Dissertation
Transcriptional Control of Arabidopsis Development by AHLs
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/117039
Abstract
The AT-HOOK MOTIF NUCLEAR LOCALIZED (AHL) family of plant-specific transcription factors play important roles during development. The model plant Arabidopsis thaliana was used to investigate how AHL-mediated changes in transcription influence development. YUCCA8 (YUC8), a gene involved in auxin biosynthesis, and members of the SMALL AUXIN UP RNA (SAUR) 19 subfamily, which act at the end of the auxin signaling pathway and promote hypocotyl cell expansion, were misregulated in SUPPRESSOR OF PHYTOCHROME B4-#3 (SOB3)/AHL29 mutant seedlings. Specifically, transcripts for these genes were depleted in the short-hypocotyl SOB3-D over-expression line, but elevated in the tall, dominant-negative sob3-6 mutant. Further, ectopic expression of SAUR19 partially rescued the short-hypocotyl phenotype characteristic of SOB3-D, and SOB3 bound the promoters of YUC8 and SAUR19 subfamily members. This indicated that SOB3 represses hypocotyl elongation by inhibiting the transcription of both YUC8 and SAUR19 subfamily members. Although YUC8 and SAUR19 are both primarily associated with auxin, links between SOB3, these genes, and other signaling pathways were also identified. Light intensity also impacted the severity of hypocotyl phenotypes in SOB3 mutants. A link between SOB3 and light-mediated signal transduction was also identified at the molecular level, as expression of YUC8 and SAUR22 were affected by both light fluence rate and the transcription factor PIF4. SOB3 phenotypes and SAUR22 expression were also affected by brassinosteroid signaling, as evidenced by growth in the presence of brassinolide, an active form of the hormone, or the biosynthesis inhibitor brassinazole. Transgenic seedlings expressing a mutant form of BZR1 which codes for a constitutively active version of the protein also had higher levels of SAUR22, revealing a link between SOB3 and brassinosteroid signaling at the molecular level. Finally, physical interactions between histone H2B and SOB3 were also found to be essential for modulation of hypocotyl growth. Therefore, interactions with histones must also be important for regulation of gene expression by SOB3.
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Details
- Title
- Transcriptional Control of Arabidopsis Development by AHLs
- Creators
- David Seth Favero
- Contributors
- Michael M Neff (Advisor)Karen A Sanguinet (Committee Member)Scot H Hulbert (Committee Member)ChulHee Kang (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
- 349
- Identifiers
- 99900581834901842
- Language
- English
- Resource Type
- Dissertation