Abstract
The objective of this study was to induce mutation in Chrysanthemum morifolium cv. 'Delistar White' through in vitro mutagenesis by treating the ray florets with two doses of gamma irradiation (0.5 and 1.0 gamma ray) and to apply RAPD analysis for the detection of genetic polymorphism among chrysanthemum mutants and their parent. Callus induction and shoot formation percentages were affected by gamma ray doses, whereas, the variation between medium protocols and the variations due to the interaction among medium protocols and doses were statistically insignificant. The shoot length was decreased with gamma ray treatment in comparison to the control. The results indicated that the irradiation dose 0.5 Gy was the most effective dose in inducing mutations in flower shape and number of florets per flower head, although no change in flower colour was observed, but conversion from tubular florets to spoon-shaped florets indicating no chimera formation, which concludes that flower colour/shape mutations can be developed through direct in vitro mutagenesis by avoiding chimeric phase. Five RAPD primers were used to amplify DNA segments from the genomic DNA of chrysanthemum and its 13 somaclones. The genetic similarity among the fourteen genotypes ranged from 0.43 to 0.95. The chrysanthemum cultivar and its 13 somaclones were classified into five clusters.