In 1997 fluorescence in situ hybridization (FISH) with a rDNA probe, pTa 71 isolated from wheat, was applied to investigate chromosomes of Chrysanthemum sensu lato in Japan.
Tetraploid species, D.indicum, D.yoshinaganthum and D.chanetii which was distributed in China commonly showed rDNA site at the satellite of the sat-chromosome at mitotic metaphase. The numbers of chromosomes displaying rDNA site were eight in D.indicum and D.chanetti, and ten in D.yoshinaganthum, and were very stable within each species. Thus, they must be the promising method to analyze their phylogenetical relationship and hybridization among species. Moreover, the nembers of rDNA sites of certain chromosomes at interphase and mitotic prophase corresponded with that at mitotic metaphase in all species.
Diploid species, D.boreale and D.japonicum were collected from Hiroshima and Yamaguchi Prefectures in 1997, and were conserved in the Laboratory of plant Chromosome and Gene Stock, Faculty of Science, Hiroshima Unive
rsity. These two species showed rDNA site at the satellite like the tetraploid species studied. The numbers of chromosomes displaying rDNA site were six in D.boreale and four in D.japonicum. These results contributed to verify the phenomenon of introgressive hybridization between the two species studied.
Chromosomes of Chrythanthemum lineare, C.nipponicum and their artificial hybrid were also investigated by FISH.Two species and one hybrid commonly showed rDNA site at the satellite of the sat-chromosome ; C.lineare showed four major and two miner hybridization sugnals ; C.nipponicum showed two hybridization signals ; and artificial hybrid showed four hybridization signals. On the other hand, total genomic in situ hybridization (GISH) with total genomic DNA of C.lineare was performed to investigate chromosomes of artificial hybrid. Artificial hybrid showed hybridization signal on larger chromosome set which must be orgin ated from C.lineare, especially, hybridization signals at the terminal regions of the long and short arms of each chromosomes were brighter than the other region on chromosomes. Moreover, meiotic chromosomes of artificial hybrid F_1 was observed with GISH,and some bivalent chromosomes and translocations were observed. Less