Wang, Q., Department of Virology, Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel, Institute of Horticulture, Sichuan Acad. of Agric. Science, Chengdu 610067, Sichuan, PR China, China
Li, P., Department of Virology, Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel, Institute of Horticulture, Sichuan Acad. of Agric. Science, Chengdu 610067, Sichuan, PR China, China
Hanania, U., Dept. Fruit Tree Breed. Molec. G., Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel
Sahar, N., Dept. Fruit Tree Breed. Molec. G., Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel
Mawassi, M., Department of Virology, Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel
Gafny, R., Department of Virology, Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel
Sela, I., The Otto Warburg Biotech. Center, Faculty of Agricultural, Food Environ. Sci., Hebrew Univ. J., Germany
Tanne, E., Department of Virology, Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel
Perl, A., Dept. Fruit Tree Breed. Molec. G., Agricultural Research Organization, Volcani Ctr., Bet Dagan 50250, I., Israel

Various concentrations of kanamycin and paromomycin were examined for their effect on embryogenic cell suspension viability, transformation efficiency, and transgenic plant regeneration. Paromomycin (10-25 mg/l) induced an earlier killing effect on cell suspensions than kanamycin (40-100 mg/l). Transformation efficiency and the number of embryos developed on selection medium were positively correlated with an increase in paromomycin concentrations from 10 to 20 or 25 mg/l. Paromomycin was more effective than kanamycin in selection of transformed cells and induction of embryo development during selection. Although no differences in transformation efficiency were observed between cryopreserved and non-cryopreserved cells, conversions of transformed cells to embryos and plantlets were significantly improved when cryopreserved cells were used as the target material. With the improved transformation procedure proposed, 65-80% of GUS-positive cells and embryos were produced with about 40% of transformed embryos regenerated into plants. © 2004 Elsevier Ireland Ltd. All rights reserved.