GM CROPS PART 3: What have GM crops done so far?

Other articles in this series:
Part 1: What are GM crops?
Part 2: Why do we need to improve our crops? What's wrong with the way they are now?

What have GM crops done so far?

Farmers have been growing GM crops since 1994 and they are now grown in 29 different countries. Most of the GM crops currently being grown are modified in one of three ways - they are either herbicide tolerant, insect resistant, or both. This article will explain what these things are and what they have achieved. I will then briefly introduce some of the other GM crops that have been grown.

If you like graphs and want to know more about the history and current status of GM crops around the world, I thoroughly recommend these slides.

Herbicide tolerant crops
When crops are grown in fields they have to compete with other plants (weeds) for the things that they need (water, soil nutrients, sunlight). This is a big problem for farmers because it means that the crops produce less food than they would if there were no weeds competing with them.

Farmers have a number of methods for dealing with weeds. Before the crop is planted, the field can be ploughed to destroy weeds. Once the crop is growing, the farmer can go into the field and remove weeds by hand. The general word used to describe mechanical methods such as these is 'tillage'. Another option is to spray the field with herbicides (chemicals that kill plants). Some herbicides are 'specific', meaning that they only kill certain types of plant, so the crop itself is unharmed.

However, all of these methods have their downsides. Tillage disturbs the soil, which causes greenhouse gasses to be released and results in soil being removed by the wind and rain. It is also time consuming and requires a lot of work. Herbicides pollute the environment, and the use of specific herbicides means that many different herbicides have to be used to make sure that all the different types of weed are killed. Also, herbicides are expensive, especially if you have to buy many different specific ones. As I mentioned in part II, many of the world's poorest farmers cannot afford herbicides.

Not all herbicides are specific. There are some that kill almost all types of plant. These are known as 'broad-spectrum' herbicides. Of course, the problem with using them is that they would also kill the crop. This is where GM comes in. Some plants and some bacteria have genes that tell them how to survive the broad-spectrum herbicides. These genes can be transferred to a crop, making it resistant to the herbicide. GM crops that have been created in this way are known as 'herbicide tolerant crops'. A farmer who grows herbicide-tolerant crops can spray their fields with broad-spectrum herbicides safe in the knowledge that the crop will be unharmed, while almost all weeds will be killed.

Farmers have been growing herbicide-tolerant crops for about 16 years now and it has had three main impacts:

Firstly, it has meant that weeds are killed more effectively. This means that more food is produced per unit of land and farmers no longer have to use mechanical methods such as ploughing which release greenhouse gasses and lead to soil degradation.

Secondly, it has caused farmers to switch from using many different specific herbicides to using just one of the broad-spectrum herbicides. Not only does this save the farmer money, it also benefits the environment because the commonly used broad-spectrum herbicides are less damaging to the environment than most specific ones.

Thirdly, the use of broad-spectrum herbicides means that less herbicide has to be used, because one spray of herbicide kills almost all of the weeds. Research shows that in the 12 years from 1996 to 2008, the use of HT crops caused a 5% reduction in the amount of herbicide used worldwide on cotton, soybean, maize and canola. This benefits the farmer because they spend less money on herbicide and less time spraying it, and the environment because less herbicide is released.

Insect resistant crops
Another problem that farmers face is insects eating their crops. One way to deal with this is to spray crops with insecticides (chemicals that kill insects).

However, there are a number of downsides to this approach. Many insects (such as the corn borer) are able to dig their way inside plants and lay their eggs there. Since insecticides are only sprayed onto the outside of the plant, the insects on the inside are not affected. Also, insecticides can be washed away by rain (which can lead to contamination of rivers). Also, although it is usually only one or two types of insects that are eating the crop, many insecticides are very general and kill lots of different types of insects (including natural enemies of the target insects). Insecticides are generally quite expensive and many of the world's poorest farmers cannot afford them. Poor farmers who can afford them often spray them onto the crops by hand. This means that the farmer comes into contact with a large amount of insecticide and poisonings are common in countries such as India and China.

There is a soil bacterium known as 'Bt' which has a special set of genes. Each of these genes tells it how to make one particular protein, and each of these proteins is poisonous to one specific type of insect. It is possible to take one (or more) of these genes and transfer it into a crop plant. This results in a 'Bt crop', which is able to produce its own insect poison. So far, Bt genes have mostly been used in cotton and maize and it has had many benefits.

