23 Signaling in plant embryogenesis John J Harada Embryogenesis is a critical stage of the sporophytic life cycle heart-stage of embryogenesis, localized cell divisions gen- during which the basic body plan of the plant is established. erate the cotyledons, embryonic storage organs. Fifth, by Although positional information is implicated to play a major the torpedo-stage, both the shoot and root apical meristems role in determining embryo cell fate, little is known about the are visible as organized structures (Figure 1g). nature of positional signals. Recent studies show that the monopterous and hobbit mutations reveal signaling during Although progress has been made in establishing a frame- patterning of the embryonic axis. The LEAFY COTYLEDON1 work for understanding the mechanisms involved in and PICKLE genes have been implicated to play important embryo development, many questions remain. Little is roles in controlling embryo development. known about the molecular processes that induce embryo formation. The morphogenetic events that underlie forma- Addresses tion of the embryo also remain to be defined. Because cell Section of Plant Biology, Division of Biological Sciences, University of fate is largely determined by positional information in California, One Shields Avenue, Davis, CA 95616, USA; plants, signaling and intercellular communication play crit- e-mail:
[email protected] ical roles in development [8,9]. In this article, I review Current Opinion in Plant Biology 1999, 2:23–27 primarily information published during the past year that provide examples of signaling during plant embryogenesis. http://biomednet.com/elecref/1369526600200023 Due to space limitations, this review will not be compre- © Elsevier Science Ltd ISSN 1369-5266 hensive but will focus on specific examples.