Production of transformed soybean plants by electroporation of protoplasts

Abstract
Protoplasts obtained from immature seeds of Glycine max (L.) Merr. cv. Clark 63 (soybean) were electroporated with DNA carrying either the kanamycin or hygromycin resistance genes and the reporter genes, β‐glucuronidase or opine synthesis. Antibiotic resistance could be selected for at the frequency of about one colony from 2 000 electroporated protoplasts (0.05%) and the reporter genes were expressed in from 75 to 90% of the selected colonies. Antibiotic resistance and reporter gene expression were not found in untreated protoplasts. Shoots formed within about 5 months after a number of transfers of selected portions of the callus on the regeneration medium. The shoots have been rooted to form plants which express the reporter genes and contain the transforming DNA in their leaves as shown by Southern hybridization. The reporter genes are expressed (opine synthesis) in all leaves and roots and NPTII activity was present in all leaves, indicating that the transformed plants are not chimeral. We expect these plants to set seed since untransformed plants regenerated from protoplasts did. We can obtain shoots from several of the soybean genotypes we have used so far. Thus, we should have a method for the efficient production of nonchimeral, transformed plants of the important crop plant soybean.