Thesis
Late maturity alpha-amylase in North American spring wheat (Triticum aestivum L.)
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000000047
Handle:
https://hdl.handle.net/2376/119136
Abstract
Late maturity alpha-amylase (LMA) is considered a genetic defect in wheat (Triticum aestivum
L.), resulting in the induction of alpha-amylase enzyme in response to a low or high temperature
shock during late grain filling. The wheat industry uses the Hagberg-Perten Falling Number
(FN) method to detect loss of gelling capacity due to the presence of alpha-amylase in meal or
flour. Low FN is associated with higher risk of poor end-product quality, such as cakes that fall
and sticky bread or noodles. To improve selection for LMA resistance, LMA testing methods
were optimized and then used to characterize the LMA susceptibility in North American wheat
varieties. Preliminary LMA testing results were highly variable in cold-treated and in untreated
controls. Warmer (25°C day/ 18°C night) and drier (~55-65% relative humidity) conditions
reduced alpha-amylase levels in untreated controls. Colder LMA-induction experiments did not
result in stronger or more consistent LMA-induction in spring wheat variety, WA8124. The
most significant cause of LMA phenotypic variability appeared to be associated with the
developmental window during which a 7-day low temperature shock triggered LMA. This window varied with environmental conditions prior to grain development and by genotype, such
that LMA was induced in WA8124 at 20-24 days past anthesis (dpa) whereas Australian
‘Kennedy’ induced at 25-29 dpa. Only 21% of the 256 North American breeding lines
characterized showed LMA resistance, suggesting that improved selection for LMA resistance is
needed. In this panel, the tall rht-B1a rht-D1a genotype was associated with higher LMA in
both cold-treated and untreated experiments, suggesting the presence of a constitutive LMA
phenotype that did not require cold treatment. However, some rht-B1a rht-D1a lines required
cold induction whereas some semi-dwarf lines had constitutive LMA, suggesting that the
constitutive LMA phenotype is genetically complex. A preliminary genome-wide association
study identified six significant marker-trait associations on chromosomes 1A, 3A, 3B, 6B, 7B,
and 7D. The QLMA.wsu.6B and QLMA.wsu.7B loci detected in this study co-localized a QTL
detected in four previous studies of Australian and CIMMYT germplasm. Future work will
determine if these molecular markers are effective in selecting LMA resistance in U.S. wheat.
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Details
- Title
- Late maturity alpha-amylase in North American spring wheat (Triticum aestivum L.)
- Creators
- Chang Liu
- Contributors
- MICHAEL O. PUMPHREY (Degree Supervisor) - Washington State University, Crop and Soil Sciences, Department ofCAMILLE M STEBER (Committee Member) - Washington State University, Crop and Soil Sciences, Department ofANDREW MCCUBBIN (Committee Member) - Washington State University, Biological Sciences, School of
- 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
- Format
- pdf
- Number of pages
- 113
- Identifiers
- 99900591863701842
- Language
- English
- Resource Type
- Thesis