Monday, July 16, 2012

The “Arctic Grape” Sneaks Through Public Approval

We are currently witnessing the USDA public commentary period on the Arctic Apple, a transgenic apple that does not exhibit browning upon injury or cutting.  The anti-browning trait was installed by scientists at Okanagan Specialty Fruits. A copy of the apple gene for polyphenol oxidase (PPO) was overexpressed, which triggers a plant response to silence the over-expressed gene.  The same process also suppresses the apple’s endogenous PPO genes.

Trees have been growing for ten years and are poised for widespread adoption.  But as expected, the critics have now emerged against this non-browning apple.  They say that the apples are untested in humans, that the pollen will contaminate other plants.  They say that it is unnatural and will need more pesticide. 

But the same criticisms were strangely silent against what was essentially the Arctic Grape.  A major genetic alteration affected the PPO gene of the ‘Sultana’ grape, a genetic change that was unknown, uncharacterized and uninvestigated. All the scientists knew is that they didn't brown. The resulting grape exhibited the same anti-browning properties as the current Arctic Apple, and gained rapid favor for the production of light-colored raisins and low-oxidation wines.  Unlabeled and untested, this genetic aberration spread quickly throughout the dried-grape industry, as consumers and farmers realized great gains from the sweet, white and golden raisins.  

Worse, it turns out that scientists later deciphered the molecular basis for the disorder. The normal PPO protein was unprocessed, a new protein created!  Just like the anti-GMO folks warn us about all the time, the new protein, untested for allergenicity and long-term feeding consequences, accumulated in the modified Franken-fruit background.  This new freakish protein was the unnatural reason that the grapes did not brown, and the raisins remained white or golden.

The Punchline.  You’ve likely eaten them.  You might have even bought them at an organic market.  You never cared.

In fact, the PPO mutant occurred spontaneously in 1962 in a grape line called “Sultana”.  A mutation in the grapevine changed a gene so that the PPO oxidase protein (the one suppressed in Arctic Apple) could not be processed and made functional.  The fruits were largely white and did not show PPO activity. 

Why?  The active enzyme is about 40 kilodaltons in size, but in ‘Bruce’s Sport’, the ppo mutant, the protein was not processed.  The modified protein was not a functional PPO.  A new protein was formed and caused the lack of browning. How did this mutant atrocity ever escape regulation?  Surely Monsanto ram-rodded this through the FDA and USDA!

Not so much.

In fact, not at all. 

The PPO mutant was found in 1962.  Nobody cared about why the grapes didn’t brown, they just knew was a great trait.  In 1992 scientists finally figured out that the non-browning trait was caused by the fact that a new protein was formed in the plant, an unprocessed form of PPO that could not complete the browning process.

The year 1962.  The year 1992.  Changes in genes, new proteins formed.  All untested, unlabeled, and accepted as perfectly fine; happy golden raisins to go with your granola.  De-lish.

Turn ahead to 2012.  The same gene is suppressed in apples with great precision.  A group of people object to the process. They worry about allergies, cross-pollination and GMO Franken-dangers.

Questions.

Why is this process completely acceptable when unknown, unpredictable and untested back in the 1960's? 

Why is the process decried when it is understood, documented and tested now?

These two questions frame an intellectual inconsistency of the anti-GMO movement that I cannot understand, and show that it is not the product, but the process that activists find objectionable.



References

Rathjen and Robinson (1992)  Aberrant Processing of Polyphenol Oxidase in a Variegated Grapevine Mutant Plant Physiol. 99(4): 1619–1625.

Dry and Robinson (1994) Molecular cloning and characterisation of grape berry polyphenol oxidase Plant Molec. Biol. 26: 495-502

 

Antcliff (1962)  Bruce’s Sport:  A Mutant of the Sultana.  

4 comments:

Anonymous said...

Dear Kevin,
Responding to your questions:

Why is this process completely acceptable when unknown, unpredictable and untested back in the 1960's?

Why is the process decried when it is understood, documented and tested now?

These two questions frame an intellectual inconsistency of the anti-GMO movement that I cannot understand, and show that it is not the product, but the process that activists find objectionable.

The answer is simple: When nature creates a mutation, it does so with precision, integrated as it is, in the dna chain.

When humans insert foreign dna into the dna chain it is totally random, could appear anywhere in the chain, and the resultant effect on the plant and all of nature are totally unknown and unpredictable. There is great risk of an unanticipated negative genetic trait in this random, uninformed, limited scope technology.

Kevin M. Folta said...

Anonymous!!! No, no, no, no, no.

Spontaneous mutations are not precise- they are completely random, at least within the constraints of the organism's genome. When biotech inserts a gene it is possible to find out exactly where it is. No problem.

I'm sorry but your answers are completely goofy. Take it from a guy that knows genes and genomes!

khh1138 said...

Yes, anonymous, you've actually got it completely backwards. We, all living organisms, are constantly mutating in a "totally random [way that] could appear anywhere in the chain and the resultant effect on [living organisms is] totally unknown and unpredictable."
That's the *natural* way.
-from another biologist

Anonymous said...

One look at the ingredients of a box of golden raisins confirms that it is the addition of sulfur dioxide (SO2) as a preservative that retards both enzymatic and non-enzymatic browning. Unsulfured sultana raisins appear more golden brown.

Besides, Bruce's sport yielded variegated fruit and only the white portions were reported to lack PPO activity. [1992]

Apparently, the natural random mutation wasn't as complete in suppressing PPO activity as the purposefully designed mutation.