Endophytic bacteria have been demonstrated to be one of the most potentially important biocontrol agents for their efficiently improved plant growth and protection of host plants from infection by phytopathogens. Nine strains of endophytic bacteria isolated from Glycyrrhiza uralensis Fisch. (G. uralensis) seeds were screened for the inhibitory effect against 5 fungal phytopathogens by using dual culture method. Among which, the isolate FT2 showed the highest percentage of inhibition to all the test fungal phytopathogens. Detached root assay showed that FT2 significantly reduced disease index and rotted area on Angelica sinensis root slices caused by Fusarium acuminatum. FT2 also exhibited multiple plant growth promotion traits by qualitative analytical method. Based on phenotypic, physiological and biochemical characterization and genotypic characterization, the FT2 strain was identified as Stenotrophomonas rhizophila. Application of strain FT2 reduced the disease index of Cucumber Fusarium Wilt, and the biocontrol effect was equal to chemical fungicide, carbendazim. Moreover, strain FT2 increased the plant height, stem diameter, leaf number and fresh weight of cucumber seedlings and the activities of the defense-related enzymes including phenylalanine ammonia-lyase, polyphenol oxidase and peroxidase. In addition, strain FT2 could promote seed germination and seedling growth of G. uralensis and increase enzyme activities, available nutrient contents and bacterial count in G. uralensis rhizosphere soil. The results demonstrated that the strain FT2 could be used to develop environmentally friendly microbial products to improve the activity against pathogenic and promote plant growth.

中文翻译：

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从甘草种子中分离出的内生细菌的潜在生防和植物生长促进作用

内生细菌已被证明是最重要的生物防治剂之一，因为它们有效地改善了植物生长并保护宿主植物免受植物病原体的感染。从甘草中分离出的九株内生细菌。采用双重培养法筛选(G. uralensis)种子对5种真菌植物病原体的抑制作用。其中，分离株FT2对所有受试真菌植物病原体的抑制百分比最高。离根试验表明，FT2显着降低了由尖镰孢引起的当归根片的病害指数和腐烂面积。通过定性分析方法，FT2 还表现出多种植物生长促进性状。根据表型，经生理生化鉴定和基因型鉴定，FT2菌株被鉴定为根际窄食单胞菌。FT2菌株的施用降低了黄瓜枯萎病的病害指数，生防效果与化学杀菌剂多菌灵相当。此外，FT2菌株提高了黄瓜幼苗的株高、茎粗、叶数和鲜重，以及苯丙氨酸解氨酶、多酚氧化酶和过氧化物酶等防御相关酶的活性。此外，FT2菌株能促进乌拉尔乌尔的种子萌发和幼苗生长，提高乌拉尔根际土壤中酶活性、速效养分含量和细菌数。