Dr Meinke has isolated over 200 embryonic mutants of Arabidopsis thaliana with a wide range of developmental abnormalities. He has been mapping genes with essential functions during embryogenesis and an analyzing of T-DNA insertional mutants produced following seed transformation. The proposed research will continue a molecular analysis of tagged embryonic mutants and examine several untagged mutants with particularly unusual phenotypes. The molecular analysis will focus on four mutants in which flanking sequences have already been recovered. Detailed analysis will be limited to mutant genes with interesting patterns of expression, sequence homology to known genes, or transcripts that can be recovered from existing cDNA libraries. Dr. Meinke has recently identified a novel homeotic mutant that appears to be defective in a regulatory gene that functions to activate a wide range of embryo specific pathways. Mutant embryos are abnormal, occasionally viviparous, and desiccation intolerant, but can be rescued in culture prior to desiccation. The resulting seedlings have a phenotype consistent with a model that mutant cotyledons are partially transformed into leaves, and that this regulatory gene functions to maintain the distinction between leaves and cotyledons. This mutant is not tagged, but merits detailed analysis and Dr. Meinke proposes to map the gene in preparation to further characterization of this interesting mutant.
