New Researches in Biotechnology - Facultatea de Biotehnologii ...

Proceeding of the 4 rd International Symposium“NEW RESEARCH IN BIOTECHNOLOGY” USAMV Bucharest, Romania, 2011root-derived calluses also developed rounded tissue clusters, but they were grey and lessvisible. The spherical cluster of white tissue, formed on a leaf explants in the C2 medium,degenerated.Fig. 1. Callus of C. caliacrae on theCC2 medium (magnification 20x).Fig. 2. A C. caliacrae plant withtwo stems.Some leaf-derived calluses on the solid C6 medium, which has a high BAPconcentration, formed clusters of new stems which had no signs of vitrification (Fig. 3). Ina medium with the same composition, Wildi & al. (1998) obtained an average of 10 shootsper leaf explant in Petasites hybridus Gaertn., Mey. & Scherb.On the CG medium, calluses did form from leaf explants, but they soon turned brownand died. The unusually high concentration of 2,4-D in that medium was expected tostimulate somatic embryogenesis by a stress-induced mechanism, but it apparently had atoxic effect instead.Eighteen plants rooted in the MS medium were transferred to ex vitro conditions. Theywere placed in the soil mixture and were covered with transparent plastic foil for the firstweek. The survival rate was high – 84%, and the plants were placed in a greenhouse, wherethey flowered (Fig. 4).Fig. 3. Calluses of C. caliacrae formingnew leaves on the C6 medium.Fig. 4. Flowering C. caliacrae plants after exvitro adaptation.136