title: Pseudomonas fluorescens induces strain-dependent and strain-independent host plant responses in defense networks, primary metabolism, photosynthesis, and fitness.
abstract: Colonization of plants by nonpathogenic Pseudomonas fluorescens strains can confer enhanced defense capacity against a broad spectrum of pathogens. Few studies, however, have linked defense pathway regulation to primary metabolism and physiology. In this study, physiological data, metabolites, and transcript profiles are integrated to elucidate how molecular networks initiated at the root-microbe interface influence shoot metabolism and whole-plant performance. Experiments with Arabidopsis thaliana were performed using the newly identified P. fluorescens GM30 or P. fluorescens Pf-5 strains. Co-expression networks indicated that Pf-5 and GM30 induced a subnetwork specific to roots enriched for genes participating in RNA regulation, protein degradation, and hormonal metabolism. In contrast, only GM30 induced a subnetwork enriched for calcium signaling, sugar and nutrient signaling, and auxin metabolism, suggesting strain dependence in network architecture. In addition, one subnetwork present in shoots was enriched for genes in secondary metabolism, photosynthetic light reactions, and hormone metabolism. Metabolite analysis indicated that this network initiated changes in carbohydrate and amino acid metabolism. Consistent with this, we observed strain-specific responses in tryptophan and phenylalanine abundance. Both strains reduced host plant carbon gain and fitness, yet provided a clear fitness benefit when plants were challenged with the pathogen P. syringae DC3000.
authors.affiliation: Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. westondj@ornl.gov
authors.forename: David J
authors.initials: DJ
authors.lastname: Weston
authors.forename: Dale A
authors.initials: DA
authors.lastname: Pelletier
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Morrell-Falvey
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Tschaplinski
authors.forename: Sara S
authors.initials: SS
authors.lastname: Jawdy
authors.forename: Tse-Yuan
authors.initials: TY
authors.lastname: Lu
authors.forename: Sara M
authors.initials: SM
authors.lastname: Allen
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Melton
authors.forename: Madhavi Z
authors.initials: MZ
authors.lastname: Martin
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Schadt
authors.forename: Abhijit A
authors.initials: AA
authors.lastname: Karve
authors.forename: Jin-Gui
authors.initials: JG
authors.lastname: Chen
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Yang
authors.forename: Mitchel J
authors.initials: MJ
authors.lastname: Doktycz
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Tuskan
mesh_terms: D017360:Arabidopsis / Q000145:classification* / Q000378:metabolism / Q000382:microbiology*; D020013:Calcium Signaling; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D054884:Host-Pathogen Interactions; D010788:Photosynthesis / Q000502:physiology*; D010802:Phylogeny; D010935:Plant Diseases / Q000276:immunology*; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000502:physiology*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism
chemical_list: D012331:RNA, Fungal