Park, Soomin , Pelletier, Julie , Braybrook, Siobhan A. , Kwong, Raymond W. , Fischer, Robert L. , Goldberg, Robert B. , Harada, John J. .
Transcriptional Control of Embryo Development by LEAFY COTYLEDON1.
We are investigating the mechanisms by which LEAFY COTYLEDON1 (LEC1) transcriptionally regulates genes required for embryo development. LEC1 is required for many aspects of embryo development, including processes that occur early in embryogenesis during the morphogenesis phase and during the later maturation phases. Furthermore, LEC1 is sufficient to confer embryonic characteristics to vegetative organs when expressed ectopically. Thus, LEC1 is a central regulator that promotes embryo development.
LEC1 encodes a novel HAP3 subunit of the CCAAT binding transcription factor (CBF). Of the ten Arabidopsis HAP3 subunits, eight designated non-LEC1-type AHAP3 (NLH3) subunits are most similar to those found in yeast and animals. The LEC1-type HAP3 subunits differ structurally and functionally. Unlike NLH3 subunits, LEC1-type HAP3 subunits are expressed primarily in seeds and induce embryonic characteristics. These results suggest that LEC1 CBF and NLH3 CBF regulate different sets of genes during plant development.
To define how LEC1 regulates genes required for embryogenesis and why NLH3 subunits do not, we have compared the LEC1 CBF and the NLH3 CBF biochemically. Both complexes bind CCAAT DNA sequences in vitro, and the DNA binding properties of the two complexes are similar but not identical. We have also used an inducible form of LEC1 to identified target genes regulated transcriptionally by the LEC1 CBF. Experiments to define DNA binding sites in planta are being done to verify the assignment of LEC1 target genes and to compare DNA sequences bound by the LEC1 CBF and the NLH3 CBF in planta. These studies will provide mechanistic information about the control of embryonic processes in a higher plant.
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1 - National Horticultral Research Institute, Korea, Horticultural Biotechnology Division
2 - University of California, Davis, Section of Plant Biology
3 - University of California, Berkeley, Department of Plant and Microbial Biology
4 - UCLA, Department of Molecular, Cell, and Developmental Biology
5 - University of California, Davis, Section of Plant Biology, One Shields Avenue, Davis, CA, 95616, USA
CCAAT-binding transcription factor
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM