Induced Trisomics in Chrysanthemum coronarium Linn

Two singly trisomics (2n=19) and one doubly trisomic (2n=20) were obtained in the open pollinated progeny of the colchicine induced hypertriploid (2n=30) of Chrysanthemum coronarium. Open pollinated progeny of one singly trisomic consisted of diploids only whereas the frequency of trisomics was rather low (12%) in the progeny of other trisomics. Trisomy is found to have no morphological effect. In about 50% of the PMCs, the extra chromosome constitutes a trivalent. In one singly trisomic, interchanges also involve the triple chromosome leading to the formation of multiple association of five and seven chromosomes.