Dissertation
INTEGRATIVE APPROACHES TO UNDERSTANDING AND IDENTIFYING LACTUCA SPECIES: PHYLOGENETICS, MORPHOLOGY, AND MACHINE LEARNING APPLICATIONS AT A GENEBANK LEVEL
Doctor of Philosophy (PhD), Washington State University
12/2025
DOI:
https://doi.org/10.7273/000008407
Abstract
The USDA National Plant Germplasm System (NPGS) faces a significant challenge in accurately identifying and characterizing its vast collection of plant germplasm, with hundreds of accessions remaining unidentified due to time and resource constraints. For example, 65 accessions of lettuce (Lactuca) lack species designations, limiting their utility for research and breeding. This study aimed to address this issue by providing increased clarity on the taxonomy of the genus Lactuca. The research utilized hybrid-exome capture sequencing (Hyb-Seq) to create a robust phylogeny of 26 Lactuca species, compiled a thorough morphological examination of these species, and explored the potential of supervised machine learning to accurately identify species using Hyb-Seq data. The first study established a robust phylogeny of 26 Lactuca species, clarified crop breeding pools and proposed the name Maculospermae for the North American and Azorean lettuce species. The second study reviewed the history of the genus and its complex morphology, presenting a consolidated monograph and a dichotomous key for species identification. The third study tests the potential of a supervised machine learning model being utilized for high throughput species identification at a genebank level and provided a preliminary model for future work. This research offers new, more economical methods for species identification, enabling genebanks to enhance the accuracy of their characterization data for Lactuca accessions and improve the understanding of species interrelatedness within the genus.
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Details
- Title
- INTEGRATIVE APPROACHES TO UNDERSTANDING AND IDENTIFYING LACTUCA SPECIES
- Creators
- Alexander Cornwall
- Contributors
- Carol A Miles (Chair)Eric Roalson (Committee Member)Deven See (Committee Member)Stephen Ficklin (Committee Member)Cameron Peace (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Horticulture
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 164
- Identifiers
- 99901356784801842
- Language
- English
- Resource Type
- Dissertation