Incidence of fungal endophyte in the palatable grass Hordeum comosum associated to environmental stress gradients in Patagonia

CASAS, C.; DEL TORO, C.; DELIENS, E.; CASABELLA, M.P.; GARCÍA MARTÍNEZ, G.C.; NAGAHAMA, N.; VIGNALE, M.V.; IANNONE, L.J.; SCHNYDER, H.; GUNDEL, P.E.

Buenos Aires

Simposio; 5th International Symposium of Forage Breeding; 2015

Facultad de Agronomía, Universidad de Buenos Aires

Naturalgrasslands sustain animal production in semiarid environments and certain grassspecies form symbiotic associations with Epichloë fungal endophytes. Basedon mesophitic grasses, endophyte confrere mechanisms of tolerance to aridity and resistanceto herbivory. The endophyte incidence in H. comosum is high in dry andhumid (mostly grazed) extremes of the stress-gradient. We studied the incidence of Epichloëin H. comosum populations, a sheep-preferred perennial grass, alongstress-gradient transects. H. comosum plants need to achieve a minimalfitness to ensure the endophyte maintenance. Below this threshold, othervariables may control the persistence of the symbiosis. Further analyses haveto be done tofind out who are they. Aridity (high altitude and low precipitation) may favour H. comosumrelative cover but not necessary the endophyte symbiosis. In turn, in humidconditions, endophytes are positively selected but do not prevent the hostcover from declining likely due to herbivory or intraspecific competition. Under conditions of extreme aridityand reduced fitness, Epichloë may generate critical costs reducing evenmore the fitness of the host grass. Our results suggest that it is not wisepredicting the importance /ecological meaning of this symbiosis in aridenvironments based on well studied mesophytic species.