Epichloe and Neotyphodium species show specificity for their host grasses, and usually a grass species is infected by one particular endophyte species. However, Lolium perenne is an exception, in this grass several endophyte species have been described: Epichloe typhina, Neotyphodium loUt, and LpTG-2, a heteroploid originating from a hybridization ofthe two other species (Schardl et al., 1994). In addition, wide morphological variation among asymptomatic Lolium endophytes has been observed (Christensen et al., 1991; Bony et al., 2001). In semiarid grasslands ofwestern Spain, several grass species have been found to be infected by Epichloe and Neotyphodium endophytes. Preliminary observations in plants of 1. perenne from these ecosystems revealed the presence ofseveral types offungal endophytes (Zabalgogeazcoa et al., 2003). The objectives of this paper were to estimate the incidence of endophyte infection rates in populations of 1. perenne from natural permanent grasslands, and to identify the fungí isolated from these plants.

Resumen del trabajo presentado en el 5th International Symposium on Neotyphodium/Grass Interactions, celebrado en Fayetteville, AR (Estados Unidos), del 23 al 26 de mayo de 2004