Plant Sexual Reproduction : Aspects of Interaction , History and Regulation Michiel

Sexual reproduction in angiosperms is an interactive process involving the sporophyte, gametophytes, embryo and endosperm as well as the environment, aimed at achieving pollination, fertilization and dispersal. This interaction occurs via an interface with nutrients and signals outside the cell and even outside the plant. Sexual reproduction has a history. In water, algae have different types of sex organs and gametes, and in some cases the female gamete stays on the plant. The zygote uses water movement and gravity for dispersal. Some algae have alternation of generations in the life cycle, and only the gametophyte functions in sexual reproduction. On land, ferns and mosses inherited alternation of generations, with oogamy and zygote development on the gametophyte, with wind dispersal of the meiospore. In angiosperms, heterospory and the retention of the megaspore, megagametophyte and embryo on the sporophyte lead to a seed with gravity and biotic dispersal. The history of sexual reproduction is based on sex determination, due to cross-fertilization and recombination. Sex differentiation is manifested in the increasing complexity of interaction in the nutrient supply, the retention of the gametophyte or even the embryo, and the type of vector of dispersal. Regulation of sexual reproduction in angiosperms is governed mainly by the sporophyte, with the expression of new genes for biotic pollination and seed dispersal. In the heterotrophic gametophyte some gene expression is suppressed. The development of sexual reproduction is due to the communication between the organism and a dynamic environment.