Optimization of factors affecting efficient shoot regeneration in chrysanthemum cv. Shinma

Factors affecting shoot regeneration were optimized in order to develop an efficient protocol for shoot regeneration in leaf explants of the chrysanthemum (Chrysanthemum morifolium Ramat) cultivar Shinma. The maximum number of shoots per explant (9.7) was regenerated in leaf explants of 6-week-old donor plants cultured on Murashige-Skoog medium containing a combination of 0.5 mg L-1 6-benzyladenine and 0.5 mg L-1 alpha-naphthaleneacetic acid with initial dark treatment for 7 days. Among the different auxins tested, indolebutyric acid was the most effective for root induction and development, whereas the presence of ethylene inhibitors strongly suppressed shoot regeneration. Ploidy levels were analyzed by flow cytometry: there was no ploidy variation between the regenerated plants and the mother plant grown under greenhouse conditions. The new protocol will facilitate genetic transformation and micropropagation of chrysanthemum cv. Shinma.