Epichloe Endophytes Research Articles

An asexual Epichloë endophyte modifies the nutrient stoichiometry of wild barley (Hordeum brevisubulatum) under salt stress

Background and aims Salinization of soils causes severe problems to plant growth. With the important role of stoichiometry in many ecological processes, this study investigated the effect of an asexual Epichloe endophyte on the nutrient stoichiometry of wild barley (Hordeum brevisubulatum) under salt stress.

An Epichloë endophyte affects the competitive ability of Festuca rubra against other grassland species

Festuca rubra plants are asymptomatically infected by the systemic fungal endophyte Epichloe festucae and high infection rates have been found in natural grasslands. Our objective was to determine the effect of endophyte infection on the competitive ability of Festuca rubra in binary mixtures against other grassland species. In two glasshouse experiments, endophyte-infected (E+) and non-infected (E−) plants of two half-sib lines (PEN, RAB) of Festuca rubra were grown in monocultures and in binary mixtures against five grassland species: Trifolium repens, Trifolium pratense, Trifolium subterraneum, Lotus corniculatus and Plantago lanceolata. Biomass production of F.rubra was affected by endophyte infection and plant line but not by competition with T.pratense. In the PEN line E+ plants produced less root biomass than E−; and in the RAB line E+ plants produced less shoot biomass than E−. In spite of these differences shoot and root biomass production of Trifolium pratense were more inhibited when growing with endophyte-infected plants of Festuca rubra than with E− plants, regardless of the plant line. In both F.rubra lines, the endophyte increased the phosphorus concentration in shoots. Regardless of F.rubra plant line, root biomass of the five target species was more inhibited when growing with endophyte-infected than with endophyte-free plants. Irrespective of F.rubra line, endophyte-infected plants had a better competitive ability than non-infected plants, as indicated by the lower relative yield of companion plants when growing in mixture with E+ plants. We suggest an allelopathic effect of E+ red fescue on other grassland species.

Benefits of a fungal endophyte in Elymus virginicus decline under drought stress

Abstract In most natural systems, it remains unclear whether microbial symbionts can help plants adapt to rapidly changing environments. Here, we tested the hypothesis that fungal endophyte symbiosis in a widespread, native grass species, Elymus virginicus, would promote host tolerance of drought. In a growth chamber experiment, we manipulated water availability to plants naturally infected with the endophyte Epichloe elymi and to plants that were experimentally disinfected. The drought treatment imposed a ∼67% reduction in water, corresponding to the very high end of drought predictions for the Midwestern US, where E. virginicus is common. In contrast to expectations, E. virginicus benefited more from the endophyte under daily watering than under drought. Disinfected plants had 45% less aboveground biomass than naturally infected plants under daily watering and only 23% less under drought. Both the number of tillers produced and root biomass were reduced by disinfection, with a greater difference between endophyte treatments under daily watering than under drought. There were no effects of either the endophyte or drought on aphid colonization of the plants. To put these results into a broader geographic context, we surveyed endophyte infection frequencies across 43 populations, including wild populations, commercial stock and germplasm resources. Endophyte frequencies varied from 0% to 100%, and frequencies were much higher for wild populations than germplasm resources. Natural variation in endophyte frequencies combined with the heritable transmission of endophytes from plants to seeds provides opportunities for climate change to affect selection on the maintenance of endophyte symbiosis in E. virginicus.

Biosynthesis of insecticidal loline alkaloids by epichloe endophytes of grasses

Epichloë endophytes are protective mutualists of cool-season grasses.

Genetics tests of ecological roles of ergot alkaloids produced by an epichloe endophyte of ryegrass

Ergot alkaloids are produced by ergot fungi (Claviceps spp.) that parasitise ears of grain, and related epichloë endophytes (Epichloë and Neotyphodium spp.) that systemically persist in grasses as protective mutualists.

The Evolutionary Origins of Epichloe Endophytes from Annual Ryegrasses

The annual Lolium (ryegrass) species were surveyed for seedborne, asexual Epichloe endophytes (i.e., Neotyphodium spp.). Endophytes that were extremely slow growing in culture were identified from ...

Mating compatibility and phylogenetic relationships among two new species of Epichloë and other congeneric European species

Epichloe species are endophytic symbionts of grasses which may differ in the relative importance of their sexual or asexual life cycles. Sexual reproduction of the fungus by stroma-formation prevents host flowering (choke) and thus is highly antagonistic, whereas asexual reproduction through clonal propagation in host seeds does not affect host fitness. Stroma-forming Epichloe endophytes from Bromus erectus and non-stromal strains from B. benekenii and B. ramosus were recognized as a distinct mating population (MP) based on complete sexual compatibility among strains and intersterility between other MPs established by mating tests. This biological species represents the only documented case of highly antagonistic strains interfertile with highly mutualistic strains. A second distinct MP of Epichloe was evident on Brachypodium sylvaticum including both stroma-forming and non-stromal isolates. These two MPs were further characterized by distinct morphologies of fruiting structures, allozyme divergence, β-tubulin gene phylogeny, and host preferences, and were described as new species: E. bromicola associated with Bromus spp. and E. sylvatica with Bp. sylvaticum. Additional mating tests among Epichloe from several, previously unexamined, hosts including Brachypodium pinnatum, Calamagrostis villosa, Festuca spp., Phleum pratense , and Poa spp., expanded the known host ranges of three other European species, E. typhina, E. festucae and E. baconii. Genetic variability of all five European species and gene diversity of host subpopulations were analysed based on allozyme data from a total of 497 Epichloe isolates. Average gene diversity ( H 8 ) within MPs ranged from 0.09 to 0.36 with E. typhina being the most diverse, and G ST values, a measure for between subpopulation differentiation, ranged from 0.73 to 0.90 indicating that genetic isolation of endophytes on many host grasses is likely.

Double-stranded RNA and virus-like particles in the grass endophyte Epichloë festucae

Two double-stranded ribonucleic acid (dsRNA) elements were detected in an isolate of the clavicipitaceous grass endophyte Epichloe festucae obtained from an asymptomatic Festuca rubra plant. No dsRNA was detected in three other isolates of E. festucae. The size of the two dsRNA elements isolated from mycelium was of 5.2 and 3.2 kbp. Hybridization experiments with a cDNA probe complementary to the 5.2 kbp dsRNA showed that there was no sequence similarity between the dsRNA elements. Isometric virus-like particles of about 50 nm in diameter were observed by electron microscopy in sucrose-gradient purified virus preparations from the isolate containing dsRNA. The 5.2 kbp dsRNA element was present in the partially purified virus preparations, suggesting that this element is encapsidated. There was no difference with respect to growth rate or colony morphology between the dsRNA containing and dsRNA-free isolates. The presence of dsRNA and virus-like particles suggests the presence of a mycovirus in the Vit5 strain of E. festucae.