title: A novel interaction between plant-beneficial rhizobacteria and roots: colonization induces corn resistance against the root herbivore Diabrotica speciosa.
abstract: A number of soil-borne microorganisms, such as mycorrhizal fungi and rhizobacteria, establish mutualistic interactions with plants, which can indirectly affect other organisms. Knowledge of the plant-mediated effects of mutualistic microorganisms is limited to aboveground insects, whereas there is little understanding of what role beneficial soil bacteria may play in plant defense against root herbivory. Here, we establish that colonization by the beneficial rhizobacterium Azospirillum brasilense affects the host selection and performance of the insect Diabrotica speciosa. Root larvae preferentially orient toward the roots of non-inoculated plants versus inoculated roots and gain less weight when feeding on inoculated plants. As inoculation by A. brasilense induces higher emissions of (E)-β-caryophyllene compared with non-inoculated plants, it is plausible that the non-preference of D. speciosa for inoculated plants is related to this sesquiterpene, which is well known to mediate belowground insect-plant interactions. To the best of our knowledge, this is the first study showing that a beneficial rhizobacterium inoculant indirectly alters belowground plant-insect interactions. The role of A. brasilense as part of an integrative pest management (IPM) program for the protection of corn against the South American corn rootworm, D. speciosa, is considered.
authors.affiliation: Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, SP, Brazil.
authors.forename: Franciele
authors.initials: F
authors.lastname: Santos
authors.affiliation: Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, SP, Brazil.
authors.forename: Maria Fernanda G V
authors.initials: MF
authors.lastname: Peñaflor
authors.affiliation: Departments of Chemistry and Biology, Texas Tech University, Lubbock, TX, USA.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Paré
authors.affiliation: Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, SP, Brazil.
authors.forename: Patrícia A
authors.initials: PA
authors.lastname: Sanches
authors.affiliation: Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, SP, Brazil.
authors.forename: Aline C
authors.initials: AC
authors.lastname: Kamiya
authors.affiliation: Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, SP, Brazil; Department of Agronomy, Mid-West State University, Guarapuava, PR, Brazil.
authors.forename: Mateus
authors.initials: M
authors.lastname: Tonelli
authors.affiliation: Department of Agronomy, Mid-West State University, Guarapuava, PR, Brazil.
authors.forename: Cristiane
authors.initials: C
authors.lastname: Nardi
authors.affiliation: Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, SP, Brazil.
authors.forename: José Mauricio S
authors.initials: JM
authors.lastname: Bento
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015806:Azospirillum brasilense; D001517:Coleoptera / Q000472:pathogenicity / Q000502:physiology*; D060434:Herbivory / Q000502:physiology*; D007814:Larva / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D018517:Plant Roots / Q000737:chemistry / Q000382:microbiology* / Q000648:ultrastructure; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes / Q000378:metabolism; D018709:Statistics, Nonparametric; D013559:Symbiosis; D055549:Volatile Organic Compounds / Q000032:analysis; D003313:Zea mays / Q000378:metabolism / Q000382:microbiology*
chemical_list: D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; D055549:Volatile Organic Compounds; C024714:caryophyllene