Characterisation of a novel endophyte NRPS gene and its role in endophyte-grass symbioses

Abstract

Symbiotic grass associations with fungal endophytes (genera Neotyphodium and Epichloë) display enhanced fitness as well as prolonged field persistence over their endophyte free equivalents. Perennial ryegrass, an important agronomic grass, is typically associated with the N. lolii endophyte. The endophyte lives within the intercellular spaces without inducing any symptoms in the plant. The aim of this study is to elucidate the biosynthetic function of fungal secondary metabolite gene clusters. Non-ribosomal peptide synthetase genes (NRPSs) of unknown function were targeted, as these genes are commonly associated with the production of bioactive peptides some of which are ecologically important. Some novel endophyte NRPS genes have been identified using a degenerate PCR screen; one of these, NRPS5 will be discussed here. Clones were obtained by screening a fosmid Epichloë festucae genomic DNA library and we are currently determining gene function by using targeted gene replacement followed by an assessment in vitro and in planta using metabolomics and appropriate bioassay screens. Keywords: endophyte, NRPS, secondary metabolism