title: Major cereal crops benefit from biological nitrogen fixation when inoculated with the nitrogen-fixing bacterium Pseudomonas protegens Pf-5 X940.
abstract: A main goal of biological nitrogen fixation research has been to expand the nitrogen-fixing ability to major cereal crops. In this work, we demonstrate the use of the efficient nitrogen-fixing rhizobacterium Pseudomonas protegens Pf-5 X940 as a chassis to engineer the transfer of nitrogen fixed by BNF to maize and wheat under non-gnotobiotic conditions. Inoculation of maize and wheat with Pf-5 X940 largely improved nitrogen content and biomass accumulation in both vegetative and reproductive tissues, and this beneficial effect was positively associated with high nitrogen fixation rates in roots.15N isotope dilution analysis showed that maize and wheat plants obtained substantial amounts of fixed nitrogen from the atmosphere. Pf-5 X940-GFP-tagged cells were always reisolated from the maize and wheat root surface but never from the inner root tissues. Confocal laser scanning microscopy confirmed root surface colonization of Pf-5 X940-GFP in wheat plants, and microcolonies were mostly visualized at the junctions between epidermal root cells. Genetic analysis using biofilm formation-related Pseudomonas mutants confirmed the relevance of bacterial root adhesion in the increase in nitrogen content, biomass accumulation and nitrogen fixation rates in wheat roots. To our knowledge, this is the first report of robust BNF in major cereal crops.
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|Instituto de Genética Ewald A. Favret (CICVyA-INTA), Buenos Aires, Argentina.
authors.forename: Ana Romina
authors.initials: AR
authors.lastname: Fox
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|Instituto de Genética Ewald A. Favret (CICVyA-INTA), Buenos Aires, Argentina.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Soto
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|LBMIBS, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina.
authors.forename: Claudio
authors.initials: C
authors.lastname: Valverde
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|Fundación Instituto Leloir and IIBBA CONICET, Buenos Aires, Argentina.
authors.forename: Daniela
authors.initials: D
authors.lastname: Russo
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|LBMIBS, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina.
authors.forename: Antonio
authors.initials: A
authors.lastname: Lagares
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|Fundación Instituto Leloir and IIBBA CONICET, Buenos Aires, Argentina.
authors.forename: Ángeles
authors.initials: Á
authors.lastname: Zorreguieta
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|Departamento de Fisicomatemática, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Karina
authors.initials: K
authors.lastname: Alleva
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|Instituto de Genética Ewald A. Favret (CICVyA-INTA), Buenos Aires, Argentina.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Pascuan
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina.|Instituto de Genética Ewald A. Favret (CICVyA-INTA), Buenos Aires, Argentina.
authors.forename: Romina
authors.initials: R
authors.lastname: Frare
authors.affiliation: Department of Crop Protection, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Córdoba, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Mercado-Blanco
authors.affiliation: Department of Molecular Microbiology, John Innes Centre, Norwich, NR4 7UH, UK.
authors.forename: Ray
authors.initials: R
authors.lastname: Dixon
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cuidad Autónoma de Buenos Aires, Buenos Aires, Argentina. nicoayub@gmail.com.|Instituto de Genética Ewald A. Favret (CICVyA-INTA), Buenos Aires, Argentina. nicoayub@gmail.com.
authors.forename: Nicolás Daniel
authors.initials: ND
authors.lastname: Ayub
mesh_terms: D059827:Agricultural Inoculants / Q000235:genetics / Q000502:physiology*; D018556:Crops, Agricultural / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology*; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D011549:Pseudomonas / Q000235:genetics / Q000502:physiology*; D014908:Triticum / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D003313:Zea mays / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology
chemical_list: D009584:Nitrogen