专性真菌Phakopsorapachyrhizi引起的大豆锈病(SBR)的管理主要依靠合成杀菌剂的使用,特别是在这种疾病造成严重产量损失的地区。对合成杀真菌剂来控制这种疾病的依赖导致了P.pachyrhizi种群对大多数杀真菌剂的抗性。在这项研究中,使用大豆离叶法和在生长室中的植物上评估了从不同环境中分离的细菌对P.pachyrhizi的生物防治潜力,温室,和字段。在使用离叶方法评估的998种细菌分离物中;58%从植物相关材料中分离,27%来自土壤,10%来自昆虫,5%来自其他环境。在筛选的分离株中,73是活性的(它们具有75%的锈蚀减少),活性率为7.3%。从活性分离物中,在生长室中的植物上重新测试65个分离株,以确认活性。在确认测试中,从植物相关材料中分离出的49种细菌以75%的确认率保持了其活性。大多数具有确认活性的细菌属于分类学类别芽孢杆菌和γ变形杆菌(70%)。根据初始筛选和确认测试中的活性,将活性分离株优先用于温室和田间测试。6种细菌分离株AFS000009(Pseudomonas_Echororaphis),AFS032321(枯草芽孢杆菌),AFS042929(巨大芽孢杆菌),AFS065981(Bacillus_Xsimplex_A),AFS090698(苏云金芽孢杆菌),和AFS097295(Bacillus_Atoyonensis)从那些在确认测试中保持活性的细菌中选择,并在温室中进行评估,其中5人进行了实地评估。根据阿拉巴马州的实地评估,所有细菌分离物都能减少锈病感染,并能减少唑菌酯(Quadris®,0.3L/ha)作为杀菌剂对照(P>0.05)。此外,扫描电子显微照片显示了AFS000009和AFS032321对P.pachyrhiziurediniospiosores拮抗活性的证据。通过发酵和配方优化,可以改善始终表现出与唑菌酯相当的活性的细菌分离株,开发,并部署。这些细菌菌株将为合成杀真菌剂提供有价值的替代品,并且可以在该疾病的综合疾病管理计划中发挥有用的作用。
The management of soybean rust (SBR) caused by the obligate fungus Phakopsora pachyrhizi mostly relies on the use of synthetic fungicides, especially in areas where the disease inflicts serious yield losses. The reliance on synthetic fungicides to manage this disease has resulted in resistance of P. pachyrhizi populations to most fungicides. In this study, bacteria isolated from diverse environments were evaluated for their biocontrol potential against P. pachyrhizi using soybean detached-leaf method and on-plant in the growth chamber, greenhouse, and field. Among 998 bacterial isolates evaluated using the detached-leaf method; 58% were isolated from plant-related materials, 27% from soil, 10% from insects, and 5% from other environments. Of the isolates screened, 73 were active (they had ⪖ 75% rust reduction) with an active rate of 7.3%. From the active isolates, 65 isolates were re-tested on-plant in the growth chamber for activity confirmation. In the confirmation test, 49 bacteria isolated from plant-related materials maintained their activity with a confirmation rate of 75%. The majority of bacteria with confirmed activity belonged to the taxonomic classes Bacilli and Gammaproteobacteria (70%). Active isolates were prioritized for greenhouse and field testing based on activity in the initial screen and confirmation test. Six bacterial isolates AFS000009 (Pseudomonas_E chlororaphis), AFS032321 (Bacillus subtilis), AFS042929 (Bacillus_C megaterium), AFS065981 (Bacillus_X simplex_A), AFS090698 (Bacillus_A thuringiensis_S), and AFS097295 (Bacillus_A toyonensis) were selected from those bacteria that maintained activity in the confirmation test and were evaluated in the greenhouse, and five among them were evaluated in the field. From the Alabama field evaluation, all bacterial isolates reduced rust infection as well as azoxystrobin (Quadris® at 0.3 L/ha) used as the fungicide control (P > 0.05). Moreover, the scanning electron micrographs demonstrated evidence of antagonistic activity of AFS000009 and AFS032321 against P. pachyrhizi urediniospores. Bacterial isolates that consistently showed activity comparable to that of azoxystrobin can be improved through fermentation and formulation optimization, developed, and deployed. These bacteria strains would provide a valuable alternative to the synthetic fungicides and could play a useful role in integrated disease management programs for this disease.