Abstract
Background and aims
It is proposed that Epichloë endophytes have a role protecting host grasses against pathogens. However, it is unclear whether this protection is extended to other non-symbiotic plants. Here we explored the effect of the asexual fungal symbiont, Epichloë occultans, on the interaction between Lolium multiflorum host plants and soil pathogens, and its potential positive side-effect on neighbouring plants.
Methods
We conducted two microcosm experiments to assess the endophyte effect on seedling establishment of the host grass and other non-symbiotic grasses in the presence of soil pathogens. With an in-vitro experiment, we tested whether the endophyte inhibits, during seed germination, the growth of these pathogens.
Results
Independently of pathogen identity, the endophyte improved host establishment (6 %). The endophyte also enhanced the establishment of the neighbouring grass Bromus catharticus (≈20 %) only in soil with Rhizoctonia solani. The endophyte in seed reduced the growth (≈20 %) of two out of four pathogens (Fusarium acuminatum and R. solani).
Conclusions
We conclude that asexual endophytes could protect host grasses against pathogens but most importantly, that they can have protective effects beyond their hosts. Since effects depended on pathogen and plant identity, more experiments are needed in order understand the ecological meaning of these positive side-effects.
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Acknowledgments
Useful comments of two anonymous reviewers helped to improve previous versions of this manuscript. Gonzalo Irisarri, Florencia Spirito and María Semmartin provided useful comments on earlier versions of the manuscript. This work was funded by the University of Buenos Aires (UBA), the National Research Council (CONICET) and the National Scientific and Technological Promotion (FONCYT). L.I.P. holds a Research Scholarship from the National Research Council of Argentina.
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Fig. S1
Seedling establishment of Lolium multiflorum, Brisa subaristata and Stipa neesiana in soil seeded along with symbiotic (black bars) and non-symbiotic (white bars) L. multiflorum seeds and inoculated with sterile culture medium (control) or with pathogens [Fusarium graminearum (Fg) or Rhizoctonia solani (Rs)] (grey box). Values are means and SE (n = 10). (GIF 54 kb)
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Pérez, L.I., Gundel, P.E. & Omacini, M. Can the defensive mutualism between grasses and fungal endophytes protect non-symbiotic neighbours from soil pathogens?. Plant Soil 405, 289–298 (2016). https://doi.org/10.1007/s11104-015-2568-4
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DOI: https://doi.org/10.1007/s11104-015-2568-4