Thesis
NOVEL BIOTECHNOLOGICAL APPROACH TO INCREASE ABIOTIC STRESS TOLERANCE AND SEED DEVELOPMENT IN BRASSICA NAPUS
Washington State University
Master of Science (MS), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004487
Handle:
https://hdl.handle.net/2376/124820
Abstract
In plants, E3 ubiquitin ligases play crucial roles in facilitating rapid reactions to environmental stresses by triggering the degradation of proteins. The E3 ligase CRL3BPM regulates the stability of specific transcription factors involved in complex biological processes, including growth, development, and stress response. CRL3BPM can recognize and bind to two specific motifs, called PEST and SBC, on targeted transcription factors. CRL3BPM-substrate interaction leads to the buildup of a chain of ubiquitin molecules that serve as a signal for degradation by the 26S proteasome. From signal perception to substrate degradation, this process may only minutes and because of this, E3 ligases are regarded as regulators of quick responses to environmental changes. However, they also represent interesting targets for affecting substrate stability. By modulating their activities to either delay or promote substrate degradation, they can be a suitable tool to improve critical plant traits such as biomass, seed yield, or abiotic stress tolerance.
In this master's thesis, Brassica napus plants were transformed with two expression constructs containing either the PEST or the SBC motif. Both constructs were expressed under the control of a WRINKLED1.2 promoter that confers gene expression in young seedlings and developing seeds. The central hypothesis of this study was that expression of the PEST or the SBC motif at specific developmental stages would result in the transient blocking of CRL3BPM activity, leading to extended half-lives of CRL3BPM substrates. Since substrates of CRL3BPM play roles in abiotic stress responses and seed fatty acid biosynthesis, we tested our hypothesis by exposing germinating seeds to abiotic stress and investigated the transgenic plants for altered seed development. We observed that transgenic B. napus expressing the PEST motif under the control of the WRI1.2 promoter significantly increased tolerance under osmotic and salt stress in germinating seedlings and produced heavier seeds. These data support our hypothesis and validate our approach of using an E3 ligase as a novel tool for generating crop plants with improved traits.
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Details
- Title
- NOVEL BIOTECHNOLOGICAL APPROACH TO INCREASE ABIOTIC STRESS TOLERANCE AND SEED DEVELOPMENT IN BRASSICA NAPUS
- Creators
- Alexandra MacGregor
- Contributors
- Hanjo Hellmann (Advisor)Mechthild Tegeder (Committee Member)Andrew McCubbin (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Biological Sciences
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 75
- Identifiers
- 99900882139101842
- Language
- English
- Resource Type
- Thesis