Identification of pathogen causing root rot of Sophora tonkinensis Radix in Guizhou

【Objective】 To identify the pathogen causing root rot of Sophora tonkinensis Radix in Guizhou, and to provide a theoretical basis for disease control of S. tonkinensis Radix root rot and for breeding resistant varieties.【Method】 The pathogen causing root rot on S. tonkinensis Radix was isolated and purified from plant samples with root rot disease symptoms. The pathogenicity of representative strains were determined according to Koch's law, and the pathogen strains were identified by morphological characterization and molecular biology.【Result】 According to the collected diseased plant tissues, a total of 200 fungal isolates were obtained from 23 strains out of 67 strains collected, and 67 of them with different growth and morphology characters were selected for ITS sequencing on PDA media, and BLASTN comparison was conducted in NCBI database. There were 35 strains of Fusarium oxysporum, 7 strains of F. solani, 23 strains of Clonostachys rose and 2 strains of Eutypella scoparia. The results of pathogenicity test revealed that representative strains of F. oxysporum and F. solani could infect the root of S. tonkinensis Radix and cause typical symptoms of root rot, and F. solani showed stronger pathogenicity compared with F. oxysporum. In addition, combined with morphological characteristics and molecular biological identification results, the isolated fungal pathogens were identified as F. oxysporum and F. solani, respectively.【Conclusion】 The root rot of S. tonkinensis Radix in Guizhou is mainly caused by simultaneous infection of F. oxysporum and F. solani.