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Dissertation
CHEATING CHEATGRASS: UNDERSTANDING THE GENETIC AND PHENOTYPIC VARIATION UNDERLYING ADAPTIVE TRAITS IN DOWNY BROME
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004351
Handle:
https://hdl.handle.net/2376/125009
Abstract
Bromus tectorum L., known as cheatgrass or downy brome, is arguably the most damaging invasive species in North America. Bromus tectorum reduces crop yields, increases the frequency of wildfires, and displaces indigenous species in North America, especially the intermountain west. The broad scale of damage to ecosystems and reductions in crop yields caused by B. tectorum necessitate action to mitigate ecosystem destruction and food shortages, and thus the on society. As a near obligate self-fertilizing species, B. tectorum has a life cycle uniquely adapted to the intermountain western United States. To adapt to natural ecosystems and cropping systems B. tectorum relies on variation in phenology traits and herbicide resistance. However, the source, maintenance, and impact, of the variation in phenology and herbicide resistance remains uncharacterized in B. tectorum. Using B. tectorum from the germplasm resource information network, the inland Pacific Northwest and Montana, we observed repeatable variation in phenology across the global accessions, between regions in North America and between genotypes sampled within the same location. A genome wide association study identified quantitative trait loci (QTL) controlling height and phenology traits, revealing punitive candidate genes underlying the variation in phenology traits. However, a genome wide scan for genomic indicators of selection revealed multiple putative candidate genes from the ATP-binding cassette transporter, cytochrome P450, glutathione s-transferase, and glycosyltransferase gene families implicated in non-target site resistance, but only one gene implicated with phenology. Identifying non-target site resistance genes under selection and not phenology genes, implies that herbicide resistance is a greater driver of selection for B. tectorum, in the invasive range. Using stochastic forward genetic simulations we identified migration and selection as key factors to maintain the genetic and phenotypic variation present in B. tectorum. Individual-based simulations revealed that marginal environments, where annual plants have a low fecundity, outcrossing does not confer an advantage to adaptation. Developing novel management strategies for B. tectorum by should be based on both the genetic and phenotypic variation present in B. tectorum and the theoretical basis for maintenance of the variation observed.
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Details
- Title
- CHEATING CHEATGRASS
- Creators
- Samuel Robert Revolinski
- Contributors
- Ian C Burke (Advisor)Richard Gomulkiewicz (Committee Member)Kimberly A Garland-Campbell (Committee Member)Arron H Carter (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 162
- Identifiers
- 99900883035101842
- Language
- English
- Resource Type
- Dissertation