Since the insect poison is constantly produced by the plant itself throughout the whole of the plant, there is no risk of it being washed away and it works inside the plant as well as outside. This means that the plant is better protected so more cotton is produced per field¹. Secondly, since each Bt protein is only poisonous to one particular type of insect, there is no harm to other insects² and there is no harm to the people who eat it or the farmers who grow it. Thirdly, there is no need for the farmer to buy or spray insecticide. This saves the farmer money³, prevents farmer poisonings⁴, and reduces the amount of insecticide released into the environment⁵.

What other GM crops are being grown?
Almost all of the GM crops that are currently being grown are plants that have been modified in one or both of the ways discussed above. However, there are a few other GM crops being grown in relatively small amounts. For a full list, see the slides I mentioned in the introduction, but here I will just mention one type that I think is quite interesting: the virus-resistant crops.

Just like animals, plants can be affected by viruses. It is possible to protect plants from viruses by transferring a harmless gene from the virus to the plant. This tells the plant how to produce a harmless protein that the virus usually produces. The plant's immune system then trains itself to recognise the protein, so that if it is attacked by the virus the plant will be able to recognise it quickly and destroy it. Papaya that has been modified in this way is grown in the USA and has been credited with saving the Hawaiian papaya industry.

PART 4: What could GM crops do in the future? (coming soon)
There are a lot of new GM crops that have been developed and are going to start being grown in the next few years. Most of these are very different to the ones currently being grown and often address different problems. Part 4 will introduce you to these new GM crops and what they could achieve.

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FIND OUT MORE ABOUT:
Herbicide-tolerant crops
Bt crops
The impacts that GM crops have had so far

REFERENCES:
1 Huang and co-workers, 2002 (table 3)^{↩(return to article)}

2 Lu and co-workers, 2012 analysed twenty years worth of data on the number of different types of insects in fields in northern China. They found that the introduction of Bt cotton over the last 16 years has led to a decrease in the number of aphids (which eat crops) and an increase in the number of spiders, ladybirds and lacewings (which eat aphids). They found that the presence of these aphid-eaters also protects nearby fields of non-GM cotton.^{↩(return to article)}

3 Huang and co-workers, 2002 (table 5)^{↩(return to article)}

4 Huang and co-workers, 2002 (table 6)^{↩(return to article)}

5 Huang and co-workers, 2002 (table 4)^{↩(return to article)}

GM CROPS PART 2: Why do we need to improve our crops? What's wrong with the way they are now?

Other articles in this series:
Part 1: What are GM crops?
Part 3: What have GM crops done so far?

Why do we need to improve our crops? What's wrong with the way they are now?

We need to produce more food. While it is true that the world currently produces enough food to feed everyone on Earth, this will not be the case for long if we do not improve our crops. By the year 2050, world population will have risen from its current level of around 7 billion to around 9 billion (an increase of about 30%). If our ability to produce food does not increase then we will not be able to feed these people.

Although we are currently producing enough food to feed everyone, a large chunk of the world's population is starving. This is because rich countries are producing more food than they need, while poor countries are not able to produce enough food. One solution might be for the rich countries to donate their extra food to the poor countries, but there are obvious problems with this strategy. Surely it would be better to give people in poor countries the ability to produce more food for themselves? One of the reasons that poor countries cannot produce enough food is that their farmers cannot afford the large amounts of fertilisers, weed-killers and insecticides that are currently needed to produce large amounts of food.

Hunger isn't the only problem that we face. Many of the world's poorest people suffer from what are called 'nutrient deficiencies'. This means that their diet does not contain enough of certain things (like vitamins, iron and zinc) that are needed to live a healthy life. This is often because their diet mainly consists of one crop, such as rice, and this crop does not contain all of the things that are needed to be healthy. This often means that these people do not develop properly and have weak immune systems. Many of these people live in parts of the world where they do not have access to the medicine needed to treat infections, so having a weak immune system is a serious problem. (Read more about this here).

