EMB30 IS ESSENTIAL FOR NORMAL-CELL DIVISION, CELL EXPANSION, AND CELL-ADHESION IN ARABIDOPSIS AND ENCODES A PROTEIN THAT HAS SIMILARITY TO SEC7

The EMB30 gene is involved in apical-basal pattern formation in the Ar abidopsis embryo. Mutations in this locus produce mutants with a wide range of seedling phenotypes, but all of the mutants lack a root and a true hypocotyl. We have cloned the EMB30 gene, and it encodes a prote in that has similarity to the yeast Sec7 protein and to two other open reading frames identified in clones from humans and C. elegans. We re fer to the region of similarity among these four sequences as the Sec7 domain. The emb30-1 allele has a mutation in the Sec7 domain that alt ers a residue conserved in all four of these sequences, suggesting tha t this domain may be important for EMB30 function. Molecular date and microscopy studies of emb30 seedlings presented here indicate that EMB 30 affects cell division, elongation, and adhesion and functions in Se edling and adult plants as well as during embryogenic pattern formatio n.