Occurrence of Epichloë fungal endophytes in the sheep-preferred grass Hordeum comosum from Patagonia

Abstract

Grazing by exotic herbivores on native vegetation in Patagonian steppes has led to the deterioration of forage resources, where grasses are replaced by shrubs and preferred grasses by non-preferred ones. In this region, Hordeum comosum is one of the widely spread native-grasses highly preferred by sheep. Contrary to other preferred grasses, H. comosum establishes symbiosis with vertically-transmitted fungi of genus Epichloë. However, the level of incidence of the fungus and the phylogenetic diversity of the endophyte remained unclear. We found that endophyte incidence ranged from 0 to 100%, with higher incidence in populations from more arid sites. This would suggest an endophyte-conferred drought tolerance to host. Although the isolates presented several morphological differences, phylogenetic analyses of tubB and tefA genes separated them into only two lineages. One of these lineages was Epichloëtembladerae, the most common endophyte in temperate grasses of southern South America. Strikingly, the other lineage was a hybrid between Epichloëtyphina and Epichloëamarillans detected for the first time in this part of the world and opening new questions about the grass-endophyte co-evolution. These results represent a starting-point in the potential use of fungal endophytes in breeding programs and natural grassland restoration in marginal environments.