Functional analysis of the Epichloe festucae-perennial ryegrass symbiosis

Abstract

Although much is known about the beneficial and detrimental effects of the interaction between Neotyphodium lolii and Lolium perenne in the field comparatively little is known about the molecular and cellular events that underlie these effects and how mutualism is maintained. Because N. lolii is quite intractable to genetic analysis we have developed the synthetic association between Epichloë festucae and perennial ryegrass as our model experimental system to study the epichloë endophytegrass symbiotic interaction. Using this system we have recently shown that reactive oxygen species (ROS) produced by a specific endophyte NADPH oxidase (NoxA) have a critical role in regulating hyphal growth and development in perennial ryegrass. We have also shown that two additional components, NoxR and RacA, are required to regulate ROS production to maintain a mutualistic interaction. Using a combined molecular and genetic approach we have recently cloned and characterised genes for peramine and lolitrem biosynthesis. An overview of these advances and the opportunities now available to better understand and exploit this important fungal-grass interaction is presented. Keywords: Epichloë festucae, Neotyphodium lolii, Lolium perenne, peramine, lolitrems, reactive oxygen species