Numeral Stability and Morphological Instability of Chromosomes in Spore Calli of Osmunda japonica, a Fern

Karyotype analysis was performed on spore calli of Osmunda japonica on MS media containing 2, 4-D and kinetin in order to clear up the cytogenetical behavior of callus cells from the haploid cells of a fern.The spore calli showed a fair stability in haploid chromosome number (n=22). However, these calli showed a remarkable variation in karyotype as follows. The normal karyotype corresponding to that of the sopre donor was observed only in a few callus cells. The other karyotypes in many spore calli were multiple, and not systematically consolidated. These karyomorphological aspects were concluded that gross rearrangements of chromosome structures with maintaining a fair stability in haploid chromosome number are associated with spore cultures of O. japonica as a nuclear response to callus induction and to established culture condition.