In vitro fertilisation of maize by single egg and sperm cell protoplast fusion mediated by high calcium and high pH.

We present evidence for the fusion of isolated single maize egg and sperm cell protoplasts in a mannitol solution (400-430 mosmol/kg H2O) containing 0.05 M CaCl2 at pH 11.0, followed by cell division of the fusion products. These findings allow the performance of in vitro fertilisation of higher plants by combining single gametes as in lower plant and animal systems. Further, our findings open new avenues for investigating the basic mechanisms of adhesion and fusion of higher plant gametes and eventually for examining processes that inhibit polyspermy in higher plants.