Dissertation
EXPLORING THE NATURAL VARIATION OF PHOTOSYNTHESIS AND ABIOTIC STRESS IN WHEAT VARIETIES AND REDUCED HEIGHT MUTANTS
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/117514
Abstract
Bread wheat (Triticum aestivum) is an important cereal crop that is generally susceptible to even small temperature increase over the optimal level. High temperature stress reduces photosynthesis in plants which can adversely affect yield and biomass. In this study, a wheat collection carefully made to capture natural variation while reducing redundancy, was screened to evaluate effect of high temperature stress on various aspects of photosynthesis. Systematic screening of the collection of ~1200 wheat lines using five different controlled condition screening protocols identified 24 lines carrying different parameters of heat stress tolerance during various wheat growth stages. The lines were specifically selected to have complementary mechanisms of heat tolerance. Preliminary photosynthetic experiments indicated that light intensity and changing CO2 concentrations significantly impacts photosynthetic rate throughout the day. A wheat line with the highest photosynthetic rate and higher dry weight biomass was identified that can be used as a donor for the traits. Another line was selected that showed no change in evapotranspiration and water use efficiency under heat stress.
Most of the currently grown wheat varieties contain Reduced Height-1 (Rht) mutant that shows negative affect on early seedling growth and grain yield under abiotic stress conditions. Nineteen relatively uncharacterized dwarfing mutants and Rht1/Rht2 double mutant were studied along with most of their parents. Genetic mapping of Rht18 localized the gene on chromosome 6A flanked by markers barc146 and cfd190. Among the genotypes we observed several fold differences in coleoptile length, first leaf length, and root length. Specialized pot emergence test revealed that Rht5, Rht6, Rht8, and Rht13 mutants have significantly improved emergence compared to their respective parents while Rht3 and Rht1Rht2 mutations severely reduced the emergence from deep planting. Majority of the mutations have positive effect on root length while the root angle was decreased in majority of the mutants compared to their respective parents. Photosynthetic gas exchange measurements identified Rht9 as photosynthetically promising line. The information on various traits can be utilized in breeding programs and in deciphering the underlying molecular mechanisms.
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Details
- Title
- EXPLORING THE NATURAL VARIATION OF PHOTOSYNTHESIS AND ABIOTIC STRESS IN WHEAT VARIETIES AND REDUCED HEIGHT MUTANTS
- Creators
- Nathan Grant
- Contributors
- Kulvinder S Gill (Advisor)Amit Dhingra (Committee Member)Kevin Murphy (Committee Member)Mechthild Tegeder (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
- 155
- Identifiers
- 99900581610201842
- Language
- English
- Resource Type
- Dissertation