There are other factors that mean we will need to produce more food in the future. Firstly, some poor countries are becoming less poor. This is clearly a good thing, but it does mean that people in those countries will start wanting to eat more of a mixed diet than they currently do, including more meat. Meat production requires a lot more land than growing crops (partly because the animals have to be fed and that food comes from crops). This is land that we do not have available. Also, meat production is much worse for the environment that growing crops (read more about the environmental impact of eating meat here). Another problem is global warming. Although it might seem like warmer weather should help with growing crops, the reality is that climate change will make it much harder to produce food in the future.

The way that we currently produce food causes a lot of damage to the environment. Fertilisers, weed-killers and insecticides cause serious pollution. Their use also contributes massively to our global greenhouse gas emissions. But we can't just stop using them. We absolutely rely on them for food production. If we stopped using them then a lot more people would be starving. Fortunately, there are ways of using them more effectively so that smaller amounts are needed. However, the ideal solution would be if we had plants that produced large amounts of food without any need for these inputs.

Unfortunately, food production has another impact on the environment that is worse than anything I have mentioned so far. Land that is used for farming is much, much, much worse at absorbing carbon dioxide (one of the major greenhouse gasses that cause global warming) than land that is left to grow naturally. In fact, research has shown that the increased use of fertiliser, weed-killers and insecticides in the past 40 years has actually had an overall positive effect on the environment, because it meant that we could produce more food per field, which meant that we needed less farmland than we otherwise would have.

So what can GM crops do to help with these problems? Well actually they have done quite a lot already and have the potential to do a lot more in the future. Find out more in Part III (coming soon). 

GM CROPS PART 1: What are GM crops?

Other articles in this series:
Part 2: Why do we need to improve our crops? What's wrong with the way they are now?
Part 3: What have GM crops done so far?

What are GM crops?
GM stands for 'genetically modified'. This post explains what that means.

Every living thing contains a set of instructions that tell it how to be itself. These instructions are called 'genes'. An elephant has a set of genes that tell it how to be an elephant. An oak tree has a set of genes that tell it how to be an oak tree. A bacterium has a set of genes that tell it how to be a bacterium.

Most living things have thousands of genes (a human has about twenty thousand) and each gene is the instruction for doing one particular thing. If you compared the genes in two different living things (a cat and a sunflower, say), you would find that there are quite a lot of genes that they have in common. This is because there are many things that they both need to do. For example, a cat and a sunflower both need to burn food to release energy. In order for a living thing to burn food it needs to produce a set of tiny machines called 'enzymes'. Therefore the cat and the sunflower both have genes that tell them how to produce these machines. However, there are obviously also a lot of differences between a cat and a sunflower, so they don't have all the same genes. A cat has genes that tell it how to make eyes, a sunflower doesn't. A sunflower has genes that tell it how to make petals, a cat doesn't. It is a living thing's complete set of genes that make it what it is. A living thing's complete set of genes is called its 'genome'. 

All of the genes (instructions) that exist are written in the same language (the language of DNA). This means that if a gene is transferred from one living thing to another it will still work. This happens naturally all the time because viruses and bacteria are able to physically move genes from one living thing to another. For example, bacteria regularly pass useful genes on to each other (such as genes that allow them to survive antibiotics). It isn't just tiny bacteria that share genes though, all living things do it. For example, it has recently been discovered that a quarter of the cow genome was transferred over from a snake!

Scientists have found their own ways of moving genes from one living thing to another. This means that we can add genes to crops (the plants that produce our food). We can give a crop a new gene that we have taken from another living thing. This new gene tells the crop how to do something that it couldn't do before. The crop is now called a 'genetically modified (GM) crop' because it has had its genome modified. 

Click here to read Part II. It's called 'Why do we need to improve our crops? What's wrong with the way they are now?'

Coming Soon: 'Genetically modified crops, good or bad? My thoughts.'

When I first applied to Cambridge University, they sent me the following question and told me that I would be expected to discuss it at interview:

'What are the benefits and potential risks of genetic modification?'

It was a question that I had wanted to know the answer to for a while, so I was glad to have something to motivate me to do some reading about it. I had heard about genetic modification, and genetically modified crops in particular, on the news, but didn't feel very well informed. All I really knew was that GM crops were something that scientists had made for farmers and that a lot of people were opposed to them.

So I did some reading. I found out about the different types of genetically modified crops, why they have been developed, what advantages they have and what concerns people have about them. I didn't exactly become an expert, but I felt informed enough to have an interesting discussion on the topic. I was looking forward to that part of the interview.

