Thursday, May 22, 2014

Are Organic Apples At Risk of Being Redefined As Contaminated?

An Apple Orchard In Bloom

There is an interesting new "GMO" apple nearing approval in the US and in Canada called the "Arctic Apple."  It was developed by a British Columbia, grower-based organization called Okanagan Specialty Fruit.  Certain genes in these apples are turned off so that the fruit doesn't  express the enzymes that make the apples turn brown after cutting.  You could slice the apples, put them in your lunch or your kid's lunch, and they would still have full flavor, vitamins, and color when it was time to eat them.  I think this is a useful, consumer-oriented trait. Predictably, there are opponents for this sort of scientific innovation.

An Arctic Apple on the right has not browned like the unmodified apple on the left

I've written before about this issue before, but in this post I want to specifically address a particular objection to the commercialization of this technology - the concept that the growing of these "GMO" apples could put the local organic apple industry at risk of becoming "genetically contaminated." I absolutely agree that the organic industry is at risk, but not from the Arctic Apples.  They are at risk from this new definition of "contamination" driven by the "defenders" of organic, which would unintentionally classify all organic apples as being particularly "contaminated."

The "contamination" scenario is based on the potential movement of pollen from flowers of the Arctic Apples to apple flowers in organic orchards.  It is useful to consider this from a biological perspective.

Plant Sex

A Honey Bee Doing Its Normal Job in an Apple Flower

What we are really talking about here is not a new phenomenon associated with a "GM Crop."  This is about normal plant sex.  Apple flowers are not "self-fruitful" meaning that for an apple flower to be successfully fertilized, the pollen has to come from a genetically distinct apple -  usually carried by a bee.  One efficient way to foster this DNA exchange is to graft some branches of crabapples onto some of the trees in an orchard or to simply grow some crabapples within the orchard.  The bees visit those flowers and carry the pollen to flowers of the desired variety. The only part of the resulting apples that contains the DNA from the crabapple is the embryo portion of the seed.  All of the rest of the apple that we eat only has the genes of the intended variety. Thus, even though apples might be pollinated from marginally edible crabapples, we have never considered them to be "contaminated."

If Arctic Apples are commercialized in BC (or anywhere), there might be some small percentage of seeds in other varieties that would be pollinated by a bee that moved between the two types of orchards.  As with the crab apples, but at a vastly lower incidence, there will be the DNA from the arctic apple, a tiny part of which has been changed to prevent expression of the apple genes for browning.  Someone would have to intentionally sample lots of apple seed using very sensitive lab techniques to find this.  If that sort of DNA in seeds is redefined as "contamination," then all apples are contaminated with the DNA from a different apple variety or a crabapple.

But What About The Seeds?

The only thing that could be "scary" about the apple seeds with the Arctic Apple DNA is the same thing that is "scary" about all apple seeds.  They are "cyanogenic" meaning that if chewed, they produce hydrogen cyanide. You would have to eat a lot of apple seeds to be affected, but apple seed consumption is a non-issue for any normal sort of consumer.

The next important thing to know about apple trees is that they are not grown from seeds.  Almost no fruit crops are grown from seed because what you will get will not be the desirable variety you started with, but usually a much inferior type that results from the cross of two different lines. The apple varieties we eat are always "cloned", meaning they are reproduced by grafting - not seeds. Long ago some apple seeds were used to make root stocks, but in modern orchards (including organic), the growers use cloned "dwarfing rootstocks" so that their trees can be kept in a size range that is much safer and more efficient for harvest.  So just as it is no problem to grow many distinct apple varieties in the same area, there is nothing newly problematic about adding Arctic Apples to that variety list.

But What About the Bacterial or Viral DNA?

In the process of genetic engineering, there are some sequences of DNA from a bacterium and from a virus which end up in the modified plant. The bacterium in question is called Agrobacterium and it is nature's own genetic engineer.  It makes a circular bit of DNA called a plasmid which it uses to get some genes inserted in plants it infects. We use a "disarmed" version of that plasmid so a little bit of Agrobacterium DNA is in the modified plant, but it is not "expressed" meaning that no proteins are made based on that DNA.  That DNA has been a part of most GMO crops for a very long time without any issues, but if the presence of bacterial DNA is going to be called "contamination," the there will be a problem with every apple we eat, not just the seeds of some of them.

Why You Get Bacterial DNA With Every Apple, And More From Organic

You may have heard about "microbiomes" which are communities of bacteria and other organisms that inhabit everything from our intestines to our skin.  On plants there are similar microbial communities we call epiphytes (living on the plant surface) and endophytes (living among the plant cells).  All apples have abundant bacterial populations of this nature with all of their bacterial DNA - not just some tiny fragment as in the modified apples.  If that presence is going to be defined as "contamination" then every apple everywhere is contaminated with bacterial genes!

For apples in general, and for organic apples in particular, there are widely used, very safe biological control agents which are based on whole bacteria and thus include the DNA of bacteria.  Bt sprays are based on the bacterium Bacillus thuringiensis and are commonly sprayed on apples to control caterpillars.  There are biocontrols to suppress apple diseases based on the bacteria Bacillus subtilis and Bacillus pumilus.  These products are often sprayed on organic apples.  In these cases we are talking about the full compliment of bacterial DNA expressing the bacterial genes.  If bacterial DNA introduced by human activity is defined as a contaminant, then all apples are "contaminated," particularly the organic ones.

There is also a specific piece of virus DNA in an engineered plant like the Arctic Apple, and it has been raised as a "contamination issue."  That piece is called a promoter and it is what turns on the gene that follows it in a DNA sequence.  Again, that promoter in the embryo of an uneaten seed is a functional non-issue, but it is certainly not the only viral DNA on or in an apple.  There are viruses called phages present in some of the bacteria that live on the plant.  However, none of this even compares to the amount of virus (with its DNA) that is quite intentionally sprayed on apples. There are biocontrol products, also approved for organic, based on Cydia pomonella granulosis virus. This is an agent which infects and kills the larvae of the codling moth - one of the biggest pests of apples.  The growers use these viruses as part of an integrated pest management system, but by the new definition being promoted, that means "contamination."

The Organic Precedents For This Sort of Issue

If there is ever any problem for organic growers because of the commercialization of the Arctic Apple, that injury will be entirely self-inflicted by the wing of the organic community that makes the rules.  It will be the result of a state of mind, not any rational risk.  It will also go against well-established precedents for organic.  The USDA Organic rules allow for a degree of "unintentional" contamination of organic produce with synthetic pesticides.  The same is true for fertilizers.  In California there were two historical instances where companies were "spiking" an organic fertilizer product with "synthetic nitrogen." For some time, a majority of California organic growers were using such products.  When the fraud was exposed, none of the farms that had used that fertilizer lost their organic status or had to go through the three year transition again.  It was ruled to have been unintentional.  Why wouldn't the same logic be used for the "unintentional" presence of a tiny bit of harmless DNA in a few apple seeds we don't eat or plant?

The organic apple growers of British Columbia are not threatened in any rational way by the potential commercialization of genetically engineered apples.  The only threat comes from those who want to re-define genetic contamination in a way which makes no practical sense.  This doesn't serve the interests of consumers, nor does it really serve the interests of the organic growers.

Honey bee on apple flower image from Wikipedia.  Arctic Apple image from Okanagan Specialty Crops.  Apple orchard image mine.

Disclaimer:  I am not employed by Okanagan Specialty Fruit in any way.  My opinions on this topic are my own.

You are welcome to comment here and/or to email me at  My speaking website is

No comments:

Post a Comment

Please send comments if you wish. Sorry about the word verification, but I'm getting tons of spam comments