Our lab uses the small flowering plant Arabidopsis
thaliana as a model for the study of hormonal control of
plant growth and development. Our primary goals are to
resolve how biosynthesis of the plant hormone auxin is
developmentally regulated. The phytohormone auxin is
fundamentally important in plant growth and development as a
regulator of numerous biological processes. These include
apical dominance (the suppression of lateral shoot formation
by the primary shoot), fruit ripening, tropisms (response to
gravity and light), as well as cell elongation, division,
and differentiation. It is still not clear how this hormone
is synthesized in plants or how it affects these biological
responses at the molecular level. We do know that levels of
the primary auxin, indole-3-acetic-acid (IAA) are maintained
throughout the plant by a complex network of pathways, many
of which are redundant. For example, we know that IAA can be
derived from tryptophan or from precursors to tryptophan
(see below) and these pathways are utilized differentially
throughout the life cycle of the plant. |
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As part of a NSF-sponsored Plant Genome Initiative, our lab is working to identify mutants that are involved in all aspects of auxin biology. We are developing a high throughput assay for mutants with small changes in IAA levels. Using automated sample handling and mass spectral quantification we can identify mutants with defects in redundant pathways that would not be detected in a simple visual screen. Sequence information is currently available for the entire Arabidopsis genome, so identifying the genes that correspond to these mutants will be straightforward. Transgenic technology is also simple in Arabidopsis, so any candidate genes can be re-introduced into Arabidopsis in a variety of formats (antisense, overexpression, inducible expression, tissue-specific expression) in order to test their function. |
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