Transgenic rice plants: Characterization of two generations of seed progeny

Abstract

Transgenic rice plants have been regenerated from kanamycin‐resistant callus of Oryza sativa (cv. Taipei 309) derived from protoplasts electroporated with pCaMVNEO carrying the neomycin phosphotransferase II (nptII) gene. Of 6 randomly selected plants, all contained the nptll gene, but only 2 plants expressed NPTII activity. The transgenic plants were significantly shorter, produced fewer tillers, took longer to flower and had reduced fertility compared to non‐transformed protoplastderived plants. Fifty‐six seeds collected from one transgenic plant expressing NPTII activity germinated on medium containing kanamycin sulphate to give 16 green, first seed generation (R1) plants. The latter could be divided into 3 groups: (i) Plants which set seed, had normal floret morphology and produced a total of 76 seeds; (ii) Plants which flowered, but which failed to set seed; (iii) Plants which failed to flower, were shorter and had significantly fewer tillers than plants of groups (i) and (ii). The nptII gene was present in all transgenic R1 plants, but only 8 plants expressed the gene. Phenotypic characteristics, observed in transgenic R1 plants were also seen in the transforned R2 plants. These included reduced stature, a longer vegetative phase and reduced fertility compared to non‐transformed plants.