Transformation of Maize by Electroporation of Embryos

Plant cell walls present a barrier to DNA uptake not present in mammalian cells or plant protoplasts. Transformation methods that force DNA through this network of cellulose fibers include particle gun technology (ballistics; 1 ), imbibition of dried seeds (2 ), and use of silicon carbide “whiskers” (3 ). Each of these methods has associated limitations. Ballistics, the bombarding of cells or tissues with high-velocity, DNA-coated microprojectiles, has been used most widely and successfully with both cell cultures (4 –6 ) and embryos serving as target tissues. Electroporation has several advantages over ballistics in that it does not require the expensive particle gun apparatus, associated consumable supplies, and licensing. We describe in this chapter an electroporation protocol that has been used successfully to introduce DNA into maize embryos and has resulted in the recovery of stably transformed, fertile, transgenic maize plants.