Date of Award

2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Committee Chair

Leland Cseke

Committee Member

Luciano Matzkin

Committee Member

Robert O. Lawton

Subject(s)

Mycorrhizas., Plant-fungus relationships., Nitrogen cycle., Poplar., Plants--Effect of nitrogen on., Soils--Nitrogen content.

Abstract

Nitrogen deficiency is the most common and widespread nutritional deficiency affecting plants worldwide. Ectomycorrhizal symbiosis involves the beneficial interaction of plants with soil fungi and plays a critical role in nutrient cycling, including the uptake of nitrogen from the environment. The main goal of this study is to understand how limiting nitrogen in the presence or absence of an ectomycorrhizal fungi, Laccaria bicolor, affects the health of aspen trees, Populus tremuloides. Under limited nitrogen conditions, aspen tree growth and development is reduced, and mycorrhizal symbiosis may significantly improve plant biomass, providing sufficient nitrogen is available. The results of biochemical analysis also indicate that the supply of carbon to fungus associated with aspen roots is reduced as a result of aspen utilizing more sugar resources for the production of sucrose and starch within shoot tissues. Identification of metabolic pathways in aspen tree roots revealed that carbohydrate and nitrate metabolism was impacted by changing environmental conditions, including interactions with the fungi.

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