The goal of this proposed research is to investigate genetic and molecular mechanisms underlying plant embryo development by characterizing embryo-defective (emb) mutants of Arabidopsis thaliana. Emphasis is on the characterization of the twn1 mutant, which is disrupted in embryonic morphogenesis and maintenance of cell type in the suspensor, and on emb88, a T-DNA insertion mutant that exhibits abnormal cell organization and arrested morphogenesis. Specific goals with twn1 include: 1) constructing double mutant lines with Arabidopsis mutants that have altered levels or sensitivity to plant growth regulators, and 2) characterizing the pleiotropic effects of the twn1 mutation on post embryonic development. These studies should provide insight into the function of the wild type TWN1 gene, and elucidate the mechanism of the dramatic embryogenic transformation observed in the mutant twn1 suspensor. Specific goals with emb88 include completing characterization of the EMB88 genomic locus and isolation of the EMB88 cDNA. This work should elucidate the biochemical function of the EMB88 gene product, and provide the foundation for a long term molecular study of the role of this gene in Arabidopsis embryogenesis. Molecular information on emb88 will have an impact on our understanding of Arabidopsis embryogenesis and emb mutants, because to date only a handful of Arabidopsis embryo mutants have been characterized at the molecular level. Together, twn1 and emb88 should yield valuable information on key processes of plant embryogenesis, including morphogenesis, maintenance of differentiated cell type, and intercellular communication in the developing embryo.
