In my last post, “10 Amazing GMOs” we discussed little-known GMOs that are ubiquitous. Now I would like to discuss some food crops that are not thought of as GMOs, however their genomes are anything but “natural”.
You might have a feeling that mini, seedless vegetable varieties are not simply found in NATURE. But, have you ever wondered how these varieties get on store shelves? Maybe you imagined a monkish farmer, puttering around an idyllic farm with stooped shoulders, painstakingly cross pollinating plants by hand with a Q-tip. You may have never imagined that a scientist using DNA mutating technique like intense radiation bombardment and toxic chemical baths was most likely the source of these endless and wonderful varieties. Does this sound scary? It’s not, we promise!
Crop scientists are folks who improve our food crops and the productivity of our fields. They apply soil and plant sciences to crop production, incorporating the smartest use of natural resources and conservation practices to produce food, feed, fuel, fiber, and pharmaceutical crops, while maintaining and improving the environment.
Lettuce, for example, is a hugely important crop. It is the second most consumed vegetable in the USA. Lettuce grew in the wild prior to domestication by humans. It is still not exactly clear which species turned into today’s lettuce. “Boston Bibb” has a soft buttery texture that is compelling. It has been selectively (meaning the mutation was found in the field and propagated from there) bred to resist the herbicides sulfonylurea, imidazolinone (imazethapyr) and triazolopyrimidine (flumetsulam).
Farmers wanted lettuce that was specifically resistant to these herbicides because they are some of the safest herbicides in use today. They are also some of the most potent and highly selective, so therefore farmers only need to apply a small amount. The biological pathway they affect exists only in plants, not in animals. This food crop would never be labeled as a “GMO” under current guidelines, even though the mutated gene produces an effect that people insist they want to be informed about (i.e., herbicide resistance).
“Mutation” breeding techniques have generated a vast amount of genetic variability and they play an enormous role in modern agriculture- food, flower and tree breeding. There is a handy website that collects SOME of the non-transgenic mutant varieties (for a basic explanation of what IS transgenic visit Nature Education). They list more than 3200 mutant varieties, which are sold in more than 70 countries. I poked through the database, it’s easily searchable by country of origin, mutation method, trait that was changed, and plenty of other search criteria.
The database lists physical and chemical mutation agents (agents that can cause a change in DNA) that have been used to make mutations in plant genomes, such as; X-rays, ultraviolet radiation, neutrons, protons, alpha, beta, and gamma rays, and ethyl methane sulfonate (EMS) treatment.
These are used to either increase mutation rates or yield mutants unavailable from natural sources. “GMOs” (i.e. transgenic) crops are regulated by three federal agencies- FDA, EPA, and the Department of Agriculture. This is not the case for crops where new traits have been created by non-transgenic methods- even though the OUTCOME is often the same (for example, glyphosate resistance). There is no mandated requirement to list new mutant varieties in the database. Many small seed developers use a whole range of new, emerging genetic technologies that fall outside the current range of regulated processes.
A couple of great examples are:
Sometimes scientists modify crops for no real reason other than profit, for example, to turn a once unwanted fruit, albeit one that grows well, into something that consumers love to buy.
Created sometime in the 18th century, a grapefruit is a hybrid of an orange and a pummelo. It was bitter, thick skinned, and unappetizing, but citrus crops grow well in southern USA. Dr. Richard Hensz of the Texas A&I Citrus Center (now known as the A&M Citrus Center) spent many years in the laboratory, working to produce the reddest grapefruit possible through mutations induced by ionizing radiation, to give us the dark pink, sweet, seedless, thin-skinned variety we love today “Star Ruby” and “Rio Red”!
Scientists use radiation mutagenesis commonly to breed resistance to diseases. Some examples include in Ghana, which produces about 15 percent of the world’s chocolate, where scientists used radiation mutagenesis to fight a virus that was killing and crippling millions of cocoa trees. In the USA “verticillium wilt” a disease with no known chemical control was contaminating all of the regions where peppermint can grow, until radiation induced resistance was bred.
Often, the characteristics that are manipulated are to produce higher crop efficiency, to make more off of less land. Scientists used gamma rays on barley to produce Golden Promise, a mutant variety with high yields and improved malting. After its debut in 1967, brewers in Ireland and Britain turned it into premium beer and whiskey. This barley is still used today to make premium Irish whiskey and is even made into organic beer (Golden Promise Organic Ale)!
Other (non-transgenic) methods exist to transfer genes between species of plants, such as by “somaclonal variation” (plant tissue culture), activation of endogenous transposable elements, or irradiation facilitated translocation. Basically, plants have their own ways to swap genes back and forth, they do it “naturally” all the time.
What most people think of as “GMOs” are really produced through recombinant DNA technologies, a very small subset of techniques used to modify the genomes of plants. WHY DO GMOs get THE BAD RAP?! The above mentioned breeding methods are considered non-transgenic, they face little opposition from environmentalists, governments, growers, and the general public. Under organic regulation radiation breeding and induced mutagenesis are completely acceptable. Mutated food crops that are currently sold as organic include, lettuce, beans, grapefruit, rice, oats, and wheat.
One example of “translocation”, transfer DNA from a very distantly related plant to one that is commonly grown, genes from wild relatives of wheat can be transferred into common (bread) wheat. These hearty genes from these distant relatives provide resistance to diseases like “powdery mildew” and “leaf rust” that strike wheat crops.
All of the techniques mentioned above are really pre-cursors to today’s “genetically modified organisms”. Plants developed via these older techniques possess random, multiple and unspecified genetic changes. These imprecise methods can and do occasionally generate food with potentially hazardous traits. Scientists prefer using newer methods to genetically modify crops, i.e. inserting just one or two specific and targeted genes into well known locations in the genome (the old techniques are like pounding the genome with a hammer, the new techniques are like slicing the genome with a scalpel).
In the United States, the plant breeding community is mostly self–monitored. Regulatory agencies do not evaluate conventional new crop varieties for health and environmental safety prior to commercial release, except for those crops (and animals) produced through recombinant DNA technologies. In the past 5 years, up to 30 genetically modified organisms have worked around the USDA regulatory system on technicalities of process— most recently a mushroom developed with CRISPR/Cas9 to resist browning.
We wanted to introduce you to some other ways that scientists modify crop genomes other than by recombinant technologies and the reasons why they do. What is or isn’t a GMO is practically impossible to define. I will leave you with this quote so you can ponder and decide!
“There are GMOs that reduce pesticide spraying, and GMOs that increase pesticide spraying. There are GMOs designed to serve monoculture, and GMOs made for small farmers with mixed plots. There are GMOs made to work hand-in-hand with herbicide, and non-GMOs made to work hand-in-hand with herbicide. There are GMOs controlled by big corporations, and GMOs given away for free by universities.”
This article also appears on Medium.