Toma Maíra Akemi, Soares de Carvalho Teotonio, Azarias Guimarães Amanda, Martins da Costa Elaine, Savana da Silva Jacqueline, de Souza Moreira Fatima Maria
Universidade Federal de Lavras (UFLA), Departamento de Ciência do Solo (DCS), Lavras, MG, Brazil.
Universidade Federal de Mato Grosso do Sul (UFMS) - Campus de Chapadão do Sul, Chapadão do Sul, MS, Brazil.
Braz J Microbiol. 2017 Oct-Dec;48(4):680-688. doi: 10.1016/j.bjm.2017.03.007. Epub 2017 Jun 29.
Sophora tomentosa is a pantropical legume species with potential for recovery of areas degraded by salinization, and for stabilization of sand dunes. However, few studies on this species have been carried out, and none regarding its symbiotic relationship with beneficial soil microorganisms. Therefore, this study aimed to evaluate the diversity of nitrogen-fixing bacteria isolated from nodules of Sophora tomentosa, and to analyze the occurrence of colonization of arbuscular mycorrhizal fungi on the roots of this legume in seafront soil. Thus, seeds, root nodules, and soil from the rhizosphere of Sophora tomentosa were collected. From the soil samples, trap cultures with this species were established to extract spores and to evaluate arbuscular mycorhizal fungi colonization in legume roots, as well as to capture rhizobia. Rhizobia strains were isolated from nodules collected in the field or from the trap cultures. Representative isolates of the groups obtained in the similarity dendrogram, based on phenotypic characteristics, had their 16S rRNA genes sequenced. The legume species showed nodules with indeterminate growth, and reddish color, distributed throughout the root. Fifty-one strains of these nodules were isolated, of which 21 were classified in the genus Bacillus, Brevibacillus, Paenibacillus, Rhizobium and especially Sinorhizobium. Strains closely related to Sinorhizobium adhaerens were the predominant bacteria in nodules. The other genera found, with the exception of Rhizobium, are probably endophytic bacteria in the nodules. Arbuscular mycorrhizal fungi was observed colonizing the roots, but arbuscular mycorhizal fungi spores were not found in the trap cultures. Therefore Sophora tomentosa is associated with both arbuscular mycorhizal fungi and nodulating nitrogen-fixing bacteria.
绒毛槐是一种泛热带豆科植物，具有恢复盐碱化退化地区和稳定沙丘的潜力。然而，针对该物种的研究较少，且尚无关于其与有益土壤微生物共生关系的研究。因此，本研究旨在评估从绒毛槐根瘤中分离出的固氮细菌的多样性，并分析海滨土壤中该豆科植物根系上丛枝菌根真菌的定殖情况。于是，采集了绒毛槐的种子、根瘤和根际土壤。从土壤样本中建立了该物种的诱捕培养体系，以提取孢子、评估丛枝菌根真菌在豆科植物根系中的定殖情况以及捕获根瘤菌。根瘤菌菌株从田间采集的根瘤或诱捕培养物中分离得到。基于表型特征，对相似性树状图中获得的菌群的代表性分离株进行16S rRNA基因测序。该豆科植物的根瘤呈不定型生长，颜色微红，分布于整个根系。从这些根瘤中分离出51株菌株，其中21株被归类于芽孢杆菌属、短短芽孢杆菌属、类芽孢杆菌属、根瘤菌属（尤其是中华根瘤菌属）。与粘附中华根瘤菌密切相关的菌株是根瘤中的主要细菌。除根瘤菌属外，发现的其他属可能是根瘤中的内生细菌。观察到丛枝菌根真菌定殖于根系，但在诱捕培养物中未发现丛枝菌根真菌孢子。因此，绒毛槐与丛枝菌根真菌和结瘤固氮细菌均有关联。
