字幕表 動画を再生する 英語字幕をプリント Hello, my name is Pam Ronald. Thank you for joining me today with iBioSeminars. Today I'm going to talk about one of the most important issues of our time. To introduce you to the subject, I'd like to start with a short video that was put together by the University of Minnesota's Institute for the Environment. How do we feed the world without destroying it? This is the question that my husband, Raoul Adamchak, and I have been discussing for many years. Raoul is an organic farmer. Here he is at the UC Davis Student Farm, talking to his students. He's been an organic farmer for 30 years, and we've had quite an opportunity to talk about these issues together. Some people believe that organic farmers and plant geneticists represent opposite ends of the agricultural industry, and some people think we might even not be able to talk to each other. But, we can. And that's because we have the same goal -- how to create an ecologically-based agricultural system. Still, many of our friends and family have asked us if organic agriculture is enough to feed the world. And they've also asked us, "Are genetically engineered crops safe to eat and safe for the environment?" So, in order to answer these questions, Raoul and I recently wrote a book together. And, in the book, what we tried to do is to introduce the reader to what an organic farmer actually does and what a plant geneticist actually does. So, we take the reader through some events of our days and answer questions that come up on the topics of farming and food. So, the first step was to establish criteria for more sustainable agriculture. And, a sustainable agriculture rests on three pillars: social, economic, and environmental. For social, it's important that communities have local food security, and they must have access to abundant, safe, and nutritious food. In order for an agriculture to be sustainable, the farmer must be able to sell their crops, and the communities must be economically viable. The food that's produced must be affordable to community members. Environmental aspects are critically important, and one of the goals of sustainable agriculture is to reduce harm to the environment, reduce energy use, reduce soil erosion, and foster self-fertility. We also want to minimize use of land and water, and this is very important because today we have 4-fold reduced access to water, compared to individuals 50 years ago, and we have very little arable land left to farm on the planet. It's also important that crop systems be genetically diverse, both to reduce the possibility of disease outbreaks and also to foster beneficial insects. Now, the USDA National Organic Program Standards really evolved in response to the environmental aspects of conventional agricultural systems. And I wanted to give you a couple examples of the power of farming practices to achieve a sustainable agriculture. So, organic agriculture uses fewer pesticides than many conventional systems, and one of the reasons is that the National Organic Program Standards prohibit the use of synthetic pesticides. This is my husband's farm at the UC Davis campus, and you can see that he also uses a strategy of genetic diversity. So, they plant many different types of crops, and this will reduce harm from pests and disease. Organic farms are 2x as energy efficient, and they have improved soil fertility, primarily through the use of the addition of compost and crop rotation. And as I mentioned, this genetic diversity also enhances microbial and insect diversity, which is important to maintain these non-harmful insects in the field because these insects will actually prey on pests that can harm the crops. So, with all these benefits, many people ask, "Is organic agriculture enough to feed the world?" "Can we rest with the USDA National Organic Program Standards, or are there reasons that we need to look towards the future?" Now, organic agriculture, like all agricultural systems, have problems with pests, diseases, and stresses. And many of these are very difficult to control using organic methods. Some pesticides used by organic farmers are not sustainable, in the sense that even though they're not synthetic, some of these pesticides are highly toxic to animals in the environment. Although the yields of an organic farm really depend on the farmer, the crop, the particular year... so it's difficult to generalize about the yield of organic agriculture, studies have shown that the yield is 45-100% of conventional systems, depending on the particular crop and farmer and year. Organic food is often more expensive than conventionally grown food, and this can be a problem for low-income consumers. So, I want to talk about the power of improved seed and discuss whether modern genetic approaches can contribute to a sustainable agriculture. In this slide, I wanted to give you a short history of agriculture and plant breeding. It's estimated that 10,000 years ago, the first primitive domestication was carried out, in wheat, rice, and corn. A few thousand years later, the first grafting was carried out in 100 BC. Grafting is mixing two different species onto one plant, so it's the first example of biotechnology. Then, we can see, over the last 400 