Tokgöz Serkan, Lakshman Dilip K, Ghozlan Mahmoud H, Pinar Hasan, Roberts Daniel P, Mitra Amitava
Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
Sustainable Agricultural Systems Laboratory, USDA-ARS, Beltsville, MD 20705, USA.
Plants (Basel). 2020 Nov 5;9(11):1494. doi: 10.3390/plants9111494.
The root nodules are a unique environment formed on legume roots through a highly specific symbiotic relationship between leguminous plants and nodule-inducing bacteria. Previously, Rhizobia were presumed to be the only group of bacteria residing within nodules. However, recent studies discovered diverse groups of bacteria within the legume nodules. In this report soybean nodule-associated bacteria were studied in an effort to identify beneficial bacteria for plant disease control and growth promotion. Analysis of surface-sterilized single nodules showed bacterial diversity of the nodule microbiome. Five hundred non-rhizobial colonies from 10 nodules, 50 colonies per nodule, were tested individually against the tomato wilt causing bacterial pathogen subsp. (Cmm) for inhibition of pathogen growth. From the initial screening, 54 isolates were selected based on significant growth inhibition of Cmm. These isolates were further tested in vitro on another bacterial pathogen pv. tomato (Pst) and two fungal pathogens and . Bacterial metabolites were extracted from 15 selected isolates with ethanol and tested against pathogen Cmm and Pst. These isolates were identified by using MALDI-TOF mass spectrometry and 16S rRNA gene sequencing. spp. were the dominant soybean nodule-associated non-rhizobial bacterial group. Several isolates imparted significant protection against pathogens and/or plant growth promotion on tomato seedlings. The most promising nodule-associated bacterial isolate that suppressed both Cmm and Pst in vitro and Pst in tomato seedlings was identified as a species. Isolation and identification of beneficial nodule-associated bacteria established the foundation for further exploration of potential nodule-associated bacteria for plant protection and growth promotion.
根瘤是豆科植物根上通过豆科植物与根瘤诱导细菌之间高度特异性的共生关系形成的独特环境。以前，根瘤菌被认为是根瘤内唯一存在的细菌群体。然而，最近的研究发现豆科植物根瘤内存在多种细菌群体。在本报告中，对大豆根瘤相关细菌进行了研究，以确定对植物病害控制和生长促进有益的细菌。对表面消毒的单个根瘤进行分析，显示了根瘤微生物群的细菌多样性。从10个根瘤中分离出500个非根瘤菌菌落（每个根瘤50个菌落），分别针对引起番茄枯萎病的细菌病原体亚种（Cmm）进行病原体生长抑制测试。从初步筛选中，基于对Cmm的显著生长抑制选择了54个分离株。这些分离株在体外进一步针对另一种细菌病原体番茄致病变种（Pst）以及两种真菌病原体和进行测试。用乙醇从15个选定的分离株中提取细菌代谢物，并针对病原体Cmm和Pst进行测试。通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）和16S rRNA基因测序对这些分离株进行鉴定。属是大豆根瘤相关的主要非根瘤菌细菌群体。几种分离株对番茄幼苗的病原体具有显著的保护作用和/或促进植物生长。在体外抑制Cmm和Pst以及在番茄幼苗中抑制Pst的最有前景的根瘤相关细菌分离株被鉴定为一个种。有益根瘤相关细菌的分离和鉴定为进一步探索潜在的根瘤相关细菌用于植物保护和生长促进奠定了基础。
