Structural heterozygosity inIris variegataL.

Abstract

SUMMARYFour chromosomes in the karyotype of a clone of Iris variegata L. were heteromorphic. On the basis of somatic chromosome morphology and meiotic associations, it is established that the heteromorphicity is due to translocation involving shifting of a large segment of the long arm of the longest chromosome with nearly median centromere on the short arm of the smallest chromosome with submedian centromere, giving rise to two medium sized chromosome with nearly median and submedian centromeres. Bridge-fragment configurations at metaphase I also suggest the involvement of paracentric inversion heterozygosity. While the basic karyotype of I. variegata appears to be similar to that of the other species of bearded irises with 24 chromosomes, structural alterations, similar to the one presently recorded, have probably been responsible for the reported variations in its karyotype.