title: Calcium- and ROS-mediated defence responses in BY2 tobacco cells by nonpathogenic Streptomyces sp.
abstract: OBJECTIVE
  The early molecular events underlying the elicitation of plant defence reactions by Gram-positive bacteria are relatively unknown. In plants, calcium and reactive oxygen species are commonly involved as cellular messengers of a wide range of biotic stimuli from pathogenic to symbiotic bacteria. In the present work, we checked whether nonpathogenic Streptomyces sp. strains could induce early signalling events leading to defence responses in BY2 tobacco cell suspensions.
  
  
  RESULTS
  We have demonstrated that nonpathogenic Streptomyces sp. OE7 strain induced a cytosolic Ca(2+) increase and a biphasic oxidative burst in the upstream signalling events, leading to defence responses in BY2 tobacco cell suspensions. Streptomyces sp. OE7 also elicited delayed intracellular free scopoletin production and programmed cell death. In agreement with scopoletin production, OE7 induced accumulation of PAL transcripts and increased accumulation of transcripts of EREBP1 and AOX genes that are known to be regulated by the jasmonate/ethylene pathway. Transcript levels of PR1b and NIMIN2α, both salicylic acid pathway-linked genes, were not modified. Moreover, Streptomyces sp. OE7 culture filtrates could reduce Pectobacterium carotovorum- and Pectobacterium atrosepticum-induced death of BY2 cells and soft rot on potato slices.
  
  
  CONCLUSIONS
  New insights are thus provided into the interaction mechanisms between Streptomyces sp. and plants; Streptomyces sp. could be sensed by plant cells, and through cytosolic Ca(2+) changes and the generation of reactive oxygen species, defence responses were induced.
  
  
  CONCLUSIONS
  These induced defence responses appeared to participate in attenuating Pectobacterium-induced diseases in plants. Thus, Streptomyces sp. OE7 could be a biocontrol agent against Pectobacterium sp.
authors.affiliation: LEM, Institut de Biologie des Plantes, Université Paris Diderot, Sorbonne Paris Cité, Orsay, France.
authors.forename: M
authors.initials: M
authors.lastname: Baz
authors.forename: D
authors.initials: D
authors.lastname: Tran
authors.forename: M
authors.initials: M
authors.lastname: Kettani-Halabi
authors.forename: S E
authors.initials: SE
authors.lastname: Samri
authors.forename: A
authors.initials: A
authors.lastname: Jamjari
authors.forename: B
authors.initials: B
authors.lastname: Biligui
authors.forename: P
authors.initials: P
authors.lastname: Meimoun
authors.forename: H
authors.initials: H
authors.lastname: El-Maarouf-Bouteau
authors.forename: M
authors.initials: M
authors.lastname: Garmier
authors.forename: P
authors.initials: P
authors.lastname: Saindrenan
authors.forename: M M
authors.initials: MM
authors.lastname: Ennaji
authors.forename: M
authors.initials: M
authors.lastname: Barakate
authors.forename: F
authors.initials: F
authors.lastname: Bouteau
mesh_terms: D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D044043:Pectobacterium / Q000378:metabolism; D016973:Pectobacterium carotovorum / Q000378:metabolism; D059828:Plant Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012603:Scopoletin / Q000378:metabolism; D015398:Signal Transduction; D011198:Solanum tuberosum / Q000378:metabolism; D013302:Streptomyces / Q000378:metabolism / Q000472:pathogenicity; D014026:Nicotiana / Q000166:cytology / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology*
chemical_list: D017382:Reactive Oxygen Species; D012603:Scopoletin; D002118:Calcium