| Co-Investigator(Kenkyū-buntansha) |
MIYAMOTO Junko Kagoshima University, Faculty of Science, Associate Professor, 理学部, 助教授 (40244222)
WATANO Yasuyuki Kanazawa University, Graduate School of Science and Technology, Associate Professor, 大学院・自然科学研究科, 助教授 (70192820)
TAKIO Susumu Faculty of Science, Kumamoto University, Professor, 理学部, 教授 (60188109)
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| Research Abstract |
The origin of high basic chromosome numbers of pteridophytes was analysed by a fluorescence in situ hybridization (FISH) method. The chromosome number of three species of Osmunda, O.japonica Thunb., O.lancea Thunb. ex Murray, and O.banksiifolia (Pr.) Kuhn, was 2n=44, and their karyotypes were very similar to each other. FISH revealed eight 18 S ribosomal DNA (rDNA) loci within a metaphase plate of O.japonica and O.lances. In O.banksiifolia, however, two loci were detected. To obtain other diploid species, we determined somatic chromosome numbers of 23 taxa of Dryopteris (Dryopteridaceae), 44 taxa of (Dryopteridaceae), and 54 taxa of Diplazium (Woodsiaceae). Out of 121 taxa examined, 12 of Dryopteris, 27 of Arachniodes, and 13 of Diplazium were diploids. FISH revealed six to eight 18 S rDNA loci within each metaphase plate of diploid species of Diplazium wichurae (Mett.) Diels, Di.amamianum Tagawa, Dryopteris handeliama C.Chr., and Arachniodes sporadosora (Kunze) Nakaike. This evidence suggested that the duplication of 18 S rDNA should be a plesiomorphic character in pteridophytes and exist homosporous ferns should be originated with high chromosome numbers.
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