Molecular Genetics of Arabidopsis Titan Mutants

点击翻译按钮获取中文摘要

Meinke 9723090 The long-term goal of the PI's research is to identify large numbers of genes with essential functions during plant embryogenesis through the isolation and characterization of embryo-defective (emb) mutants of Arabidopsis. The PI's laboratory has played an active role in promoting the use of this model organism for research in plant developmental genetics. In this proposal a novel class of emb mutants, called titan mutants, is described which exhibit a dramatic phenotype that should facilitate the analysis of cell cycle control during seed development. The common feature among these mutants is that endosperm nuclei become gigantic and highly polyploid. The PI proposes here a combination of descriptive, genetic, and molecular studies designed to identify TITAN genes, explain the mutant phenotype, and determine what role these genes play in regulating cell cycles. Descriptive studies will provide further details on nuclear and cytoskeletal organization in titan seeds. Genetic studies will focus on completion of gene mapping, construction of double mutants, analysis of marker gene expression, and characterization of additional titan mutants. Molecular cloning of TTN genes is a major focus of the proposal. Emphasis will be placed first on ttn3 because it appears to be tagged. The PI also proposes to isolate TTN1 through map-based cloning. How double fertilization leads to the establishment of distinct patterns of mitosis and cytokinesis in the embryo and endosperm is a central question in plant reproductive biology. Results obtained from this project should provide valuable insights into cell cycle regulation and embryo-endosperm interactions in angiosperms. Although research on cell cycle regulation in yeast and Drosophila should provide a wealth of information applicable to plants, analysis of Arabidopsis mutants such as those described here will be needed to establish the precise mechanisms of cell cycle control employed throughout plant development.