An Epichloë endophyte affects the competitive ability of Festuca rubra against other grassland species

Abstract

Festuca rubra plants are asymptomatically infected by the systemic fungal endophyte Epichloe festucae and high infection rates have been found in natural grasslands. Our objective was to determine the effect of endophyte infection on the competitive ability of Festuca rubra in binary mixtures against other grassland species. In two glasshouse experiments, endophyte-infected (E+) and non-infected (E−) plants of two half-sib lines (PEN, RAB) of Festuca rubra were grown in monocultures and in binary mixtures against five grassland species: Trifolium repens, Trifolium pratense, Trifolium subterraneum, Lotus corniculatus and Plantago lanceolata. Biomass production of F.rubra was affected by endophyte infection and plant line but not by competition with T.pratense. In the PEN line E+ plants produced less root biomass than E−; and in the RAB line E+ plants produced less shoot biomass than E−. In spite of these differences shoot and root biomass production of Trifolium pratense were more inhibited when growing with endophyte-infected plants of Festuca rubra than with E− plants, regardless of the plant line. In both F.rubra lines, the endophyte increased the phosphorus concentration in shoots. Regardless of F.rubra plant line, root biomass of the five target species was more inhibited when growing with endophyte-infected than with endophyte-free plants. Irrespective of F.rubra line, endophyte-infected plants had a better competitive ability than non-infected plants, as indicated by the lower relative yield of companion plants when growing in mixture with E+ plants. We suggest an allelopathic effect of E+ red fescue on other grassland species.