title: Exploring new roles for the rpoS gene in the survival and virulence of the fire blight pathogen Erwinia amylovora.
abstract: Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-protection against oxidative, osmotic, and acid stresses and was essential for cross-protection against heat shock, but nonessential against acid shock. RpoS also mediated regulation of motility, exopolysaccharide synthesis, and virulence in immature loquats, but not in pear plantlets, and contributed to E. amylovora survival in nonhost tissues during incompatible interactions. Our results reveal some unique roles for the rpoS gene in E. amylovora and provide new knowledge on the regulation of different processes related to its ecology, including survival in different environments and virulence in immature fruits.
authors.affiliation: Departmento de Microbiología y Ecología, Universitat de València, Burjassot, Valencia, Spain; Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Parque Científico y Tecnológico de la UPM, Madrid, Spain.
authors.forename: Ricardo D
authors.initials: RD
authors.lastname: Santander
authors.forename: Mercedes
authors.initials: M
authors.lastname: Monte-Serrano
authors.forename: José J
authors.initials: JJ
authors.lastname: Rodríguez-Herva
authors.forename: Emilia
authors.initials: E
authors.lastname: López-Solanilla
authors.forename: Pablo
authors.initials: P
authors.lastname: Rodríguez-Palenzuela
authors.forename: Elena G
authors.initials: EG
authors.lastname: Biosca
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D031983:Eriobotrya / Q000382:microbiology; D044084:Erwinia amylovora / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*; D005798:Genes, Bacterial; D018869:Heat-Shock Response / Q000235:genetics; D006602:Hexosyltransferases / Q000378:metabolism; D009154:Mutation; D009997:Osmotic Pressure; D018384:Oxidative Stress / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology*; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D031989:Pyrus / Q000382:microbiology; D027824:Rosaceae / Q000382:microbiology; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology*; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D012808:Sigma Factor; C100769:amylovoran; C069567:sigma factor KatF protein, Bacteria; D006602:Hexosyltransferases; C021513:levansucrase
keywords: cross-protection; exopolysaccharides; incompatible plant-pathogen interactions; loquats; motility; starvation