Abstract: An endophytic fungus YX-28, possessing antimicrobial activity, was isolated from branches of Ginkgo biloba L. After incubation for 7days, the white colony of YX-28 became dark gradually. While on the surface of PD liquid culture broth, black and stick-like fruit bodies appeared, with a white head. As time went on, the white head disappeared and the fruit body got stringy and hollow. No spores were observed. 18S rDNA and internal transcribed spacers were amplified and sequenced. The 2315bp sequences was compared with the known sequences in the GenBank database. The similarity of 18S rDNA between YX- 28 and Xylaria sp. F14 is 99% and the divergence 0.009. There is no difference between the (G+C)%. There is only one base in ITS region of YX-28 different from Xylaria sp. MS 358 that is showing the highest similarity. But the phylogenetic analysis showed that YX-28 does not come together in the same known strains either on the basis of 18S rDNA sequence or ITS sequence.

Key words: sterile mycelia, phylogenetic analysis, fruit body, 18S rDNA, internal transcribed spacer