DAPI-bands characterizing certain chromosomes in Chloranthus japonicus, Chloranthaceae

The chromosomes of three species of Chloranthus, C. japonicus, C. serratus, and C. spinulosa were investigated by fluorescent banding method. The chromosome number of 2n=30 and the karyotypes observed in three species were supported previous studies. The karyotype of C. japonicus was different from that of the other two species according to the symmetry of chromosomes. To reveal mechanism of this karyotype variation a fluorescent banding using DAPI was adapted to the chromosomes of the three species. In C. japonicus having long metacentric chromosomes had ten bright DAPI-bands at the short arms of the subetelocentric chromosomes and numerous DAPI-bands were also observed at the terminal and proximal regions in the long metacentric and short chromosomes. The chromosomes of C. serratus and C. spinulosa showed a homogeneous DAPI fluorescence and were not stained differentially as a DAPI-band. An addition or generation of the AT-rich DAPI segments might cause karyotype change from asymmetric to symmetric long chromosomes in Chloranthus species. This result is discussed with taxonomical and molecular phylogenetic treatments.