Characterization of dekl: A Maize Embryo-Lethal Mutation

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The goal of this project is to obtain a greater understanding of the role of genes in plant embryogenesis by analyzing the dek1 locus. Dr. Sheridan will characterize ten mutations at the dek1 locus. All ten mutant alleles produce a recessive embryo lethal and a defective endosperm phenotype lacking anthocyanin and carotinoids. The dek1 mutant embryo is blocked at the proembryo state and is unable to form a shoot apical meristem but can enlarge and form a root apical meristem late in development. The mutant alleles will be analyzed for uniformity of phenotype and level of expression by dosage analysis including deletion studies. Five of the alleles arose in stocks that were active for the transposable element Mutator and two of these alleles display mutability. Segregation analysis on one of these alleles by Southern blotting and hybridizing with a Mu1 probe has revealed a cosegregating DNA band. This allele will be used for an initial cloning effort while continuing to search for new tagged alleles and DNA cosegregating bands. The cloned mutant allele will be used to identify a normal allele clone and to isolate a cDNA clone. The latter will be used to examine spatial and temporal expression in developing embryos. X-ray induced sectors will be used to examine the cellular autonomy of dek1 morphogenesis expression, and to evaluate the role of this locus in anthocyanin gene expression. New 1S B-A translocation will be induced that will aid in the genetic and structural analysis. In addition to studying the blockage of shoot apical meristem formation by the dek1 mutation, X-ray and structural approaches will be used to follow up promising preliminary observation of x-ray blockage of shoot apical meristem formation of normal embryos and the capacity of irradiated normal embryos to regulate and produce multiple embryos.