Do the costs and benefits of fungal endophyte symbiosis vary with light availability?
• Here, we examined whether fungal endophytes modulated host plant responses to light availability. First, we conducted a literature review to evaluate whether natural frequencies of endophyte symbiosis in grasses from shaded habitats were higher than frequencies in grasses occupying more diverse light environments. Then, in a glasshouse experiment, we assessed how four levels of light and the presence of endophyte symbioses affected the growth of six grass species. • In our literature survey, endophytes were more commonly present in grasses restricted to shaded habitats than in grasses from diverse light environments. • In the glasshouse, endophyte symbioses did not mediate plant growth in response to light availability. However, in the host grass, Agrostis perennans, symbiotic plants produced 53% more inflorescences than nonsymbiotic plants at the highest level of shade. In addition, under high shade, symbiotic Poa autumnalis invested more in specific leaf area than symbiont-free plants. Finally, shade increased the density of the endophyte in leaf tissues across all six grass species. • Our results highlight the potential for symbiosis to alter the plasticity of host physiological traits, demonstrate a novel benefit of endophyte symbiosis under shade stress for one host species, and show a positive association between shade-restricted grass species and fungal endophytes.
Davitt
Andrew J
AJ
Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA. ajd3@rice.edu
Stansberry
Marcus
M
Rudgers
Jennifer A
JA
D003624:Darkness; D005658:Fungi; D056626:Inflorescence / Q000254:growth & development*; D018515:Plant Leaves / Q000254:growth & development*; D006109:Poaceae / Q000254:growth & development*; D013472:Sunlight; D013559:Symbiosis / Q000502:physiology*