Rewiring Plant Genes: And Not a Single Mutant Mammoth in Sight


In theory, DNA is quite easy. It has fewer letters than the periodic table, for one thing, and a team of scientists have already mapped out the genomes—or gotten pretty close, anyways.

In practice, the realm of genetics involves a little more work—and some DNA research just seems unavoidably worrying. I distinctly remember pondering articles about whether scientists should use traces of DNA to bring mammoths back to life, which smacks of Frankenstein. It’s awesome that science has progressed so far, but I can’t help my fear that we’d end up with mutant mammoths. (Jurassic Park was really eye-opening.)

Of course, you don’t need mammoth DNA to do impressive things. Groundbreaking genetics can be as simple—and more importantly, as harmless—as a transgenic plant. For the past few years, a team led by the plant biologist Dr. Richard T. Sayre has been doing experimental work to boost the nutritious value of an edible root called cassava.

Normally, I’m kind of against attempting to improve what nature has perfected. If you’ve ever had wild fruit or homegrown veggies off the vine, it’s hard to approve of the flavorless wannabes in the produce aisle. But genetically modified crops are definitely the good guys in this story.

Cassava, also called manioc or tapioca, feeds people all across Africa, Asia and South America. There are several species of the starchy root, but the main two are the sweet and the bitter species. The bitter one serves as a staple in the diet of those living in countries in sub-Saharan Africa. Since the bitter version involves cyanide, it has to be soaked properly to get rid of the toxicity. Cassava’s pretty safe if it’s been prepared right, but if there’s any lingering cyanide, eating the crop can cause a horrible condition known as “konzo,” or “tied legs,” which makes it difficult or impossible to walk. Recently, researchers discovered eating toxic cassava might also cause mental deficiencies similar to the effects of lead exposure damage--though more subtle.

The nutritious facts don’t make cassava look much better. Although millions of people rely on cassava for most of their daily calories, the root crop delivers a measly amount of minerals and vitamins—hovering around 10-20 percent of a person’s daily iron, zinc, vitamin A and vitamin E—and a little protein.

Luckily, we’re centuries past Mendel’s famous pea plant experiment, where he systematically tracked how plants inherited genetic traits. Dr. Sayre’s team has the ability to explore genetic solutions. Their goal is to make a transgenic variation that will fit the nutritious needs of these communities. This means raising levels of the vitamins and minerals within the crop, while decreasing the amount of cyanide.

It’s definitely an ongoing experiment. The team had been working on the project for a few years already in 2005. They’ve seen some successes and published some papers, but it’s a very delicate process to rewire something genetically. Take the cyanide, for instance. Its very toxicity, which hurts humans who eat cassava, protects the plant from rotting and acts as a natural pesticide. Balancing plant and human needs will require creativity.

It might not be mammoth-scale, but the genetic engineering is an impressive feat. Maybe in time projects like these will even make way for the mammoth projects. Until then, I’m happy the cassava experiments are on their way towards success, without a single mutant mammoth in sight.

Photo courtesy of the National Cancer Institute.



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