title: Volatile-Mediated Effects Predominate inParaburkholderia phytofirmansGrowth Promotion and Salt Stress Tolerance ofArabidopsis thaliana.
abstract: Abiotic stress has a growing impact on plant growth and agricultural activity worldwide. Specific plant growth promoting rhizobacteria have been reported to stimulate growth and tolerance to abiotic stress in plants, and molecular mechanisms like phytohormone synthesis and 1-aminocyclopropane-1-carboxylate deamination are usual candidates proposed to mediate these bacterial effects.Paraburkholderia phytofirmansPsJN is able to promote growth of several plant hosts, and improve their tolerance to chilling, drought and salinity. This work investigated bacterial determinants involved in PsJN stimulation of growth and salinity tolerance inArabidopsis thaliana, showing bacteria enable plants to survive long-term salinity treatment, accumulating less sodium within leaf tissues relative to non-inoculated controls. Inactivation of specific bacterial genes encoding ACC deaminase, auxin catabolism,N-acyl-homoserine-lactone production, and flagellin synthesis showed these functions have little influence on bacterial induction of salinity tolerance. Volatile organic compound emission from strain PsJN was shown to reproduce the effects of direct bacterial inoculation of roots, increasing plant growth rate and tolerance to salinity evaluated bothin vitroand in soil. Furthermore, early exposure to VOCs fromP. phytofirmanswas sufficient to stimulate long-term effects observed inArabidopsisgrowth in the presence and absence of salinity. Organic compounds were analyzed in the headspace of PsJN cultures, showing production of 2-undecanone, 7-hexanol, 3-methylbutanol and dimethyl disulfide. Exposure ofA. thalianato different quantities of these molecules showed that they are able to influence growth in a wide range of added amounts. Exposure to a blend of the first three compounds was found to mimic the effects of PsJN on both general growth promotion and salinity tolerance. To our knowledge, this is the first report on volatile compound-mediated induction of plant abiotic stress tolerance by aParaburkholderiaspecies.
authors.affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo IbáñezSantiago, Chile; Center of Applied Ecology and SustainabilitySantiago, Chile; Millennium Nucleus Center for Plant Systems and Synthetic BiologySantiago, Chile.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ledger
authors.affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez Santiago, Chile.
authors.forename: Sandy
authors.initials: S
authors.lastname: Rojas
authors.affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo IbáñezSantiago, Chile; Center of Applied Ecology and SustainabilitySantiago, Chile; Millennium Nucleus Center for Plant Systems and Synthetic BiologySantiago, Chile.
authors.forename: Tania
authors.initials: T
authors.lastname: Timmermann
authors.affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez Santiago, Chile.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Pinedo
authors.affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo IbáñezSantiago, Chile; Center of Applied Ecology and SustainabilitySantiago, Chile; Millennium Nucleus Center for Plant Systems and Synthetic BiologySantiago, Chile.
authors.forename: María J
authors.initials: MJ
authors.lastname: Poupin
authors.affiliation: Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile Santiago, Chile.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Garrido
authors.affiliation: Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile Santiago, Chile.
authors.forename: Pablo
authors.initials: P
authors.lastname: Richter
authors.affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez Santiago, Chile.
authors.forename: Javier
authors.initials: J
authors.lastname: Tamayo
authors.affiliation: Laboratorio de Bioingeniería, Facultad de Ingeniería y Ciencias, Universidad Adolfo IbáñezSantiago, Chile; Center of Applied Ecology and SustainabilitySantiago, Chile; Millennium Nucleus Center for Plant Systems and Synthetic BiologySantiago, Chile.
authors.forename: Raúl
authors.initials: R
authors.lastname: Donoso
keywords: ACC deaminase; Arabidopsis thaliana; Paraburkholderia phytofirmans PsJN; abiotic stress tolerance; plant growth promoting rhizobacteria (PGPR); volatile organic compounds (VOCs)