Precipitation increases the abundance of some groups of root-associated fungal endophytes in a semiarid grassland

José Herrera,Scott L Collins,Katherine A Nebel,Ravin Poudel

doi:10.1890/es11-00001.1

José Herrera, Scott L Collins + Show 2 more

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https://doi.org/10.1890/es11-00001.1

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Journal: Ecosphere	Publication Date: Apr 1, 2011
Citations: 34	License type: cc-by

Affiliation: University of New Mexico, Truman State University

Abstract

Diverse communities of Root-Associated Fungal (RAF) species, including Dark Septate Endophytes (DSE), inhabit grasses in semiarid soils. These aridlands are often distinguished by large but variable precipitation events (monsoons). We sought to compare the composition and fungal load of the RAF community inhabiting the roots of Sporobolus cryptandrus, a dominant forage grass, exposed to variable precipitation events. We used a rainfall manipulation experiment at the Sevilleta National Wildlife Refuge (SNWR) to examine the abundance and composition of the RAF communities using molecular and microscopic techniques. Molecular data reveals that the RAF communities are dominated by Ascomycetes and few sequences were related to Arbuscular Mycorrhizal Fungi (AMF). The most dominant group (Paraphaeosphaeria spp.) clearly increased in abundance in response to water amendments and the addition of similar volumes of water appeared to increase similarity among the RAF communities, irrespective of size and distribution of precipitation events. Microscopic examinations of the roots also revealed an increased fungal load when exposed to elevated moisture, irrespective of rainfall frequency. We suggest that the increase in these cosmopolitan and abundant groups of Ascomycete fungi, in part, represents a common but complicated strategy of water translocation in a variety of soil types, similar to that proposed and shown in the arbuscular mycorrhizal fungi (AMF). Additional work should examine whether many (or most) members of the Ascomycete RAF also can facultatively broker water in the larger biological network in the soil.

Highlights

Aridlands constitute approximately one-third of the earth’s land surface and, by most accounts, continue to increase in area (Noy-Meir 1973, Schlesinger et al 1990, UNESCO 1977)
Because previous work in the same study area (Khidir et al 2010) suggested only a few groups dominated the root-associated fungal (RAF) community of S. cryptandrus, we focused our effort on assessing how variable precipitation events affected the prevalence of these core fungal groups
Based on data obtained from meteorological station #49 (SNWR database), most monsoonal events (.5 mm) occur primarily during July–September (Fig. 1), some occasional pre-monsoonal rains occur in the spring of some years (Kurc and Small 2007)

Summary

Introduction

Aridlands constitute approximately one-third of the earth’s land surface and, by most accounts, continue to increase in area (Noy-Meir 1973, Schlesinger et al 1990, UNESCO 1977). Recent evidence suggests that many grass species within these areas form intimate and long-lasting symbiotic relationships with a large and diverse community of fungal endophytes, within their roots (Jumpponen 2001, Kovacs and Szigetvari 2002, Lucero et al 2006, Petrini 1996, Smith and Read 1997). This root-associated fungal (RAF) endophyte community often is dominated by a few taxonomically undescribed fungal clades (Khidir et al 2010, Porras-Alfaro et al 2008). Grass-fungal interactions appear to be common and consistent over wide areas in aridland ecosystems

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