| The influence of various 2,4-D concentrations on induction of callus from leaf tissues of Rosa hybrida cvs. Carefree Beauty and Grand Gala and R. chinensis minima cv. Red Sunblaze was evaluated. Following transfer of calli to a regeneration medium containing different concentrations of thidiazuron (TDZ), 6-benzyladenine (BA), or gibberellic acid (GA3), alone or in various combinations, somatic embryogenesis, secondary somatic embryogenesis, and shoot organogenesis were observed.; By using the isoschizomers HpaII and MspI which display differential sensitivity to cytosine methylation, a modified amplified fragment length polymorphism (AFLP) technique has been developed to investigate DNA methylation profiles in eukaryotic organisms. With this method, dynamic variation in DNA methylation associated with in vitro subcultures of apple (Malus x domestica cv. Gala), sequential in vitro subcultures, shoot organogenesis, and somatic embryogenesis of R. hybrida cv. Carefree Beauty was investigated. This study provided evidence that changes in methylation occurred in both apple and rose leaf tissues subjected to tissue culture growth conditions. For rose tissues at different regeneration stages, dramatic demethylation occurred in both embryogenic callus and its regenerants. This indicated that genomic reprogramming of DNA methylation occurred during somatic embryogenesis, and this was passed on to their regenerants.; The effects of different concentrations of kanamycin, carbencillin, cefotaxime, and combinations of carbencillin and cefotaxime on regeneration from different tissues of rose (Rosa hybrida cv. Carefree Beauty) were investigated. Agrobacerium tumefaciens strain GV3101 containing pCAMBIA 2301 plasmid was used for transformation. A transformation protocol by taking advantage of a secondary somatic embryogenesis system was developed. Then, a microbial protein gene, Ace-AMP1, was introduced into Rosa hybrida cv. Carefree Beauty via Agrobacterium-mediated transformation. These lines were confirmed for stable integration of Ace-AMP1 and npt II genes by PCR, Southern blotting, and Northern blotting. Transgenic rose lines inoculated with conidial spores of Sphaerotheca pannosa (Wallr.: Fr.) Lev. var. rosae showed enhanced resistance to powdery mildew. |
