A First Draft of the Core Fungal Microbiome of Schedonorus arundinaceus with and without Its Fungal Mutualist Epichloë coenophiala

Abstract

Tall fescue (Schedonorus arundinaceus) is a cool-season grass which is commonly infected with the fungal endophyte Epichloë coenophiala. Although the relationship between tall fescue and E. coenophiala is well-studied, less is known about its broader fungal communities. We used next-generation sequencing of the ITS2 region to describe the complete foliar fungal microbiomes in a set of field-grown tall fescue plants over two years, and whether these fungal communities were affected by the presence of Epichloë. We used the Georgia 5 cultivar of tall fescue, grown in the field for six years prior to sampling. Plants were either uninfected with E. coenophiala, or they were infected with one of two E. coenophiala strains: The common toxic strain or the AR542 strain (sold commerically as MaxQ). We observed 3487 amplicon sequence variants (ASVs) across all plants and identified 43 ASVs which may make up a potential core microbiome. Fungal communities did not differ strongly between Epichloë treatments, but did show a great deal of variation between the two years. Plant fitness also changed over time but was not influenced by E. coenophiala infection.

The growth promotion in endophyte symbiotic plants does not penalise the resistance to herbivores and bacterial microbiota

“…(e.g., Bastías, Bustos, et al, 2022;Liu, Tang, et al, 2022). This is also in agreement with another experimental findings that showed that Epichloë altered root-associated bacterial communities and shoot-or root-associated fungal communities (Jin, Wang, et al, 2023;Nissinen et al, 2019;Rasmussen et al, 2023;Zhong et al, 2018) (but see e.g., Dale & Newman, 2022). Our results showed that the most substantial Epichloë-based changes in bacterial composition occurred at Days 14 and 28 post-GA treatment.…”

Epichloë Endophytes Shape the Foliar Endophytic Fungal Microbiome and Alter the Auxin and Salicylic Acid Phytohormone Levels in Two Meadow Fescue Cultivars

“…This is in agreement with our previous study, where Epichloë symbiosis in tall fescue ( Schedonorus phoenix ) impacted only the endophytic fungal community in leaves, not the bacterial community [ 38 ]. However, Epichloë symbiosis in tall fescue have also been reported not to impact foliar fungal community structures [ 39 ]. Significant differences in the structures of fungal communities were observed in the dataset, with and without depleting Epichloë taxa and, hence, confirming the role of Epichloë in shaping the endophytic mycosphere.…”

“…Epichloë in perennial ryegrass ( Lolium perenne ) did not significantly affect fungal community structure [ 37 ], but Epichloë in tall fescue ( Festuca arundinaceae = Schedonorus phoenix) altered the community of fungal endophytes, but not the bacterial endophytes, in leaves of the host plants [ 38 ]. In another study, the foliar fungal communities in S.phoenix were not different between Epichloë -symbiotic and Epichloë -free plants, but the fungal community structures between the two consecutive sampling years differed [ 39 ]. In Festuca rubra , the presence of Epichloë festuca along with the habitat of the host plant affected the infection frequencies of nonsystemic fungal endophytes [ 40 ].…”