title: Broad-range antagonistic rhizobacteria Pseudomonas fluorescens and Serratia plymuthica suppress Agrobacterium crown gall tumours on tomato plants.
abstract: OBJECTIVE
  To examine the biocontrol activity of broad-range antagonists Serratia plymuthica IC1270, Pseudomonas fluorescens Q8r1-96 and P. fluorescens B-4117 against tumourigenic strains of Agrobacterium tumefaciens and A. vitis.
  
  
  RESULTS
  Under greenhouse conditions, the antagonists, applied via root soak prior to injecting Agrobacterium strains into the wounded stems, significantly suppressed tumour development on tomato seedlings. A derivative of P. fluorescens Q8r1-96 tagged with a gfp reporter, as well as P. fluorescens B-4117 and S. plymuthica IC1270 marked with rifampicin resistance, stably persisted in tomato tissues for at least 1 month. Mutants of P. fluorescens Q8r1-96 and S. plymuthica IC1270 deficient in 2,4-diacetylphloroglucinol or pyrrolnitrin production, respectively, also proficiently suppressed the tumour development, indicating that these antibiotics are not responsible for the observed biocontrol effect on crown gall disease. The volatile organic compounds (VOCs) produced by the tested P. fluorescens and S. plymuthica strains inhibited the growth of A. tumefaciens and A. vitis strains in vitro. Solid-phase microextraction-gas chromatography-mass spectrometry analysis revealed dimethyl disulfide (DMDS) as the major headspace volatile produced by S. plymuthica IC1270; it strongly suppressed Agrobacterium growth in vitro and was emitted by tomato plants treated with S. plymuthica IC1270. 1-Undecene was the main volatile emitted by the examined P. fluorescens strains, with other volatiles, including DMDS, being detected in only relatively low quantities.
  
  
  CONCLUSIONS
  S. plymuthica IC1270, P. fluorescens B-4117 and P. fluorescens Q8r1-96 can be used as novel biocontrol agents of pathogenic Agrobacterium. VOCs, and specifically DMDS, might be involved in the suppression of oncogenicity in tomato plants. However, the role of specific volatiles in the biocontrol activity remains to be elucidated.
  
  
  CONCLUSIONS
  The advantage of applying these antagonists lies in their multiple activities against a number of plant pathogens, including Agrobacterium.
authors.affiliation: Otto Warburg Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: N
authors.initials: N
authors.lastname: Dandurishvili
authors.forename: N
authors.initials: N
authors.lastname: Toklikishvili
authors.forename: M
authors.initials: M
authors.lastname: Ovadis
authors.forename: P
authors.initials: P
authors.lastname: Eliashvili
authors.forename: N
authors.initials: N
authors.lastname: Giorgobiani
authors.forename: R
authors.initials: R
authors.lastname: Keshelava
authors.forename: M
authors.initials: M
authors.lastname: Tediashvili
authors.forename: A
authors.initials: A
authors.lastname: Vainstein
authors.forename: I
authors.initials: I
authors.lastname: Khmel
authors.forename: E
authors.initials: E
authors.lastname: Szegedi
authors.forename: L
authors.initials: L
authors.lastname: Chernin
mesh_terms: D016960:Agrobacterium tumefaciens / Q000254:growth & development; D008401:Gas Chromatography-Mass Spectrometry; D018551:Solanum lycopersicum / Q000382:microbiology*; D010696:Phloroglucinol / Q000031:analogs & derivatives / Q000378:metabolism; D010941:Plant Tumors / Q000382:microbiology; D011551:Pseudomonas fluorescens / Q000378:metabolism / Q000502:physiology*; D012705:Serratia / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D055549:Volatile Organic Compounds / Q000032:analysis / Q000378:metabolism
chemical_list: D055549:Volatile Organic Compounds; C059817:2,4-diacetylphloroglucinol; D010696:Phloroglucinol