THE MECHANISM RESPONSIBLE FOR SOME X‐RAY INDUCED CHANGES IN FLOWER COLOR OF THE CARNATION, DIANTHUS CARYOPHYLLUS

Abstract

ALTHOUGH NUMEROUS STUDIES have shown that changes in flower color are induced by ionizing radiations, very little consideration has been given to the mechanisms responsible for these alterations except to consider them as somatic mutations. A very high frequency of changes in flower color has been reported by Richter and Singleton (1955) after chronic gamma irradiation of cuttings of a carnation clone, William Sim, and several of its flower color variants. This high frequency made it unlikely that these changes were due to mutation. This study presents data on the frequency of flower color changes after acute irradiation of three carnation clones with X rays as well as evidence which shows that a mechanism other than somatic mutation is responsible for these changes. MATERIALS AND METHODS.-The greenhouse carnation, a form of Dianthus caryophyllus L., was selected as the test organism because the inheritance of flower color in this plant has been fairly well established (Mehlquist and Geissman, 1947), the breeding behavior of a red-flowered commercial seedling, William Sim, as well as several of its spontaneous flower color variants has been thoroughly studied (Mehlquist et al., 1954), and the carnation is readily propagated asexually by stem cuttings.