Abstract: Cenococcum geophilum Fr. (Cg) is an ectomycorrhizal fungus that has a wide host range and distribution. This mycobiont has been suggested to provide isolate-dependant drought protection to fine roots. It lacks asexual or sexual spores and froms abundant sclerotia that serve as resistant structures under environmental stress. The traditional classification method is very difficult to satisfy to the Cg classification and research of genetic diversity, so little is known about its genetic structure at fine scale. We obtained 27 Cg strains isolated from 6 hosts in China and 5 Cg strains introduced from France as our tested materials, and made identification based on morphological charactertics and PCR method. The genetic diversity of 20 Cg strains was estimated using RAPD and PCR-RFLP of the rDNA internal transcribed spacer (ITS) in this study. PCR-RFLP method used universal primers ITS1/ITS4 to amplified the rDNA ITS of mycelium, then amplified products were digested with HinfⅠand MboⅠ. The digested fragments of PCR products were run on 2% agarose gel, showed that there were obvious differences among strains. RAPD method used selected random primer (5'- CGCACCGCAC-3') to amplified genomic DNA of Cg RAPD produced 19 detectable and reliable DNA bands in the 300bp-2000bp size range. According to the number、position and strength of the DNA bands in agar gel, using PopGen Version 1.31 dendrogram analysis software calculated the genetic distance and genetic similarity among all tested strains. According to the genetic distance to constructed phylogenetic tree of 20 strains, the results indicated that a high degree of genetic diversity was observed among the Cg strains from the same or different hosts.

Key words: Cenococcum geophilum Fr., RFLP, RAPD, Genetic diversity