This research was carried out to evaluate whether gamma ray is a useful tool for breeding new strains of mushrooms. For this research, 5 mutant groups, 20 strains of Hypsizigus marmoreus, 2 strains of Lyophyllum decastes, and 1 strain of Lyophyllum shimeji were used. Monokaryon spores from one variety of H. marmoreus were irradiated with 50~2,000 Gy of gamma ray. The propriety dose was 50~200 Gy for mutagenesis. Mutant monokaryon mycelia crossed each order to become dikaryon mycelia. The internal transcribed spacer (ITS) regions of rDNA were amplified using PCR, and the products were sequenced. The sequences of the ITS regions (16 partial rDNA, complete ITS1, 5.8 rDNA and partial rDNA) were analyzed by PCR, and strains of H. marmoreus, L. decastes, and L. shimeji were autosequenced. The lengths of the sequenced ITSs were 1,052~1,143 nucleotides. Genetic matrices were calculated using Nei-Li's genetic distance coefficient based on ITS sequence. The dissimilarities were 0~3.35% in strains of H. Hypsizigus. In addition, a phylogenetic tree was constructed based on ITS sequences using the neighbor-joining (NJ) method. The phylogenetic tree revealed that 23 strains and 5 mutant groups were divided into 12 clusters; the mutant groups fell into different clusters. These results show that mushroom spores were mutated effectively by gamma ray; therefore, gamma ray could be a useful tool for breeding new strains of mushrooms.Key words : Hypizigus marmoreus, ITS sequence, mutagenesis gama ray *Corresponding author *Tel : +82-53-850-3775, Fax : +82-53-850-3727 *E-mail : jbkim@cu.ac.kr This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

This research was carried out to analyze the genetic variation of 18 wild strain, 2 breed varieties and 20 mutants of Hypsizygus marmoreus by random amplification of polymorphic DNA(RAPD). Also, 3 strains of Lyophyllum decartes and 1 strain of Lyophyllum shimeji were used. These mushrooms were collected from korea, china, Taiwan and Japan. Spores of H. marmoreus JV-2 strain were irradiated by gamma ray for mutagenesis. 40 kind of primers were used for this reaserch. Number of reaction primer were 31. Electrophorectic patterns of RAPD showed genetic variation. In phylogenetic tree, they were divided into seven group. Discriminative differences were observed between wild strain and mutants in H. marmoreus. These results might suggest that these primers and gamma ray irradiation of spores were useful tools for developing new strain for mushroom.