title: Differential growth responses of Brachypodium distachyon genotypes to inoculation with plant growth promoting rhizobacteria.
abstract: Plant growth promoting rhizobacteria (PGPR) can associate and enhance the growth of important crop grasses. However, in most cases, the molecular mechanisms responsible for growth promotion are not known. Such research could benefit by the adoption of a grass model species that showed a positive response to bacterial inoculation and was amenable to genetic and molecular research methods. In this work we inoculated different genotypes of the model grass Brachypodium distachyon with two, well-characterized PGPR bacteria, Azospirillum brasilense and Herbaspirillum seropedicae, and evaluated the growth response. Plants were grown in soil under no nitrogen or with low nitrogen (i.e., 0.5 mM KNO3). A variety of growth parameters (e.g., shoot height, root length, number of lateral roots, fresh and dry weight) were measured 35 days after inoculation. The data indicate that plant genotype plays a very important role in determining the plant response to PGPR inoculation. A positive growth response was observed with only four genotypes grown under no nitrogen and three genotypes tested under low nitrogen. However, in contrast, relatively good root colonization was seen with most genotypes, as measured by drop plate counting and direct, microscopic examination of roots. In particular, the endophytic bacteria H. seropedicae showed strong epiphytic and endophytic colonization of roots.
authors.affiliation: Divisions of Plant Science and Biochemistry, C. S. Bond Life Science Center, University of Missouri, Columbia, MO, 65211, USA.
authors.forename: Fernanda P
authors.initials: FP
authors.lastname: do Amaral
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba, 81531-980, Brazil.
authors.forename: Vânia C S
authors.initials: VC
authors.lastname: Pankievicz
authors.affiliation: Department of Food Science and Technology, Federal University of Santa Catarina, Florianópolis, 88034-001, Brazil.
authors.forename: Ana Carolina M
authors.initials: AC
authors.lastname: Arisi
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba, 81531-980, Brazil.
authors.forename: Emanuel M
authors.initials: EM
authors.lastname: de Souza
authors.affiliation: Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba, 81531-980, Brazil.
authors.forename: Fabio
authors.initials: F
authors.lastname: Pedrosa
authors.affiliation: Divisions of Plant Science and Biochemistry, C. S. Bond Life Science Center, University of Missouri, Columbia, MO, 65211, USA. staceyg@missouri.edu.
authors.forename: Gary
authors.initials: G
authors.lastname: Stacey
mesh_terms: D015806:Azospirillum brasilense / Q000502:physiology*; D058431:Brachypodium / Q000235:genetics* / Q000254:growth & development* / Q000382:microbiology*; D060026:Endophytes / Q000502:physiology; D042803:Herbaspirillum / Q000502:physiology*; D018517:Plant Roots / Q000382:microbiology
keywords: Azospirillum brasilense; Brachypodium distachyon; Herbaspirillum seropedicae; Plant-beneficial bacteria interaction