Evening Standard

Genetic Engineering: Sifting The Facts From The Fiction

At least two conclusions can be drawn from the present explosion of genetically-engineered crops, says Massey University plant biology professor Paula Jameson.

One, the new technology is unavoidable, and it's here to stay. Reverting to old technologies that fed a much smaller world population would be impossible.

Second, New Zealand should take on board these recent advances, using the best of both conventional and organic practices -- and the best of recombinant DNA technologies -- to produce a sustainable agriculture system that will feed the world in 2025.

"New technologies take a long time to develop, and we must use this lead-time we have at the moment as wisely as possible," Prof Jameson says. "Because the other options -- using this technology stupidly or unwisely, or not looking at it at all -- are not really options at all."

New plant breeding technologies are now being developed at Massey. Prof Jameson believes genetic engineering could give a much deeper understanding of basic cellular processes and could also enable the rapid introduction genes to provide resistance to viruses, fungi, insects and herbicides. It could also enable a plant to manipulated as a chemical "factory" producing a whole new range of oils, plastics, cheese starters or vaccines. Improved shelf life of fruit and vegetables was also possible.

Set against those benefits, serious environmental issues were being created as genetically-engineered crops were released into the environment. The public needed to understand those issues.

The next flash-point was likely to centre on American chemical giant Monsanto, which had just applied to grow Roundup-ready canola in New Zealand on a commercial scale.

So-called "classical" agriculture was reliant on the use of herbicides to keep weeds down and increase yields. That was fine with cereal crops threatened by broadleaf weeds, because in those cases, selective herbicides against those weeds were very effective.

But with crops such as soya bean or canola, it wasn't that easy. In the case of canola, the classical technique was to use a triazine- type herbicide to control the weeds, but that had "appalling" residue problems. Large areas of cropping land in the United States were now contaminated.

"So we have to decide if it is better to continue using triazine- based herbicides, or to use Roundup-ready variety of canola, where the crop has been given a resistance to the herbicide," she said.

Prof Jameson said the debate about genetically-modified plants versus classical plant breeding had become almost immaterial, because the real issue was about managing the crop in the field. Irrespective of how the herbicide-resistant plant was developed -- either by classical or genetic engineering techniques -- the import issue was about preventing that resistance transferring out to wild relatives. "And that is about crop management, not how you developed the plant."

So could a genetically-modified plant become a weed? Not with domesticated crop plants now used in the developed world, says Prof Jameson, because such plants had lost their ability to disperse seed, and most of their dormancy mechanisms. Also lost was the ability to respond to the season, and control when they should flower.

Placing into such plants a gene for herbicide resistance, drought tolerance or even longer shelf life would not give back to that plant any characteristic that could aid its survival in the wild.

In addition, crop plants generally came from the green revolution era; they required high fertility and good water. "So if such a crop was dispersed into the wild, they would end up in a low-fertility and drought situation -- they would be competed against by weedy species that were better adapted to those conditions."

So what about the escape of the gene itself, into a wild relative? Here, it was important to know if the crop was classically-bred. If it was, then would it naturally cross with its wild relatives? If the answer was yes, then there was no reason why a new gene in a transgenic crop would also move to a wild relative, she said.

"Therefore, it doesn't surprise me that a new gene crossed out into a weed," Prof Jameson said of the recent British discovery, where a herbicide-resistant gene in canola crossed into wild turnips.

"That comes down to crop husbandry; we've been breeding resistance to all sorts of things for years, using classical techniques. We know these genes have sometimes escaped to weeds. This is not a problem unique to a genitically-modified plant."

Another issue was between-crop gene transfer, particularly between genetically-modified and organically grown crops. "Of course these genes will transfer, but again, it comes back to good husbandry, and establishing what boundaries we want to put around particular styles of cropping."

One "ray of hope" amid all this controversy over genes escaping was the fact that plants had a third set of DNA associated with the chloroplast. The chloroplast genomes were not passed out through the pollen, they were internally inherited. Thus, if the new genes were placed into the chloroplast genome, they would not be attached to the pollen, and they could not get out into the wild.

Prof Jameson said it was critically important for New Zealand to be field testing genetically-modified plants within contained environments. Plant variants arose during the breeding process, it was standard practice to select for those variants.

"But we can't select for all the traits in a genetically-modified plant by growing it in a contained glasshouse. We must put plants out into the environment, where they are subjected to the full suite of environmental stresses, which includes high UV rates. This is unique to New Zealand.

"Plants respond to stress by producing different compounds some of which could be toxic. So if we don't know where the gene goes in, it might disturb various biosynthetic pathways, including those associated with stress. We would be making an assumption to presume we could bring in northern hemisphere plants and they would respond in exactly the same way."

Associate professor Brian Jordan, who heads Massey University's nutrition and health cluster, says genetically engineered foods were rapidly entering the market, and the testing of such food products was extensive. Where the media had seized on issues like the cauliflower mosaic virus, which was used as a promoter to permanently switch on a particular gene, allegations that it could also transfer a virus were false, because it had been so well characterised. "It is not considered to be a problem at all, but if the media want to bring it up, it's an issue."

Prof Jordan said the it was enzyme action that genetic engineers were most interested in -- the ability to change the DNA so that enzyme activity was changed. That changed activity could change the composition of a product such as the oils or carbohydrates within the plant. "The food industry can then take that changed product away from the process of genetic engineering -- it is simply a product, which many people fail to understand."

Prof Jordan said by 2050 the world's population would double the present level. The existing population could be fed by existing supplies -- any shortages could be attributed to distribution problems -- however solving those distribution problems could not solve hunger problems when the population reached 11 billion.

At the moment, 30-40 percent of crops were lost to diseases. If those diseases could be tackled through genetic engineering, and major benefit could be gained. In addition, the total land area under cropping could be increased by giving stress and salt tolerance to particular plants.

"This technology is so powerful, and we're only just begining," Dr Jordan said.

"At the moment we're all wrapped up with Monsanto, but that's not where the technologies are going to lead us."

With food processing, scientists will soon be altering the carbohydrate, food protein and saturated oil compositions, producing healthier foods which could be targeted at specific diseases and ailments.

Vaccines had already been put into plants, enabling delivery via foods, rather then syringes. Within five years the human genome would be sequenced, providing huge potential health benefits. And Silicon Valley technology was now being blended with the new biotechnology industries -- genes could now be placed on computer chips. If New Zealand's dairy industry was not up to speed on the new technologies, it would be very quickly left behind.

"I believe the key will be public understanding. That means we can't just say `we're scientists, trust us' we need to debate and deal with the issues as they arise," he said.

"This a powerful technology, we should be using it beneficially, but we can't steamroller everyone out of the way."