TED日本語 - パメラ・ロナルド: 実際の遺伝子組換え食料

I am a plant geneticist. I study genes that make plants resistant to disease and tolerant of stress. In recent years, millions of people around the world have come to believe that there's something sinister about genetic modification. Today, I am going to provide a different perspective.

First, let me introduce my husband, Raoul. He's an organic farmer. On his farm, he plants a variety of different crops. This is one of the many ecological farming practices he uses to keep his farm healthy. Imagine some of the reactions we get: "Really? An organic farmer and a plant geneticist? Can you agree on anything?"

Well, we can, and it's not difficult, because we have the same goal. We want to help nourish the growing population without further destroying the environment. I believe this is the greatest challenge of our time.

Now, genetic modification is not new; virtually everything we eat has been genetically modified in some manner. Let me give you a few examples. On the left is an image of the ancient ancestor of modern corn. You see a single roll of grain that's covered in a hard case. Unless you have a hammer, teosinte isn't good for making tortillas. Now, take a look at the ancient ancestor of banana. You can see the large seeds. And unappetizing brussel sprouts, and eggplant, so beautiful.

Now, to create these varieties, breeders have used many different genetic techniques over the years. Some of them are quite creative, like mixing two different species together using a process called grafting to create this variety that's half tomato and half potato. Breeders have also used other types of genetic techniques, such as random mutagenesis, which induces uncharacterized mutations into the plants. The rice in the cereal that many of us fed our babies was developed using this approach.

Now, today, breeders have even more options to choose from. Some of them are extraordinarily precise.

I want to give you a couple examples from my own work. I work on rice, which is a staple food for more than half the world's people. Each year,40 percent of the potential harvest is lost to pest and disease. For this reason, farmers plant rice varieties that carry genes for resistance. This approach has been used for nearly 100 years. Yet, when I started graduate school, no one knew what these genes were. It wasn't until the 1990s that scientists finally uncovered the genetic basis of resistance. In my laboratory, we isolated a gene for immunity to a very serious bacterial disease in Asia and Africa. We found we could engineer the gene into a conventional rice variety that's normally susceptible, and you can see the two leaves on the bottom here are highly resistant to infection.

Now, the same month that my laboratory published our discovery on the rice immunity gene, my friend and colleague Dave Mackill stopped by my office. He said, "Seventy million rice farmers are having trouble growing rice." That's because their fields are flooded, and these rice farmers are living on less than two dollars a day. Although rice grows well in standing water, most rice varieties will die if they're submerged for more than three days. Flooding is expected to be increasingly problematic as the climate changes. He told me that his graduate student Kenong Xu and himself were studying an ancient variety of rice that had an amazing property. It could withstand two weeks of complete submergence. He asked if I would be willing to help them isolate this gene. I said yes -- I was very excited, because I knew if we were successful, we could potentially help millions of farmers grow rice even when their fields were flooded.

Kenong spent 10 years looking for this gene. Then one day, he said, "Come look at this experiment. You've got to see it." I went to the greenhouse and I saw that the conventional variety that was flooded for 18 days had died, but the rice variety that we had genetically engineered with a new gene we had discovered, called Sub1, was alive. Kenong and I were amazed and excited that a single gene could have this dramatic effect. But this is just a greenhouse experiment. Would this work in the field?

Now, I'm going to show you a four-month time lapse video taken at the International Rice Research Institute. Breeders there developed a rice variety carrying the Sub1 gene using another genetic technique called precision breeding. On the left, you can see the Sub1 variety, and on the right is the conventional variety. Both varieties do very well at first, but then the field is flooded for 17 days. You can see the Sub1 variety does great. In fact, it produces three and a half times more grain than the conventional variety. I love this video because it shows the power of plant genetics to help farmers. Last year, with the help of the Bill and Melinda Gates Foundation,three and a half million farmers grew Sub1 rice.

(Applause)

Thank you.

Now, many people don't mind genetic modification when it comes to moving rice genes around, rice genes in rice plants, or even when it comes to mixing species together through grafting or random mutagenesis. But when it comes to taking genes from viruses and bacteria and putting them into plants, a lot of people say, "Yuck." Why would you do that? The reason is that sometimes it's the cheapest, safest, and most effective technology for enhancing food security and advancing sustainable agriculture. I'm going to give you three examples.

First, take a look at papaya. It's delicious, right? But now, look at this papaya. This papaya is infected with papaya ringspot virus. In the 1950s, this virus nearly wiped out the entire production of papaya on the island of Oahu in Hawaii. Many people thought that the Hawaiian papaya was doomed, but then, a local Hawaiian, a plant pathologist named Dennis Gonsalves, decided to try to fight this disease using genetic engineering. He took a snippet of viral DNA and he inserted it into the papaya genome. This is kind of like a human getting a vaccination. Now, take a look at his field trial. You can see the genetically engineered papaya in the center. It's immune to infection. The conventional papaya around the outside is severely infected with the virus. Dennis' pioneering work is credited with rescuing the papaya industry. Today,20 years later, there's still no other method to control this disease. There's no organic method. There's no conventional method. Eighty percent of Hawaiian papaya is genetically engineered.

Now, some of you may still feel a little queasy about viral genes in your food, but consider this: The genetically engineered papaya carries just a trace amount of the virus. If you bite into an organic or conventional papaya that is infected with the virus, you will be chewing on tenfold more viral protein.

