Symbiosis Establishment and Ecological Effects of Endohyphal Bacteria on Foliar Fungi

Persistent Link:
http://hdl.handle.net/10150/347140
Title:
Symbiosis Establishment and Ecological Effects of Endohyphal Bacteria on Foliar Fungi
Author:
Arendt, Kayla Rae
Issue Date:
2015
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release after 12-Jul-2015
Abstract:
Plant microbiomes are increasingly appreciated as major drivers of plant health and ecosystem services, and are of ever-greater interest for their potential in human applications. However, plant-associated microorganisms often live in complex associations in nature. Here, I characterize one of these microbial associations: the symbiosis between foliar fungal endophytes and their bacterial endosymbionts (endohyphal bacteria, EHB). EHB influence fungal phenotypes and can shape the outcomes of plant-fungal interactions. EHB are thought to form facultative associations with many foliar fungi in the species-rich Ascomycota, but little is known about how these symbioses are initiated and maintained, or how EHB shape the ecology of their fungal hosts. In this study, I assessed factors mediating the relationships between two foliar fungi (Microdiplodia sp., Dothideomycetes; Pestalotiopsis sp. Sordariomycetes) and their EHB. I first established methods for introducing EHB into axenic mycelia of their fungal hosts, providing an important step forward for understanding the establishment of EHB associations and a critical tool for experimental tests of the effects of EHB on fungal phenotypes. Through experiments in vitro, I found that both the identity of the fungal host and the conditions under which fungi and bacteria are grown influence the establishment of EHB/fungal associations. Moreover, I showed EHB of foliar fungi can be transferred across fungal classes, thus creating experimental strains that could be used for the first time to examine the contribution of each symbiont to important fungal traits. Using these strains I evaluated how EHB influence the capacity of foliar fungi to degrade plant material as saprotrophs. I found that the presence and identity of EHB significantly influenced fungal growth on particular media, cellulase and ligninase activity, and mass loss from senescent tissue of their native host plant species in a partnership-specific manner. Because EHB can be acquired horizontally, they may help shape plant-fungal interactions, resultant ecosystem services, and the functional diversification of plant-associated fungi along the saprotroph-endophyte continuum. By manipulating EHB/fungal interactions in new ways, we can potentially influence fungal phenotypes for diverse human applications.
Type:
text; Electronic Thesis
Keywords:
decomposition; fungal endophytes; symbiosis; Plant Pathology; bacterial endosymbionts
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Plant Pathology
Degree Grantor:
University of Arizona
Advisor:
Arnold, Anne E.; Baltrus, David A.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleSymbiosis Establishment and Ecological Effects of Endohyphal Bacteria on Foliar Fungien_US
dc.creatorArendt, Kayla Raeen_US
dc.contributor.authorArendt, Kayla Raeen_US
dc.date.issued2015-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.releaseRelease after 12-Jul-2015en_US
dc.description.abstractPlant microbiomes are increasingly appreciated as major drivers of plant health and ecosystem services, and are of ever-greater interest for their potential in human applications. However, plant-associated microorganisms often live in complex associations in nature. Here, I characterize one of these microbial associations: the symbiosis between foliar fungal endophytes and their bacterial endosymbionts (endohyphal bacteria, EHB). EHB influence fungal phenotypes and can shape the outcomes of plant-fungal interactions. EHB are thought to form facultative associations with many foliar fungi in the species-rich Ascomycota, but little is known about how these symbioses are initiated and maintained, or how EHB shape the ecology of their fungal hosts. In this study, I assessed factors mediating the relationships between two foliar fungi (Microdiplodia sp., Dothideomycetes; Pestalotiopsis sp. Sordariomycetes) and their EHB. I first established methods for introducing EHB into axenic mycelia of their fungal hosts, providing an important step forward for understanding the establishment of EHB associations and a critical tool for experimental tests of the effects of EHB on fungal phenotypes. Through experiments in vitro, I found that both the identity of the fungal host and the conditions under which fungi and bacteria are grown influence the establishment of EHB/fungal associations. Moreover, I showed EHB of foliar fungi can be transferred across fungal classes, thus creating experimental strains that could be used for the first time to examine the contribution of each symbiont to important fungal traits. Using these strains I evaluated how EHB influence the capacity of foliar fungi to degrade plant material as saprotrophs. I found that the presence and identity of EHB significantly influenced fungal growth on particular media, cellulase and ligninase activity, and mass loss from senescent tissue of their native host plant species in a partnership-specific manner. Because EHB can be acquired horizontally, they may help shape plant-fungal interactions, resultant ecosystem services, and the functional diversification of plant-associated fungi along the saprotroph-endophyte continuum. By manipulating EHB/fungal interactions in new ways, we can potentially influence fungal phenotypes for diverse human applications.en_US
dc.typetexten
dc.typeElectronic Thesisen
dc.subjectdecompositionen_US
dc.subjectfungal endophytesen_US
dc.subjectsymbiosisen_US
dc.subjectPlant Pathologyen_US
dc.subjectbacterial endosymbiontsen_US
thesis.degree.nameM.S.en_US
thesis.degree.levelmastersen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePlant Pathologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorArnold, Anne E.en_US
dc.contributor.advisorBaltrus, David A.en_US
dc.contributor.committeememberOrbach, Marc J.en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.