Huebner, Cynthia , McQuattie, Carolyn , Rebbeck, Joanne .
A Preliminary Microscopical Assessment of Mycorrhizal Associations in Ailanthus altissima from Two Habitats.
Ten Ailanthus altissima tree seedlings under a half meter in height were excavated from each of two habitat types: (1) a trail adjacent to a stream and a mature forest (i.e., relatively nutrient-rich soil in partial sun) and (2) a steep, barren slope adjacent to a major highway and devoid of other vegetation (i.e., relatively nutrient-poor soil in full sun). Each seedling root system was examined for the presence of mycorrhizae. Fine root segments were chemically preserved and embedded in epoxy resin. Thick sections (2 um) of roots were examined by light microscopy and corresponding ultrathin (100 nm) sections by transmission electron microscopy. Roots of A. altissima appear to be colonized by one or more endomycorrhizal fungi. In the slope habitat, fungal hyphae were present in large intercellular spaces between cortical cells of all 10 roots, and arbuscular structures or intracellular hyphae within the cortical cells were observed in 8 roots. In the trail habitat, intercellular hyphae were observed in 6 roots, and intracellular hyphae were seen in 4 roots. Lipid-like storage vesicles were observed in 3 roots from the slope habitat but were not observed in any root sections from the trail habitat. This type of endomycorrhizal colonization, in which the fungus spreads rapidly in the root cortex by intercellular hyphae, is typical of fast-growing crop species or woodland plants with longitudinal air channels in their roots (e.g., Arisaema atrorubens) and is often termed Arum-type colonization. Mycorrhizal colonization often is increased in roots of plants growing in nutrient-poor or high-light areas; therefore, the higher percentage of roots colonized in the slope habitat compared to the trail habitat may be related to site conditions. The invasiveness of A. altissima in various habitats may be explained in part by this species' ability to be rapidly colonized by endomycorrhizal fungi.
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1 - NE Research Station, USDA Forest Service, 180 Canfield St., Morgantown, West Virginia, 26505, USA
2 - NE Research Station, USDA Forest Service, 359 Main Road, Delaware, Ohio, 43015, USA
Presentation Type: Poster
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM