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 d ifferent doses of gamma rays. Sectorial somatic mutations both in flower co lour and shape were detected in ail the doses. The original floret colour o f '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 mut ant floret colour was yellow-orange with tubular florets. Original and muta ted ray florets were cultured on agar-solidified Murashige and Skoog basal medium supplemented with sucrose and different combinations of 1-naphthalen eacetic acid (NAA) and 6-benzylaminopurine (BAP). Direct shout organogenesi s 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 rege nerated 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 tr ue to type in two successive generations.