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Vitamin C Origin

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Vitamin C is a key nutrient in the human diet, and strawberries are one of the best sources of it. In this Science Update, you'll hear about a scientist who's trying to tap into the secrets of the strawberry to make other plants more nutritious.


Transcript

A vitamin "C" change. I'm Bob Hirshon and this is Science Update.

Strawberries are naturally high in vitamin C. Now, scientists in Spain have found a way to pass on the berry's vitamin-C-making ability to other plants.

Miguel Botella is a molecular biologist at the University of Malaga. He and his colleagues first identified a gene in the strawberry that boosts the level of vitamin C in the fruit as it ripens. Recently, he and his colleagues inserted this gene into the DNA of a research plant called Arabidopsis, and they found it functioned in the same way.

Botella:

So it seems that just the use of a single gene can allow us to increase vitamin C at least two, three times in a different plant species—this is very important.

Botella says now they're testing whether the gene can boost vitamin C levels in other plants.

Botella:
We are trying to see if we can produce vitamin C in other important vegetables, like lettuce, or other fruits, like tomatoes.

Botella says they're also putting the gene into microorganisms, which could be part of a more cost-effective way to manufacture vitamin C supplements. The result could be many different ways to get your daily requirement of an important nutrient. For the American Association for the Advancement of Science, I'm Bob Hirshon.


Making Sense of the Research

For decades, food companies have been fortifying all kinds of foods with extra vitamin C. That vitamin C is made in factories, using complicated processes that leave behind a lot of toxic waste products. But they had no choice. That's because until very recently, scientists didn't really understand how vitamin C was made in nature.

Finally, in 1998, scientists discovered one chemical pathway that plants use to make vitamin C. But they suspected there were others. The pathway that Botella and his colleagues have identified in strawberries is an alternative pathway that scientists had suspected was used, but hadn't yet proven.

This pathway makes vitamin C out of a chemical that's released when a strawberry's cell wall breaks down as it ripens. This particular chemical is found in many different plants, but for some reason, strawberries make a lot of vitamin C out of it. The researchers discovered that one particular gene plays a big role in that process, and that putting that gene into another plant made that plant crank out more vitamin C as well.

One important point here is that the strawberry's genes were not changed at all in Botella's experiment. They were just transferred into another plant. Botella isn't sure if the trick will turn other fruits and vegetables into vitamin C machines, since the gene will probably work a little differently in each one. But because the chemical reaction triggered by the gene is fairly simple, he has high hopes.

Harnessing this chemical process could make it easier to get more vitamin C into people's diets. Instead of just adding the vitamin to foods in the lab, farmers could also grow foods that have higher vitamin C levels to begin with. And vitamin C supplements could be made either by imitating this cleaner, simpler chemical reaction, or getting helpful bacteria to do it for you.

This study was originally published in Nature Biotechnology. Other researchers included Fernanda Agius, Rocio Gonzalez-Lamonthe, Jose Caballero, Juan Munoz-Blanco, and Victoriano Valpuesta.

Now try and answer these questions:

  1. Why do strawberries have so much vitamin C?
  2. What was new about Botella's team's findings?
  3. How might this knowledge be used to change the way humans get vitamin C in their diet?
  4. If you were conducting experiments in which you transferred the strawberry gene into a lettuce plant (for example), what would you look out for? What kinds of benefits would you want to see to make this kind of genetic engineering worthwhile? What kinds of drawbacks would you look out for?

For Educators

The Ascorbic Acid Gallery, from the Florida State University's Microscopy Lab, has cool microscopic images of vitamin C at work.

How Vitamin C Works, by How Stuff Works, describes the chemistry of vitamin C and why it's important in the human diet.


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