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CC BY-NC V4.0, Open Access
Dissertation
DETERMINING TRAITS INFLUENCING PHOTOSYNTHETIC WATER USE EFFICIENCY IN C4 PLANTS
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004422
Handle:
https://hdl.handle.net/2376/123288
Abstract
Agriculture uses more than 80% of the fresh water in the world and climate change may reduce the water that is currently available. Therefore, there is a need to improve the water use efficiency of crops intrinsically from their leaf-level physiology through genetic improvement. However, detailed understanding of the mechanisms of leaf-level water use efficiency (WUEi) and how they are genetically controlled are poorly understood. Generally, biochemical or diffusional mechanisms are expected to alter WUEi. These mechanisms within species that use C4 photosynthesis have been difficult to determine because C4 photosynthesis uses a complex biochemical pathway to increase photosynthetic efficiency. Additionally, methods to identify natural variation in WUEi are low-throughput. This dissertation describes some physiological factors that influence WUEi and how those traits relate to a high-throughput method to detect natural variation for WUEi. First, a specific biochemical component of the C4 pathway was probed to characterize how it impacts photosynthesis and diffusional traits. Genetic knock-down mutants of carbonic anhydrase (CA) were characterized with gas exchange measurements, and we found that in high temperatures CA’s contribution to biochemical efficiency can have a significant impact on WUEi. In the second research chapter we expand the search for mechanisms that influence natural variation in leaf level water use efficiency with carbon isotope composition (δ13Cleaf). δ13Cleaf has been proposed as a high-throughput proxy for detecting variation in C4 WUEi but its relationship to biochemical and diffusional traits can be unclear. We identified a pair of genotypes that were distinct for δ13Cleaf but genetically similar and characterized their physiology. We found their contrast in δ13Cleaf stems from speed of stomatal closure in dynamic light and CO2 levels which impacts WUEi. Finally, in chapter 4 we surveyed δ13Cleaf as a trait in a phenotypically diverse population of a C4 species and quantified the contributions from genetics or environmental factors. We associated δ13Cleaf phenotypes to candidate genes that may confer variation in δ13Cleaf and WUEi through genome-wide association. Collectively, this dissertation advanced the understanding of biochemical and diffusional mechanisms of C4 WUEi and their genetic control.
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Details
- Title
- DETERMINING TRAITS INFLUENCING PHOTOSYNTHETIC WATER USE EFFICIENCY IN C4 PLANTS
- Creators
- Joseph Daniel Crawford
- Contributors
- Asaph B Cousins (Advisor)Hans-Henning Kunz (Committee Member)Zhiwu Zhang (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 139
- Identifiers
- 99900883239501842
- Language
- English
- Resource Type
- Dissertation