Evolutionary Origins and Ecological Consequences of Endophyte Symbiosis with Grasses

  title={Evolutionary Origins and Ecological Consequences of Endophyte Symbiosis with Grasses},
  author={Keith Clay and Christopher L. Schardl},
  journal={The American Naturalist},
  pages={S99 - S127}
Over the past 20 yr much has been learned about a unique symbiotic interaction between fungal endophytes and grasses. The fungi (Clavicipitaceae, Ascomycota) grow intercellularly and systemically in aboveground plant parts. Vertically transmitted asexual endophytes forming asymptomatic infections of cool‐season grasses have been repeatedly derived from sexual species that abort host inflorescences. The phylogenetic distribution of seed‐transmitted endophytes is strongly suggestive of… 
Symbioses of grasses with seedborne fungal endophytes.
The endophytes gain shelter, nutrition, and dissemination via host propagules, and can contribute an array of host fitness enhancements including protection against insect and vertebrate herbivores and root nematodes, enhancements of drought tolerance and nutrient status, and improved growth particularly of the root.
Chemical Ecology Mediated by Fungal Endophytes in Grasses
It is proposed that endophyte-grass symbiosis provides an excellent model to study microbially mediated multirophic interactions from molecular mechanisms to ecology, and joint approaches of (bio)chemists, molecular biologists, plant physiologists, evolutionary biologists, and ecologists are urgently needed.
Asexual Endophytes of Grasses: Invisible Symbionts, Visible Imprints in the Host Neighborhood
This chapter identifies different pathways through which the presence of endophytic plants or their dead tissues (litter) can alter the fitness of nonsymbiotic plants and discusses the relevance of placing these pathways under the spotlight in order to understand the processes that determine the frequency of symbiotic plants within a population.
The interplay between the effectiveness of the grass-endophyte mutualism and the genetic variability of the host plant
It is proposed that compatibility is necessary but not sufficient to explain the outcomes of Neotyphodium‐grass symbiosis, and a model that links genetic compatibility, mutualism effectiveness, and endophyte transmission efficiency is advanced.
Endophytic fungi of grasses protect other plants from aphid herbivory
Microbial plant symbionts are widely spread in nature changing the way their hosts interact with their environment. Neotyphodium fungal endophytes (Clavicipitaceae) are grass symbionts known by their
Symbiosis Lost: Imperfect Vertical Transmission of Fungal Endophytes in Grasses
Endophytes were lost at all possible stages: within adult plants, from adult tillers to seeds, and from seeds to seedlings, and the type and degree of loss differed among host populations and species and between endophyte genera.
Bioactive alkaloids in vertically transmitted fungal endophytes
With future research, vertically transmitted fungi from diverse clades with narrow host ranges and that produce bioactive compounds are likely to be found as important mutualists in additional plants.
A fungus among us: broad patterns of endophyte distribution in the grasses.
Using endophytic fungi-grass symbioses, it is found that Neotyphodium hosts had 40-130% higher symbiont frequencies than Epichloë hosts, and hosts may reduce the transmission of more pathogenic symbionts to seeds.


Fungal Endophytes in Stems and Leaves: From Latent Pathogen to Mutualistic Symbiont
It is surmised that endophytes may be as common among plants as are mycorrhyzae, and inducible mutualists grow rapidly and produce toxins against herbivores when damaged host tissues provide new sites for infection.
FUNGAL ENDOPHYTES: A Continuum of Interactions with Host Plants
How life history traits—such as fungal reproduction and pattern of infections and genotypic variation and ecological factors—in the ecology and evolution of endophytes and host plants is discussed are discussed.
EPICHLOE SPECIES: fungal symbionts of grasses.
  • C. Schardl
  • Environmental Science, Biology
    Annual review of phytopathology
  • 1996
Epichloë species and their asexual descendants (Acremonium endophytes) are fungal symbionts of C3 grasses that span the symbiotic continuum from antagonism to mutualism depending on the relative
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 and are the only documented case of highly antagonistic strains interfertile with highly mutualistic strains.
Endophyte-host associations in forage grasses. XI: A proposal concerning origin and evolution
It is evident that coevolution has occurred between Epichloe spp.
Evolution and Stasis in Plant‐‐Pathogen Associations
The Red Queen hypothesis suggests that parasites provide a selective advantage to host sexual recombination sufficient to explain it persistence despite the twofold advantage of asexual reproduction.
Evolutionary diversification of fungal endophytes of tall fescue grass by hybridization with Epichloë species.
  • H. Tsai, J. S. Liu, C. Schardl
  • Biology, Medicine
    Proceedings of the National Academy of Sciences of the United States of America
  • 1994
Phylogenetic analysis of tub2 sequences indicated that the presence of multiple copies in the tall fescue endophytes was a consequence of hybridization with Epichloë species, suggesting that interspecific hybridization is the major cause of genetic diversification of the tallfescueendophytes.
Hereditary symbiosis in the grass genus Danthonia
Hereditary symbiosis between the systemic, clavicipitaceous fungus Atkinsonella hypoxylon (Pk.) Diehl and five taxa of eastern North American Danthonia (Poaceae) was investigated by cultural and histological techniques and revealed that the fungus occurred epiphytically on meristems, in leaf axils, and on leaf primordia.
Origin of a fungal symbiont of perennial ryegrass by interspecific hybridization of a mutualist with the ryegrass choke pathogen, Epichloë typhina.
Results indicate that LpTG-2 is a heteroploid derived from an interspecific hybrid, and a proposed model for the evolution of Lp TG-2 involves infection of a L. perenne-A.