years, there have been many different advances in plant genetics. So, for example, Gregor Mendel discovered the law of heredity in 1866. In 1876, the first intergeneric crosses were carried out. That is two very different species -- wheat and rye -- were combined to develop new varieties, We also saw the beginning of mutation breeding. So what mutation breeding is, and we still use it today, is you take a random chemical mutagen... You take a chemical mutagen or radiation... you randomly mutagenize the entire genome. So what that means is you're introducing changes to those genes. And then, what a breeder will do is he'll sort through a lot of those seeds, and then pick out those that have traits of interest. So there won't be any information about the genes that have been changed, but just that there's a new trait. The first recombinant DNA molecule was discovered in 1973. And the first genetically engineered crop was engineered in 1993. So, since that time, we've seen a vast growth in the development of genetically-engineered crops and, in fact, in 2005, farmers planted a billion acres of genetically-engineered crops. And today, I think the cumulative is about 2 billion acres. So, what is this plant breeding? And just to give you an idea of how dramatically the plants that we eat today have changed from those of our ancestors, I show you here teosinte corn on top, and this is the progenitor of modern-day corn. And the progenitor corn, you have to take a hammer to break it open to release the kernels. Through a long process of breeding initiated by Native Americans 8,000 years ago, today we have modern corn, which yields hundreds, if not thousands, more grains per plant. So this shows you the dramatic power of genetics, using conventional plant breeding approaches. This is another example of plant breeding over the ages. These are versions of a single crop species... these are Brassica species. And these were developed in Europe over the last 800 years. So, you can see that plant geneticists have used conventional breeding to generate dramatically different plants, and of course, some of us prefer some of these vegetables over others. So, what is genetic engineering, and what is precision breeding, and how does it differ from conventional breeding? And I want to mention that precision breeding is also called marker-assisted breeding, and it's also a modern genetic approach. So, with conventional breedings, what I've shown here are, you can imagine two parents, one in orange, one in red... They each have their own set of genes. And what breeders have done over the years is, they will take the pollen from one plant, put it on another and essentially by doing that, they're mixing all the genes of the two different varieties. And they end up with a progeny that is a mixture of the two parental genomes. So, in this case, many uncharacterized genes are mixed together, and then what breeders will do is they will carry out additional breeding experiments to try to get rid of unwanted genes. Now, one important aspect of conventional breeding is that gene transfer is limited to closely related species. In contrast, with genetic engineering or precision breeding, one to few well-characterized genes are introduced. So, in this case, you can take, for example, one variety, and you can simply add a gene of interest. And, with genetic engineering, this gene can come from any species... so that's a big difference between conventional breeding. Finally, what you end up with is a new variety that has one gene introduced. So it's a very precise introduction of a single gene. So, one big question is ... It's necessary that anything we eat is safe to eat and safe for the environment. And so this has been a subject of study or the National Academy of Sciences in the United States as well as 15 other countries around the world. And there's a very useful report that can be looked at called the Safety of Genetically Engineered Foods. So, this is one of several reports that have been put out by the National Academy of Sciences. What we can say is that after planting of 2 billion acres of genetically engineered crops, there hasn't been a single case of adverse health or environmental impacts. And this is really important to remember, because any time we introduce a new plant variety, whether it's genetically engineered or developed through conventional breeding, there is always some risk of unintended consequences. But, importantly, the method of introducing genes through genetic engineering presents similar risk to the methods of introducing genes by conventional approaches of breeding. So, it's not the method of introducing genes that's critical, but it's the product. What is the variety that's being developed? And, who do those varieties benefit? So, because of the importance of looking at the new variety that's developed, all new crops must be considered on a case-by-case basis. So, we cannot simply say that genetic engineering is all beneficial or all harmful. We really need to look at the crops developed through this technique. So, let me give you an example of one genetically engineered crop that was developed over several years. This is a papaya that's infected with papaya ringspot virus.