PARENT SESSION
Oral Session # 81: Soil Ecology II: Microorganisms and Mycorrhizae.
Presiding: SJ Hall
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 106.

Assessment of the mycorrhizal community by soil DNA sequencing and its correlation with soil N and P fractions.

Rachel, Gary^*,1, Hendrick, Ronald ¹, ¹ University of Georgia, Athens, Georgia

ABSTRACT- We assessed the distribution of extra-matrical hyphae within soil horizons of the three major types of mycorrhizae (arbuscular, ericoid, and ectomycorrhizae). We also determined the distribution of soil N and P fractions within these same soil horizons to assess whether a correlation exists between these fractions and the hyphal distribution. The study was carried out within forested stands of the Coweeta Hydrological Laboratory, in Otto, North Carolina. The stands were chosen for their occupation by plant hosts of each of the three mycorrhizal types. Mycorrhizal distribution assessments were carried out using DNA based techniques. Total soil DNA was extracted using five different techniques to determine which protocol provided the highest amount of total DNA and greatest diversity of fungal DNA. A combination of spectrophotometer, Picogreen, and ARDRA assays were utilized to determine best protocol. For extraction of mycorrhizal fungal DNA from the soil, commercial kits utilizing bead beating followed by GITC/silica gel purification proved the most efficient, providing almost twice the DNA content and greater banding in the ARDRA assay, indicating a higher diversity of amplified fragments, than the other extraction methods. The total soil DNA extracts were then PCR amplified using several sets of specific primers. The products were cloned, sequenced, and analyzed for their phylogenic relationships with sequences of known mycorrhizal species. The distribution of the mycorrhizal fungi were then compared to various soil N and P fractions. The fractionation procedure provides measures of the inorganic, amino and sugar N concentrations, as well as several organic and inorganic P pools. Preliminary results indicate a correlation between mycorrhizal fungal distribution and soil N and P fractions. Ectomycorrhizal fungi were detected in all soil horizons, with several species ubiquitous throughout the soil profile, while other species were more discreetly localized. Arbuscular mycorrhizal fungi were detected in predominately A horizons, with some species extracted from O horizon soil. Ericoid mycorrhizal fungi were the predominant mycorrhizal fungi in the O horizon, and were extracted from A and B horizon soil as well.

Key words: ectomycorrhiza, arbuscular, mycorrhiza, ericoid