Pasture Biotechnology update #2

Gene editing and genetic modification technologies can be used to change the DNA of a living organism, such as a plant or animal, through either inserting, replacing, or deleting genetic material.

Opportunities from these technologies include greater farm productivity, better animal health and improved environmental results that may include reduced greenhouse gas emissions and less nitrogen loss that has the potential to contaminate waterways.

Work is underway to understand the potential benefits of these technologies and to ensure that those benefits  outweigh any potential risks. In this newsletter, we provide the second in a series of six monthly updates on the progress of three pasture programmes that are currently underway; either indoors in containment in New Zealand or in field trials offshore.

Gene edited endophytes

AgResearch and its partners have commenced a process toward seeking permission to operate a ‘contained’ outdoor growing trial of ryegrass with gene-edited additions, in what would be the first application of its type in New Zealand in well over a decade.

Written material was lodged recently to start the process, and it is expected that a full formal application may be made in the coming months to the Environmental Protection Authority (EPA) to grow ryegrass that contains gene-edited Epichloë endophytes at a suitable site in New Zealand. The continuation of the application process will be contingent on the outcomes of engagement with affected parties that is now underway.

These Epichloë endophytes live inside ryegrass and form a mutually beneficial relationship with the ryegrass. Natural substances released by the endophytes deter 
insect pests from eating the ryegrass and improve plant growth and persistence,which collectively results in a reduced need for chemical pesticides and increases efficiencies in milk and meat production for New Zealand.

An estimated 90 per cent of proprietary ryegrass now sold in New Zealand contains a selected endophyte strain, while the economic impact in New Zealand of the AR37 version alone has been estimated at NZ$3.6 billion over 20 years.

The challenge has always been that some endophytes that protect ryegrass against pests also produce toxins that can be harmful to the livestock which feed on the ryegrass, causing heat stress or a disease called ryegrass staggers.

AgResearch scientists, supported by commercial partners PGG Wrightson Seeds and Grasslanz Technology, have identified in the lab targeted changes to the DNA of selected endophytes via gene editing that result in either greater plant protection or less harm to livestock.

The last approval of its type for an outdoor plant growing trial in New Zealand was by the then Environmental Risk Management Authority in December 2010, for research institute Scion to grow genetically modified Radiata pine trees.

The process is underway with ryegrass containing gene-edited endophytes, ahead of other edited or modified plant organisms, partly due to the very low  risk of genetic material travelling outside of the trial site. A contained trial means that genetic material that can be reproduced is confined to that site. The edited endophytes are contained in the ryegrass seed and do not travel via the ryegrass pollen.

As part of the application process, AgResearch and its partners will be engaging with various interested and affected parties to understand and address any concerns that are raised.

If approved, the proposed trial would allow scientists to test how the ryegrass with gene-edited endophytes grow in outdoor conditions in New Zealand, as well as their 
resistance to insect pests.

Meanwhile, outdoor trialling of ryegrass containing these gene-edited endophytes is underway in Australia and the ryegrass seed has recently been sown by partners at locations in both Victoria and New South Wales.

These Australian trials are each expected to run for a total of three years and measurements will be taken along the way on the plant persistence, yield, insect  damage, chemistry and the level of endophyte presence in the ryegrass.

High Metabolisable Energy (HME) Ryegrass

The latest development in the journey of AgResearch’s High Metabolisable Energy (HME) ryegrass has seen scientists successfully replace a sesame component with one from rice to provide added reassurance about the low risk of allergic reactions.

The genetically modified ryegrass developed by AgResearch and its partners is aimed at reducing environmental impacts while boosting animal nutrition and farm productivity; with evidence suggesting that methane reductions of 10 to 15 percent may be achievable (though animal feeding trials are still to be undertaken to definitively test this).

This modified ryegrass is being achieved by adding and modifying two plant genes to increase fat content in the leaf and enhance photosynthesis in the plant under 
some conditions. The improved animal nutrition is also expected to lead directly to a reduction in urinary nitrogen excretion, resulting in reduced nitrous oxide emissions and lower nitrate leaching.

AgResearch scientists have been working over many years with the support of the government and commercial partners Grasslanz Technology, PGG Wrightson Seeds and DairyNZ, to develop the HME ryegrass.

One of the components of the modification had been a protein known as sesame oleosin – from the sesame plant – which helps in the formation and stabilising of the increased fats in the plant.

However, in the course of applying to Australia’s Office of the Gene Technology Regulator (OGTR) last year for permission to conduct growing trials in Australia, the team involved in the HME ryegrass programme encountered concerns about the risk from sesame, as a known food allergen.

While the AgResearch scientists had confidence that this sesame oleosin was not being expressed in the pollen of HME ryegrass, a decision was made to identify an alternative oleosin to provide certainty for external parties such as the OGTR.

Rice was chosen as it is widely consumed globally and rice oleosins are not considered allergenic.

Importantly, the change from sesame to rice does not affect the quality or function of the ryegrass.

Meanwhile, the scientists are continuing to prepare for a trial that is expected to start later this year, in which lambs will be fed both the HME ryegrass and a control (unmodified) ryegrass. This means growing enough of the ryegrass in contained glasshouses in New Zealand that can be ensiled (preserved) for feeding to the lambs when the trial begins.

This trial is expected to provide insights on reductions in methane emissions and urinary nitrogen excretion. Further confirmation in cattle will need to be performed 
in outdoor trials, most likely in Australia at a later date.