Friday, 30 November 2012

Links


  • The genome of bread wheat has been sequenced. Not only is this an impressive feat (the wheat genome is a very large and complicated thing which arose through the fusion of three other genomes) it is also very promising in terms of feeding the world. About 20% of human calories come from wheat, and knowing the genome will make it easier to improve the crop in the future. 


Sunday, 25 November 2012

"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 

Wednesday, 21 November 2012

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. 
  • 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. 
  • 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.  

Thursday, 15 November 2012

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.


Wednesday, 7 November 2012

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]