When the interview did roll around, the interviewers made it clear early on that they didn't want to discuss the advantages and disadvantages of genetic modification. Instead, they wanted to quiz me on my understanding of the technical aspects of how scientists genetically modify things in the lab. I don't really mind though. Being set that question started me on the path that I am still following today. I am still trying to improve and refine my answer the question they set me.

The good news is that they accepted me and I spent three years studying science in Cambridge. In the third year I specialised in plant sciences, which gave me plenty of opportunity to learn more about genetic modification. I learnt new things about genetically modified crops, I met some of the scientists who develop them and I read more about some of the risks that might be associated with them.

Since graduating, I have started this blog. I try to write about a wide range of plant and food related topics, but the issue of GM does seem to come up quite a lot. For a while now, I have been aware of the fact that although I mention GM a lot on here, and I generally seem to give the impression that I am in favour of it, I have never explicitly explained my stance on the issue.

Then, a few weeks ago, a friend posed the following question to me: "What are the main good things about GM crops and what are the main legitimate concerns about their use?" Apparently he recently came close to disagreeing with a stranger on a bus who was bad-mouthing GM crops, but then realised that he didn't really know much about it so kept quiet (he is clearly very brave, I would never do that). So he has turned to me for answers (which is fair enough, I do talk about crop science quite a bit).

Up until now, I haven't really felt too worried about the fact that I haven't gotten round to explaining my position on GM crops. This is because I know that no-one actually reads my blog posts (friends keep telling me that they opened the page but then "it all got sciency" so they closed it. I'm trying to work on this.). But, now that someone has actually asked me directly, I feel like now is the time to write about it, because I know that at least one person will read it.

In late 2008, Cambridge University asked me a question that motivated me to read about something that I had been meaning to read about for ages. Now, my friend has asked me a question that has motivated me to write about something that I have been meaning to write about for ages.

In the next day or two, I will put up a post explaining my stance on GM crops. I will try to make it as readable as possible and avoid scientific terms as much as possible. Hopefully it will be something that I could show to the me of four year ago and save him a lot of time. [Update: in the end I decided to do a series of posts called 'GM Crops'. Click here for part one. (Also, it definitely took me more than a day or two).]

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P.S. Yeah, I know. It is quite weird that I have posted a post about an upcoming post. I did consider adding the second post to the bottom of this one, but that would mean that it had a 600 word introduction, which makes me feel uneasy. Sorry if you read this hoping that it would contain anything other than self-indulgent anecdote. 

Links

Hello to all my regular readers! Since you don't exist, you probably won't have noticed that I haven't posted here for quite some time. This is because I decided that I was going to 'take December off'. I realise now that this was a very poor decision because it meant that I started the new year with a list of articles that I wanted to read so long that it has taken me until mid-January to get through them (I use google reader).

The good news is that I am now back and have a big old stack of links for you. A few of them are things that I haven't actually read yet myself but since they look interesting and I don't want to leave the blog dormant for even longer while I get round to reading them, I have decided to just post them anyway. Enjoy!

• If you only follow one of these links, follow this one. It is a video of a talk given by the journalist and environmental activist Mark Lynas to the recent Oxford Farming Conference. In the talk, he apologises for the years that he spent campaigning against GM crops, says that he has now 'discovered science' and explains why he is now in favour of GM. Not only it is amazing that this has happened, it is also a really well-delivered talk, in which he explains his reasons very clearly. 

• Getting bacteria to produce useful chemicals for us is probably a much better idea than making them ourselves from oil. Mainly because it makes us less dependent on oil.

• Bread that lasts for 60 days could cut food waste. 

• A nice video from Kew Gardens about the Millenium Seed Bank Partnership. 

• 'Redrawing the Tree of Life' is a fantastic piece by Carl Zimmer about the way in which scientists have been rethinking evolution since the days of Darwin. 

• 'The GM crop risk-benefit debate: science and socio-economics' - this looks really good, but it is also quite long and I haven't gotten round to reading it yet. If you have read it, then let me know what you think. 

• Karl from the Biofortified Blog guides us through a recent talk he gave about the benefits and risks of genetically engineered crops.

• 'Counting the Cost of the Anti-GMO Movement' - argues that opponents of GM crops have actually done a lot of harm. 

