Effects of natural hybrid and non‐hybridEpichloëendophytes on the response ofHordelymus europaeusto drought stress

Abstract

SummaryInterspecific hybrid endophytes of the genus Epichlo€ e (Ascomycota, Clavicipitaceae) are prevalent in wild grass populations, possibly because of their larger gene variation, resulting in increased fitness benefits for host plants; however, the reasons are not yet known. We tested hypotheses regarding niche expansion mediated by hybrid endophytes, population-dependent interactions and local co-adaptation in the woodland grass Hordelymus europaeus, which naturally hosts both hybrid and non-hybrid endophyte taxa.Seedlings derived from seeds of four grass populations made endophyte free were re-inoculated with hybrid or non-hybrid endophyte strains, or left endophyte free. Plants were grown in the glasshouse with or without drought treatment.Endophyte infection increased plant biomass and tiller production by 10-15% in both treatments. Endophyte types had similar effects on growth, but opposite effects on reproduction: non-hybrid endophytes increased seed production, whereas hybrid endophytes reduced or prevented it completely.The results are consistent with the observation that non-hybrid endophytes in H. europaeus prevail at dry sites, but cannot explain the prevalence of hybrid endophytes. Thus, our results do not support the hypothesis of niche expansion of hybrid-infected plants. Moreover, plants inoculated with native relative to foreign endophytes yielded higher infections, but both showed similar growth and survival, suggesting weak co-adaptation.

Interspecific hybridization and bioactive alkaloid variation increases diversity in endophyticEpichloëspecies ofBromus laevipes

“…Bromus laevipes has a narrow distribution limited to the United States west coast, yet the number of distinct Epichlo€ e species hosted by this grass, and the extensive chemotypic variation within, suggests that considerably more diversity exists within Epichlo€ e species in other hosts. Other studies have identified single host populations that harbor multiple endophyte species, but have not yet determined the chemotypic diversity among and between these species (Moon et al, 2004;Iannone et al, 2012;Leuchtmann & Oberhofer, 2013;Card et al, 2014;Oberhofer et al, 2014). Recent collections of the European woodland grass Hordelymus europaeus, spanning the latitudinal distribution transect of this host were found to associate with six distinct Epichlo€ e taxa (Oberhofer & Leuchtmann, 2012).…”

Epichloë endophyte affects the ability of powdery mildew (Blumeria graminis) to colonise drunken horse grass (Achnatherum inebrians)

“…The asexual species of this genus had previously been classified as Neotyphodium spp. (Leuchtmann et al 2014). Previous studies that have focused mainly on species that are endophytes of Lolium and Festuca spp., have reported that endophyte infection may increase host resistance to biotic (Meister et al 2006;H€ arri et al 2009;Saari et al 2010;Vignale et al 2013;Matsukura et al 2014;Thom et al 2014) and abiotic stresses (Malinowski et al 2005;M€ uller and Krauss 2005;Schardl et al 2007;Oberhofer et al 2014).…”

Effects of Hybrid and Non-hybrid Epichloë Endophytes and Their Associated Host Genotypes on the Response of a Native Grass to Varying Environments

“…There are three sources of variation that may change interaction outcomes: (1) endophyte strain or species, (2) host plant genotype, and (3) the local abiotic (e.g., soil nutrients and moisture) and biotic (e.g., the presence of herbivores and natural enemies of herbivores) environments. Recent molecular studies show remarkable genetic variation in Epichloë endophytes (e.g., [4]) across host grass species but also within a given grass species (e.g., [9]). Host phenotypic differences stemming from different endophyte strains may even be greater than that from infection itself (e.g., [10]).…”