High frequency shoot regeneration from petal explants of Chrysanthemum morifolium Ramat. in vitro.

An efficient and novel method was developed to initiate multiple shoots from the petal which is indispensable for normal and transgenic plant of Chrysanthemum morifolium. The study indicates that high frequency of plant regeneration that would be crucial for the application of genetic transformation methods. The 7 mm petal explants were cultured on a Murashige and Skoog's (MS) basal nutrient medium containing plant growth regulators (cytokinin or auxin-cytokinin) with various combinations and concentrations for the study of callus formation and shoot induction. The highest callus formation (96%) in 4037 genotype cultured in MS medium supplemented with 2 mg L(-1) BA and 0.1 mg L(-1) NAA. The highest number of shoots was obtained from genotype 89 and 4037 in MS medium supplemented with 2 mg L(-1) BA and 0.1 mg L(-1) kinetin, 1 mg L(-1) kinetin and 0.1 mg L(-1) NAA, respectively. A significant difference in regeneration capacity was observed among five genotypes. Genotypes x growth regulators interaction caused considerable variation in the expression of regeneration responses, suggesting that determination of specific level of growth regulator concentration in the medium is necessary for a particular genotype to obtain optimum response. Strong seasonal variation in plantlet regeneration frequency was observed for every genotype. The elongated shoots were multiplied on a multiplication medium, rooted and acclimatized in a green house.