Endophytic fungi in grasses from semiarid grasslands in Spain

Dehesas are savanna-like semiarid grasslands which constitute a traditional, low-input, livestock production system in the Iberian Peninsula. In dehesas, the arboreal stratum is dominated by Quercus species, whereas the pastures are composed by a large number of plant species. More than 1000 species of vascular plants have been catalogued in the dehesas of the province of Salamanca. The grass family is the most important, comprising about 12% of the identified plant species (Hernandez, 1992), and an average of 50% of the herbage dry weight (Corona et al., 1995). Since the middle ages, dehesa pastures have been subjected to grazing pressure from the livestock which was reared on them. The climate of dehesas is of semiarid-mediterranean type, with annual precipitation values averaging about 500 mm (Calabuig, 1992). Since there is evidence that infection by clavicipitaceous endophytes may improve the fitneess of the grass host in situations of water limitation and herbivore grazing, dehesas may constitute an environment where grasses infected by endophytes may be favourably selected. If this were the case, elevated infection rates could be found in host species, and this could be a factor of negative impact in animal production in dehesas. The objective of this study was to made a preliminary survey of the incidence of endophytic fungi in grass species of dehesa pastures.