| Summary: | Psammosilene tunicoides is an important ethnic medicine in Southwest China and the main raw material for Chinese patent medicines like Yunnan Baiyao. The purpose of this study was to isolate and identify the pathogenic fungus of root rot of Psammosilene tunicoides in Yunnan. In this study, the disease-health junction of the root tissue of diseased plant was isolated and purified by pure culture method to obtain the main pathogenic microorganisms of P. tunicoides. Pathogenicity of isolated pathogenic microorganisms was analyzed the according to Koch’s Postulates, and then were identified by morphological observation, rDNA-ITS and TEF-1α sequence analysis and phylogenetic tree construction. The results were as follows: (1) A total of 85 strains of fungi were obtained, among which PSD-1, PSD-2 and PSD-3 of Fusarium fungi caused root rot of Psammosilene tunicoides. (2) These three strains were re-inoculated into the P. tunicoides, which produced similar disease symptoms occurred with field plants, and the disease incidences after inoculation with pathogenic fungi were 60%, 61.7% and 71.7%, respectively. (3) Combined with morphological observation and gene sequence analysis, the three strains were identified as Fusarium oxysporum. This study firstly found that the F. oxysporum was one of the main pathogenic fungi causing root rot of Psammosilene tunicoides. The results of this study lay a foundation for the in-depth exploration of the endophytic flora with biological control of root rot and its mechanism, and serve as a theoretical basis for the follow-up prevention and control of the disease.
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