Barnes, Christopher James (2014) Characterizing environmental, temporal and spatial scaling of Rhizosphere fungi in bioenergy crops : and their role in belowground carbon cycling. PhD thesis, University of Warwick.

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Abstract

The rhizosphere consists of plant roots and the adjoining soil, which contains a functionally and genetically rich fungal community. The obligate plant symbionts, the mycorrhizal fungi, have been shown to receive substantial quantities of plant-derived C and play an important role in belowground C dynamics. The flux and residence time of C is however likely to be highly species-specific for rhizosphere fungi, and therefore their abundance and composition will likely have important implications on C storage belowground. Rhizosphere fungal community formation is extremely complex and despite being an area of intense research, current understanding is limited.
The composition and abundance of rhizosphere fungi have been shown to vary with temporal and environmental parameters, and potentially geographical separation. However, no studies to date have analysed these parameters simultaneously to isolate the independent effects of each. Clone libraries in conjunction with TRFLP were performed before progressing to 454-pyrosequencing to profile the rhizosphere fungal community of a short rotation coppice (SRC) willow filed site. In this work, distinct seasonal fungal assemblages were shown, with N availability having a large effect in summer and geographical distance effects in autumn sampling points. Additionally, a rare large transition in the composition of the rhizosphere fungi was also demonstrated, which was most likely driven by extreme rainfall earlier in the growing season of the year of transition. Finally, using ₁₃C-labelled-CO₂ the belowground movement of recently derived photo-assimilates was shown to differ between Miscanthus x giganteus and SRC willow, however no significant fluxes were associated with rhizosphere fungal pathways in either crop. Results from this work demonstrate that some of the considerable complexity of microbial communities could have between overlooked in previous community analyses, whilst the flow of C within through mycorrhizal pathways maybe less important in bioenergy cropping systems compared to other ecosystems.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QK Botany
Library of Congress Subject Headings (LCSH):	Rhizosphere, Fungi -- Ecology, Energy crops, Biogeochemical cycles, Roots (Botany) -- Ecology
Official Date:	August 2014
Dates:	Date Event August 2014 Submitted
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Gast, Christopher van der ; McNamara, Naill ; Bending, G. D. (Gary D.)
Sponsors:	Natural Environment Research Council (Great Britain)
Extent:	xiii, 139 leaves : illustrations (chiefly colour), charts (chiefly colour)
Language:	eng

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