Abstract:In vitro fertilization technique using male and female gametes completely isolated from their paternal and maternal structures has been developed for ten years. Using electric fusion, zygote, embryo and fertile plants of maize can now be produced in vitro from individual fusions of pairs of sperm and egg cells. The culture conditions allow control of the parameters of fertilization and early steps of zygote development. Although this technique was successfully performed only in maize it helped us to understand a lot of information about fertilization mechanism of higher plants. Following successful isolating male and female gametes and culturing artificial zygote, in vitro fertilization as a research platform can be extended to more purposes in the research of sexual reproduction in higher plants. We knew the phenomenon of sperm dimorphism in many plants and also confirmed the preferential fertilization of both sperm cells in Plumbago zeylanica since 1985. We, however, know nothing for molecular mechanism of gamete recognition in higher plants. Now the special genes of male and female gametes, and zygote can be screened out using isolated gametes, which changes the research method from cell structure to molecular level. Zygote activation is a very interesting topic in plant developmental biology. But it is difficult to probe the mechanism of zygote activation because egg cell and zygote are imbedded deeply in ovules. Using microculture of zygote from both in vivo and in vitro created, the zygote can be observed on schedule and manipulated using modern biological techniques. The first confirmed zygote activation was free calcium change at the beginning of development after fusion of both male and female gametes of maize. Fertile plants can be easily developed from few zygotes under in vitro condition by means of embryogenesis, which is greatly interested in transgenic study in higher plants. in vitro fertilization and zygote culture also have great potential in overcoming incompatibilities of interspecies barriers in creating new hybrid plants. The fusion of isolated gametes from different plants can create a artificial hybrid zygote which can not be obtained from normally sexual crossing. This review describes the significant advances in in vitro fertilization in the research of sexual plant reproduction of angiosperms and discusses its use in plant improvement in higher plants.
