Shifting fungal endophyte communities colonizeBouteloua gracilis: effect of host tissue and geographical distribution

Abstract

Communities of root-associated fungi (RAF) commonly have been studied under the auspices of arbuscular mycorrhizal fungi (AMF) or ectomycorrhizal fungi. However many studies now indicate that other groups of endophytic RAF, including dark septate endophytes (DSE) are more abundant in some plants and environments. The common forage grass, Bouteloua gracilis, was used as a model to examine whether RAF also colonize different organs within the same plant and to compare RAF communities from sites across North America, spanning the latitudinal range of B. gracilis (from Canada to Mexico). We compared the RAF communities of organs within individual plants at one site and within plant roots among six sites. With the possible exception of one group related to genus Paraphaeosphaeria there was little evidence that RAF colonized vertically beyond the crowns. Furthermore, although there was some variation in the constitution of rare members of the RAF communities, several taxonomically related groups dominated the RAF community at all sites. These dominant taxa included members in the Pleosporales (related to the DSE, Paraphaeosphaeria spp.), Agaricales (related to Moniliophthora spp., or Campanella spp.) and Hypocreales (related to Fusarium spp.). AMF were notable by their near absence. Similar phylotypes from the dominant groups clustered around adjacent sites so that similarity of the RAF communities was negatively correlated to site inter-distance and the RAF communities appeared to group by country. These results increase the possibility that at least some of these common and widely distributed core members of the RAF community form important, intimate and long lasting relationships with grasses.

Fungal Assemblages Associated with Roots of Halophytic and Non-halophytic Plant Species Vary Differentially Along a Salinity Gradient

“…Most of them could be classified within the Pleosporales, as found in previous surveys in Mediterranean [43,44] or semiarid areas [9,[46][47][48][49]. DSF were also abundant within the root tissues, especially along the longitudinal root axis, and appeared tightly associated to the vascular system as previously observed by [9], who postulated that this demand an active participation in a mutualistic relationship with the host.…”

Diversity and composition of fungal endophytes in semiarid Northwest Venezuela

“…In B. gracilis the largest species richness and diversity of fungal endophytes were estimated in South Dakota, USA and Saskatchewan, Canada, in northerly temperate sites. According to Herrera et al (2010), this difference may be due to the influence of fundamentally different conditions between above-ground and below-ground environments.…”

“…However, the opposite pattern was observed in the diversity of the fungal endophyte communities associated with the roots of a single host plant, the grass Bouteloua gracilis (Kunth) Lag. ex Griffiths (Herrera et al, 2010). In B. gracilis the largest species richness and diversity of fungal endophytes were estimated in South Dakota, USA and Saskatchewan, Canada, in northerly temperate sites.…”

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

“…Then, the roots were surface sterilized for one min with a 5% Clorox and 1% Triton X solution before being rinsed twice in sterile distilled water (as described elsewhere, Herrera et al 2010). Clean and surface-sterilized roots from each plant were cut into two approximately equally-sized sections and placed into 2 separate 1.5 ml microcentrifuge tubes and frozen at À308C until the roots were assessed (within seven months of collection).…”