A PROTOCOL FOR CONSISTENT, LARGE-SCALE PRODUCTION OF FERTILE TRANSGENIC RICE PLANTS

A protocol for consistent production of fertile transgenic rice plants was established utilizing microparticle bombardment of embryogenic ti ssues (Oryza sativa L. japonica cv. Taipei 309). This system has been employed to produce several thousand independently transformed plant l ines carrying the hygromycin phosphotransferase (hph) gene and various genes of interest. The most efficient target tissue was highly embryo genic callus or suspension cell aggregates, when they were given an os motic pre- and post-transformation treatment of 0.6 M carbohydrate. By optimizing the age of the tissue at the time of gene transfer and app lying an improved selection procedure, transgenic plants were recovere d in 8 weeks from the time of gene transfer, at an average of 22.3+/-9 .7 per 100 calli and 22.4+/-8.0 plant lines per dish of suspension cel l aggregates. This system has facilitated a number of studies using ri ce as a model for genetic transformation and will enable the large-sca le production of transgenic rice plants for genomic studies.