ANALYSIS OF A LARGE NUMBER OF INDEPENDENT TRANSGENIC RICE PLANTS PRODUCED BY THE BIOLISTIC METHOD

Over 500 independent transgenic rice plants have been obtained by the biolistic method with an average transformation frequency of 9.7% for japonica variety Taipei 309. A tight selection procedure using 50 mg/l of hygromycin B successfully prevented the growth of nontransformed t issues. Analysis of the T0 transgenic rice plants revealed that more t han 97% of the transgenic plants were morphologically normal and more than 80% were at least partially fertile. The hyg(r) trait was inherit ed as a dominant trait in a Mendelian manner in 8 out of 11 transgenic events assayed. Thirty-seven out of fifty transgenic plants were esti mated to contain no more than five copies of the transgenes. In six ou t of seven transformation events, unlinked, co-transformed genes co-se gregated in the T1 generation. The hyg(r) trait has been stably inheri ted to the T4 generation. No chimerical transgenic plant has been foun d in an intensive search. Novel phenomena observed in transgenic rice plants are also reported.