Reaction to powdery mildew fungus, Blumeria graminis in endophyte-infected and endophyte-free tall and meadow fescues

Interactions between Neotyphodium endophytes and cool season grasses may improve host performance especially under stress conditions. In this research, Neotyphodium-endophyte effects were evaluated for reaction of tall and meadow fescues to powdery mildew, Blumeria graminis, in greenhouse and field trials. Field grown and potted plants of endophyte-infected and endophyte-free clones of two tall fescue (A75 and A83) and one meadow fescue (P60) genotypes were rated for mildew infection type (1-9 scale) after inoculation with Blumeria graminis. Additionally, the reaction of 27 accessions of tall and meadow fescues and 65 accessions from 14 other plant species of the Poaceae family to powdery mildew was tested. No difference between endophyte-infected (E+) and endophyte-free (E-) counterparts regarding disease score in potted plants was found. However, in A75 tall fescue and P60 meadow fescue genotypes, E+ clones had fewer powdery mildew infected leaves and lower disease indicies when compared with E- clones. Accessions of tall fescue and meadow fescue were all susceptible (rated a parts per thousand yen5) at the seedling stage but at the adult plant stage, tall fescue accessions were resistant and meadow fescue accessions remained susceptible. In the field trial, E+ and E- meadow fescue adult plants were damaged with up to 90 % dead leaves due to mildew infection however; tall fescue adult plants were resistant (rated < 5) regardless of endophyte status. Among the 65 accessions from the Poaceae family, the accessions of Lolium species were susceptible at the seedling stage whereas the other species did not react to powdery mildew. We concluded that endophyte had no effect on infection type of powdery mildew in tall and meadow fescues. In addition, susceptibility was observed in tall fescue and Lolium species to powdery mildew only at the seedling stage while meadow fescue genotypes were susceptible at both the seedling and adult plant stages. Therefore Lolium species may provide a source of resistance for breeding meadow fescue against powdery mildew at the adult plant stage through interspecific hybridization.