Epichloë endophytes alter inducible indirect defences in host grasses

• Autores: Li, Tao; Blande, James D.; Gundel, Pedro Emilio; Helander, Marjo; Saikkonen, Kari
• Año de publicación: 2014
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Plos One; Vol.9, no.6; e101331; http://www.plosone.org/
• Materia: 1 OCTEN 3 OL; 3 HEXEN 1 OL; 3 HEXEN 1 OL ACETATE; 6 METHYL 5 HEPTEN 2 ONE; ALPHA TERPINOLENE; BETA PHELLANDRENE; CARYOPHYLLENE; COMPARATIVE STUDY; CONTROLLED STUDY; ENDOPHYTE; ENDOSYMBIOSIS; EPICHLOE; EPICHLOE COENOPHIALA; EPICHLOE UNCINATA; FESTUCA PRATENSIS; GRASS; GROWTH INHIBITION; HERBIVORY; HOST PATHOGEN INTERACTION; LEAF DAMAGE; LIMONENE; LINALOOL; MYRCENE; NONHUMAN; OCIMENE; PEST POPULATION; PINENE; PLANT DEFENSE; PLANT FUNGUS INTERACTION; PLANT GROWTH; PLANT HERBIVORE INTERACTION; POACEAE; RHOPALOSIPHUM PADI; SALICYLIC ACID METHYL ESTER; TALL FESCUE; TERPENE; TERPENOID DERIVATIVE; UNCLASSIFIED DRUG; VOLATILE ORGANIC COMPOUND
• Institución: Universidad de Buenos Aires. Facultad de Agronomía

Fil: Li, Tao. University of Eastern Finland. Department of Environmental Science. Kuopio, Finland.
Fil: Blande, James D. University of Eastern Finland. Department of Environmental Science. Kuopio, Finland.
Fil: Gundel, Pedro Emilio. Plant Production Research, MTT Agrifood Research Finland. Jokioinen, Finland.
Fil: Gundel, Pedro Emilio. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Ecología. Buenos Aires, Argentina.
Fil: Gundel, Pedro Emilio. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.
Fil: Gundel, Pedro Emilio. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.
Fil: Helander, Marjo. University of Turku. Department of Biology. Turku, Finland.
Fil: Saikkonen, Kari. Plant Production Research, MTT Agrifood Research Finland. Jokioinen, Finland.
Epichloë endophytes are common symbionts living asymptomatically in pooid grasses and may provide chemical defences against herbivorous insects. While the mechanisms underlying these fungal defences have been well studied, it remains unknown whether endophyte presence affects the host's own defences. We addressed this issue by examining variation in the impact of Epichloë on constitutive and herbivore-induced emissions of volatile organic compounds (VOC), a well-known indirect plant defence, between two grass species, Schedonorus phoenix (ex. Festuca arundinacea; tall fescue) and Festuca pratensis (meadow fescue). We found that feeding by a generalist aphid species, Rhopalosiphum padi, induced VOC emissions by uninfected plants of both grass species but to varying extents, while mechanical wounding failed to do so in both species after one day of damage. Interestingly, regardless of damage treatment, Epichloë uncinata-infected F. pratensis emitted significantly lower quantities of VOCs than their uninfected counterparts. In contrast, Epichloë coenophiala-infected S. phoenix did not differ from their uninfected counterparts in constitutive VOC emissions but tended to increase VOC emissions under intense aphid feeding. A multivariate analysis showed that endophyte status imposed stronger differences in VOC profiles of F. pratensis than damage treatment, while the reverse was true for S. phoenix . Additionally, both endophytes inhibited R. padi population growth as measured by aphid dry biomass, with the inhibition appearing greater in E. uncinata-infected F. pratensis. Our results suggest, not only that Epichloë endophytes may play important roles in mediating host VOC responses to herbivory, but also that the magnitude and direction of such responses may vary with the identity of the Epichloë-grass symbiosis. Whether Epichloë-mediated host VOC responses will eventually translate into effects on higher trophic levels merits future investigation.