Ectomycorrhizal Fungal Associates of Pinus contorta in Soils Associated with a Hot Spring in Norris Geyser Basin, Yellowstone National Park, Wyoming

Abstract

Molecular methods and comparisons of fruiting patterns (i.e., presence or absence of fungal fruiting bodies in different soil types) were used to determine ectomycorrhizal (EM) associates of Pinus contorta in soils associated with a thermal soil classified as ultra-acidic to extremely acidic (pH 2 to 4). EM were sampled by obtaining 36 soil cores from six paired plots (three cores each) of both thermal soils and forest soils directly adjacent to the thermal area. Fruiting bodies (mushrooms) were collected for molecular identification and to compare fruiting body (above-ground) diversity to below-ground diversity. Our results indicate (i) that there were significant decreases in both the level of EM infection (130 ؎ 22 EM root tips/core in forest soil; 68 ؎ 22 EM root tips/core in thermal soil) and EM fungal species richness (4.0 ؎ 0.5 species/core in forest soil; 1.2 ؎ 0.2 species/core in thermal soil) in soils associated with the thermal feature; (ii) that the EM mycota of thermal soils was comprised of a small set of dominant species and included very few rare species, while the EM mycota of forest soils contained a few dominant species and several rare EM fungal species; (iii) that Dermocybe phoenecius and a species of Inocybe, which was rare in forest soils, were the dominant EM fungal species in thermal soils; (iv) that other than the single Inocybe species, there was no overlap in the EM fungal communities of the forest and thermal soils; and (v) that the fungal species forming the majority of the above-ground fruiting structures in thermal soils (Pisolithus tinctorius, which is commonly used in remediation of acid soils) was not detected on a single EM root tip in either type of soil. Thus, P. tinctorius may have a different role in these thermal soils. Our results suggest that this species may not perform well in remediation of all acid soils and that factors such as pH, soil temperature, and soil chemistry may interact to influence EM fungal community structure. In addition, we identified at least one new species with potential for use in remediation of hot acidic soil.Ectomycorrhizae (EM) are complex interactions between fungi and plant roots, are formed mainly by basidiomycete fungi (39,47), and are the dominant nutrient-gathering organ in temperate ecosystems (45). These structures provide plants with nitrogen and phosphorus and protect plants from disease (18) and heavy metal contamination (34, 52). Different fungal species, and even isolates of the same species, can vary in their tolerance of harsh conditions (33, 50) and in the ability to help plants grow in extreme environments, such as acidic mine tailings (51) and coal spoils (24, 28). Because of these abilities, EM fungi are used to aid tree growth in programs designed to reclaim habitats altered by factors such as mining, nutrient deposition, and acid rain (11, 17). Thus, it has become increasingly important to determine in situ reactions of EM fungal communities to soil modifications that could inhibit plant growth.Soil pH and temperature ca...

Diversity of fungi associated with plants growing in geothermal ecosystems and evaluation of their capacities to enhance thermotolerance of host plants

“…Similarly, the number and diversity of fungi in rhizospheric soils in the present study were significantly lower than those reported in nongeothermal soils (Cabello & Arambarri 2002;Nesci et al 2006). The reason for this may be due to high temperatures, high heavy metal content, sparse vegetation, and limited organic carbon, all of which are disadvantageous for fungal survival and selects against non-tolerant species (Redman et al 1999;Cullings & Makhija 2001). From Table 1 we see that almost all of the taxa found in soils also occur as endophytes of plants, and the dominant genera in the rhizospheric soils were also the dominant genera in the plants, except for Gibberella.…”

Effects of Litter Addition on Ectomycorrhizal Associates of a Lodgepole Pine ( Pinus contorta ) Stand in Yellowstone National Park

“…The remainder of the EM fungal communities was composed of relatively rare species (seven species per plot in controls and plots to which perlite was added and three species per plot in plots to which litter was added), each of which was detected in only a single core (Table 2). This pattern of relatively few dominant species along with many rare species has been detected previously (12,16,18). Since the latter species were rare and changes in their relative abundance in response to treatment could not be analyzed statistically, they are not included in Table 2.…”

“…Restriction fragment length polymorphism (RFLP) patterns that were identical for EM and fruiting bodies were deemed a match. The utility and accuracy of this method have been demonstrated previously (26) and have used by workers in our laboratory in Yellowstone National Park (5,12,17,18).…”

“…To ensure genetic consistency within morphotypes, two individuals of each morphotype were selected for identification of fungi forming individual EM. This sampling scheme has been used successfully by workers in our laboratory in Yellowstone National Park (16,17,18) and also by other workers (29).…”

“…Mycorrhizae were separated by color morphology (1) and then stored dry at Ϫ20°C within 10 days of collection. EM tips of each morphotype in each core were pooled for quantification (17,18,29) and then freeze-dried for long-term storage. All morphotypes from all cores were archived for future analyses, but no living cultures were stored or deposited in international culture collections.…”