Exopolysaccharides of Erwinia amylovora and related pathogens

K. Geider*, Z. Du, M. Hildebrand, W. S. Kim, V. Jakovljevic, S. Jock

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

2 Scopus citations


Exopolysaccharides (EPS) are synthesized by many bacteria to modulate the interactions between the bacteria and the environment. Erwinia amylovora produces amylovoran and the homopolymer levan, similar to a glucose side chain in the complex capsular EPS. Levan is not synthesized by the Asian pear pathogens. Genes coding for capsular EPS synthesis in the cps operon of E. pyrifoliae are highly homologous to the ams genes of E. amylovora. Ams mutants were not virulent in plant assays, and the bacteria were exposed to plant defense reactions inactivating the pathogen. EPS synthesis of these three pathogens is regulated by several genes including rcs A, rcsB and hns. With RcsC as sensor, RcsB is the activator protein in a two-component system enhanced by RcsA. As for E. amylovora, E. pyrifoliae mutants in rcsB completely lacked EPS. Mutations in rcsC in E. pyrifoliae decreased EPS synthesis. The hns genes affected amylovoran synthesis and expression of levansucrase. Levan production in E. amylovora is activated by rlsC, rlsB upstream of lsc and rlsA adjacent to the hrp region. Cells can survive in necrotic plant lesions, but without EPS capsules they decay rapidly in dry environments.

Original languageEnglish (US)
Title of host publicationProceedings of the Xth International Workshop on Fire Blight
PublisherInternational Society for Horticultural Science
Number of pages4
ISBN (Print)9066054077, 9789066054073
StatePublished - Feb 2006

Publication series

NameActa Horticulturae
ISSN (Print)0567-7572


  • Amylovoran
  • H-NS protein
  • Levan
  • Pyrifolan
  • Regulation of EPS synthesis

ASJC Scopus subject areas

  • Horticulture


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