New research from China has demonstrated that a novel technique to enhance photosynthetic efficiency in rice crops can increase grain yields by up to 27 percent. The study follows other recent demonstrations of food bioengineering designed to enhance worldwide food productivity by improving the photosynthesis process in crops.

A big focus for scientists working to increase crop yields is finding ways to enhance the efficiency of photosynthesis. Anywhere from 20 to 50 percent of the energy a plant produces through photosynthesis can be diverted into a process called photorespiration.

One scientist recently described photorespiration as "anti-photosynthesis." Plants generate the chemical energy they needs to grow by grabbing carbon dioxide molecules from the surrounding environment. However, around 25 percent of the time the plant incorrectly collects oxygen molecules, creating a plant-toxic byproduct that disrupts the entire photosynthesis process, and ultimately releases carbon dioxide. Photorespiration is the process plants use to remove these problematic byproducts.

One recent strategy developed to increase photosynthetic efficiency focussed on engineering more efficient photorespiration pathways within a plant. These techniques essentially engineered alternate routes within a plant cell so the toxic byproducts could be removed using less energy.

The latest study, from a team of scientists in China, demonstrates a different strategy to increase a plant's energy efficiency. This technique diverts carbon dioxide produced during photorespiration to photosynthesis. The process is named GOC bypass, and utilizes three enzymes to convert a molecule called glycolate into carbon dioxide.

In field tests using rice crops the results were impressive, with the GOC bypass plants displaying overall grain yield improvements of between 7 and 27 percent. Photorespiratory rates were suppressed by up to 31 percent, and net photosynthetic rates increased up to 22 percent.

The researchers suggest these results can be further optimized through larger field testing and experimenting with different rice varieties. Future work will also investigate whether the technique applies to other food crops such as potatoes. Of course, there are plenty of questions that need to be resolved before these kinds of engineered crops can be widely deployed.

"Although we don't expect this approach would affect the taste of these plants, both the nutritional quality and taste are yet to be comprehensively evaluated by independent labs and governmental agencies," says Xin-Xiang Pen, senior author on the new research.

Optimizing rice, the world's third-largest crop after wheat and maize, is a major focus for many scientists around the globe. Recent innovations have revealed new techniques to make rice more drought-resistant and environmentally friendly, however this is the first demonstration of a more photosynthetically efficient form of the crop.

The new study was published in the journal Molecular Plant.