Identification of NRPS gene families from Neotyphodium/Epichloe endophytic fungi that form mutualistic associations with cool season grasses

Abstract

Neotyphodium and Epichloë species are closely related asexual and sexual endophytic fungi, respectively, that form symbiotic associations with cool season grasses of the sub family Pooideae, including several important forage and turf grass species. The endophytes confer a number of advantages to their hosts, but also can cause animal toxicosis. These positive and negative effects are, in many cases, due to the production of fungal secondary metabolites. In filamentous fungi secondary metabolite genes are commonly clustered and are well documented to often contain non-ribosomal peptide synthetases (NRPSs) at their core. Members of this gene family encode large multifunctional proteins that synthesise a diverse range of bioactive compounds, many of which have been shown to serve as pathogenicity or virulence factors, in addition to suggested roles in niche adaptation. We have used a degenerate PCR approach to identify members of the NRPS gene family from Neotyphodium and Epichloë species, and have shown that at least 13 NRPS genes exist among these genomes. The distribution of these genes among different Neotyphodium/Epichloë lineages suggests that a common ancestor contributed most of the complement of NRPS genes, which have been either retained or lost during the evolution of these fungi. Keywords: Neotyphodium, Epichloë, non-ribosomal peptide synthetase, NRPS