Reaction to powdery mildew fungus, Blumeria graminis in endophyte-infected and endophyte-free tall and meadow fescues Mohammad R. Sabzalian & Aghafakhr Mirlohi & Bahram Sharifnabi Received: 19 August 2011 / Accepted: 30 April 2012 / Published online: 29 May 2012 # Australasian Plant Pathology Society Inc. 2012 Abstract Interactions between Neotyphodium endophytes and cool season grasses may improve host performance especially under stress conditions. In this research, Neoty- phodium-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. Addi- tionally, 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 differ- ence 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 ≥5) 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 suscepti- ble at both the seedling and adult plant stages. Therefore Lolium species may provide a source of resistance for breeding mead- ow fescue against powdery mildew at the adult plant stage through interspecific hybridization. Keywords Blumeria graminis . Endophyte . Neotyphodium . Resistance Introduction Cool-season grasses harboring Neotyphodium endophytes have been subjected to a broad range of studies during the last 30 years. Interactions between Neotyphodium endophytes and the host grass may result in enhanced biotic and abiotic stress tolerance. Endophyte containing (E+) hosts are more resistant to insects (Popay 2005), nematodes (Kimmons et al. 1990), drought (Malinowski and Belesky 2000), and salinity (Sabzalian and Mirlohi 2010) and are more persistent (Hopkins and Alison 2006) than endophyte-free (E-) plants. This has led to sustainable strategies in which endophytes are viewed as beneficial components of grassland ecosystems. However, reports on resistance of endophyte-infected grasses to diseases and pathogens are limited and often inconsistent. The negative impact of Neotyphodium endophytes on in vitro growth of plant fungal pathogens is suggested in some experiments (White and Cole 1985; Siegel and Latch 1991; M. R. Sabzalian (*) : A. Mirlohi Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran e-mail: sabzalian@cc.iut.ac.ir B. Sharifnabi Department of Plant Pathology, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran Australasian Plant Pathol. (2012) 41:565–572 DOI 10.1007/s13313-012-0147-1