Cotransformation frequencies of foreign genes in soybean cell cultures

Through the use of electroporation and a soybean (Glycine max L.) protoplast system, we generated stably transformed cell lines expressing a number of foreign genes (neomycin phosphotransferase,β-glucuronidase, chloramphenicol acetyl transferase, and phosphinothricin acetyl transferase). Selected and unselected marker genes were cointroduced either linked on a single plasmid or as separate plasmids. Calli expressing multiple genes were recovered, and Cotransformation frequencies were established for both cases. Our results show a 50% cotransformation frequency in the case of linked genes. In situations in which two genes are introduced on independent plasmids, cotransformation frequencies are 18%-27%. Similar rates of cotransformation were observed among various marker pairs.