Abstract Detail

Ecology/Pathology

Tobias, Terri [1], Sinsabaugh, Robert [2], Suding, Katharine [3], Farrer, Emily [3], Porras-Alfaro, Andrea [1].

Seed associated fungi: mutualists and pathogens, and their potential impact on seed recruitment and community composition.

Alpine tundra ecosystems are characterized by harsh environmental conditions including a short growing season with temperatures below freezing, high solar radiation and winds, soil erosion, and the increase in nitrogen deposition caused by anthropogenic activity. Plants in the alpine tundra also rely on endophytic and mycorrhizal fungi for acquisition of nutrients and protection.  Given these harsh conditions, microbial interactions with plants could play an extremely important role in maintaining plant biodiversity in the alpine tundra. The objectives of this study were to describe the dominant fungal taxa found in seeds of six dominant species of plants in the alpine tundra and evaluate their potential function using a cultivated plant as a model.  Seed samples collected from a moist meadow in the alpine tundra at the Long Term Ecological Research Site in Niwot, Colorado included: Geum rossii, Erigeron simplex, Artemisia scopulorum, Deschampsia caespitosa, Bistorta bistortoides, and Trisetum spicatum. Fungal cultures were sequenced using the Internal Transcribed Spacer rDNA and identified using BLASTN and phylogenetic analysis. Dominant orders included Capnodiales (23% of the isolates), Pleosporales (23%), and Eurotiales (16%).  A total of 54 fungal cultures were isolated from seeds consisting of 12 unique genera.  Germination experiments using commercial corn seeds were conducted for each fungal species to determine potential mutualistic or pathogenic roles.  Sixty-six percent of the endophytes tested were closely related to seed pathogens and had pathogenic activity affecting germination and causing root necrosis.  The most common genus isolated was Alternaria accounting for 26% of the isolates.  Phylogenetic analysis indicated 4 unique clades of Cladosporium all of which showed positive effects on seed germination and plant growth. The high number of pathogenic fungi found in this study suggests that seed associated fungi could have a direct effect on community composition and seed recruitment.

1 - Western Illinois University, Biological Sciences, Waggoner Hall 372, 1 University Circle, Macomb, IL, 61455, USA
2 - University of New Mexico, Department of Biology, 167A Castetter Hall , Albuquerque, NM, 87131 , USA
3 - University of California-Berkeley, Department of Environmental Science, Policy & Management, 137 Mulford Hall, #3114, Berkeley, CA, 94720, USA

Keywords:
none specified

Presentation Type: Offered Paper - Paper
Session: 1
Location: Room 103 AB/Kellogg Hotel and Conference Center
Date: Monday, June 9th, 2014
Time: 9:30 AM
Number: 1005
Abstract ID:140
Candidate for Awards:Graduate Student Oral Presentation Award