The cultivated strawberry (Fragaria × ananassa) is a crop that has been historically maligned as having a genetically narrow base. To develop deeper insights into the domestication and breeding history of cultivated strawberry, pedigree records and DNA forensics were used reconstructed the genealogy as deeply as possible. The resulting pedigree network is a complex labyrinth of ancestral interconnections. Social network and population genetic analyses of the pedigree network provide evidence, presented in Chapter 1, that the modern strawberry hosts more genetic diversity than previously thought, countering the dogma that the modern strawberry is genetically narrow, and providing much-needed information to the continuing conversation about germplasm conservation in strawberry. While broad diversity exists in the publicly available germplasm, there is a lack of phenotypic data for key traits, including disease resistance. With continuing and increasing restrictions of fumigant chemicals, vascular wilts have emerged as a threat. A broad panel of accessions sampling both the species, geographic, and temporal diversity of the available public germplasm was characterized for two important diseases: Verticillium wilt caused by Verticillium dahliae and Fusarium wilt caused with Fusarium oxysporum f. sp. fragariae. The results, presented in Chapter 2 and Chapter 3 for V. dahliae and F. oxysporum f. sp. fragariae respectively, paint these two vascular wilts as opposites, necessitating their own approach in the context of breeding resistant cultivars. While the underlying genetic architecture of resistance is complex, genomic selection has promise to increase genetic gains for Verticillium wilt resistance and accelerate the development of much-needed resistant cultivars. On the other hand, Fusarium wilt of strawberry has had a single dominant resistance gene identified; however, the durability of this resistance into the future is unknown as the threat of novel races emerges. The identification of novel Fusarium wilt resistance genes and the development of diagnostic markers targeting these genes expands the tools available to breeders. Furthermore, the identification of host plants resistant to Race 2 of the pathogen establishes the basis for future studies and the development of cultivars resistant to multiple races.
|Advisor:||Knapp, Steven J.|
|Commitee:||Gordon, Thomas R., Brummer, Edward C.|
|School:||University of California, Davis|
|Department:||Horticulture and Agronomy|
|School Location:||United States -- California|
|Source:||DAI-B 82/8(E), Dissertation Abstracts International|
|Subjects:||Horticulture, Plant Pathology, Plant sciences|
|Keywords:||Fragaria, Fusarium wilt, Genealogy, Host resistance, Resistance genes, Verticillium wilt|
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