Gamma ray-induced genetic manipulations in flower colour and shape in Dendranthema grandiflorum and their management through tissue culture

Rooted cuttings of Dendranthema grandiflorum cv. 'Puja' were treated with different doses of gamma rays. Sectorial somatic mutations both in flower colour and shape were detected in ail the doses. The original floret colour of 'Puja' is red-purple and florets are flat spoon shaped. One of the mutant floret colour was yellow-orange with original flat florets and another mutant floret colour was yellow-orange with tubular florets. Original and mutated ray florets were cultured on agar-solidified Murashige and Skoog basal medium supplemented with sucrose and different combinations of 1-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP). Direct shout organogenesis was seen within 2 weeks of culture initiation. The best regeneration was obtained on medium supplemented with 1 mg/l BAP + 0.5 mg/l NAA. Shoots regenerated from all explant types were rooted in vitro and transferred to the field. Regenerated plants flowered true-to-explant floret colour and shape. The isolated yellow floret colour mutants and yellow floret colour mutants with tubular florets were maintained vegetatively and have proved to he true to type in two successive generations.