Date of Award
Honors College Thesis
Kevin A. Kuehn
This study used molecular techniques to examine the diversity of fungal species inhabiting leaf and stem litter of the freshwater emergent macrophyte, Typha angustifolia, during decomposition. Because morphological identification of fungal species is frequently inaccurate and underestimates the number of fungal species present, molecular techniques involving rRNA genes such as ITS regions (internal transcribed spacer regions) are used to better determine specific fungal species within a sample. In this study, samples of decaying leaf and stems litter of Typha angustifolia were obtained from Independence Lake, Michigan over the span of a year. DNA from litter samples obtained from the months of October (early), March (intermediate), and August (late) decomposition stages were extracted using MoBio PowerSoil© DNA Isolation Kit, followed by polymerase chain reaction (PCR) amplification of the fungal ITS region using ITS3 and ITS4 primers. The presence of PCR products were checked by agarose gel electrophoresis and then subjected to denaturing gradient gel electrophoresis (DGGE) to identify all varying DNA fragments (i.e., fungal operational taxonomic units, OTUs) that were amplified. A total of 34 and 63 operational taxonomic units (OTUs) were observed in Typha leaf and stem litter, respectively. NMDS statistical analysis using Jaccard index statistics revealed a significant (p> 0.001) shift in fungal communities associated with decaying Typha leaf litter, indicating that there is a succession in certain fungi during the stages of decomposition. In contrast, no observable successional pattern was observed in fungal communities associated with decaying Typha stems (p<0.504). Future efforts will be directed at cloning and sequencing individual bands in order to identify the species present. This data in conjunction with measures of respiration, fungal biomass and production will allow greater understanding of the quantitative role of fungal decomposers in carbon and nutrient cycling in wetland ecosystems.
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Chesteen, Kimberly, "Determining the Diversity of Wetland Fungi through Molecular-based Species Identification" (2012). Honors Theses. 20.