Resource use efficiency in grass-endophyte interaction under environmental stress gradient: Epichloë fungal endophyte in Hordeum comosum.

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

Praga

Congreso; Plant Biology Europe. EPSO /FESPB 2016 Congress.; 2016

EPSO

In many temperate grasses Epichloë asexual fungal endophytes are obligate symbionts that are generally related to plant fitness improvements through conferring tolerance to herbivory and drought. As obligate symbionts, this fungus depends entirely on the host plant for C supply. Here, we present Hordeum comosum, a perennial grass, in association with E. tembladerae as a model to study the underlying eco-physiological mechanisms by which the symbiont interacts and affects the C economy and nutritional state of the host. We collected eight H. comosum plants in each of 30 sites (total 240 plants) along four transects from extreme arid to humid conditions (from 150 to 1200 mm annual precipitation) in a region of 5500 km² in central Patagonia. We recorded climatic variables (temperatures, precipitation, PET), productivity (EVI), altitude, soil texture and vegetation community structure at each site, and measured plant size, endophyte incidence, rhizosphere pH, concentration and natural isotope composition of C and N (δ13C and δ15N) in plant and rhizosphere. Preliminary results showed that endophytic plants had a greater nitrogen concentration than non-endophytic plants. δ15N followed a quadratic relationship with aridity index (AI = precipitation/PET) that interacted with endophyte presence and peaked at about 0.4 and 0.25 AI for endophytic and non-endophytic plants, respectively. Likewise, δ13C depended on the interaction between AI and endophyte presence. These results reveal significant effects of the endophyte on the nitrogen and water economy of its host that might enhance its fitness under different environments.