THE MAIZE GENE EMPTY PERICARP-2 IS REQUIRED FOR PROGRESSION BEYOND EARLY STAGES OF EMBRYOGENESIS

The defective kernel mutation empty pericarp2-R (emp2-R) causes retard ation and subsequent abortion of maize kernel development Analyses of genetic aneuploid kernels indicate that the embryo phenotype is not de pendent on the endosperm genotype; the mutation conditions embryo defe cts even in the presence of a normal endosperm. Embryos reach an abnor mal coleoptilar stage before aborting and disintegrating. The mutants form primary embryonic organs only; the scutellum and coleoptile devel op, but no leaves are formed. Immunohistolocalization studies utilized KNOX homeodomain proteins as markers of meristem formation and identi ty. These analyses indicate that the shoot meristem forms in emp2-R mu tant embryos, but does not mature to a tunica-corpus shape. No evidenc e of leaf founder cell initialization was revealed in the mutant meris tems. These data indicate that the emp2 gene may be required for embry ogenic patterning beyond the coleoptilar stage of development.