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Thesis
Exploring Vivipary As a Cause of Low Falling Numbers From Elevated Alpha-Amylase in Wheat Grain; Is it a Novel Mechanism, or Is it Related to Preharvest Sprouting and Late Maturity Alpha-Amylase?
Washington State University
Master of Science (MS), Washington State University
2022
DOI:
https://doi.org/10.7273/000005211
Abstract
Wheat (Triticum aestivum L.) is a staple food crop, providing 20% of human calories. In a world with increasing demand for stable food supplies, we must breed for high quality wheat crops with environmental stress tolerance. Elevated grain alpha-amylase is a risk to the end-use quality because starch digestion in dough reduces the gelling capacity of flour/water mixtures, resulting in cakes that fall and sticky noodles and bread. The enzyme alpha-amylase is induced during grain germination to digest starch as food for seedling growth. Environmental stress can trigger elevated grain alpha-amylase via two genetically distinct causes, preharvest sprouting (PHS), the initiation of mature grain germination on the mother plant when it rains before harvest, and late maturity alpha-amylase (LMA), the induction of elevated levels of alpha-amylase by cool temperatures during the soft dough stage of grain development (Zadok 85). This study discovered a third potential cause of elevated grain alpha-amylase, vivipary, the initiation of immature grain germination on the mother plant. Vivipary was triggered during LMA induction experiments when cool temperatures were associated with high humidity and water condensation on wheat spikes during the soft to hard dough stages of grain filling (Zadok 85-87). Moisture associated with cooler temperatures stimulated vivipary in genetically susceptible wheat varieties. To address examine whether LMA, vivipary, and PHS are distinct or related phenomena, susceptibility to PHS and vivipary were examined in an association panel of spring wheat lines previously characterized for LMA. Significant correlations (p < 0.001) were found not only between vivipary and LMA (r=0.61), but between vivipary and PHS (r=0.66), and between LMA and PHS (r=0.52). A subsequent genome-wide association study mapped PHS tolerance in the association panel identifying 29 QTL of which 5 co-localized with the previously published LMA QTL and 16 PHS QTL. Of the seven LMA tolerance QTL previously identified in the same panel, five were significantly associated with lower preharvest sprouting scores, suggesting that partly overlapping genetic mechanisms may govern PHS and LMA. Thus, breeding for PHS tolerance may enrich for LMA or vivipary tolerance.
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Details
- Title
- Exploring Vivipary As a Cause of Low Falling Numbers From Elevated Alpha-Amylase in Wheat Grain; Is it a Novel Mechanism, or Is it Related to Preharvest Sprouting and Late Maturity Alpha-Amylase?
- Creators
- Sarah R Peery
- Contributors
- Camille M Steber (Advisor)MIchael O Pumphrey (Advisor)Kimberly A Garland Campbell (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 137
- Identifiers
- 99901019537201842
- Language
- English
- Resource Type
- Thesis