On Germs and Germination: Uncovering the Hidden Ecology of Seedborne Bacteria and Fungi in Open-Pollinated Maize

dc.contributor.advisorBohannan, B. J. M.
dc.contributor.authorNebert, Lucas
dc.date.accessioned2018-10-31T22:33:52Z
dc.date.available2018-10-31T22:33:52Z
dc.date.issued2018-10-31
dc.description.abstractPlants are inhabited by diverse species of bacteria and fungi, which affect plant health and fitness. Endophytes are bacteria or fungi that live within plant host tissues without causing symptoms of disease, and mediate important plant traits in agriculture, such as nutrient acquisition, disease resistance, and abiotic stress tolerance. However, we know little about the general ecology of endophytes, including which factors determine their compositions within plants. Seedborne transmission may represent an important source of bacterial and fungal endophytes, which can significantly impact the plant microbiome and plant traits. However, seeds are also a vehicle for transmission of plant pathogens. Seeds are commonly treated to control against seedborne pathogens, and increasingly bacteria and fungi are inoculated onto seeds to serve as biological control against pathogens. My dissertation explores the theoretical and applied ecology of seedborne endophytes of maize, including their interactions with pathogenic Fusarium fungi, and with seed treatments designed to control Fusarium. In Chapter II, I examine factors that affect the transmission of seedborne fungal endophytes and Fusarium into maize seedlings, including the influence of soil microbiota, and the impact of disinfection and biological control seed treatments. In Chapter III, I determine the long-term effects of seed disinfection and biological control inoculants on maize bacterial and fungal endophytes and Fusarium pathogenicity across three different farms. In Chapter IV, I recruit maize seed growers across the Pacific Northwest and U.S. to participate in a broadscale study of seedborne endophytes. Across submitted seed samples, I find commonly occurring seedborne endophyte taxa, and delineate how maize varieties interact with environmental factors to affect the composition and diversity of seed-associated endophytes in seeds. Throughout these chapters, I explore the potential applications of seedborne endophytes in agriculture, particularly as a source for biological control against Fusarium in maize, and speculate how seed treatments can have significant, lasting impacts on the plant microbiome.en_US
dc.identifier.urihttps://hdl.handle.net/1794/23909
dc.language.isoen_US
dc.publisherUniversity of Oregon
dc.rightsCreative Commons BY-NC 4.0-US
dc.subjectCornen_US
dc.subjectEndophyteen_US
dc.subjectFusariumen_US
dc.subjectMaizeen_US
dc.subjectMicrobiomeen_US
dc.subjectSeedsen_US
dc.titleOn Germs and Germination: Uncovering the Hidden Ecology of Seedborne Bacteria and Fungi in Open-Pollinated Maize
dc.typeElectronic Thesis or Dissertation
thesis.degree.disciplineEnvironmental Studies Program
thesis.degree.grantorUniversity of Oregon
thesis.degree.leveldoctoral
thesis.degree.namePh.D.

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