Epichloë – a key element of New Zealand’s agricultural landscape

ABSTRACT

Epichloë is a genus of filamentous fungal endophytes that have co-evolved with cool-season grasses with which they form long-term, symbiotic associations. In natural ecosystems Epichloë have implications for species diversity, food web structures and fundamental ecological processes. Epichloë produce a range of secondary metabolites that can have negative effects on herbivores, be they invertebrates or vertebrates. In many managed pastoral systems, selected asexual Epichloë strains are purposefully associated with grass cultivars (termed novel endophyte-grass associations) as they confer beneficial traits that protect the host from abiotic stresses (e.g. drought) and biotic stresses (e.g. herbivory from invertebrates) while having minimal impact on the health and welfare of ruminant livestock. As well as conferring beneficial traits, agriculturally selected strains of Epichloë can also increase plant biomass and seed yield. Epichloë endophyte-technology has and continues to be a scientific, agricultural, and marketing success with selected asexual strains of Epichloë now essential components of many pasture ecosystems, within New Zealand and abroad. An estimated 90% of proprietary ryegrass now sold in New Zealand contains a selected endophyte strain while the economic impact in New Zealand of AR37 alone has been estimated at NZ$3.6 billion over 20 years. With a changing climate, agriculture will continue to experience increasing temperatures, elevated atmospheric CO₂ levels and changing precipitation patterns that will likely increase the geographic range and overwintering survival rates of pests. Furthermore, plant disease outbreaks are expected to intensify due to increases in the severity of existing phytopathogens and/or invasions by new phytopathogens. Functional symbioses, such as those between temperate grasses and Epichloë, are among the most successful mechanisms by which plants can improve their ability to tolerate stress. Future research is likely to utilise targeted genetic manipulation techniques to broaden the biocontrol ability of Epichloë strains, particularly to mitigate climate related stresses.

KEYWORDS:

• Alkaloid
• biological control
• endophyte
• mutualistic symbiosis
• perennial ryegrass

Acknowledgements

We thank Alan Stewart, Anouck de Bonth and Sushma Prakash for valuable comments on the manuscript.

Disclosure statement

J.R.C. is employed by Grasslanz Technology Limited, a company that is a part-owner of the intellectual property associated with Epichloë strains marketed under the brands AR1®, AR37®, Endo5®, MaxQ®, MaxQII®, MaxP®, MaxR®, Avanex®, (although this trademark is owned by PGG Wrightson Seeds Limited) and has the rights to license the Epichloë strains marketed under the brands Happe and Protek. D.E.H. is among the patent inventors of AR1, AR37, AR542 and AR584.

Additional information

Funding

Strategic Science Investment Fund (SSIF) from the New Zealand Ministry of Business, Innovation and Employment (MBIE) (contract number A20067).