Expression of a foreign gene in callus derived from DNA-treated protoplasts of rice (Oryza sativa L.)

Summary Protoplasts isolated from suspension cultures of rice cells were treated with bacterial plasmid DNA carrying a chimaeric gene consisting of the nopaline synthase promoter, the aminoglycoside phosphotransferase II (APH(3)II) structural gene from bacterial transposon Tn5 and the terminator region from cauliflower mosaic virus DNA. Colonies capable of proliferating in medium containing kanamycin (100 g/ml) were selected. A transformation frequency of approximately 2% to 3% was recorded in several experiments. The enzyme (APH(3)II) was also detected in kanamycin-resistant callus, which had survived after repeated selection. There was some variation in the APH(3)II activity in the transformants which paralleled the copy number of the inserted genes.