ORGAN AND CELL FUSIONS IN THE ADHERENT1 MUTANT IN MAIZE

The plant epidermis is only rarely involved in fusion events. These ev ents often occur when the epidermis has been wounded or removed. The a dherent1 (adl) mutation in maize shows fusions between cells and organ s in the presence of an intact epidermis. Fusions are not limited to a particular stage of organ development. The first fusion events occur very early in development and adherent leaves,can be seen in ungermina ted embryos. In the vegetative parts of the plant the coleoptile can f use to the first leaf and juvenile leaves can fuse to each other. At t he onset bf reproduction, tassel branches can adhere to each other, th e flag leaf can fuse to the tassel, and the glumes can fuse to the ant hers. While fused regions appear to have an intact cuticle, cell surfa ces are perturbed in die mutation, Time-lapse replicas reveal that tri chome fusion on organ surfaces is postgenital. The extracellular matri x can exert control over organs and tissues in piano; the Adl gene may represent a product that determines the composition or function of th is extracellular matrix.