The Cytology of an Interspecific Hybrid in Zinnia

抄録

The morphological characteristics and cytological behaviour of hybrids between two garden species of Zinnia viz., Z. linearis (2n=22) and Z. elegans (2n=24) are described. The hybrid (2n=23) resembled the male parent, Z. elegans in gross morphology but showed intermediate expressions in respect of many metric attributes. The maximum chromosome association was 1_III+5_II+10_I. The most frequent association was represented by 6_II+11_I. indicating the pairing of partially homologous chromosome sets of the parental species. Hybridisation between the basic types (2n=10 and 2n=12) could have been the primary step in the development of Z. linearis; in the origin of Z. elegans, two 12-chromosome types were probably involved. The chromosome complements of the two taxa have been analysed and found to possess differences with regard to the number and size of chromosomes, total chromatin and position of constriction. The asymmetry of the karyotype of Z. linearis was brought out.