• An interesting article about new food preservation techniques that are being developed.                (hat-tip to The Science of Food)

• 'GM crops increase biodiversity, study finds'. This is obviously very exciting news, but I think the headline should probably be more like 'one particular type of GM crop has been shown to increase biodiversity in one particular region of China'. If you're wondering how this is possible, the explanation is that this crop (BT cotton) requires less insecticide to protect it, so there is less damage to local insects. For more detail, see my post on BT crops or this 'BT cotton Q&A' document. 

• The cotton genome has been sequenced

"We Must Remove the Landmines That Limit Access to Biotechnology in Africa" - Motlatsi Musi

An interesting article about the potential benefits of GM in Africa:

"GM technology is not a panacea. It won’t solve all of our problems. African farmers face a long series of challenges, from an inadequate infrastructure to political corruption. Yet access to the latest crop technologies will give us a fighting chance, especially as the climate changes and we try to adapt to new and possibly harder conditions. Drought-resistant plants represent an especially hopeful opportunity.

Too much of Africa missed out on the Green Revolution. We cannot afford to let Africa ignore the Gene Revolution. Unfortunately, many people, especially in Europe, don’t want us to benefit from these developments..."

Read the full article here: http://www.truthabouttrade.org/2012/11/21/we-must-remove-the-landmines-that-limit-access-to-biotechnology-in-africa/

Hat tip: GMO Pundit 

Genetically Modified Apples That Don't Brown!

Read all about it here: http://www.biofortified.org/2012/07/okanagan-specialty-fruits/

Here is a jack-o'-lantern made from one of the apples. Note how white the flesh is.

Picture from http://www.biofortified.org/2012/11/contest-winner-ghoulish/

Links

• One of the oldest, and most controversial, groups of GM crops are the so-called 'herbicide-tolerant' crops. These crops have been engineered to be resistant to certain chemical herbicides, so these herbicides can be sprayed to kill weeds without having to worry about having any affects on the crop. There is a lot of debate about them, and I'm not really sure where I stand on it. Anyway, this PDF from Purdue University explains some of the basic facts. 

• This brilliant article explains that Italian scientists, who failed to predict an earthquake that was impossible to predict, should not have been sued for manslaughter. 

• The genome of a pear has been sequenced. The exciting thing is that we live in an age of such advanced sequencing technology that this isn't really big news. 

• One of the most promising avenues for developing new biofuels is to break down cellulose (the material that plant cell walls are made of) to form sugars that can be fermented to make fuel. This would allow us to convert inedible parts of crops, such as the stems of corn plants, into fuel. Scientists are constantly looking for better ways of breaking the cellulose down, and this report suggests that we may be able to get algae to do it for us. 

• More exciting biofuels news. 

• A fantastic paper about some really common problems with the way that statistics are reported in scientific research. Anyone who plans on writing a scientific paper about any kind of research should read this.  

• ATTACK OF THE KILLER BROCCOLI!!!!

Is Resistance Futile? How useful can GM really be in the battle to protect our crops?

Anyone who has studied military history will probably be familiar with the concept of an 'arms race'. One army develops some new type of weaponry which gives them the edge over their rival. The rival responds by developing a slightly better type of weaponry so that they now have a slight edge. This prompts a new development from the first army, which then prompts another new development from the second, and so on. As the process continues, both armies make a great deal of progress in terms of military technology, but very little progress in terms of their ability to overpower the other rival. They are both always either slightly stronger than, slightly weaker than or roughly the same strength as the other army.

Arms races are not just a human phenomenon, but are also a key part of evolution, including plant evolution. All plants are constantly locked into evolutionary arms races with two groups of living things: pathogens (organisms such as microbes and viruses that cause disease) and pests (organisms such as insects and grazing mammals that eat plants). As soon as a plant species evolves a new line of defence (a new poison perhaps), these pathogens and pests begin evolving some way of overcoming that defence (an antidote, for example). This arms race occurs not because the organisms want to outdo each other, but because of the inevitable pull of natural selection.

