Science finds a way to boost key part of plant growth

Photosynthesis is the most important reaction on the planet, the process that ensures life exists at all. But it is also seriously flawed, with a glitch that greatly reduces its efficiency.

Now scientists have hacked the genetic code of tobacco plants to short-circuit this problem, and in doing so produced plants that are 40 per cent more productive. If it can be made to work in food crops, billions more people could one day be fed without using any more of the Earth’s resources.

Photosynthesis is a means of turning the sun’s energy into food. In the process plants take in carbon dioxide and give out the oxygen we breathe.

In this way, this one reaction sustains all but the most extreme of the planet’s ecosystems. But it is not perfect.

In plants, the system evolved billions of years ago, before there was oxygen in the atmosphere, and they still struggle to cope with it. Sometimes, particularly in warmer climates, rather than taking in carbon dioxide to produce sugars, photosynthesis goes wrong and the plant takes in oxygen instead.

When this happens, instead of making food the plant makes a toxic by-product. Removing this routinely wastes a huge proportion of the plant’s energy.

Although this occasional error in the process seems an inevitable part of the chemistry, the cost of dealing with it is not. Other photosynthesising organisms, such as E. coli and algae, have evolved far more efficient ways of dealing with the toxins.

Now researchers have managed to hijack their technique. After inserting genes from E. coli, and other organisms, into tobacco plants, they showed they could make the detoxification process far less expensive.

When they then grew these plants outside, the finding translated into improved yield. The modified plants had 40 per cent more biomass than those that had not been altered.

Amanda Cavanagh of the University of Illinois carried out the research, published in the journal Science.

She said it was very exciting, not least because researchers are now trying to transfer the technology to important crops such as soybeans, rice and potatoes.

The same yield increases there would make an agricultural improvement similar to that created by pesticides and fertilisers in the Green Revolution of the 1950s, but without the need for chemicals.

‘‘If these 30 to 40 per cent gains could be potentially realised, that’s really powerful,’’ Cavanagh said. ‘‘The difference here is that these increases will come without investing in more nitrogen and chemical inputs.’’

Another difference, and one reason the research is backed by the Bill and Melinda Gates Foundation, is that with no special inputs such plants could be grown everywhere. ‘‘The Green Revolution didn’t help African growers,’’ Cavanagh said. ‘‘This opens up the potential to reach an audience that the last Green Revolution did not.’’

Howard Griffiths of the University of Cambridge said the important advance in the latest work was that plants had been grown in realworld conditions.

‘‘Anyone can produce these plants and show subtle growth responses in controlled conditions,’’ he said.

‘‘It’s getting it to work in a field, where there is wind, high temperatures and water stress. That’s when you can start to think this is real, cool, and very impressive.’’

However, he added that if the technology did successfully transfer to crops, the public would have to change its opinion of genetic engineering. In Britain, we import some genetically modified foods, but they are not grown commercially. ‘‘These plants are clearly genetically modified in a big way,’’ he said. ‘‘If this is to be used in wheat or rice then you will have to get the crop accepted in the general populace.’’

Amanda Cavanagh of the University of Illinois ‘‘If these 30 to 40 per cent gains could be potentially realised, that’s really powerful.’’