In Vitro Callus Induction of Dendranthema indicum Var. Aromaticum, a Scented Chrysanthemum

Dendranthema indicum var. aromaticum is a fragrant, medicinal chrysanthemum variety that has hairy stems and leaves, producing desirable aromas. A breeding objective is to create selections that also possess large, showy flowers for a new product of fragrant cut, potted, or garden chrysanthemums. Several methods are being used to create new interspecific hybrids with cultivated chrysanthemums, D. xgrandiflora: interspecific hybridization, protoplast fusion, and genetic transformation. Breeding requires polyploidization of D. i. var. aromaticum (a diploid, 2n=2x=18) to cross with cultivated D. xgrandiflora (hexaploid, 2n=6x=54). In order to transform this species, a regeneration system has to be developed. The effects of different plant growth regulators at different concentrations on callus induction were investigated using stem segments, leaves, petioles and buds of D. i. var. aromaticum as explants. The best in vitro propagation was achieved with axillary buds from nodal stem segments cultured on MS medium, based on callus induction rate, callus hardness, growth potential and the number of shoots differentiated. The optimal induction mediums were MS + 1.0 mg/l 2.4 D + 0.2 mg/l 6-BA. Rooting of shoots was also achieved.