Improving Photosynthesis in Rice to Reduce Hunger & Poverty

Professor Jane Langdale, Dr Steve Kelly and colleagues are part of an international research consortium working towards a step change improvement in the yield of rice.

Improving the yield of rice, one of the world’s most important crops, is an essential part of ensuring global food security and a key goal for reducing poverty and hunger in the developing world. The international C4 Rice Consortium is working towards a step change improvement in rice yields by changing how the rice plant photosynthesises, which if successful will boost productivity and reduce water use.

The concept is to switch rice from using the C3 photosynthetic pathway, which is not very efficient, to using the more efficient C4 photosynthetic pathway.

Photosynthesis is the process by which plants convert carbon dioxide (CO2) from the atmosphere into sugar using sunlight. In most plants, including rice, CO2 is first fixed into a compound with three carbon atoms, hence it is known as “C3 photosynthesis”. The enzyme that fixes CO2 into sugar can also react with oxygen in an energy-wasting process known as photorespiration. This process occurs especially at higher temperatures, such as in the tropics where most rice is grown, and causes a dramatic reduction in the amount of CO2 that is converted into sugar.

Rice field on terraces in Vietnam, by cristaltran, iStockPhoto

C4 plants, on the other hand, have naturally evolved a way to minimise this energy wasting process by using an oxygen insensitive enzyme to first fix CO2 and thus are more efficient at converting CO2 into sugar. This increased efficiency is accompanied by increased water and nitrogen use efficiency and improved adaptation to hotter and dryer environments. C4 photosynthesis has naturally evolved more than 60 times in a wide range of flowering plants, including several staple food plants such as maize, sorghum and sugarcane.


Oxford University’s role within the C4 Rice Consortium is to identify and test the genes that enable plants to do C4 photosynthesis. Using a combination of cutting edge computational and experimental approaches the researchers are mining the natural variation present in plants to reverse engineer C4 photosynthesis. This approach has identified a few hundred genes (out of around 30,000) as candidate regulators of the switch from C3 to C4.

They are currently carrying out state of the art laboratory work to test the function of these candidate genes. This work will further narrow down the search and will identify those genes necessary to make the very precise changes that will allow rice to photosynthesise using the C4 pathway instead of C3.

Screening apparatus to assess C4 phosynthetic properties of wild rice and C4 revertants. By IRRI on Flickr

Wider Interest

In the long term, this research has the potential to increase photosynthetic efficiency and rice yields by up to 50%. This would have a huge global impact in both developed and developing countries by increasing farmer income and improving supply chain stability and food security.

Everyone involved in producing and consuming rice would benefit, from smallholder farmers to multinational biotechnology companies, and from individual consumers to corporate food and energy suppliers.

On top of this, the ability to convert C3 plants to the more efficient C4 pathway could be applicable to many other plants, including other crops and trees, giving this technology enormous potential to enhance future sustainability.


The international C4 Rice Consortium is funded by a grant from the Bill and Melinda Gates Foundation to the International Rice Research Institute.

Read More

Jane Langdale's Lab Wesbite

Steve Kelly's Lab Website

Plants for the 21st Century

C4 Rice at the International Rice Research Institute

Photo of loose rice from Pixabay

Photo of rice field on terraces in Vietnam by cristaltran, iStockPhoto

Photo of screening apparatus to assess C4 phosynthetic properties of wild rice and C4 revertants by IRRI on Flickr