A general suite of fungal endophytes dominate the roots of two dominant grasses in a semiarid grassland

Although research has shown that root associated fungi (RAF) are necessary for plant success in harsh environments, few studies have examined RAF community variability between different plant species coexisting in arid habitats. We compared the diversity and composition of the fungal communities colonizing dominant and important forage grasses, Bouteloua gracilis and Sporobolus cryptandrus, inhabiting the Sevilleta National Wildlife Refuge, a semiarid grassland in New Mexico. A third sympatric plant, Yucca glauca (Agavaceae), also was analyzed. ITS rDNA from roots, collected and amplified in 2007, yielded 447 fungal sequences. Sequences obtained from all three species suggest that grasses share a core group of RAF (90% of sequences representing the orders Pleosporales, Agaricales, and Sordariales). Conversely, 57% of the fungal community within Y. glauca was dominated by a different RAF cohort. The two most common OTUs within the grasses are related to Paraphaeospheria sp. and Moniliophthora sp. (91 and 85 of 331 sequences, respectively). These same two species accounted for 58% of isolates in culture-based analysis of the same grass root tissue. The presence of these RAF in several grass species, over several years, and at several sites suggests that grasses in semiarid landscapes share a similar cohort of fungal dominants.