A cabbage plant which happens (not through design, but through sheer genetic luck) to be born with a new type of anti-slug poison will be more successful than the other cabbages around it and will produce more seed. Its offspring (which inherit the new line of defence) will similarly out-compete the cabbages around them. Within a few generations, the entire field will be full of slug-proof cabbages. It is only a matter of time, however, before a slug is born which (not through design, but through sheer genetic luck) is resistant to the poison. This fortunate creature will have access to all of the cabbage that the other slugs cannot eat and will therefore grow big and strong and produce lots of babies. Before long, all of the slugs in the field will be resistant to the poison. And so the arms race goes on. It is important to note the this slug only had an advantage because the poison existed. If the the poison did not exist then this slug would have had an antidote to a non-existent poison, which is no advantage. The existence of a defence actually causes the evolution of a counter-defence. It is a battle that has been raging for hundreds of millions of years and is not going to stop any time soon.

At some point, just a few thousand years ago, we got ourselves involved in this fight, and ever since we have been doing everything we can to protect our crops from pests and disease. Our most recent weapon is the use of genetic modification to give crops defence mechanisms that they might never have evolved naturally. For example, there are a group of genetically modified (GM) crops called the 'Bt crops' which have been given genes from a bacterium in order to protect them from insects that like to eat them.

The bacterium which donated the genes is a soil-dweller called Bacillus thuringiensis (Bt for short). Bt has a set of genes that allow it to produce a special group of anti-insect proteins. If an insect eat the bacterium, these proteins damage the inside of that insect's stomach, causing it to die. For decades, farmers (including organic farmers) have sprayed the bacterium onto their crops as a form of natural pesticide. Each of the anti-insect proteins affects only one type of insect, meaning that there is no harm to other organisms in the field, or to humans who eat the food.

There are two drawbacks to spraying crops with the bacterium. Firstly, it can be washed off by rain. Secondly it does not get inside plant stems, which is where some insects (such as the corn borer) like to lay their young. Transferring the Bt genes to crops solves these problems because it means that the plants themselves produce the proteins.

In the late 90s Bt cotton and Bt corn (which each contain one Bt gene for one Bt protein) were invented. They are now grown on hundreds of millions of acres around the world (mostly in the USA, Australia, China and India, but they are becoming more widespread in other countries; other Bt crops such as Bt rice are also in the pipeline). Not only has this raised yields, it has also reduced the use of pesticides, which can be harmful to the environment due to, among other things, their effects on non-target insects. In many countries, such as India and China, farmers previously sprayed powerful pesticides from containers on their backs, resulting in many farmers being poisoned. Since the introduction of Bt cotton the number of poisonings has gone down significantly.

But there is a problem with Bt crops, which you might be able to guess by now. At some point an insect might be born which is resistant to one of the Bt proteins. This would give it an advantage and before long there would be many resistant insects. Unfortunately, this has already happened, multiple times in multiple countries (including the USA, Pakistan and China). At the moment, resistant insects account for only few percent of the insect pests in those areas, but if nothing is done, it is only a matter of time before Bt-resistance spreads and Bt-crops become completely useless. But what can be done?

Well, ever since Bt crops were first grown, scientists have tried to prevent insects from becoming resistant by urging farmers to plant 'refuges' of non-Bt crops next to their Bt crops. This reduces the advantage that a Bt-resistant insect would have, since the other insects can still find some food. However, the advantage is only reduced, not completely eliminated, so while this strategy can delay the problem it cannot completely prevent it.

So is it hopeless to expect GM to protect our crops in a sustainable way? Well, actually, it might not be.There is a new technique called 'engineering durable resistance' that might just put an end to the arms race. It is a very simple idea and it works like this: rather than giving a GM crop one way to kill a pest or pathogen, you give give it multiple ways to kill that one pest or pathogen. For example, a new version of Bt cotton has been released in the US and Australia, which has two different Bt proteins that both kill the cotton bollworm. Now, a cotton bollworm which is born with resistance to one of the proteins has absolutely no advantage, because the cotton plant will still kill it. In order to have an advantage a bollworm would have to be born with resistance to both proteins, which is very unlikely. If the number of proteins was increased to say, 4 or 5, then the chances of a bollworm being born with resistance to all of them are vanishingly small.

Of course, it is impossible to know for certain whether this represents a long-term victory. In theory, durable resistance should provide lasting protection, but theory doesn't always turn out to be right. The appropriate response at this stage is probably something along the lines of quiet optimism.

I just discovered these 3 short videos about genetic modification...

