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Abstract

Fertilization involves interaction between two gametes and exchange of genetic infortnation. In addition, infortnation is transferred which results in triggering of the particular cellular and de\ elopmental responses of the organism. This review considers the cellular signals inv{>lved during different stages of gamete interactions in plants, including gamete attraction, recognition, fusion, zygotic activation and development. A wide range of signalling mechanisms can he seen to operate during fertilization, reflecting both the di\ crsity of systems bringing gametes together and the different cellular responses to fertilization throughout the plani kingdom. Moreover, signals involved in triggering early development following gamete fusion appear to differ significantly even Note added in proof Faure, Digonnet & Dumas (1994) have recently shown that female gametes of maize fertihzed /« vitro will not fuse with additional male sperm, suggesting the existence of a block to polyspermy at the gametic level.