Regulation of Gene Expression by Ethylene

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The long term objective of this research is to understand the molecular and cellular processes by which ethylene controls fruit ripening and gene expression. The model system is Lycopersicon esculentum (tomato). By analyzing the effect of promoter deletions on gene expression in fruit from transformed plants, and in a recently developed microprojectile transient assay system, 5'-flanking regions that control gene expression in a positive and negative manner have been identified. Sites that react with developmentally regulated DNA-binding activities have been delineated, and a clone encoding a DNA-binding protein has been isolated. The specific goal is to elucidate the mechanisms of ethylene action at the gene level. Ethylene-inducible promoter fine structure will be analyzed by determining the effect of promoter mutations on gene expression in a transient gene expression system and in transgenic fruit. Specific mutations will include deletion of sites that react with DNA binding proteins, and alterations of binding site position and orientation within the promoter. Factors that regulate ethylene inducible gene expression will be studied by cloning DNA binding proteins that bind to critical DNA regulatory sequences. The cloned gene will be used to generate specific antibodies and these tools will be used to determine the mechanism that regulates DNA binding activity. DNA binding protein function will be elucidated genetically by analyzing the phenotype of transgenic plants with reduced levels of DNA binding activity due to the expression of an antisense DNA binding protein gene. The interaction of the DNA binding protein with ethylene and/or other nuclear proteins will be analyzed. %%% The plant hormone, ethylene, controls fruit ripening. This project is an investigation, at the molecular and genetic level, of how that control is carried out.