Abstract

Higher plant shoot meristems are multicellular structures that are the site of postembryonic organogenesis. Analysis of chimeric plants has indicated that cells in different regions of the meristem can interact with each other so that their activities are coordinated during developmental processes. Correlations have not been demonstrated between events at a molecular level and the interactions observed at a phenotypic level in chimeras. Two recent papers(1,2) address this problem by reporting that expression of the floricaula gene in one region of chimeric snapdragon meristems is sufficient to promote the transition from inflorescence to floral development and to induce the expression of the downstream organ identity genes deficiens and plena throughout the meristem.