Vol. 197 August 1, 2018 GMO Tomatoes?

August 1, 2018

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“ The sad reality is that industry is not really committed to making a better tasting tomato.”
– Harry J. Klee, Ph.D., University of Florida

 

It’s August on Cape Cod, and I have yet to taste a big red luscious locally grown tomato! How long do I have to settle for the bland, tasteless, but very red (they gas green tomatoes with ethylene to turn them red) commercially grown ones?! Is there any hope for a better tasting commercial tomato?

GM (genetic modification) has been going on for centuries through selective breeding and artificial selection by the hands of mankind to improve plants and animals. Pre-Columbian natives, by selecting and re-planting those wild scrubby plants that had bigger, redder, and more fruits, started the development of the beefsteak heirloom tomato we know today. There is probably no vegetable or fruit that we eat today, including corn, soybean, and potatoes, that is not the result of mankind’s genetic selection over thousand of years.

But now those initials, GM or GMO, spark great controversy because scientists can do the genetic selections in a much shorter time in the laboratory. The initial GMO crops introduced by Monsanto in the 1990’s were “transgenic” products;. foreign DNA, even from other species, was introduced or “spliced” into the genes of plants to make them more resistant to Monsanto’s herbicides. Corn and soybean which could thrive in the rain of a new, “more effective” herbicide ignited wide-spread concern and speculation about the long-term effects of the “foreign DNA” GMO crops.

In the same year of 2012 the Tomato Genome Project completed its listing of the 900 million DNA base pairs on 12 chromosomes of the tomato AND a gene-cutting technique dubbed CRISPR  was first described.  Scientists from three universities  published their CRISPR research separately in the same year. UC Berkley , MIT, and Harvard continue the legal battles over the patent rights which will be worth billions. CRISPR is basically a pair of biological scissors that allow scientists to precisely snip and delete part of a gene. It is referred to as “gene-editing”. It is not “transgenic”. No “foreign DNA” is involved or inserted.

For example, for the past 60 years growers have been trying to develop a “jointless” tomato. The classic tomato plant develops a swollen knuckle of tissue in its stem just above the fruit. When the tomato is ripe, the stem knuckle gets a signal from the plant for its cells to die, the stem breaks at this “joint”, and the tomato falls to the ground to happily spread its seeds and make new plants. The problem for the tomato grower who is mechanically harvesting tons of tomatoes is that the residual long stem pierces lots of other tomatoes in the picking process. The damage makes them unsellable. By CRISPRing the gene responsible for the knuckle and deleting it, a “jointless” tomato plant results in a bigger, undamaged crop, and more money for the grower.

Other CRISPR experiments are aimed at developing “self-pruning” tomato plants that are half as tall, less bushy, and with more fruits. Some experiments hope to develop plants that flower earlier, that ignore daylight clues, that require a smaller footprint, and that space their fruit on a stem like an accordion. If you discern that these efforts are all aimed at improving the tomato’s financial return in the market place, you are right. One cynic has stated that the “perfect tomato will be one that exactly matches the size of a MacDonald hamburger… A better tasting tomato always plays second fiddle to market economics.”

CRISPR is great at knocking out or deleting genes. It edits genes. The US Department of Agriculture has determined that crops developed with gene editing mutations are “indistinguishable” from those produced by traditional breeding and “do not require regulatory oversight”. It is a long way from the research lab to the market place via the three agricultural mega-conglomerates, but a variety of start-up companies are developing CRISPR-like technologies for getting cheaper, and maybe better tasting, gene-edited produce to market.

So, just when you hoped that life would be getting simpler and choices might become fewer, you now have to ask yourself a new question, “If it’s GMO, is it transgenic (jury is still out) or just gene-edited (approved)?” Although we may be a long way from getting commercially grown tomatoes that taste as good as our locally grown beefsteak heirlooms, do not fear, CRISPR may soon produce a gluten-free wheat!

Reference: “Tomorrow’s Tomato”, Stephen S. Hall, WIRED, August 2018, pg.053-061

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