Interesting and unusual flux patterns of nitrogen and carbon in pinus contorta germinants colonized by the ectomycorrhizal fungus suillus tomentosus
department or school: Arts and Sciences, Irving K. Barber School of (Okanagan)
department or school: Biology, Department of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Smith, Joshua Michael
issued: 2018-10-02T18:31:40Z
issued: 2018
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The most commonly known characteristics of the ectomycorrhizal symbiosis are translocation of soil nitrogen by fungi to plant roots, and the allocation of plant carbon to the fungi. Here, I report on observations that contradict these well-known ecophysiological pathways: movement of nitrogen from the plant toward the fungus, and the fungus behaving saprotrophically while in symbiosis. In both experiments for this thesis mycorrhizal Pinus contorta and Suillus tomentosus were used. In the first experiment, these organisms were in low-nitrogen microcosms where some nitrogen was accessible only by hyphae. After 73 days, the hyphal nutrient medium was replaced with water or fresh nitrogen solutions. Forty-eight hours after nutrient manipulations, shoot nitrogen concentrations had dropped by 70% in microcosms where nitrogen was added to the hyphal compartment. These seedlings contained only 55% of the nitrogen present in the seed. Loss of nitrogen did not occur if water was added to the hyphal compartment or if hyphal connections to the fresh nitrogen were severed prior to nitrogen addition. Because severing of hyphae prevented loss of nitrogen I speculate that seedling nitrogen was translocated to S. tomentosus. If a similar effect occurs in the field with germinants, the nitrogen would be especially beneficial to ectomycorrhizal fungi colonizing from spores after wildfire, a scenario typical for lodgepole pine. For the second experiment I used microcosms where the substrate was amended with soil organic carbon (SOC) that was at natural abundance or 13C-enriched. After 148 days of growth, both the CO₂ respired by a combination of plant plus fungus, and that respired by S. tomentosus alone, were significantly enriched in 13C over natural abundance levels. An isotope mixing model was used to determine that 35% of the carbon respired by the fungus came from the SOC. This indicates that S. tomentosus possesses the ability to behave saprotrophically while in symbiosis to sup…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/67302
note: Interesting and Unusual Flux Patterns of Nitrogen and Carbon in Pinus contorta Germinants Colonized by the Ectomycorrhizal Fungus Suillus tomentosus by Joshua Michael Smith B.Sc., The University of British Columbia, 2014 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in The College of Graduate Studies (Biology) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) September 2018 © Joshua Michael Smith, 2018 ii The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, a thesis/dissertation entitled: Interesting and Unusual Flux Patterns of Nitrogen and Carbon in Pinus contorta Germinants Colonized by the Ectomycorrhizal Fungus Suillus tomentosus submitted by in partial fulfillment of the requirements of the degree of . Dr. Melanie Jones, Irving K. Barber School of Arts and Sciences Supervisor Dr. Daniel Durall, Irving K. Barber School of Arts and Sciences Supervisory Committee Member Dr. Louise Nelson, Irving K. Barber School of Arts and Sciences Supervisory Committee Member Dr. Peter Millard, Manaaki Whenua - Landcare Research, New Zealand Supervisory Committee Member Dr. Jeff Curtis, Irving K. Barber School of Arts and Sciences University Examiner Master of Science Joshua Michael Smith iii Abstract The most commonly known characteristics of the ectomycorrhizal symbiosis are translocation of soil nitrogen by fungi to plant roots, and the allocation of plant carbon to the fungi. Here, I report on observations that contradict these well-known ecophysiological pathways: movement of nitrogen from the plant toward the fungus, and the fungus behaving saprotrophically while in symbiosis. In both experiments for this thesis mycorrhizal Pinus contorta and Suillus tomentosus were used. In the first experiment, these organisms were in low-nitrogen microcosms where some nitrogen was accessible only by hyphae. After 73 days, the hyphal nutrient medium was replaced with water …
has type: Thesis/Dissertation
date issued: 2018-11
is shown at: 10.14288/1.0372341
language: eng
degree discipline: Biology
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-ShareAlike 4.0 International
rights URI: http://creativecommons.org/licenses/by-sa/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/67302