Effect of epichloid endophytes and soil fertilization on arbuscular mycorrhizal colonization of a wild grass

Abstract

Background and aims Plants often establish multiple simultaneous symbiotic associations with different micro-organisms; however, the way in which each symbiont affects the other symbionts and the effects of these multiple interactions on plant performance are not well understood. The aim of this study was to evaluate how two different asexual Epichloë species modulate the establishment of arbuscular mycorrhizal fungi (AMF) in a wild forage grass under different soil fertilization levels. Methods We performed a completely randomized 12month-long field experiment to evaluate the effect of two B. auleticus-endophyte ecotypes and two soil fertilization levels on the colonization of AMF, in seedlings and adult plants. Plant biomass and reproductive tillers production were also measured. ResultsThe symbiosis, measured as the total extent of AM fungal colonization and frequency of arbuscules was significantly higher in Epichloë-infected plants and was not affected by fertilization either in seedlings or in adult plants. Plant biomass was increased by fertilization but no differences were observed due to the endophytic status. However, E+ plants produced more panicles than their E− counterparts. Conclusions Our findings strongly support the hypothesis of positive association between Epichloë endophytes and AMF in wild grasses, making this model important for agronomic improvement.

Editorial special issue: soil, plants and endophytes

“…However, asymptomatic endophyte and choke diseased plants differed in nutrients, fibers, and digestibility, indicating that Epichloë may affect aboveground, and possibly underground, processes involved in nutrient absorption. Vignale et al (2016) also worked on Epichloë species and evaluate how two different asexual species can modulate the establishment of arbuscular mycorrhizal fungi in a wild forage grass under different soil fertilization levels. The authors showed that endophyteinoculated plants produced more panicles than noninoculated plants.…”

The Inhibitory Effect of Endophyte-Infected Tall Fescue on White Clover Can Be Alleviated by Glomus mosseae Instead of Rhizobia

“…Endophyte-infected grasses can also be infected with AMF simultaneously [64][65][66][67]. Studies show that endophyte infection can reduce the AMF colonization rates in tall fescue and perennial ryegrass [68][69][70]. Mack and Rudgers [65] further found that there was a negative correlation between the endophytic hyphae density in the leaf sheath of tall fescue and the colonization rate of AMF (Glomus intraradices).…”

Tall Fescue and E. coenophiala Genetics Influence Root-Associated Soil Fungi in a Temperate Grassland

“…In contrast, Rojas et al (2016) found that E+ tall fescue regardless of CTE or NTE status increased relative abundance of the AMF phylum Glomeromycota via ITS1 rRNA sequencing but not the AMF lipid biomarker 16:1ω5cis in rhizosphere soil samples. Evaluation of other asexual Epichloë symbionts in cool-season grasses have similarly revealed negative (Müller, 2003; Liu et al, 2018), positive (Novas et al, 2005, 2009, 2011; Kazenel et al, 2015; Vignale et al, 2016), or mixed (Omacini et al, 2006; Liu et al, 2011; Larimer et al, 2012; Kalosa-Kenyon et al, 2018) effects on belowground AMF symbionts or microbial communities, with positive effects most prevalent in native or non-agronomic grasses. The inconsistencies described above highlight the need to better characterize the interactions between unique grass-endophyte combinations and belowground root symbionts, especially considering how new selected combinations are continually being developed and planted in agricultural grasslands.…”