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Appl. Environ. Microbiol. doi:10.1128/AEM.02769-07
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

A novel root fungal consortium associated with a dominant desert grass

Department of Biology, MSC03 2020, 1 The University of New Mexico, Albuquerque, New Mexico 87131-0001 USA; Department of Biology, 100 E. Normal, Truman State University, Kirksville MO 63501 USA

^* To whom correspondence should be addressed. Email: aporras{at}unm.edu.

	Abstract

The broad distribution and high colonization rates of plant roots by a variety of endophytic fungi suggest that these symbionts have an important role in ecosystem functioning. Semiarid and arid ecosystems cover more than one third of the terrestrial ecosystems on Earth. However, a limited number of studies have been conducted to characterize root-associated fungal communities in semiarid grasslands. We conducted a study of the fungal community associated with the roots of a dominant grass, Bouteloua gracilis, at the Sevilleta National Wildlife Refuge, New Mexico. Internal Transcribed Spacer (ITS) rDNA sequences from roots collected in May 2005, October 2005, and January 2006 were amplified using fungal specific primers and a total of 630 sequences were obtained, 69% of which were novel (less than 97% similarity with respect to sequences in the NCBI database). B. gracilis roots were colonized by at least 10 different orders including endophytic, coprophilous, mycorrhizal, saprophytic and plant pathogenic fungi. A total of 51 operational taxonomic units (OTUs) were found and diversity estimators did not show saturation. Despite the high diversity found within B. gracilis roots, the root-associated fungal community is dominated by a novel group of dark septate fungi (DSF) within the order Pleosporales. Microscopic analysis confirmed that B. gracilis roots are highly colonized by DSF. Other common orders colonizing the roots included Sordariales, Xylariales, and Agaricales. By contributing to drought tolerance and nutrient acquisition, DSF may be integral to the function of arid ecosystems.