Symbioses: Plant, Animal, and Microbe Interactions
Yeraballi, Sagar , Hicks, Sarah , Gossage, Zachary , Sinsabaugh, Robert , Suding, Katherine , Sinsabaugh, Robert , Porras-Alfaro, Andrea .
Response of plant-associated fungal communities to N deposition in an alpine tundra ecosystem.
Human activities have played a major role in increasing nitrogen (N) availability in terrestrial ecosystems. N enrichment facilitates plant productivity, but in certain conditions can negatively affect plant diversity and survival. The effects of N fertilization on plant-fungal interactions in alpine tundra ecosystems are poorly known. The main goal of this study was to evaluate the effect of N fertilization on fungal symbionts associated with two co-dominant plants: Geum rossii and Deschampsia cespitosa. Seven samples were collected for each plant species from four different treatments: control, N fertilized, N fertilized/Deschampsia removal, Deschampsia removal/no N added. The study site is located at the Niwot Ridge Long Term Ecological Research (LTER) site in Colorado. Roots were harvested from each treatment and stained to quantify fungal colonization. Ninety two pure cultures of endophytic fungi were isolated on potato dextrose agar. Fungal symbionts were identified using the Internal Transcribed Spacer rDNA. Potential functions of these symbionts were evaluated in germination and greenhouse experiments. Microscopy data from 2008 and 2010 showed an increase in percentage of colonization in N fertilized plots when compared with control plots. Geum showed the highest colonization with arbuscular mycorrhizal fungi and dark septate fungi as the dominant colonizers. Preliminary identification of cultures showed that Geum is mainly colonized by fungi in the order Heliotales including the dark septate fungus Phialocephala fortinii. Of five different fungal endophytes tested in the greenhouse, two had pathogenic activity. Direct sequencing from roots using 454 technology, showed that fungal communites are highly complex. Analysis of potential roles of these fungal symbionts needs further exploration.
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1 - Western Illinois University, Biology, Waggoner Hall. 1 University CIrcle, Macomb, IL, 61455, USA
2 - University of New Mexico, Biology, 167 Castetter Hall , Albuquerque, NM, 87131, USA
3 - University of California Berkeley, Department of Environmental Science, Policy & Management, 137 Mulford Hall #3144, Berkeley, CA, 94720, USA
Presentation Type: Poster:Posters for Topics
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM