Studying plant development in mosses: the transgenic route

The current status of transgenic studies in mosses is reviewed with particular attention being given to the mosses Physcomitrella patens and Ceratodon purpureus. This paper reviews the advantages of using mosses as models for higher plants in the study of plant development, and includes developmental processes, already partially characterized at the genetic level by mutant analysis, for which transgenic studies may be applicable. The P. patens transformation process is being studied in this laboratory and details are given for a class of transformants which contain extrachromosomal plasmid DNA. Publications which present the nucleic acid and/or protein sequence for nuclear, chloroplast and mitochondrial genes are reviewed. Areas of research in which transgenic studies promise to complement existing cell biological and physiological approaches are discussed. These include the measurement of calcium levels in mutant and wild‐type transformants expressing the apoaequorin gene and a role for phytochrome gene expression in the establishment of polarity.