Tinkering with photosynthesis pays off

In an undated handout image, tobacco seedlings, part of a study of genetic engineering techniques to alter photosynthesis at the University of Illinois.
In an undated handout image, tobacco seedlings, part of a study of genetic engineering techniques to alter photosynthesis at the University of Illinois. PHOTO: NYTIMES

URBANA (Illinois) • A decade ago, agricultural scientists at the University of Illinois suggested a bold approach to improve the food supply: Tinker with photosynthesis, the chemical reaction powering nearly all life on earth.

Now, after years of work funded by the Bill & Melinda Gates Foundation, the scientists are reporting a remarkable result.

Using genetic engineering techniques to alter photosynthesis, they increased the productivity of a test plant - tobacco - by as much as 20 per cent, they said on Thursday in a study published by the journal Science.

The scientists' plan is to try the same alterations in food crops, and one of the leaders of the work believes production gains of 50 per cent or more may ultimately be achievable.

This could prove crucial as farmers face increasing pressure to grow more food to feed an ever- growing population.

The United Nations' Food and Agriculture Organisation projects that by 2050, the world will need to grow 70 per cent more food, as the global population rises to more than nine billion people. Add in rising temperatures and more extreme weather from climate change, and the threat to global food production increases still further.

One of the leaders of the research, Dr Stephen Long, a crop scientist who holds appointments at the University of Illinois at Urbana- Champaign and at Lancaster University in England, emphasised in an interview that a long road lay ahead before any results from the work might reach farmers' fields.

The research involves photosynthesis, in which plants use carbon dioxide from the air and energy from sunlight to form new, energy- rich carbohydrates.

These compounds are, in turn, the basic energy supply for almost all animal cells, including those of humans. But for a decade, Dr Long had argued that photosynthesis was not actually very efficient.

In the initial work, the researchers transferred genes from a common laboratory plant, known as thale cress or mouse-ear cress, into strains of tobacco.

The effect was to increase the level of certain proteins that already existed in tobacco.

When plants receive direct sunlight, they are often getting more energy than they can use, and they activate a mechanism that helps them shed it as heat - while slowing carbohydrate production.

The genetic changes the researchers introduced help the plant to turn that mechanism off faster once the excessive sunlight ends, so that the machinery of photosynthesis can get back more quickly to maximal production of carbohydrates.

These genetic changes sharply increased the yields of different tobacco strains.

Because the machinery of photosynthesis in many of the world's food crops is identical to that of tobacco, theory suggests that a comparable manipulation of those crops should increase production. Work is planned to test that in crops that are especially important as dietary staples in Africa, like cowpeas, rice and cassava.

Dr Long said that if rising global temperatures cut the production of food, human society could be destabilised, while more efficient crop plants could potentially make the food system more resilient.


A version of this article appeared in the print edition of The Straits Times on November 19, 2016, with the headline 'Tinkering with photosynthesis pays off'. Subscribe