title: Phytohormone-mediated interkingdom signaling shapes the outcome of rice-Xanthomonas oryzae pv. oryzae interactions.
abstract: BACKGROUND
  Small-molecule hormones are well known to play key roles in the plant immune signaling network that is activated upon pathogen perception. In contrast, little is known about whether phytohormones also directly influence microbial virulence, similar to what has been reported in animal systems.
  
  
  RESULTS
  In this paper, we tested the hypothesis that hormones fulfill dual roles in plant-microbe interactions by orchestrating host immune responses, on the one hand, and modulating microbial virulence traits, on the other. Employing the rice-Xanthomonas oryzae pv. oryzae (Xoo) interaction as a model system, we show that Xoo uses the classic immune hormone salicylic acid (SA) as a trigger to activate its virulence-associated quorum sensing (QS) machinery. Despite repressing swimming motility, sodium salicylate (NaSA) induced production of the Diffusible Signal Factor (DSF) and Diffusible Factor (DF) QS signals, with resultant accumulation of xanthomonadin and extracellular polysaccharides. In contrast, abscisic acid (ABA), which favors infection by Xoo, had little impact on DF- and DSF-mediated QS, but promoted bacterial swimming via the LuxR solo protein OryR. Moreover, we found both DF and DSF to influence SA- and ABA-responsive gene expression in planta.
  
  
  CONCLUSIONS
  Together our findings indicate that the rice SA and ABA signaling pathways cross-communicate with the Xoo DF and DSF QS systems and underscore the importance of bidirectional interkingdom signaling in molding plant-microbe interactions.
authors.affiliation: Lab of Phytopathology, Department of Crop Protection, Ghent University, Coupure Links 653, 9000, Ghent, Belgium. jing.xu@ugent.be.
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China. lianzhou@sjtu.edu.cn.
authors.forename: Lian
authors.initials: L
authors.lastname: Zhou
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149, Trieste, Italy. venturi@icgeb.org.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Venturi
authors.affiliation: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China. yawenhe@sjtu.edu.cn.
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: He
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, 230-0045, Japan. mikiko@riken.jp.
authors.forename: Mikiko
authors.initials: M
authors.lastname: Kojima
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, 230-0045, Japan. sakaki@postman.riken.go.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakakibari
authors.affiliation: Lab of Phytopathology, Department of Crop Protection, Ghent University, Coupure Links 653, 9000, Ghent, Belgium. monica.hofte@ugent.be.
authors.forename: Monica
authors.initials: M
authors.lastname: Höfte
authors.affiliation: Lab of Phytopathology, Department of Crop Protection, Ghent University, Coupure Links 653, 9000, Ghent, Belgium. david.devleesschauwer@ugent.be.
authors.forename: David
authors.initials: D
authors.lastname: De Vleesschauwer
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001704:Biopolymers / Q000096:biosynthesis; D054884:Host-Pathogen Interactions / Q000187:drug effects*; D062385:Hydroxybenzoates / Q000378:metabolism; D008954:Models, Biological; D012275:Oryza / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology*; D010226:Parabens / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D053038:Quorum Sensing / Q000187:drug effects; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D014974:Xanthomonas / Q000187:drug effects / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D001704:Biopolymers; D062385:Hydroxybenzoates; D010226:Parabens; D010937:Plant Growth Regulators; C032948:3-hydroxybenzoic acid; C038193:4-hydroxybenzoic acid; D020156:Salicylic Acid