Ceratopteris richardii: A productive model for revealing secrets of signaling and development

Ceratopteris richardii is an aquatic fern grown in tropical and subtropical regions of the world. It is proven to be a productive model system for stu dies in the genetics, biochemistry, and cell biology of basic biologic proc esses that occur in early gametophytic development. It provides several adv antages to biologists, especially those interested in gravitational biology , polarity development, and in the genetics of sexual development. It is ea sy to culture, has a relatively short life cycle, and offers an array of at tractive features that facilitate genetic studies. The germination and earl y development of large populations of genetically identical spores are easy to synchronize, and both the direction of polarity development and cell-le vel gravity responses can be measured and readily manipulated within the fi rst 24 h of spore development. Although there is no reliable transformation system available yet in Ceratopteris, recent studies suggest that the tech nique of RNA interference can be used to block translation of specific gene s in a related fern, Marsilea, and current studies will soon reveal the app licability of this approach, as well as of other transformation approaches, in Ceratopteris. A recently completed expressed sequence tag (EST) sequenc ing project makes available the partial sequence of more than 2000 cDNAs, r epresenting a significant percentage of the genes being expressed during th e first 24 h of spore germination, when many developmentally in teresting p rocesses are occurring. A microarray of these ESTs is being constructed, so especially for those scientists interested in basic cellular phenomena tha t occur early in spore germination, the availability of the ESTs and of the microarray will make Ceratopteris an even more attractive model system.