Occurrence of Neotyphodium endophytes in permanent grassland with perennial ryegrass (Lolium perenne) in Denmark

Abstract

Abstract Perennial ryegrass (Lolium perenne), an important pasture grass also occurring on semi-natural grasslands, can form a mutualistic association with the endophytic fungus Neotyphodium lolii. The presence of this fungus is known to confer resistance against different insect pests although the occurrence is also associated with ryegrass stagger, a neurological disorder occasionally seen in livestock grazing on endophyte-infected pastures. In breeding context the benefit of this symbiotic association is of interest. Sixty-two Danish locations representing twelve different habitat types were visited and investigated for the occurrence of the perennial ryegrass endophyte. Most habitats were different types of semi-natural grassland. Perennial ryegrass was investigated using tissue print immunoblot to determine N. lolii infection status. Endophytes were found at 77% of the locations, infection ranging from 4 to 82%. The highest infection rates were found in communities, which had been grazed or intensively used by the public. This can probably be explained by an enhanced survival of endophyte-infected plants in a plant community where grazing and intensive use are environmental stress factors. The conclusion from these results is that management practice of semi-natural grasslands is considered a driving force toward higher endophyte infection rates in Denmark. The survey additionally provides the first indication that Neotyphodium ryegrass endophytes are widely spread in semi-natural grass communities in Denmark and high levels of infection are not only restricted to Mediterranean regions with summer drought.