IANNONE Leopoldo Javier
congresos y reuniones científicas
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.B.; GARCÍA MARTÍNEZ G.; NAGAHAM, N.; VIGNALE, M.V.; IANNONE L.J; GUNDEL P.E.
Congreso; 5TH International Symposium of Forage Breeding; 2015
Natural grasslands sustain animal production in semiarid environments. In central-west Patagonia wild grass species are the main forage resource for wool producing sheep. Grazing management has impoverished the vegetation communities eliminating palatable species. Understanding the underlying controls of species distribution and abundance is needed for community restoration and quality forage production. Certain grass species form symbiotic associations with fungal endophytes, related to host fitness improvements such as herbivory resistance and drought tolerance. We studied the incidence of Epichloë fungal endophytes in Hordeum comosum populations, a perennial grass that is highly preferred by sheep. We defined 32 sites along four west-east transects from humid to arid extreme conditions (1200 - 150 mm.year-1, 5500 km²) in central Patagonia. In each site, we estimated the cover of H. comosum and collected ten to fifteeneight plants to determine the endophyte incidenceinfection status. We found similar curve shapes for H. comosum cover and endophyte incidencefection in relation to mean annual precipitation, water balance (precip-evapotransp), and the Aridity Index of Martonne [(precip/(temp+10)]. Interestingly, while H. comosum cover was better described by a quadratic curve with a peak at around 500 mm. year-1, endophyte incidence tended to be low in the arid extreme and to reach a plateau from 600 mm.year-1 and above. This suggests that aridity limits both host species and endophyte persistence. While, at the humid extreme, herbivory may be limiting H. comosum cover but not the presence of the endophyte. The endophyte may be playing a more important role in drought tolerance than in herbivory deterrence in semi-arid environments.