Mycrorrhizal Ecology and Arbuscular Mycorrhizal (AM) fungi in Thermal Soils

Mycorrhizal Ecology of Thermal Soil Systems Thermal soils pose challenges to both plants and fungi (Figure 1), including high temperatures coupled with very low pH and toxic levels of many minerals.  To research the effects of temperature on fungal growth and performance and the potential for temperature adaptations, the Zabinski lab collected arbuscular mycorrhizan   (AM) fungal isolates from alpine, non-thermal, and thermal sites.  AM-inoculated plants were grown at 15ºC, 25 ºC, or 40 ºC in the greenhouse. We are comparing fungal biomass from one site grown at different temperatures, as well as the performance of fungi from different temperature origins.  To further research functional aspects of thermal AM fungi, four AM fungal species (Glomus intraradices, Gigaspora gigantea, Paraglomus occultum, Acaulospora morrowiae) common to thermal areas have been isolated from YNP soils, and we are establishing pure cultures of the fungi.

Figure 1.  Dichanthelium plants experiencing below-freezing aboveground temperatures and soil temperatures above 30 ºC

Thermophilic AM fungi The Redecker lab in Basel has characterized AM fungal communities in roots of Dichanthelium and Agrostis from three thermal areas. DNA of AM fungi colonizing roots was amplified using PCR and AM fungal family-specific primers.  Products were cloned, screened by restriction analysis (RFLP) and sequenced (Figure 2a). The AM fungal communities were surprisingly species poor compared to other North American ecosystems.  In the Zabinski lab, Dr. Ylva Lekberg has optimized our system using terminal restriction length polymorphism (T-RFLP) analysis to identify multiple AM fungal species occurring in root fragments (Fig. 2b). 
We are measuring AM fungal abundance and community composition with soil depth and increasing soil temperatures.  External hyphae of AM fungi were found as deep as 12.5 cm where the soil temperatures reached an average of 39.6°C, while plant roots had an average maximum rooting depth of 6.5 cm, and corresponding soil temperature of 31.7°C. 

Figure 2.  Typical RFLP patterns of AM fungi colonizing roots or occurring as spores (a), and T-RFLP pattern of AMF colonizing a root (b) in the Lone Star Geyser basin.

Current Laboratory Personnel:

Ylva Lekberg, Postdoctoral Associate
Julie Kray, M.S. Student
Carrie Taylor, M.S. Student
Hilary Parkinson, M.S. Student
Natalie Meyer, M.S. Student
Shawna Raden, Undergraduate Student
Doug Higgins, Undergraduate Student
Karin Neff, Laboratory Technician

The Zabinski lab group

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