Effects of the infection by the fungal endophyte Epichloe festucae in the growth and nutrient content of Festuca rubra

Festuca rubra, a commercially important turfgrass, is a common species in natural semiarid grasslands of western Spain. In natural populations of this grass, about 70% of the individuals are infected by the fungal endophyte Epichloe festucae. In most cases, infected plants are asymptomatic. To test if there were differences in growth or nutrient content between infected (E+) and uninfected (E-) plants, five half-sib lines of F. rubra were used. Each line consisted of E+ and E- individuals. These plants were used for a 5 years long field experiment in conditions typical of the surrounding semiarid grasslands. The soil was poor in nutrients, and rainfall was scarce in the spring and summer. No differences in biomass production or number of stems were observed between E+ and E- plants. Regarding nutrient content, E+ plants in vegetative state contained more phosphorus than E- plants. This effect was consistently observed in the 3 years that this type of tissue was analyzed. In one of these 3 years Mn content was lower in E+ plants than in their E- counterparts. In plants in a reproductive stage, differences between E+ and E- plants were found with respect to Ca, Mg, and Cu content. In this developmental stage, the contents of neutral detergent fiber and lignin were lower in infected plants, and their organic matter digestibility was greater. The evidence presented in this study shows that in field conditions, the content of certain nutrients, P in particular, and fiber constituents of F. rubra are altered when the plants are infected by the endophyte E. festucae. Since most nutrients were found in concentrations below the adequate range for plant growth, increased P content is a beneficial effect of E. festucae infection. This fact helps to explain why endophyte infection incidence is high in natural populations of F. rubra, and why the development of endophyte infected turfgrass cultivars may be useful for low maintenance lawns.