Souza Mayara S T, de Baura Valter A, Santos Sandra A, Fernandes-Júnior Paulo Ivan, Reis Junior Fábio B, Marques Maria Rita, Paggi Gecele Matos, da Silva Brasil Marivaine
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.
World J Microbiol Biotechnol. 2017 Apr;33(4):81. doi: 10.1007/s11274-017-2251-4. Epub 2017 Mar 29.
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 and 107-1038 µmol L, 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.
提高牧草产量和营养价值的一种可持续替代方法是使用能释放养分、合成植物激素并抵御植物病原体（以及其他机制）的植物促生细菌（PGPB）。由于在多种植物上接种后观察到有益效果，固氮螺菌属被认为是一种重要的PGPB。本研究的目的是评估新的固氮螺菌分离株的多样性，并根据在巴西潘塔纳尔湿地平原的三种牧草品种（紫花地毯草、水蔗草和查氏中柱草）中的促生长能力来筛选细菌。在PCR反应中使用固氮螺菌的特异性引物以及对16S rRNA和nifH基因进行部分测序来鉴定细菌分离株。在体外评估分离株的生物固氮（BNF）和吲哚 - 3 - 乙酸（IAA）产生情况。基于BNF和IAA的结果，对筛选出的分离株和两个参考菌株进行接种测试。在种植后31天评估株高、地上部干物质、地上部蛋白质含量和根体积。所有分离株都能够固氮并产生IAA，其值分别在25.86至51.26 mg N mL和107 - 1038 μmol L之间。接种水蔗草和紫花地毯草增加了根体积和地上部干物质。接种固氮螺菌对查氏中柱草的株高、地上部干物质和根体积有积极影响。分离株MAY1、MAY3和MAY12被认为有希望用于后续的田间接种研究。
