Category Archives: Nutrition

Tweaking plant biology to solve the food crisis

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This article was originally published at The ConversaConversation logotion.

Hacking plant ‘blood vessels’ could avert food crisis

Today’s wars are not about food, but not too far in the future they could be. The number of people dying of starvation has been falling for decades, but the decline in the numbers of hungry people is slowing down. More than 800 million people remain undernourished. With nine billion mouths to feed by 2050, the task of feeding us all is only going to get harder.

There is a solution, though, according to a recent paper in the journal Nature written by some of the world’s leading plant biologists. They show that, by hacking how  plants transport key nutrients into plant cells, we could solve the impending food crisis.

Each plant is made of billions of cells. All these cells are surrounded by membranes. The pores in these membranes are lined with special chemicals called membrane transporters. They do the job of ferrying nutrients that plants capture from soils with the help of roots.

What scientists have learnt is that if such membrane transporters are tweaked, they can enhance plant productivity. When these tweaks are applied to crops, they can produce plants that are high in calories, rich in certain nutrients or fight pests better. All these methods increase food production while using fewer resources.

Currently, world agriculture faces the problem of shrinking arable land, which is the area that is fit for food production. This is why the world’s leading plant biologists argue in the Nature paper that we must embrace genetically modified (GM) plants, many of which have better membrane transporters making them more productive without increasing land use.

Good modification

ngtpvbfh-1368974463Over two billion people suffer from iron or zinc deficiency in their diets. Biofortification involves increasing concentration of such essential minerals. Simple genetic modification increases the amount of membrane transporters that ferry these minerals. Such plants when ready for harvest can have as much as four times the concentration of iron, compared to that of common crop variety.

A little known fact (pdf) is that making fertilisers consumes about 2% of world’s energy. This makes the process a significant contributor to emission of greenhouse gases. Modifying membrane transporters can help cut those emissions, because it can make a plant more effective at using plant fertilisers.

For instance, only 20-30% of phosphorus added to soil as fertilisers is used by crop plants. Tweaking transporters such as PHT1  can increase the uptake of phosphorus. Similar results can be obtained when NRT genes are modified, which increase uptake of nitrogen from fertilisers.

Better resistance

About a third of the Earth’s ice-free land is acidic. The problem is that in highly acidic conditions aluminium in soil exists in a form that is toxic to plants. Such land cannot be used to grow food, but if crops were able to counteract the effects of acidity on growth that land would become available.

Scientists have found some varieties of wheat that have a trick to enable them to grow in acidic conditions. One of its membrane transporter called ALMT1 pumps out malate anion from its roots into the soil which traps the toxic form of aluminium.

Varieties of wheat without this natural transporter can be improved by breeding with varieties that do. But, crops such as barley, which have no comparable system of transporter in its membrane, need to be genetically modified to express the ALMT1 transporter protein. This allows for greatly increased yields even in acidic soils.

When salt is bad

Much of the world’s arable lands are becoming salty as a result of current irrigation practices. This happens when, on evaporation, salts in irrigation water are left behind inthe soil. Salts are toxic to plants and are severely limiting yields in over 30% of irrigated crops.

But there are membrane transporters which can stem the flow of salts into plants. These transporters, from the HKT family, rid the water of sodium before it is taken up by the plants. One example is that of durham wheat, which was modified to possess the HKT5 gene. The modification helped increase its yield in salty soils by 25%.

Fighting from the inside

gmbp69dh-1369048466Disease-causing micro-organisms, pathogens, manipulate a plant’s functioning and consume the fruit of its labour. Most crops have membrane transporters called SWEETs that move sucrose made by leaves from photosynthesis to other regions where it may be stored. Plant pathogens have evolved to manipulate SWEET genes so that sugars are moved to cells where they can feed on the goods.

Now scientists have found a way of disrupting this pathogen-induced manipulation by a method called RNA-silencing. These reduce, or sometimes eliminate, the pathogens’ ability to feed on the plants’ hard work, and in turn they help increase plant productivity.

Not all bad

Researchers have been quietly chugging away in labs working on making such radical improvements to crops. Breeding of plants, a form of untailored genetic modification that bestowed most of the benefits to agriculture a generation ago, is not able to keep up with the pace of change required for an ever-increasing demand for food. That is why it is important that we understand the science behind the process of tinkering with specific genes, before jumping on the “GM is bad” wagon.

Scientists are aware of the moral, ethical and environmental discussions surrounding production of GM food, and have been working carefully to address those issues. It is important that they continue to do so, while exploring the full potential of GM research to tackle the issue of hunger that looms large over the future of our species.

Can athletes keep breaking records forever?

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Will the men’s 100m race on day be run in under 5 seconds?

Listen to my BBC radio chat with Malcolm. We discuss breaking world sporting records at 1 minute 25 seconds in this clip:

[audio http://www.brookes.ac.uk/lifesci/runions/DrMolecule/20120731 – World sports records and faked moon landings.mp3]

Will humans keep getting faster, stronger… sillier?

