Saturday, July 7, 2012

Atomic Gardening- the Ultimate Frankenfoods

If you are not a fan of transgenic (GMO) technologies, just wait until you hear about the freakish practices scientists and big seed companies are sneaking under the radar!  Now, scientists soak seeds or tissues in toxic chemicals or subject them to high fields of radiation to cause random damage and genetic changes.  Random damage to DNA causes unknown effects that produce new proteins, leading to new plant traits.  The new plant lines are untested for safety and not assessed for environmental impact.  They want to put these on your dinner table and feed them to children! 

Actually it has been done for decades.  No opposition, no labels wanted, no protesters, no fear.  Okay for organic cultivation and the EU.  Let's look at a mutation breeding!

All genetic variation starts with mutation.  Mutations are changes in DNA that ultimately may affect the expression or performance of a gene product.  Mutations occur spontaneously at high rates during DNA replication and in response to natural mutagens like UV light.  Cellular surveillance mechanisms are extremely robust and fix these errors before they affect the organism-- usually.  Occasionally an error is not corrected and results in a permanent change in that gene, perhaps changing a trait of interest.  Mutations are the source for pure genetic variation, but also are the basis for many diseases.

Mutation breeding is the process of inducing genetic variation in a crop through use of chemical treatment or radioactivity.  Chemicals like ethyl methane sulfonate (EMS), sodium azide (SA), N-nitroso-N-methylurea (NMU) are used to soak seeds or treat tissue or pollen in culture.  They induce random changes in DNA, usually single bases or small deletions. These changes alter the encoded protein, forming new proteins that may be more or less functional, or perhaps truncated or even not made at all.

For radiation, fast neutrons, x-rays or gamma rays bombard seeds causing double-strand breaks in chromosomes.  These lead to larger deletions of genetic material and sometimes rearrangements.  These changes are essentially random. They are induced by short-term exposure (seconds to hours) to a powerful radioactive source, usually Cobalt-60. The Institute for Mutation Breeding in Japan has generated a number of cultivars using these techniques.

A powerful radioactive source in the center of this field hammers
surrounding plants with gamma rays.  This treatments induces random damage
DNA that results in new genetic variation.  

Actually many cultivars have been produced using this technique.  Barley, wheat, corn, bananas, grape, tomato, sunflower... at least 3000 induced-mutant plant lines in the Mutant Variety Database. Some are ornamentals, so not all food crops.

Transgenic techniques come under fire for many reasons.  Let's hold mutation breeding to the same criteria and compare the two techniques.

How do transgenic (GMO) plants compare to plants derived from mutation breeding
for commonly raised criticisms?

What about labels, organic cultivation, growth in the EU?   No problem if the plant's DNA has been scrambled by radiation or chemicals! 

Angry citizens demand to know what is in their food... 
unless it is mutation bred, then not so much. 

For intellectual consistency, mutation breeding of crops must be considered much more random, unpredictable, un-assessable and imprecise.  There is no question that genetic changes have been made, as traits of interest are selected based on visible traits, such as resistance to drought/cold in wheat.  There is no easy way to assess what additional genetic baggage comes along with that new trait.

Don't get me wrong, I don't see any problem with mutation breeding.  The techniques are proven successful at producing useful genetic variation that results in improved plants.  Awesome. As a scientist, it is difficult to reconcile how this method is freely accepted, while transgenic techniques are harshly criticized. Or is it?

Maybe it simply points out that the scientific and intellectual arguments against genetic alterations are not the real concerns-- they are just strawmen for the actual political, business or social agendas. The science of transgenics is a convenient place to cultivate misunderstanding and fear.  But somehow the same fear mongers miss mutation breeding.  It tells us a little about the real agenda.  It is not about the process or product, but rather, who makes the product.


Adam said...

Thanks for the post.

Incidentally, I once had the opportunity to ask a well-known academic critic of genetic engineering how he thought the risks of the two methods compared.

He said that he thought that there were risks to mutation breeding which should call for caution. However, he added that he thought there was an added risk with transgenics because of the vector used to inject the DNA. I don't recall him saying anything specific about this concern, but I'm wondering if you see anything to worry about there? I've read a bit of anti-GM literature and so far I haven't seen anybody else worried about that.

Kevin M. Folta said...

Hi Adam, I think it shifts the goalpost. That was the point if this blog in a overarching way. Critics say that GE is imprecise and with unknown effects. However, they freely accept a less precise and more unknown method for generating genetic variation. No problem!

So if you back someone into a corner with mutation breeding then they will shift to some other concern that is specific to transgenics- in this case a "vector".

The "vector" is just DNA. Part of it moves from Agrobacterium (the organism that does the transfer, exploiting a natural process) to the host genome. You can figure out where it integrates and what sequences are there.

Vector sequences are benign and new science is showing that there are natural sequences in most plants that are identical to the vector sequences already (Rommens et al. 2006).

My point was simply to illustrate how the arguments made are not about the science-- it is about who does the science. A small private plant breeder using poisons to induce 100,000 random changes or genomic instability is okay... but a big ag company that adds one gene of known function is waaaaay out of bounds.

That's the inconsistency I was pointing to. Thanks for your thoughts.

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