EARLY EVENT IN MAIZE LEAF EPIDERMIS FORMATION AS REVEALED BY CELL LINEAGE STUDIES

The epidermal cells of the juvenile leaves of maize are covered by a w ax layer. glossy mutants are known which reduce drastically wax deposi tion. We have used the somatically unstable glossy-1 mutable 8 allele to study the distribution on the epidermis of spontaneous revertant se ctors of wild-type tissues. Sectors tend to start and end at positions that correlate with the location on the epidermis of the long costal cells of ribs. It is concluded that in the protoderm only a few cells have a role and position in the generation of each of the developmenta l modules located between leaf midrib and margin. The module consists of an epidermal strip of cells bordered by two lateral ribs. The modul e originates from at least 4 cells, with one cell being the progenitor of the other three. Data are provided describing the mode of longitud inal anticlinal epidermal cell divisions within the module that are re sponsible for the increase in leaf width. The results suggest the exis tence of a clonal type of development during early leaf epidermis form ation.