Co-existence possible between genetically modified and conventional crops

AgResearch has developed a genetically modified ryegrass that could transform New Zealand farming.
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AgResearch has developed a genetically modified ryegrass that could transform New Zealand farming.

AgResearch scientists have developed a genetically modified (GM) ryegrass that has a 40 per cent increase in production and a 30 per cent reduction in water demand.

Animals can eat less for the same live weight gain; it contains a high metabolisable energy (HME) system giving it a 20 per cent increase in photosynthesis and in-vitro rumen investigations have measured a 15-23 per cent decrease in methane production.

AgResearch Grasslands principal plant biotechnology scientist Greg Bryan said the HME could transform farming by reducing its environmental footprint and improving animal productivity.

Federated Farmers national president, scientist and farmer believes gene editing offers an exciting new level of plant ...
Tony Benny Supplied

Federated Farmers national president, scientist and farmer believes gene editing offers an exciting new level of plant breeding with little downside.

"The potential value of GDP based on modelling we have done is in the range of $2 billion to $5 billion in additional revenue depending on the adoption rate by farmers," Bryan says.

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Ryegrass harvesting in South Canterbury. If a neighbour who wants to avoid GM takes no preventative measures he would ...
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Ryegrass harvesting in South Canterbury. If a neighbour who wants to avoid GM takes no preventative measures he would have a reasonable expectation that no more than 1 per cent of the species in question would be cross-pollinated by the neighbours GM crop.

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It sounds too good to be true.

Unfortunately, it won't be happening anytime soon because New Zealand has rules so stringent that no one can plant a single GM seed in an open paddock. Neither can scientists test new seeds developed using offshore GM technology. To gain approval for field trials, no reproductive material must leave the site, preventing plant breeding studies. HME field trials are being done on soya beans in the United States.

While some experts would argue that there is broad acceptance in New Zealand of the value of GM as a research tool, society is divided as to whether we should employ it as a technology in the field, or solely for research, or for the primary production of foodstuffs.

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From a farmer's perspective, if HME grass was released in New Zealand the question would be whether it could co-exist in our pasture- based system. Realistically, would farmers still be able to have GM and traditional pastures or would they end up as one big melting pot.

Federated Farmers national president, science advocate and farmer William Rolleston thinks the situation would be manageable.

Speaking at the NZ Grasslands Association conference in Timaru recently, Rolleston presented a paper on conditions for the co-existence of GM in New Zealand's pasture system.

"I wanted to give some perspective on what farmers would need to do if we were to use genetically modified (GM) forage crops or grasses in our livestock system," he said

"I tried to put this in the context of a real life system and current market requirements."

GM has been a contentious issue since the early 2000's when the then Labour government set up a royal commission on genetic modification.

The conclusions from the commission were that a 100 per cent organic or a GM-free future was not realistic or to New Zealand's benefit. Nor was the total deregulation of GM. The commission said New Zealand should proceed with caution on a case by case basis.

Organic standards in Australia and New Zealand call for zero tolerance of GM in any food and zero tolerance on certified farms.

"For GM to be used in New Zealand the government would need to determine where the balance of rights should be," Rolleston says.

"Should all farmers be denied the opportunity to use GM for the convenience of growers who want to set a personal standard? Or should the government allow rules and practices which give a reasonable level of protection to enable products to be traded internationally?

"If [it is] the former then many potential uses of GM would be beyond our reach. If the latter then for animal feed at least, no regulation would be required."

"It's likely that a balanced approach would be found with respect to those who want to grow GMOs and those who want to avoid them."

If a standard was set for GM growers that provided a reasonable expectation for non-GM growers, then any higher level of assurance would be the responsibility of the non-GM grower, Rolleston says.

"A one per cent level might be a useful place to start with respect to the grasses and crops used by livestock farmers in NZ.

"For example, if a neighbour who wants to avoid GM takes no preventative measures he would have a reasonable expectation that no more than 1 per cent of the species in question would be cross-pollinated by the neighbour's GM crop at the nearest point.

