PEG-MEDIATED GENE TRANSFER INTO BRASSICA NA- PUS PROTOPLASTS AND REGENERATION OF TRANSGENIC PLANTS
Cheng Zhen-dong Wei Zhi-ming Xu Zhi-hong (National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology, Academia Sinica, Shanghai 200032)
Foreign genes were introduced into protoplasts of Brassica napus L. by means of PEG treatment. Gene transfer efficiency was found to be influenced by two-valence cations and their concentrations in transformation mixture, by addition of carrier DNA, and by pH of PEG solution. With hygromycin or kanamycin resistance as selection markers, resistant calli were successfully recovered. The relative transformation frequencies for hygromycin resistance was 1.35-6, being distinctly higher than 0.2% for kanamycin resistance. Thereafter, resistant calli were transferred onto differentiation medium for shoot induction. After regenerated shoots were rooted on rooting medium, they were transplanted into pots. Most of them grew well. Enzyme assay and Southern blotting analysis showed that foreign genes had been integrated into plant genomes. Lower frequency of shoot differentiation from resistant calli was the main problem in the gene transfer system reported here, some reasons for which were suggested.