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Crop biotechnology update 2: second generation traits and legislation
Published on August 29, 2019 44 min
A selection of talks on Methods
Artificial intelligence in medicine: history & state of the art
- Prof. John Fox
- University of Oxford, UK
Understanding statistics in epidemics and pandemics: lessons learned from COVID-19
- Prof. Sarah Ransdell
- Nova Southeastern University, USA
International biobanking: overview of key practices and policies
- Dr. Jim Vaught
- Editor in Chief, Biopreservation & Biobanking, USA
On the next slide, I will start to talk about quality, sometimes called second-generation traits, and this is tomato puree from slow-ripening GM tomatoes. Despite this being called a second-generation trait, this was the first GM crop product on the market, and it came on the market in two different forms from competitors in Europe and the United States. In the United States, we saw this technology, the slow-ripening technology induced using GM as fresh fruit- it was a flavor saving fruit. It was not successful and didn't last very long back in 1994. But, the same technology or similar technology and, again, to induce slow ripening, in tomatoes was used in Europe and was used successfully. This is the product that was made then, tomato puree, it was cheaper and thicker than it's non-GM competitors, and two million cans of this were sold in the UK between 1996 and 1999. Some people will tell you it wasn't clearly labeled. Well, you can make your own mind up from that picture, it is about as clear a food label as you're ever going to get as it says, "made with genetically modified tomatoes".
That technology went, in 1999, as the GM issue became a really difficult one for producers and retailers in Europe. But, there are some other second-generation quality GMs, and so one of them addresses the fatty acid composition of crops. Here you see some fatty acids, of course, these are the constituents of plant oils or to have animal fats, and each apex on these diagrams represents a carbon atom. So, the fatty acids are basically hydrocarbon chains with a methyl group on one end and an acidic group on the other end, hence the name fatty acid. The length of the chain and also the number of double bonds between the carbon atoms in the chain determine the properties of the fatty acid- not only the properties in the oil, but also the effect that they have on us when we consume them. Some of these are quite important to our health. But, you have relatively short ones like lauric acid which is 12 carbons with no double bonds. They're called saturated fats because to go from a double bond to a single bond is a hydration reaction. The fatty acids with no double bonds are referred to as saturated and ones with double bonds are called unsaturated. So, palmitic acid from palm and coconut has 16 carbons, or your stearic acid has 18 carbons- that's as long a chain as you get in higher plants. Stearic acid is also a major constituent of our body fat; the other is oleic acid. The next one down there, that is monounsaturated-. it has a single, double bond and that double bond is at position nine relative to the methyl end of the chain. For that reason, it's called an omega 9 unsaturated fatty acid- that is present in olive oil, also in peanuts. Then, you get more highly unsaturated fatty acids or polyunsaturated fatty acids. So, linoleic acid which has two double bonds, one in the sixth position and one in the ninth position as in safflower, sunflower, maize, peanut, and oilseed rape. Because the first double bond is at position six in the chain, that is an omega-6 fatty acid, including GLA which was a derivative of LA (linoleic acid) with a third double bond. So, it's double bonds at carbons six, nine and twelve- that is in orange and evening primrose oil. You get a very long omega-6 fatty acid, called arachidonic acid, which plants don't make. We can make it ourselves, relatively inefficiently, from GLA. There is no plant source of arachidonic acid, but we can get it from meat and dairy products in our diet. Another interesting one is erucic acid, present in industrial varieties of oilseed rape and is toxic. So, very low levels as a result of breeding in the oilseed rape for human consumption and a very seasonal omega-3, which is the first double bond at position three in the chain. So, ALA or alpha-Linolenic acid is present in oilseed rape, soybean, linseed oil; three double bonds, that's an omega-3. First, because the first bond is at position three, then you have two longer ones, eicosapentaenoic acid or EPA and docosahexaenoic acid or DHA. The second of those is 22 carbons as long as six double bonds and they're not made in plants, but are present in fish oil. Again, they are not made by fish, either, but, actually, they are made by marine algae, which will accumulate in the marine food chain and are very important, particularly, for infant growth and development. So, those fatty acids in EPA and DHA are often added to human milk formulas, and those are the reasons why it's so important to eat some fish oil.