GM apples

When apple (Malus domestica) fruits are cut or bitten, we all know that the cut surfaces turn brown. To stop this happening, here’s a range of genetically modified (GM, genetically engineered, GE) apples called Arctic apples.

Ordinary apples turn brown when the fruit’s ‘phenolic’ compounds react with oxygen. We don’t want to lose phenolic compounds because, if we eat them with plenty of fats and carbohydrates, they’re good for our health. It’s one of the reasons why my grandparents’ generation learned, ‘An apple a day keeps the doctor away.’

When apple surfaces turn brown, it’s because phenolics are oxidising (reacting with oxygen in the air.) This change is driven by an enzyme called polyphenol oxidase (PPO). So if you want to eat wholesome phenolics you’ll want to eat your apples before their cut surfaces turn brown. Every chef knows that you can delay the browning by sprinkling the cut apples with lemon juice, which of course is acidic (low pH). Low pH delays the action of PPO.

If you grow apples you might want them to make plenty of PPO. It’s part of the plants’ defence against insect pests. Therefore, genetic engineers have made plants with extra PPO to improve plants’ defence against insects.

On the other hand, if you grow apples you might not want them to make very much PPO. Because PPO makes fruit turn brown after harvest, if it gets cut or damaged, and then it doesn’t look so nice. It doesn’t give consumers so much health benefit from phenolics either.

Here’s how the ‘less PPO’ strategy was used to make nonbrowning apples. Then scientists at the Canadian biotech company Okanagan Specialty Fruits (OSF) developed nonbrowning apples and called them Arctic apples. (I don’t know whether they taste good or not.)

These GM apples don’t turn brown when cut because their genes for PPO have been ‘silenced’. Scientists at OSF used the bacterium Agrobacterium tumefaciens to insert ‘antisense’ DNA sequences to make this happen.

Arctic apples haven’t yet been licensed for growing in the States or Canada but perhaps they soon will be grown there. The opportunity for public comments has been extended until the end of January 2014. OSF urges us to support Artic apples although they seem to have forgotten to update their request, to remind us that it’s not too late.

What do you think? Should apple growers continue to benefit from PPO, keeping pests away? Perhaps in time, American and Canadian growers will have the choice of GM apples which make more PPO. Or should growers have the choice of GM apples with less PPO, such as the Arctic range whose fruits keep so well? Or do you want apples which are not GM at all?

[Edit] In the States, the Organic Consumers Association urges us to comment on Arctic apples.


About argylesock

I wrote a PhD about veterinary parasitology so that's the starting point for this blog. But I'm now branching out into other areas of biology and into popular science writing. I'll write here about science that happens in landscapes, particularly farmland, and about science involving interspecific interactions. Datasets and statistics get my attention. Exactly where this blog will lead? That's a journey that I'm on and I hope you'll come with me.
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7 Responses to GM apples

  1. Thought+Food says:

    I have been following this development with interest, One aspect that I like is the potential impact on food waste. When I visit my kids’ school at lunch hour, there are so many kids who say, “ew its brown” and throw away perfectly good apples. Some consumers worry that the non-browning feature will mean that even rotten fruit will look healthy but the company that is developing it says no, that is a different process and fruit that goes bad will do so as it does now so no danger of eating bad fruit either. I wonder if something like this could work for avocados as well….

    • argylesock says:

      Do you think there are other ways to stop kids throwing apples away? I do. If not too young, they could be taught to eat the whole apple. At any age they could be taught to eat sliced apples that have been dressed with lemon juice, perhaps with another ingredient to make the dessert taste sweet. They could be taught to drink apple juice.

      What concerns me about ‘Arctic’ apples is that they’ve been engineered to need more insecticide than other apples need.

      • Thought+Food says:

        I use lemon juice for mine. Juice generally contains too much sugar. Eating the whole apple, some people worry that it would have pesticide residue and some of the apples which have been bred for looks rather than flavor have a very thick and unpleasant peel. Yes, other solutions are possible and extra insecticide gives pause but there would be some gains from the modification, in my view.

  2. Rachel says:

    One thing that came to mind was that as GM apples grown without PPO are not as good for us, won’t someone turn around perhaps and think ‘I know! Why don’t we create artificial phenolics so people still get the goodness but not the brown-ness?’

    I always believe that natural is better than artificial, and if GM apples are removing PPO just to make them look nicer for longer, it doesn’t really seem a fair exchange for removing the very thing that is good for us. (I’m speaking as someone who is intolerant of artificial additives – I’d eat brown or less aesthetically appealing fruit any day over a perfect specimen).

    • argylesock says:

      So would I, esp if I knew that GM had been necessary to make the ‘perfect’ apple. I’ve noticed a lack of hype about the flavour of these GM apples – it’s all about their appearance and shelf life. Those are, no doubt, the criteria used when catering staff decide to offer Golden Delicious (not-delicious) apples in the snack bars I use on campus. No thanks, say I!

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