Hybrid fungal endophytes symbiotic with the grass Lolium pratense

Classification of endophytes inhabiting Lolium pratense (= Festuca pratensis) based on morphological and molecular phylogenetic characteristics is reported. From an extensive survey of L. pratense collected throughout Europe, we concluded that the overwhelmingly predominant endophyte was Neotyphodium x uncinatum. We constructed phylogenies based on three unlinked, nuclear genes and analyzed allozymes to evaluate the relationship of N. x uncinatum to Epichloë endophytes. Our results suggest that N. x uncinatum is an interspecific hybrid of two Epichloë species. A second, much rarer hybrid endophyte was isolated from L. pratense which may have shared one of its two Epichloë ancestors with N. x uncinatum. This second isolate is a previously undescribed species for which we propose the name Neotyphodium x siegelii.