Files and links (1)
CC BY V4.0, Open Access
Dissertation
Characterization, Detection, and Genetics of the Spinach Fusarium Wilt Pathogen
Washington State University
Doctor of Philosophy (PhD), Washington State University
2022
DOI:
https://doi.org/10.7273/000005184
Abstract
The maritime Pacific Northwest is the only region of the United States with a climate suitable for producing spinach seed crops. However, the leached, acid soils typical of this region are highly conducive to spinach Fusarium wilt caused by the persistent and recalcitrant pathogen Fusarium oxysporum f. sp. spinaciae. Recently, two pathogenicity groups of F. oxysporum f. sp. spinaciae were identified based on: 1) differences in virulence on two spinach inbreds, 2) profiles of candidate effector genes, and 3) phylogenetic lineage. These findings motivated research to: i) determine the susceptibility of commercial spinach cultivars to isolates of each pathogenicity group, ii) develop real-time PCR assays for rapid detection of the pathogen, and iii) identify chromosomes associated with host specificity in F. oxysporum f. sp. spinaciae. Spinach cultivars (n = 68) were inoculated with isolates of each group of F. oxysporum f. sp. spinaciae. Cultivars responded differentially to isolates of each group, suggesting the pathogenicity groups are races, proposed as races 1 and 2. In addition, some cultivars exhibited a genotype-by-race-by-isolate interaction as wilt severity caused by isolates of race 2 was influenced strongly by light intensity. Real-time PCR assays were developed to detect candidate effector genes specific to F. oxysporum f. sp. spinaciae: one assay based on a candidate effector gene present in isolates of both races, and one assay for an effector unique to isolates of race 2. The assays were specific, highly sensitive, and enabled detection of the pathogen in culture and in planta. Nanopore sequencing of the genomes of a representative isolate of each race and an avirulent, spinach-associated isolate of F. oxysporum revealed accessory chromosomes unique to F. oxysporum f. sp. spinaciae. The karyotypic profiles of each isolate suggest that isolates of race 1 arose due to horizontal chromosome transfer from an isolate of race 2. This research should help breeders develop spinach cultivars with improved resistance to Fusarium wilt, and diagnosticians detect and quantify F. oxysporum f. sp. spinaciae rapidly in cultures, plants, soil, and seed. Overall, this work will support accurate risk assessment and management of this spinach pathogen.
Metrics
6 File views/ downloads
27 Record Views
Details
- Title
- Characterization, Detection, and Genetics of the Spinach Fusarium Wilt Pathogen
- Creators
- Alexander M. Batson
- Contributors
- Lindsey J. du Toit (Advisor)Robert S. Brueggeman (Committee Member)Cynthia A. Gleason (Committee Member)James W. Woodhall (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 212
- Identifiers
- 99901019537901842
- Language
- English
- Resource Type
- Dissertation