Although it seems that world record sports performances are being beaten all the time, I would suggest that a new world record is a very rare occurence indeed. We might feel like we hear about new world records alot but this generally coincides with us watching the very best the world has to offer competing in the Olympic games.

Long-established world records are broken occasionally but the longer records have been kept for a sport, the more unlikely becomes the probability of that record being broken again. The science/statistics/probability theory that tells us this is called ‘extreme-value statistics’ and is illustrated in my rather natty drawing below. Human beings capable of achieving anything close to world-record times are rare and the chances that those people are competing in a sporting event are rarer still. Every time 0.1 second is shaved off of a world record time, it becomes more unlikely that the new time will be bettered.

Extreme-value statistics demonstrates that as new records are set, the possibility of beating them is reduced.

If humans were to become bigger, stronger, and faster, then we would expect records to keep falling. Are we getting bigger? I would say yes – if I look around in the hallways of the university where I teach, I am now dwarfed by many of the undergraduate student body. This is not ‘evolution’. That process will always select for bigger and stronger, or smaller, if those characteristics aid in survival. Evolution takes millions of years. The fact that my generation is bigger than my parents generation and that the undergrads tower over me is down to nutrition. Childhood nutrition is vitally important and has never been so good for so many as it is at the moment. This results in the increased stature that I observe. Kids today are, therefore, bigger and stronger and I would say that if that trend continues – then world records will continue to fall.

5-a-day fruit and veg – what counts?

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So if I eat 5 servings of french fries will that do the trick?

Listen to my BBC radio chat with Malcolm. 5-a-day discussion starts at 1 minute 48 seconds in this clip:

[audio http://www.brookes.ac.uk/lifesci/runions/DrMolecule/20120717 – 5 a day and science on TV.mp3]

What does 5 a day mean?

The concept of 5-a-day has been widely adopted as a ‘guideline’ for how much fruit and vegetable you should consume on a daily basis. The suggestion is that 5 servings of different fruits and vegetables will have a health benefit for most people.

Some questions arise because of statements like that:

1) Do all fruits and vegetables count? 2) How big is a serving?  3) Can I eat 5 servings of just one type of fruit?

Would’t it be brilliant if 5 servings of french fries smothered in salt and ketchup (also a vegetable) did the job. I’d sign up to 5-a-day in a second. Unfortunately, that isn’t in the spirit of the suggestion. In fact, potatoes are one of the few vegetables that don’t count towards your 5-a-day. Potatoes and a couple of other vegetables are starchy and therefore count as a different component of your diet – even though they are widely believed to be vegetables 🙂

As for serving size, in total we are talking about 400 grams of fruit and veg a day or 80 grams for each of the 5 servings. I have just now weighed an apple on my lab scales and it weighed 153.47 grams. Then I ate it (only 4 more servings for me today then) and weighed the core (21.10 grams). In total therefore, I have just consumed 132.37 grams of apple goodness.

Nobody is suggesting that you should weigh out all of your fruit and veg. That’s the point of a simple to remember slogan like 5-a-day. Just eat 5 things that are roughly equivalent to an apple or slightly smaller in size.

french fries… maybe they’d count if the slogan was 6-a-day

The 5 things might be a whole fruit like a banana, apple or orange. They might be a serving of fresh or cooked vegetables like carrots, beans or corn. They could be canned or frozen vegetables. You might even have a smoothie or two (just don’t overdo the sugar). It is important to mix your vegetables to achieve the full goodness that the suggestion intends. Different fruits and vegetables contain different minerals and vitamins that are all essential for your good health. That’s why the slogan sometimes suggests that you eat different coloured fruits and veg. The colours are pigment molecules that in themselves are a source of dietary nutrition.

Can I have french fries for my remaining 4 servings today? Awww… I never get french fries…

Genetic modification – feeding the world

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Genetically modified plants will help feed the world and devrease our dependence on pesticides

Listen to my BBC radio chat with Malcolm:

[audio http://www.brookes.ac.uk/lifesci/runions/DrMolecule/20120522 – Linnaeus and genetic modification.mp3]

Super crops

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Dorothy Hodgkin

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Dorothy Hodgkin

Listen to my BBC radio chat with Malcolm:

[audio http://www.brookes.ac.uk/lifesci/runions/DrMolecule/20120508 – Coke and Dorothy Hodgkin.mp3]

Hodgkin – an Oxford science pioneer

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Coca-cola used to have what in it?!

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Before Red Bull gave us wings, Coke was the real thing

Listen to my BBC radio chat with Malcolm:

[audio http://www.brookes.ac.uk/lifesci/runions/DrMolecule/20120508 – Coke and Dorothy Hodgkin.mp3]

Cheap at twice the price!

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Is chocolate really good for you!?

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Chocolate

Listen to my BBC radio chat with Malcolm:

[audio http://www.brookes.ac.uk/lifesci/runions/DrMolecule/20120327 – Chocolate and baldness.mp3]

A ‘good news’ story

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