverse strains of either Escherichia coli or Salmonella enterica. The least virulent Ecc strain, WPP17 failed to elicit hypersensitive reaction in tobacco and was found to be missing several hrp/c genes, which encode the type III protein secretion system (TTSS). The two least virulent strains had unusual chromosomal structure, suggesting that a particular fingerprint is possibly correlated to pathogenicity. A physical map of a highly virulent strain was deduced by stepwise deletion of I-CeuI sites. Homologous housekeeping genes and several virulence genes of Ecc were mapped onto I-CeuI fragments by Southern blotting to compare the chromosomal structure of Ecc with other closely related animal pathogens. We identified portions of the genome that appear to be well conserved across enteric species and portions that have undergone significant changes due to genome rearrangements. Overall, we found the Ecc strains isolated from potatoes were surprisingly diverse compared to related human pathogens.

Technical Abstract: The diversity of Erwinia carotovora subsp. carotovora (Ecc) potato isolates representing multiple serogroups was assessed by I-CeuI-PFGE fingerprinting in combination with phenotypic analysis. All the Ecc strains examined, except one, contained seven I-CeuI fragments and at least 26 pulsotypes were identified among the strains tested. Significant polymorphism in fragment sizes ranging from 100-450 kb was observed in all Ecc strains. Intraspecies variation of Ecc was also evaluated by sequencing of two housekeeping genes, mdh and acnA. We found the average pairwise variation in mdh and acnA sequences was 2.13% and 8.97%, respectively, which were greater than that found in diverse strains of either Escherichia coli or Salmonella enterica. The least virulent Ecc strain, WPP17 failed to elicit HR in tobacco and was found to be missing several hrp/c genes, which encode the type III protein secretion system (TTSS). The two least virulent strains had unusual chromosomal structure, suggesting that a particular pulsotype is possibly correlated to pathogenicity. A physical map of a highly virulent strain was deduced by stepwise deletion of I-CeuI sites. Homologous housekeeping genes and several virulence genes of Ecc were mapped onto I-CeuI fragments by Southern blotting to compare the chromosomal structure of Ecc with other closely related animal pathogens. We identified portions of the genome that appear to be well conserved across enteric species and portions that have undergone significant changes due to genome rearrangements. Overall, we found the Ecc strains isolated from potatoes were surprisingly diverse compared to related human pathogens.