john.caradus@grasslanz.com

lisa.wood@grasslanz.com

david.hume@agresearch.co.nz

alison.popay@agresearch.co.nz

wade.mace@agresearch.co.nz

The continued use of synthetic chemistry for the protection of crops against pests and diseases is becoming more difficult due to changes in regulations, societal concerns, and loss of effectiveness of some chemistry. New solutions are required. Over many years the use of microbial bioprotectants has been promoted and used with at times poor outcomes and inconsistent results.

These microbes have been free living and used as either a spray directly onto crops or as a seed coat. The efficacy of these bioprotectants has often been reliant on using appropriate formulations to ensure microbial viability to deliver effective protection of the crop, but again often with mixed outcomes. However, another class of microbes has been effectively used for over 20 years to provide protection of some temperate grass species to pests and pathogens and improve abiotic tolerance.

These fungal microbes are found in the genus Epichloë. As obligate mutualists these fungal endophytes are only found within the plant and are maternally inherited, so passed to the next generation of plants through seed. Modern wheat does not have these Epichloë endophytes, but wild grass relatives of modern cereals do. It has been possible using chromosome substitution and replacement lines of wheat to insert these Epichloë endophytes into wheat. Early results suggest significantly improved resistance to several pathogens and insect pests.

This has resulted in reduced infection by Zymoseptoria tritici, Fusarium head blight and Puccinia triticina leaf rust compared with equivalent endophyte-free wheat. Improved resistance to insect pests Argentine stem weevil, Hessian fly and wheat sheath miner have also been observed in field trials. Improved adaptation to some environmental challenges resulting from climate change may also be mitigated by these Epichloë endophytes.

There are some challenges related to genetic compatibility between the host plant and the endophyte, but these are being solved through breeding and will be described in another paper. Here the aim will be to highlight the benefits and value that could be derived from using Epichloë endophytes in modern wheats.