...and I think they're quite good.

News from the journals

A few interesting stories from recent papers published in scientific journals:

Soybeans adapt to Chernobyl's radioactive soil by improving their heavy metal tolerance

The disaster that occurred at Ukraine's Chernobyl Nuclear Power Plant in 1986 was probably the worst nuclear accident that there has ever been. But despite the devastating size of the disaster, plant life continues to grow in the radiation-contaminated area. In order to investigate how plants manage this surprising survival trick, a team of scientists from Ukraine and Slovakia planted soybean seeds in two fields in the Chernobyl area in 2007. The two fields were very similar in terms of soil type, but one of them was radioactive and the other one wasn't. A year later the scientists harvested and analysed the soybeans. They found that after a year's exposure to radiation the plants in the radioactive field were different, in a number of interesting ways, from the plants in the non-radioactive field. Notably, they had adapted to be more tolerant of the heavy metals that cause the nuclear contamination.

Like most scientists who do something cool because of curiosity, but need to find practical reasons to justify the funding they receive, the researchers end their recent paper by suggesting ways that further experiments into this subject could be useful. Their first suggestion is that with a better understanding of how plants adapt to the radioactive environment, it could be possible develop ways of growing biofuel crops in the area (which, for obvious reasons, is not currently used for growing food crops). If you think that this represents some serious out-of-the-box thinking, then wait until you see their second suggestion:

"With a little of imagination, it is also tempting to speculate that understanding plant adaptation toward ionizing radiation (cosmic radiation) will be necessary for plant cultivation for food purposes during long space missions in the future."

[Read this paper for yourself at: dx.doi.org/10.1371/journal.pone.0048169]


Using a computer model to test ideas about plant cell wall structure

Just like animals, all plants are made up of little bags of life called cells. In plants (but not in animals) each cell is surrounded by a rigid structure called the 'cell wall'. Cell walls give plants shape, strength and stability (qualities we achieve with our muscles and bones).

Although we know what components plant cell walls are made from, we still only have educated guesses about how these components are arranged. One of the most popular ideas is that strong tubes called 'cellulose microfibrils' (they are a bit like tiny scaffolding poles) are held together by long, stringy molecules called 'hemicelluloses', in an arrangement something like that shown in the diagram below. The theory is that this binding together of the cellulose microfibrils is what gives the cell wall its large amount of strength.

In order to test this idea, two researchers from Pennsylvania State University have created a computer simulation of a cell wall, complete with simulated cellulose microfibrils and simulated hemicelluloses to hold them together. Once the simulation had been produced, they asked the computer what would happen if the cell wall was stretched, and whether the result would be different if the links between the two components were removed.

They found that the presence of the links does make a big difference. Without them, the simulated cell wall was much less able to withstand stretching. This is an important piece of evidence which suggests that this arrangement may actually be how the components are arranged in real life. However, they also found that even with the links, the cell wall was still not strong enough to withstand certain types of stretching that real-life cell walls could easily cope with. This suggests that in real-life, cell walls must have other, additional mechanisms to resist stretching.

[Read this paper for yourself at: dx.doi.org/10.1104/pp.112.201228]



Genetically Modified Soybeans with increased beta-carotene content

A few weeks ago I wrote about Golden Rice, a variety of rice which has been genetically modified to produce beta-carotene (an important, but often absent, component of human nutrition). Now, a team of Korean researchers have genetically modified Soybean to do the same thing.

[Read this paper for yourself at: dx.doi.org/10.1371/journal.pone.0048287]

Golden Rice: A GM crop designed to fight malnutrition

It is well known that there a lot of people in the world today who are malnourished. Unfortunately, this problem is actually two problems. The first is that people do not have enough food to eat. The second is that people don't have access to the right type of food. One of the most serious examples of this second problem is vitamin A deficiency. This post is the story of Golden Rice, a genetically modified (GM) crop designed to help prevent vitamin A deficiency. 

Vitamin A is an essential part of a healthy diet. Not having enough of it leads to night blindness, anemia, and a weakened immune system, with particularly bad effects in children and pregnant women. The effects on the immune system are particularly troubling since most of the countries that suffer from vitamin A deficiency also have high rates of infectious diseases. Vitamin A deficiency weakens a person's immune system leaving them vulnerable to these diseases. Infection with disease often then leads to a reduced appetite and reduced absorption of any vitamin A that is consumed, meaning that the person becomes even more vitamin A deficient, which in turn makes them even more vulnerable to disease. It is a vicious cycle.

