Mutualism effectiveness of fungal endophyte in grasses is reduced by ozone.

UENO, A.; GUNDEL, P.E. ; OMACINI, M.; GHERSA, C.M.; BUSH, L.P.; MARTÍNEZ-GHERSA, M.A.

FUNCTIONAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 30 p. 226 - 234

0269-8463

Ozone is an increasingtropospheric contaminant of climate change. Exposure to ozone may affect thesymbiotic relationship between plants and beneficial microorganisms. Inparticular, the herbivore resistance mechanism conferred by fungal endophytes(defensive mutualism) may be affected, as any of the ozone-triggered effects(such as elicitation of defence mechanisms against biotrophic fungi oroxidative stress in the apoplastic space) may target the symbiont. Symbioticand non-symbiotic Lolium multiflorum plants were exposed to ozone for two consecutivedays (2 h per day), after which half were infested with 10 aphids(Rhopalosiphum padi). We measured variables related to performance of plants,the endophyte symbiont (alkaloids) and the herbivores. Aphid populations weresmaller on symbiotic plants than in non-symbiotic plants in low ozone conditions.However, this difference disappeared in exposed plants to high-ozone conditions.Under low-ozone conditions, structure of aphid populations onendophyte-symbiotic plants was characterized by a low number of nymphs and ahigh number of adults. This pattern was not observed with high-ozone exposure.Level of fungal alkaloids (lolines) was not affected by either ozone orherbivory. Results indicate that ozone impairs the grass-endophyte symbiosiswithout affecting production of alkaloids generally linked with aphids?response to endophyte presence. Since neither plant biomass nor alkaloid levelwere affected by ozone, other ozone-mediated mechanisms at molecular orbiochemical level may underlie plant-herbivore interaction mediated by fungal endophytes.Thus, the mechanism behind this effect must be determined in futureexperiments.