A Survey of Culturable Fungal Endophytes From Festuca rubra subsp. pruinosa, a Grass From Marine Cliffs, Reveals a Core Microbiome

Abstract

Festuca rubra subsp. pruinosa is a perennial grass that inhabits sea cliffs of the Atlantic coasts of Europe. In this unhospitable environment plants grow in rock crevices and are exposed to abiotic stress factors such as low nutrient availability, wind, and salinity. Festuca rubra subsp. pruinosa is a host of the fungal endophyte Epichloë festucae, which colonizes aerial organs, but its root mycobiota is unknown. The culturable endophytic mycobiota of FRP roots was surveyed in a set of 105 plants sampled at five populations in marine cliffs from the northern coast of Spain. In total, 135 different fungal taxa were identified, 17 of them occurred in more than 10% of plants and in two or more populations. Seven taxa belonging to Fusarium, Diaporthe, Helotiales, Drechslera, Slopeiomyces, and Penicillium appeared to be constituents of the core microbiome of Festuca rubra subsp. pruinosa roots because they occurred in more than 20% of the plants analyzed, and at three or more populations. Most fungal strains analyzed (71.8%) were halotolerant. The presence of Epichloë festucae in aboveground tissue was detected in 65.7% of the plants, but its presence did not seem to significantly affect the structure of the core or other root microbiota, when compared to that of plants free of this endophyte. When plants of the grass Lolium perenne were inoculated with fungal strains obtained from Festuca rubra subsp. pruinosa roots, a Diaporthe strain significantly promoted leaf biomass production under normal and saline (200 mM NaCl) watering regimes. These results suggest that the core mycobiome of Festuca rubra subsp. pruinosa could have a role in host plant adaptation, and might be useful for the improvement of agricultural grasses.

Keywords: Diaporthe; Epichloë; Fusarium oxysporum; grass; halophyte; mycobiome; salinity.

FIGURE 1

Distribution of fungal taxa from roots of Festuca rubra subsp. pruinosa plants from marine cliffs in northern Spain according to orders.

FIGURE 2

Rank-abundance plot showing the incidence in plants of each taxon identified in roots of Festuca rubra subsp. pruinosa plants from marine cliffs in northern Spain.

FIGURE 3

Species accumulation curves for fungal species isolated from roots of Festuca rubra subsp. pruinosa at five populations from marine cliffs in northern Spain. TDH, Torre de Hércules; CED, Cedeira; EDB, Estaca de Bares; SPR, San Pedro de la Rivera; CDP, Cabo de Peñas.

FIGURE 4

Species accumulation curves of root mycobiota in Epichloë festucae infected (E+) and non-infected (E–) plants of Festuca rubra subsp. pruinosa from five marine cliff populations in northern Spain. (A) Whole plant set; (B) Cedeira; (C) Cabo de Peñas; (D) Estaca de Bares; (E) San Pedro de la Rivera; (F) Torre de Hércules.

FIGURE 5

Canonical correspondence analysis (CCA) of the fungal endophyte community composition of roots of Festuca rubra subsp. pruinosa from marine cliffs according to the presence (E+) or absence (E–) of Epichloë festucae, and population (CED, Cedeira; CDP, Cabo de Peñas; EDB, Estaca de Bares; SPR, San Pedro de la Rivera; TDH, Torre de Hércules).

FIGURE 6

Incidence in plants of Festuca rubra subsp. pruinosa from marine cliffs infected (E+) and not infected (E–) by Epichloë festucae of root species that constitute the core and abundant classes of the culturable mycobiome.

FIGURE 7

Effect of inoculation with strains Periconia S6, Penicillium E7 and Diaporthe S69, isolated from Festuca rubra subsp. pruinosa, on dry matter production, and Na and K content of Lolium perenne plants watered with 0 mM and 200 mM NaCl. For each NaCl concentration, different letters indicate significantly different means (p < 0.05).