Abstract Detail

Ecology/Pathology

Dean, Sarah [1], Warnock, Daniel [1], Litvak, Marcy [1], Sinsabaugh, Robert [1].

Drought Effects on Abiotic and Biotic Fungal Assembly Mechanisms in Root Associated Fungi.

Climate change is expected to cause southwestern North America to become hotter and more arid with increased incidences of severe drought. In piñon-juniper woodlands, piñon (Pinus edulis) dies back in response to drought while juniper (Juniperus monosperma) survives, causing a major restructuring of the vegetation community. Restructuring of the vegetation community alters root-associated fungal (RAF) community of the remaining plants. Due to the potential influence of symbionts on host environmental stress tolerance, RAF response to vegetation shifts could feed back into vegetation response to drought. We hypothesize P. edulis and J. monosperma influence each other’s fungal communities. Additionally, we hypothesize the presence of dead P. edulis neighbors will introduce saprobes and pathogens to the roots of J. monosperma. In piñon-juniper woodlands, 1,632 P. edulis trees were girdled in a 4 ha area to mimic mass mortality observed with extreme drought. We collected root samples from P. edulis and J. monosperma trees that neighbor live P. edulis, live J. monosperma, or dead P. edulis. We also collected roots from J. monosperma in lower elevation juniper savanna, which is more arid and warmer than piñon-juniper woodlands. DNA was extracted and sequenced using 454 pyrosequencing of the universal fungal ITS region. Nearly half of the sequences could not be assigned to a phylum, indicating how little work has been done on RAF in these arid ecosystems. Ascomycota were significantly higher in savanna, and Helotiales, associated with phenolic rich hosts in our previous research, were significantly more abundant in juniper. Only one unclassified endophyte was associated specifically with juniper neighboring dead piñon. We found no effect of host or neighbor on RAF community composition. However, there was a significant difference between J. monosperma RAF communities in woodland vs. savanna, indicating abiotic factors such as temperature and aridity may be more important in structuring these RAF communities than biotic factors. RAF richness was higher in hosts that were neighbored by the same species. This may indicate competitive exclusion between fungi from different plant hosts. The abundance of unclassified fungi precludes drawing conclusions about how these RAF dynamics impact host fitness. Nonetheless, characterizing these environment and neighbor effects improve our understanding of the effects of drought on piñon-juniper ecosystems, which span 19 million ha of the American southwest.

1 - University of New Mexico, Biology Department, 167 Castetter Hall, 1 University of New Mexico, Albuquerque, NM, 87105, USA

Keywords:
root endophyte
ITS
pinyon juniper woodland
drought.

Presentation Type: Offered Paper - Paper
Session: 9
Location: Room 104 AB/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 9:30 AM
Number: 9005
Abstract ID:86
Candidate for Awards:None