Expression in cowpea seedlings of chimeric transgenes after electroporation into seed-derived embryos

Cowpea (Vigna unguiculata Walp) embryos mechanically isolated from mature seeds and incubated in the presence of plasmid DNA harboring chimeric gus genes were shown to germinate into seedlings expressing β-glucuronidase activity in a variety of tissues, including the apical meristem. Embryo electroporation in the presence of DNA and protectants such as spermine and Lipofectin(TM) increased both the proportion of embryo-derived seedlings expressing the chimeric gene and the level of gene expression. Microscopic observations of thin sections showed that the blue crystals representing the end product of transgene activity on X-glu were exclusively located inside the treated cells. Histological localization of the blue dye crystals varied with the promoter used to drive the transgene.