Now, take a look at this pest feasting on an eggplant. The brown you see is frass, what comes out the back end of the insect. To control this serious pest, which can devastate the entire eggplant crop in Bangladesh, Bangladeshi farmers spray insecticides two to three times a week, sometimes twice a day, when pest pressure is high. But we know that some insecticides are very harmful to human health, especially when farmers and their families can not afford proper protection, like these children. In less developed countries, it's estimated that 300,000 people die every year because of insecticide misuse and exposure. Cornell and Bangladeshi scientists decided to fight this disease using a genetic technique that builds on an organic farming approach. Organic farmers like my husband Raoul spray an insecticide called B.T., which is based on a bacteria. This pesticide is very specific to caterpillar pests, and in fact, it's nontoxic to humans, fish and birds. It's less toxic than table salt. But this approach does not work well in Bangladesh. That's because these insecticide sprays are difficult to find, they're expensive, and they don't prevent the insect from getting inside the plants. In the genetic approach, scientists cut the gene out of the bacteria and insert it directly into the eggplant genome. Will this work to reduce insecticide sprays in Bangladesh? Definitely. Last season, farmers reported they were able to reduce their insecticide use by a huge amount, almost down to zero. They're able to harvest and replant for the next season.

Now, I've given you a couple examples of how genetic engineering can be used to fight pests and disease and to reduce the amount of insecticides. My final example is an example where genetic engineering can be used to reduce malnutrition. In less developed countries,500,000 children go blind every year because of lack of Vitamin A. More than half will die. For this reason, scientists supported by the Rockefeller Foundation genetically engineered a golden rice to produce beta-carotene, which is the precursor of Vitamin A. This is the same pigment that we find in carrots. Researchers estimate that just one cup of golden rice per day will save the lives of thousands of children. But golden rice is virulently opposed by activists who are against genetic modification. Just last year, activists invaded and destroyed a field trial in the Philippines. When I heard about the destruction, I wondered if they knew that they were destroying much more than a scientific research project, that they were destroying medicines that children desperately needed to save their sight and their lives.

Some of my friends and family still worry: How do you know genes in the food are safe to eat? I explained the genetic engineering, the process of moving genes between species, has been used for more than 40 years in wines, in medicine, in plants, in cheeses. In all that time, there hasn't been a single case of harm to human health or the environment. But I say, look, I'm not asking you to believe me. Science is not a belief system. My opinion doesn't matter. Let's look at the evidence. After 20 years of careful study and rigorous peer review by thousands of independent scientists, every major scientific organization in the world has concluded that the crops currently on the market are safe to eat and that the process of genetic engineering is no more risky than older methods of genetic modification. These are precisely the same organizations that most of us trust when it comes to other important scientific issues such as global climate change or the safety of vaccines.

Raoul and I believe that, instead of worrying about the genes in our food, we must focus on how we can help children grow up healthy. We must ask if farmers in rural communities can thrive, and if everyone can afford the food. We must try to minimize environmental degradation. What scares me most about the loud arguments and misinformation about plant genetics is that the poorest people who most need the technology may be denied access because of the vague fears and prejudices of those who have enough to eat.

We have a huge challenge in front of us. Let's celebrate scientific innovation and use it. It's our responsibility to do everything we can to help alleviate human suffering and safeguard the environment.

Thank you.

(Applause)

Thank you.

Chris Anderson: Powerfully argued. The people who argue against GMOs, as I understand it, the core piece comes from two things. One, complexity and unintended consequence. Nature is this incredibly complex machine. If we put out these brand new genes that we've created, that haven't been challenged by years of evolution, and they started mixing up with the rest of what's going on, couldn't that trigger some kind of cataclysm or problem, especially when you add in the commercial incentive that some companies have to put them out there? The fear is that those incentives mean that the decision is not made on purely scientific grounds, and even if it was, that there would be unintended consequences. How do we know that there isn't a big risk of some unintended consequence? Often our tinkerings with nature do lead to big, unintended consequences and chain reactions.

Pamela Ronald: Okay, so on the commercial aspects,one thing that's really important to understand is that, in the developed world, farmers in the United States, almost all farmers, whether they're organic or conventional, they buy seed produced by seed companies. So there's definitely a commercial interest to sell a lot of seed, but hopefully they're selling seed that the farmers want to buy. It's different in the less developed world. Farmers there can not afford the seed. These seeds are not being sold. These seeds are being distributed freely through traditional kinds of certification groups, so it is very important in less developed countries that the seed be freely available.

CA: Wouldn't some activists say that this is actually part of the conspiracy? This is the heroin strategy. You seed the stuff, and people have no choice but to be hooked on these seeds forever?

PR: There are a lot of conspiracy theories for sure, but it doesn't work that way. For example, the seed that's being distributed, the flood-tolerant rice, this is distributed freely through Indian and Bangladeshi seed certification agencies, so there's no commercial interest at all. The golden rice was developed through support of the Rockefeller Foundation. Again, it's being freely distributed. There are no commercial profits in this situation. And now to address your other question about, well, mixing genes, aren't there some unintended consequences? Absolutely -- every time we do something different, there's an unintended consequence, but one of the points I was trying to make is that we've been doing kind of crazy things to our plants, mutagenesis using radiation or chemical mutagenesis. This induces thousands of uncharacterized mutations, and this is even a higher risk of unintended consequence than many of the modern methods. And so it's really important not to use the term GMO because it's scientifically meaningless. I feel it's very important to talk about a specific crop and a specific product, and think about the needs of the consumer.

CA: So part of what's happening here is that there's a mental model in a lot of people that nature is nature, and it's pure and pristine, and to tinker with it is Frankensteinian. It's making something that's pure dangerous in some way, and I think you're saying that that whole model just misunderstands how nature is. Nature is a much more chaotic interplay of genetic changes that have been happening all the time anyway.

PR: That's absolutely true, and there's no such thing as pure food. I mean, you could not spray eggplant with insecticides or not genetically engineer it, but then you'd be stuck eating frass. So there's no purity there.

CA: Pam Ronald, thank you. That was powerfully argued. PR: Thank you very much. I appreciate it. (Applause)