Efficient gene introduction into rice by electroporation and analysis of transgenic plants: use of electroporation buffer lacking chloride ions.

We have developed a method for reproducibly obtaining transgenic rice at a high frequency (10(-4)): electroporation with a buffer in which chloride ions are replaced with organic acids. Co-transformation frequencies of the β-glucuronidase (GUS) and hygromycin phosphotransferase (HPT) genes located on two separate plasmids were higher than 50%. Transgenic rice plants contained multiple copies of introduced genes integrated into their genomes in a complex manner. GUS enzyme activity was not proportional to gene copy number. Introduced HPT genes were detected and expressed in the progeny of transformants.