Abstract: An antimicrobial endophytic fungus strain was isolated from the root of D.huoshanense,and its phylogenetic position was also investigated.Endophytic fungi were isolated from the healthy roots,stems and leaves of D.huoshanense by tissue inoculation culture.Antimicrobial activities of endophytic fungi were determined by the agar block method and oxford cup method,and then an active strain was identified by morphological characters and molecular methods.Results showed that a total of 52 strains of endophytic fungi were isolated from the host,and the most isolates came from the roots,then from stems,and leaves as the least;5 of them had antimicrobial activity to the test strains which accounts for 9.6% of all strains.Among the 5 strains,the strain DH10 was found to produce antibiotic substances which showed significant inhibitory effects on the test strains,especially Staphylococcus aureus,with a formed inhibition zone of 23.73 mm.Based on the morphological characters and ITS sequence analysis,the strain DH10 was most similar with L.aphanocladii.In summary,our research showed the abundance of endophytes from the wild D.huoshanense,and the distribution of endophytes also had a certain degree of tissue preference.The strong active strain of Lecanillium can be further studied.

Key words: Dendrobium huoshanense, endophytic fungi, antimicrobial activity, isolation, Lecanicillium aphanocladii