The easiest way to get enough vitamin A is to eat animal products, but if the human body doesn't get enough from that source then it can also make its own vitamin A from another chemical, called beta-carotene. Beta-carotene is an orange-coloured pigment found in many fruits and vegetables - for example, it gives carrots their orange colour. When you eat fruit and veg that contains beta-carotene your body turns that beta-carotene into vitamin A. Unfortunately, there are many people in the world, especially in Africa and South Asia, who do not get enough vitamin A because their diet is not high in meat or vegetables. Instead, their diets are mainly based around rice, and while the rice plant itself does produce beta-carotene, it does so only in the leaves and stem. No beta-carotene is found in the grain (the part that people eat). This means that vitamin A deficiency is a big problem in these regions. Approximately one third of the world's preschool-age children are estimated to be vitamin A deficient and when only Africa and South-East Asia are considered, this figure rises to approximately 44-50%. It has been estimated that making enough vitamin A available to all of the world's children would prevent around 2 million child deaths per year.

This is where Golden Rice comes in. Golden Rice is a variety of rice that has been genetically modified to make it produce beta-carotene in the grain. Since beta-carotene is an orange pigment, this means that the rice grains are orange instead of white (as shown on the left in the picture below), which is where the name 'Golden Rice' comes from (okay, so orange and gold aren't quite the same colour, but I guess 'orange rice' would have sounded a bit rubbish).

Golden Rice grains (left) and normal rice grains (right)

At the moment, Golden Rice is still going through the regulatory process that all new GM crops have to go through. Once it is ready to be used, the seeds will be given to poor farmers around the world for free. It has been bred with local varieties in the regions that it is being given to, so that it has the same characteristics as the rice that people are used to. Farmers won't have to change their growing practices and consumers won't have to change their cooking habits. The only difference will be that they will be getting a healthy dose of beta-carotene with each bowl of rice they eat. Just like normal rice, farmers will be able to reuse the seed from one harvest in order to grow rice for the next season. This means that the new seeds only have to be distributed to each region once. 

Although Golden Rice has not yet been given to any farmers, the project has been underway for at least twenty years. Scientists began working on it in 1992 and it was in 1999 that they first managed to produce rice that made beta-carotene in its grains. However, the levels of beta-carotene produced were considered too low. Although this rice would have provided more beta-carotene than normal rice, it did not have high enough levels to completely fulfill the needs of people who are eating little else than rice. The experiments continued and by 2005 the scientists had managed to get the beta-carotene up to a much higher level. It has been shown that about 100-150g of this new version of Golden Rice can provide about 60% of a child's daily vitamin A requirement. Since then, the rice has been going through various tests to prove that it is safe for people to eat and that it won't harm the environment. The people behind the project are currently working with regulators in some target countries and hope to transfer Golden Rice seed to some farmers in the next few years. 

Many of the people who work on the Golden Rice project feel that progress so far has been unnecessarily slowed down by excessive regulation of GM crops. One the plant's two co-inventors, Ingo Potrykus, wrote an article in the scientific journal Nature in which he argued that there is no logical reason for new GM crops to have to undergo any more tests than other types of new crop. He argues that the the current regulations on GM crops are putting unnecessary financial and time constraints on the development of crops that could otherwise be preventing death and suffering. 

There are others, however, who think that Golden Rice seeds should never be given to any farmers at all. For example Greenpeace, who are opposed to all GM crops, have written articles criticizing the Golden Rice project (for example, this one and this one). Not only do they think that the new rice is a dangerous, untested technology, they also feel that it is completely unnecessary given the other strategies that are available to combat vitamin A deficiency. 

In general, I tend to agree with the scientists from the Golden Rice project on these issues. However, a full discussion of my reasons for this would take a few more posts, and it is certainly something that I plant to write about in the future. For now though, I just wanted to present the basics of the story. Anyone who wants to read more about the Golden Rice project, or the science that enabled it should take a look at www.goldenrice.org and anyone who wants to read some of the arguments being made against it should have a look at some of these articles: 

http://www.greenpeace.org.uk/search/node/golden%20rice.