Asexual Endophytes of Grasses: Invisible Symbionts, Visible Imprints in the Host Neighborhood

  • Marina Omacini


Asexual fungi from the genus Neotyphodium, relatives of the sexual epichloë species (Clavicipitaceae, Ascomycota), are symbionts of several cool-season grasses inhabiting virtually all terrestrial ecosystems. The host plants incur carbon costs to sustain this symbiosis, but, in return, they obtain multiple benefits from the fungal partners, above all, protection from herbivores. These endophytes are often considered to be defensive mutualists or private protectors because they produce a considerable range of secondary metabolites which prove to be toxic to livestock or deterrent to insects. Over the past decade, ecologists have begun to recognize the critical role played by this grass–endophyte symbiosis in the structure and functioning of natural and human-made communities. In this chapter, I will identify different pathways through which the presence of endophytic plants or their dead tissues (litter) can alter the fitness of nonsymbiotic plants. Those pathways lead to show how these symbionts impact on the establishment and productivity of nonsymbiotic neighbors and the interaction of the latter with multiple above- and belowground ecosystem components. A set of recent studies performed with plants of Lolium multiflorum associated with Neotyphodium occultans will provide experimental evidence to those effects. Finally, I will discuss 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. Estimating endophyte impacts on host fitness must consider advantages or disadvantages transferred to conspecific plants in the neighborhood, coexisting as a consequence of inefficiencies during the transmission from plants to seeds.


Arbuscular Mycorrhizal Fungus Endophytic Fungus Tall Fescue Mycorrhizal Colonization Italian Ryegrass 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



I am grateful to the lab group; most ideas presented here were developed through our helpful discussions on the issues dealt with this essay. I wish to thank Claudio M. Ghersa, Luis I. Perez, Pablo Garcia Parisi, and Beatriz Santos for thought-provoking conversations and helpful comments on earlier versions, and to Pablo Roset for many details that improved the manuscript. Preparation of this chapter was facilitated by grants from the University of Buenos Aires (UBA), the National Research Council (CONICET), and the National Scientific and Technological Promotion (FONCYT). Mirta Rabadán provided photos.


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© Springer India 2014

Authors and Affiliations

  1. 1.IFEVA, Facultad de AgronomíaUniversidad de Buenos AiresBuenos AiresArgentina

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