STRUCTURAL HETEROZYGOSITY IN IRIS-VARIEGATA L

Four chromosomes in the karyotype of a clone of Iris variegata L. were heteromorphic. On the basis of somatic chromosome morphology and meio tic associations, it is established that the heteromorphicity is due t o translocation involving shifting of a large segment of the long arm of the longest chromosome with nearly median centromere on the short a rm of the smallest chromosome with submedian centromere, giving rise t o two medium sized chromosome with nearly median and submedian centrom eres. Bridge-fragment configurations at metaphase I also suggest the i nvolvement of paracentric inversion heterozygosity. While the bask kar yotype of I. variegata appears to be similar to that of the other spec ies of bearded irises with 24 chromosomes, structural alterations, sim ilar to the one presently recorded, have probably been responsible for the reported variations in its karyotype.