Molecular Control of Ovule Development

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AbstractArabidopsis ovule development is a useful model system to study the roles of timing and patterning of gene expression in plant development. Because ovules are the precursors to seeds, the major products of field agriculture, better understanding of ovule development has the potential to contribute to crop productivity.The INNER NO OUTER (INO) gene encodes a transcription factor essential for development of the ovule outer integument, the precursor to the outer layer of the seed coat. INO is especially suitable for gene regulation studies because it exhibits a tightly regulated pattern of expression, a relatively short region of 5'-flanking DNA (the INO promoter, P-INO) is sufficient to reproduce this expression pattern, and robust assays to evaluate P-INO function have been developed. In the current study, sequences responsible for INO regulation will be characterized and immediate upstream effectors and downstream targets will be identified.Specific sequence motifs within P-INO necessary for promoter activity will be defined through evaluating the function of altered elements in transgenic plants. Fragments containing identified regulatory elements will be used to screen for interacting regulatory proteins. In vitro DNA-binding assays, expression and mutant analysis will be performed on selected genes and gene products to evaluate roles in ovule development and INO regulation.Analysis of gene expression during ovule development will be performed by evaluating the level of expression of most Arabidopsis genes in various Arabidopsis ovule mutants using DNA microarray technology. The expression data will be used to identify new ovule regulatory genes and to assemble a model of molecular interactions governing ovule development.Completion of the proposed research will contribute to our knowledge of regulation of reproductive development in higher plants and to a general understanding of molecular control of morphogenesis. This research can have broader impacts by facilitating improvements in seed crops through exploitation of identified regulatory interactions, and through interdisciplinary education of undergraduate and graduate students.