| Summary: | 碩士 === 國立成功大學 === 生物科技研究所碩博士班 === 91 === Ascomycetous genus Cordyceps widespread distributes on earth and they are endoparasitic fungi of insects and other arthropods. There are 12 species of genus Cordyceps fungi being used as herbal medicine for thousands of years in China. Because of the value of this fungi in medicial treatment, we collected about 80 isolates of this fungi from nine culture collection centers. We set up the culturing condition and sequenced the ribosoml DNA of Cordyceps spp. as database. In our study, we found the optimum culturing temperature of Cordyceps fungi is around 18 to 24 ℃. When the culturing temperature is over 37 ℃, the fungi could not survival. The optimum culturing pH value of Cordyceps fungi is around 6, but the fungi can keep alive when pH values changed from 3 to 13. In another hand, in our study on seting up the ribosomal DNA database, we found the ribosomal DNA of Cordyceps fungi is about 8 Kb. After cloned and sequenced about 50 isolates based on 18 S, 5.8 S and the first half of 28 S ribosomal DNA. We can study the phylogenetic relationship of Cordyceps fungi based on 18 S rDNA and ITS1, 5.8 S rDNA and ITS2 region. In order to understand the connection between evolution and geographical distribution of this fungi, we investigated the phylogenetic relationships of 29 isolates, 23 belongs to genus Cordyceps, 2 from genus Beauveria, one from genus Paecilomyces, one from genus Phytocordyceps, one from genus Podostroma and one from genus Tolypocladium, collected from six culture collection centers around the world, based on their 18 S rRNA gene and the ITS1, 5.8 S rRNA gene and ITS2 region. In our study, 18 S rRNA gene of all 29 isolates are very similar, up to 96 %, shows that these fungi collected form different locations on earth may be from the common ancestor. On the other hand, even their 18 S rRNA genes are similar, they can still be divided into several groups based on phylogenetic analysis of ITS1, 5.8 S rRNA gene and ITS2 region. Cordyceps isolated from different geographical positions including Canada, China, Guyana, India, Japan, Korea, Netherlands, Taiwan, U.K. and U.S. could be correlated to their genetic diversity. Cordyceps isolated from closed geographical positions have simulated features in DNA sequences. Phylogenetic analysis strongly suggests that fungi might evolute during traveling and affected by the ecology of the last defined. In the genus Cordyceps, many agencies and factors may affect it’s distribution, they have been isolated in different locations on earth and gave them different names, but they are the same species of fungi. In the fungal evolution, it departed from the origin circumstances by any possible way and exhibited the new environment and independently evoluted individual. Our study revealed the genus Cordyceps widespread distribution on earth should compliance with this hypothesis.
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