"The practices required would depend on the plant species, its reproduction, and how it is used agriculturally."

Stewardship could be voluntary, or set by an industry standard, or regulated as part of the conditional release of a GMO, Rolleston says. It would be aimed at limiting the production and spread of pollen or seed from the GM plant.

Four factors relate to pollen. They are the species and method of dispersal; the management of the crop and role of flowering; the pollens' disposition and distance it travels; and the receptive plants fertilised as a result of the pollen disposition.

Rolleston says it is important to consider the "gene flow" of any plant rather than simply pollen dispersal . Gene flow is the transfer of genes from one population to another, and in this case depends on pollen viability , receptive flowers, fertilisation and seed development.

Several gene flow studies have been carried out on forage grasses that are wind pollinated such as ryegrass and tall fescue, including at AgResearch. Pollen has been detected up to one kilometre from the crops but gene flow is limited to 30-50 metres for ryegrass and 150m for tall fescue.

"Blue Cliff Station [owned by the Rolleston family] has produced whole-crop silage from time to time and flowering is essential for effective production. While one of our neighbour's produces maize silage he doesn't produce corn seed nor sweetcorn and the next nearest seed producer is more than five kilometres away.

"If our neighbours were keen to avoid GM corn, strategies such as ensuring a buffer distance between the GM and non-GM crops of say, 30-50m could be used. This buffer area could contain non-receptive plants or non-GM corn to increase the proportion of non-GM pollen. Cultivars with different flowering times could also be chosen."

Perennial grasses would need a different approach, Rolleston says. Stewardship protocols to reduce spread to low levels could include a 150m buffer zone; flowering controlled by grazing or topping pastures; varieties grown with different flowering dates and preventing GM ryegrass pasture from becoming fully reproductive. For hay, silage or baleage, the surrounding pasture could be managed to minimise receptive flowers.

Another approach would be to develop plants that produce no pollen, as timber research company Scion is developing in trees, Rolleston says.

"There has been plenty of protest about terminator genes (methods for restricting the use of GM plants by causing second generation seeds to be sterile) but in practice we do not save grass seed, hybrids do not reproduce true to form and the sale of modern cultivars is already covered by plant variety rights, so any supplier is paying a royalty to the developer."

"In the case of HME ryegrass, it could be developed to require a specific fertiliser regime. Rogue plants are unlikely to survive although field trials are required to confirm this."

If the aim of field trials is to ensure that GM ryegrass does not establish in New Zealand and provided GM ryegrass has no competitive advantage, then it may be possible to consider a conditional release in the same way field trials are defined overseas, Rolleston says.

Another factor limiting the potential establishment of a population of AgResearch's HME ryegrass is that they may also require specific fertiliser management which would make it less competitive than conventional plants particularly when both are grown under optimal conditions. Rogue plants are unlikely to survive although field trials are required to confirm this.

Similar principles apply when it comes to gene flow for wind pollination and insect pollination.

At Blue Cliffs brassicas are not allowed to become reproductive so pollen and gene flow is limited. This is easy to maintain because the distance between paddocks is a small proportion of the arable land area of the property.

"Our neighbour grows brassica seed crops and participates in the NZ seed crop isolation distance mapping scheme which facilitates seed purity standards by farmers mapping the crops they intend to grow. It aims for no off-types in the seed line and has isolation distances of around 1000m or greater. However, our neighbour has no concerns knowing the brassicas grown on Blue Cliffs are used for forage. We would expect GM varieties to be no different, " Rolleston says.

Measures of good stewardship for lucerne could include a buffer zone, management of flowering and control of feral plants.

"As livestock producers on Blue Cliffs, inadvertent use of GM crops may occur particularly as new gene-edited crops are not being regulated in many of the countries where they were developed."

"Gene editing techniques have been categorised as genetic modification by anti-GM purists and that will be for them to grapple with. For the remainder of us gene (modifying replacing or removing a gene) offers an exciting new level of plant breeding with little downside, particularly if deregulation by our trading partners continues."

 - Stuff

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