Dissertation
THE ROLE OF THE PLANT GA HORMONE RECEPTOR GID1 IN CONTROLLING SEED GERMINATION IN ARABIDOPSIS THALIANA
Doctor of Philosophy (PhD), Washington State University
01/2012
Handle:
https://hdl.handle.net/2376/4703
Abstract
The plant hormone gibberellin (GA, gibberellic acid) receptor GID1 (GA-INSENSITIVE DWARF1) stimulates GA responses including seed germination, stem elongation, and the transition to flowering via three mechanisms explored in this dissertation: 1) down-regulation of DELLA repressors of GA responses by triggering SCF<superscript>SLY1<superscript/>-stimulated ubiquitination and proteolysis; 2) non-proteolytic down-regulation of DELLA via GID1-GA-DELLA protein complex formation in the absence of DELLA destruction; and 3) a potential new GA signaling mechanism via GID1 interaction with the UBX-domain containing protein PUX1. Mutant <italic>sly1<italic/> seeds show increased dormancy as a result of inability to degrade DELLA protein. These mutants acquire increased germination potential through either long after-ripening (dry storage at room temperature) or overexpression of<italic> GID1<italic/> genes. It appears that after-ripening relieves dormancy through increasing GA hormone levels and increasing GID1 expression based on the observations that after-ripening of<italic> sly1<italic/> seeds is associated with increased GA hormone accumulation and after-ripening of the<italic> ga1-3 <italic/>causes increased expression of GID1 mRNA and protein associated with increased GA hormone sensitivity. Non-proteolytic GA-signaling in<italic> sly1<italic/> seeds can lead to germination associated with increased GID1-GA-DELLA complex formation, induction of GA-inducible genes, and down-regulation of the direct DELLA-activated gene<italic> XERICO<italic/>. Identification and preliminary characterization of the GID1-interacting protein PUX1 suggests that GID1 may also bypass the need to down-regulate DELLA through interaction with other protein targets involved in GA signaling. The fact that after-ripening positively regulates GID1 protein accumulation independently of transcriptional, ABA hormonal and 26S proteasomal control indicates the role of another posttranslational mechanism in the control of seed germination, possible protein translation.
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Details
- Title
- THE ROLE OF THE PLANT GA HORMONE RECEPTOR GID1 IN CONTROLLING SEED GERMINATION IN ARABIDOPSIS THALIANA
- Creators
- Amber Lynn Hauvermale
- Contributors
- Camille M Steber (Advisor)Kulvinder S Gill (Advisor)John A Browse (Committee Member)Hanjo A Hellmann (Committee Member)Raymond O Reeves (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Program in Molecular Plant Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 209
- Identifiers
- 99900581746001842
- Language
- English
- Resource Type
- Dissertation