Egg activation in flowering plants

Compared to animals and algae, egg activation in flowering, plants is still poorly understood because of the inaccessibility and complexity of the fer tilization process which is double and internal. However, the development o f in vitro fertilization (IVF) systems in maize and a few other plants, des pite some limitations, offers new possibilities for the study of early post -fusional events and signals leading to egg activation under defined condit ions. This review reports recent data on calcium events induced by gamete f usion during maize IVF and presents perspectives on the role of calcium in egg activation and in early development.