IN-VITRO POLLINATION AND FERTILIZATION IN MAIZE (ZEA-MAYS L) - TECHNICAL PROCEDURES AND PROSPECTS FOR THE DISSECTION OF THE DOUBLE FERTILIZATION PROCESS

In this review, we report the considerable worldwide progress accomplished in Angiosperm fertilisation, especially in Zen mays L. In this species, the precise sequence of events during the process of double fertilisation has been determined. A method of in vitro pollination which allows definition of the precise nutritional and environmental conditions appears to be a suitable technique to study seed set, female receptivity and the effects of environmental stress on the fertilisation process. A protocol for sperm cells and female gamete isolation has been described and offers a unique opportunity for studying gamete interactions. Different systems of in vitro fertilisation have been developed including electrofusion, calcium-induced fusion of isolated gametes and sperm nuclei microinjection into the female cells. Regeneration of electrofused zygotes into fertile hybrid plants and culture of isolated fertilised embryo sacs provide new possibilities for investigating the early steps of fertilisation and embryogenesis at the cellular and molecular level.