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Garden climate effects on endophyte abundance and morphology of Populus fremontii (Fremont cottonwoods) populations from across their temperature range

Baker, Scott Michael (2021) Garden climate effects on endophyte abundance and morphology of Populus fremontii (Fremont cottonwoods) populations from across their temperature range. Masters thesis, Northern Arizona University.

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Premise of the study: Fungal endophytes are symbionts that reside asymptomatically in plant tissues and have relationships that can range from mutualistic to parasitic. These fungi can have profound impacts on plant fitness, evolution, and communities as well as on the structure of the broader phytosphere community. It is known that biotic and abiotic factors affect the endophyte community and abundance; however, few studies have looked at the effect of source population and site simultaneously. We investigated three main questions: (1) Is endophyte abundance in Populus fremontii (Fremont cottonwood) affected by population source climate, garden climate, and their interaction? (2) Are quantitative tree traits linked to endophyte abundance? (3) Do population source climate, garden climate, and their interaction have an effect on quantitative tree traits in P. fremontii? We also present preliminary data on endophyte community composition across the three gardens.Methods: Endophytes were isolated from twigs of replicated P. fremontii populations in three common gardens across an elevational and temperature gradient and characterized with DNA sequencing. Twig length and diameter and leaf mass were also quantified. Key results:1) Fungal endophyte abundance varied by garden climate and population source climate, but there was no significant population by garden interaction. Garden climate had the greatest effect with cottonwoods from all source populations showing dramatically reduced endophyte abundance in the coldest garden. Interestingly, cottonwoods from the coldest populations had the highest endophyte abundance in all three gardens. 2) Shoot length and dried leaf mass were associated with endophyte abundance in Fremont cottonwoods while twig diameter was not. 3) Twig diameter was only affected by population source climate; however, shoot length and dried leaf mass were significantly affected by population source climate, garden climate, and their interaction. 4) The Warm and Hot gardens were dominated by endophytes of the genus Alternaria, while the Cold garden was dominated by members of the genus Valsa. Conclusions: These results suggest that even a modest change in temperature can greatly influence fungal endophyte abundance and host plant morphology; however, endophyte abundance and the plant traits we measured were not tightly linked and in the opposite direction of our prediction. Given that climate change is affecting temperatures across the globe, the relationship between host plant and endophyte abundance and community may be crucial to conservation efforts for foundation species, but difficult to predict from plant traits. Key words: Endophyte, class III endophyte, Fremont cottonwood, abundance, climate, plant response.

Item Type: Thesis (Masters)
Publisher’s Statement: © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords: abundance; class III endophyte; climate; endophyte; Fremont cottonwood; plant response
Subjects: Q Science > QK Botany
NAU Depositing Author Academic Status: Student
Department/Unit: Graduate College > Theses and Dissertations
College of the Environment, Forestry, and Natural Sciences > Biological Sciences
Date Deposited: 01 Feb 2022 18:06
Last Modified: 28 Dec 2022 08:30
URI: https://openknowledge.nau.edu/id/eprint/5619

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