title: Agroinfiltration reduces ABA levels and suppresses Pseudomonas syringae-elicited salicylic acid production in Nicotiana tabacum.
abstract: BACKGROUND
  Agrobacterium tumefaciens strain GV3101 (pMP90) is widely used in transient gene expression assays, including assays to study pathogen effectors and plant disease resistance mechanisms. However, inoculation of A. tumefaciens GV3101 into Nicotiana tabacum (tobacco) leaves prior to infiltration with pathogenic and non-host strains of Pseudomonas syringae results in suppression of macroscopic symptoms when compared with leaves pre-treated with a buffer control.
  
  
  RESULTS
  To gain further insight into the mechanistic basis of symptom suppression by A. tumefaciens we examined the effect of pre-treatment with A. tumefaciens on the growth of P. syringae, the production of the plant signalling molecules salicylic acid (SA) and abscisic acid (ABA), and the presence of callose deposits. Pre-treatment with A. tumefaciens reduced ABA levels, P. syringae multiplication and P. syringae-elicited SA and ABA production, but promoted increased callose deposition. However, pre-treatment with A. tumefaciens did not suppress necrosis or SA production in leaves inoculated with the elicitor HrpZ.
  
  
  CONCLUSIONS
  Collectively, these results show that inoculation of N. tabacum leaves with A. tumefaciens alters plant hormone levels and plant defence responses to P. syringae, and demonstrate that researchers should consider the impact of A. tumefaciens on plant signal transduction when using A. tumefaciens-mediated transient expression assays to investigate ABA-regulated processes or pathogenicity and plant defence mechanisms.
authors.affiliation: Department of Plant Sciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Arantza
authors.initials: A
authors.lastname: Rico
authors.forename: Mark H
authors.initials: MH
authors.lastname: Bennett
authors.forename: Silvia
authors.initials: S
authors.lastname: Forcat
authors.forename: Wei E
authors.initials: WE
authors.lastname: Huang
authors.forename: Gail M
authors.initials: GM
authors.lastname: Preston
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism*; D014026:Nicotiana / Q000378:metabolism* / Q000382:microbiology
chemical_list: D000040:Abscisic Acid; D020156:Salicylic Acid