title: Azospirillum spp. from native forage grasses in Brazilian Pantanal floodplain: biodiversity and plant growth promotion potential.
abstract: A sustainable alternative to improve yield and the nutritive value of forage is the use of plant growth-promoting bacteria (PGPB) that release nutrients, synthesize plant hormones and protect against phytopathogens (among other mechanisms). Azospirillum genus is considered an important PGPB, due to the beneficial effects observed when inoculated in several plants. The aim of this study was to evaluate the diversity of new Azospirillum isolates and select bacteria according to the plant growth promotion ability in three forage species from the Brazilian Pantanal floodplain: Axonopus purpusii, Hymenachne amplexicaulis and Mesosetum chaseae. The identification of bacterial isolates was performed using specific primers for Azospirillum in PCR reactions and partial sequencing of the 16S rRNA and nifH genes. The isolates were evaluated in vitro considering biological nitrogen fixation (BNF) and indole-3-acetic acid (IAA) production. Based on the results of BNF and IAA, selected isolates and two reference strains were tested by inoculation. At 31 days after planting the plant height, shoot dry matter, shoot protein content and root volume were evaluated. All isolates were able to fix nitrogen and produce IAA, with values ranging from 25.86 to 51.26 mg N mL-1and 107-1038 µmol L-1, respectively. The inoculation of H. amplexicaulis and A. purpusii increased root volume and shoot dry matter. There were positive effects of Azospirillum inoculation on Mesosetum chaseae regarding plant height, shoot dry matter and root volume. Isolates MAY1, MAY3 and MAY12 were considered promising for subsequent inoculation studies in field conditions.
authors.affiliation: Programa de Pós-Graduação em Ciências, Bioquímica, Setor de Ciências Biológicas, Universidade Federal do Paraná, Av. Cel. Francisco H. dos Santos, s/n, Jardim das Américas, Curitiba, PR, Brazil.|Programa de Pós-Graduação em Biologia Vegetal, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, 79070-900, Campo Grande, MS, Brazil.
authors.forename: Mayara S T
authors.initials: MS
authors.lastname: Souza
authors.affiliation: Programa de Pós-Graduação em Ciências, Bioquímica, Setor de Ciências Biológicas, Universidade Federal do Paraná, Av. Cel. Francisco H. dos Santos, s/n, Jardim das Américas, Curitiba, PR, Brazil.
authors.forename: Valter A
authors.initials: VA
authors.lastname: de Baura
authors.affiliation: Embrapa Pantanal, Rua 21 de Setembro, no. 1.880, 79320-900, Corumbá, MS, Brazil.
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Santos
authors.affiliation: Embrapa Semiárido, BR 428, Km 152, 56302-970, Petrolina, PE, Brazil.
authors.forename: Paulo Ivan
authors.initials: PI
authors.lastname: Fernandes-Júnior
authors.affiliation: Embrapa Cerrados, BR 020, Km 18, Planaltina, 73310-970, Brasília, DF, Brazil.
authors.forename: Fábio B
authors.initials: FB
authors.lastname: Reis Junior
authors.affiliation: Programa de Pós-Graduação em Biologia Vegetal, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, 79070-900, Campo Grande, MS, Brazil.
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Marques
authors.affiliation: Ciências Biológicas, Campus do Pantanal, Universidade Federal de Mato Grosso do Sul, Av. Rio Branco, 1270 - Universitário, 79304-902, Corumbá, MS, Brazil.|Programa de Pós-Graduação em Biologia Vegetal, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso do Sul, 79070-900, Campo Grande, MS, Brazil.
authors.forename: Gecele Matos
authors.initials: GM
authors.lastname: Paggi
authors.affiliation: Ciências Biológicas, Campus do Pantanal, Universidade Federal de Mato Grosso do Sul, Av. Rio Branco, 1270 - Universitário, 79304-902, Corumbá, MS, Brazil. marivaine.brasil@ufms.br.
authors.forename: Marivaine
authors.initials: M
authors.lastname: da Silva Brasil
mesh_terms: D016949:Azospirillum / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D004271:DNA, Fungal / Q000032:analysis; D007210:Indoleacetic Acids / Q000378:metabolism; D009586:Nitrogen Fixation; D010802:Phylogeny; D010940:Plant Proteins / Q000032:analysis; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D006109:Poaceae / Q000254:growth & development / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D004271:DNA, Fungal; D007210:Indoleacetic Acids; D010940:Plant Proteins; C030737:indoleacetic acid
keywords: Azospirillum brasilense; Biological nitrogen fixation; Diazotrophic bacteria; Indole-3-acetic acid; Inoculant