The plant hormone auxin, typified by indole-3-acetic acid (IAA) regulates various aspects of plant growth and development such as cell division, vascular differentiation, lateral root formation, apical dominance, morphogenesis, oncogenesis, tropisms, and is generally considered to be responsible for regulating plant cell growth. Despite the importance of auxin in plant development, the primary molecular mechanism of auxin action is unknown. Experimental evidence accumulated in the last 10 years indicates that the hormone acts rapidly (3-5 min) at the transcriptional level. Molecular, biochemical, genetic, and structural studies using early auxin inducible genes from Pisum sativum (pea) and Arabidopsis are proposed herein to gain insight into: (i) the molecular details of the signaling apparatus responsible for their transcriptional activation; and (ii) the role of their encoded polypeptides in plant growth and development.
The specific aims of the proposal are: 1. To isolate the transcriptional factor(s) that interact with the auxin responsive domain A (AuxRD A) of the early PS-MA 4/5 gene using molecular genetic (""""""""one-hybrid system"""""""" in yeast) or biochemical (DNA affinity chromatography) approaches. To clone and structurally characterize genomic sequences encoding this factor and determine its expression characteristics during plant development. 2. To isolate mutations in Arabidopsis that affect gene expression driven by AuxRD A using Arabidopsis lines already constructed expressing GUS via these domains. To done one of these mutations by positional cloning. 3. To biochemically characterize the PS-IAA4/5-like proteins and define the DNA sequences that bind at the putative beta-alpha-alpha DNA binding domain of these nuclear short-lived proteins. To isolate genomic sequences that contain the binding site (target/late genes). The elucidation of the primary mechanism of auxin action is of paramount importance in Plant Sciences. Understanding how auxin controls cell growth, meristem activity, xylogenesis, etc. will allow the engineering of plant species with improved properties and qualities.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Molecular Cytology Study Section (CTY)
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Anderson, James J
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University of California Berkeley
Other Basic Sciences
Schools of Earth Sciences/Natur
United States
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Overvoorde, Paul J; Okushima, Yoko; Alonso, Jose M et al. (2005) Functional genomic analysis of the AUXIN/INDOLE-3-ACETIC ACID gene family members in Arabidopsis thaliana. Plant Cell 17:3282-300
Okushima, Yoko; Overvoorde, Paul J; Arima, Kazunari et al. (2005) Functional genomic analysis of the AUXIN RESPONSE FACTOR gene family members in Arabidopsis thaliana: unique and overlapping functions of ARF7 and ARF19. Plant Cell 17:444-63
Okushima, Yoko; Mitina, Irina; Quach, Hong L et al. (2005) AUXIN RESPONSE FACTOR 2 (ARF2): a pleiotropic developmental regulator. Plant J 43:29-46
Ouellet, F; Overvoorde, P J; Theologis, A (2001) IAA17/AXR3: biochemical insight into an auxin mutant phenotype. Plant Cell 13:829-41
Oono, Y; Chen, Q G; Overvoorde, P J et al. (1998) age Mutants of Arabidopsis exhibit altered auxin-regulated gene expression. Plant Cell 10:1649-62
Kim, J; Harter, K; Theologis, A (1997) Protein-protein interactions among the Aux/IAA proteins. Proc Natl Acad Sci U S A 94:11786-91
Abel, S; Ballas, N; Wong, L M et al. (1996) DNA elements responsive to auxin. Bioessays 18:647-54
Abel, S; Theologis, A (1996) Early genes and auxin action. Plant Physiol 111:9-17
Wong, L M; Abel, S; Shen, N et al. (1996) Differential activation of the primary auxin response genes, PS-IAA4/5 and PS-IAA6, during early plant development. Plant J 9:587-99
Abel, S; Theologis, A (1995) A polymorphic bipartite motif signals nuclear targeting of early auxin-inducible proteins related to PS-IAA4 from pea (Pisum sativum). Plant J 8:87-96

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