The transcription factor LEAFY in flowering plants determines whether key meristems will go on to produce vegetative or floral tissues. In the much more primitive mosses, however, relatives of LEAFY control other aspects of the life cycle. Maizel et al. analyzed the changes in LEAFY sequence and function during this span of evolutionary time. The different functions that LEAFY took on through evolution seem to be attributable to alterations in its DNA binding domain.
A. Maizel, M. A. Busch, T. Tanahashi, J. Perkovic, M. Kato, M. Hasebe, D. Weigel, The floral regulator LEAFY evolves by substitutions in the DNA binding domain. Science 308, 260-263 (2005). [Abstract] [Full Text]