Department of Soil Science, "Luiz de Queiroz" College of Agriculture, University of São Paulo, P.O. Box 83, Piracicaba, São Paulo, 13400-970, Brazil.
Department of Biology, São Paulo State University, avenue 24-A, 1515, P.O Box 178, Rio Claro, São Paulo, 13506-900, Brazil.
Braz J Microbiol. 2022 Jun;53(2):873-883. doi: 10.1007/s42770-022-00711-7. Epub 2022 Mar 3.
Caatinga is the predominant biome in the Brazilian semiarid region. Its vegetation is composed by plants and microorganisms with high tolerance to drought. Microorganisms associated with plants in this biome can develop mechanisms to protect cells from water stress and desiccation. The aim of this study was to identify plant growth-promoting rhizobacteria associated with the drought-tolerant legume Mimosa artemisiana and to examine their effect on the growth of soybean (Glycine max L.) under drought condition (irrigation with 30% of field capacity). Rhizospheric soil was collected along the Caatinga (In the States of Bahia and Pernambuco) at 4 collection points, totaling sixty subsamples. Xerotolerant bacteria with plant growth-promotion characteristics were isolated in a selective culture medium for diazotrophic bacteria. Two strains of the genera Bacillus and one Paenibacillus were promising in in vitro and in vivo tests. Both were able to grow in a medium with low water availability (0.919 A) and could produce exopolysaccharides and indole acetic acid (up to 130 µg mL). In addition, they produced 1-aminocyclopropane-1-carboxylate (ACC) deaminase and formed biofilms under drought conditions. The inoculation with the isolated strains in the seedling root system mitigated the adverse effects of drought, increasing roots and shoots dry weights of soybean seedlings compared with non-inoculated.
卡廷加是巴西半干旱地区的主要生物群落。其植被由具有高度耐旱性的植物和微生物组成。与该生物群系中的植物相关的微生物可以发展出保护细胞免受水分胁迫和干燥的机制。本研究的目的是鉴定与耐旱豆科植物含羞草相关的促生根瘤菌，并研究它们在干旱条件下（田间持水量的 30%灌溉）对大豆生长的影响。在 4 个采集点沿卡廷加（在巴伊亚州和伯南布哥州）采集根际土壤，共采集了 60 个样本。在一种选择性的固氮细菌培养基中，分离出具有促进植物生长特性的耐旱细菌。芽孢杆菌属的两个菌株和一个类芽孢杆菌属的菌株在体外和体内试验中都很有前途。两者都能在水分可用性低的培养基中生长（0.919 A），并能产生胞外多糖和吲哚乙酸（高达 130 µg mL）。此外，它们还能产生 1-氨基环丙烷-1-羧酸（ACC）脱氨酶，并在干旱条件下形成生物膜。将分离株接种到幼苗根系中减轻了干旱的不利影响，与未接种的相比，增加了大豆幼苗的根和茎干重。
