Molecular phylogenetic relationships of nonpathogenic grass mycosymbionts and clavicipitaceous plant pathogens

Evolutionary diversification of fungal endophytes of tall fescue grass by hybridization with Epichloë species.

“…Likewise, separation of clades containing tub2-2 and tub24 from those containing (27), the relentless accumulation of marginally deleterious mutations, causing loss of fitness without the corrective influences of sexual recombination. Endophyte instability due to Muller's ratchet (2) would also be deleterious for the grass host, to which the endophytes provide important biological protection (1). The ability of endophytes to obtain new genetic information from close sexual relativesnamely, the Epichloe species-may counteract the ratchet.…”

“…These endophytes spend their entire life cycles within host tissues, are maternally transmitted in seed, are completely nonpathogenic, and are asexual. They are evolutionarily derived from the sexual (teleomorphic) fungi of genus Epichloe (Ascomycotina, Clavicipitaceae), which cause grass choke disease (2). During the pathogenic stage of Epichloe (3,4) the affected inflorescence of the host is sterilized and the fungus, if crossed with an opposite mating type of the same biological species (i.e., mating population), produces and disseminates ascospores ( Fig.…”

“…Each of four termination reaction mixtures (6 p1) contained 50 mM tris(hydroxymethyl)aminomethane hydrochloride (pH 9.0); 2 …”

Molecular Evidence for Host-Adapted Races of the Fungal Endophyte Epchloë Bromicola After Presumed Host Shifts

“…Symbioses of grasses with asexual endophytes may be highly mutualistic in the short term, because both host and fungus contribute to the persistence of the association. However, benefits for the fungus is diminished in the long-term because of the absence of sexuality, which may result in the accumulation of deleterious mutations known as Muller's ratchet (Schardl et al 1991;Rispe and Moran 2000). Grass plants in a balanced symbiosis, where both fertile tillers and fungal stromata are produced, should be the most stable associations in the long term (Schardl 1996).…”

Creation of stable associations between perennial ryegrass or tall fescue and fungal endophytes

“…Neotyphodium species are closely related to species of Epichloe (family of Clavicipitaceae), with which they share many characteristics. However, the sexual stage (perithecia produced in mycelial stromata surrounding host tillers) is lacking in Neotyphodium species, which are regarded as asexual descendants of Epichloe [34]. The term 'e-endophytes' is often used to regroup both Neotyphodium and Epichloe species.…”