Scientists hack plant photosynthesis to boost crop yields by 40%

An international team of researchers has, for the first time, demonstrated that by fixing a common glitch in photosynthesis, a crop's yield could be improved by around 40 percent. The landmark study suggests optimizing a plant's photosynthetic efficiency could significantly increase worldwide food productivity.

Photosynthesis, the process by which a plant converts light energy into chemical energy, is not a wholly efficient process. A key stage in the photosynthesis process involves an enzyme called RuBisCO grabbing carbon dioxide molecules. However, around 25 percent of the time RuBisCO incorrectly collects oxygen molecules instead, creating a plant-toxic byproduct that disrupts the entire photosynthesis process. Photorespiration is the process plants use to remove these problematic byproducts.

"Photorespiration is anti-photosynthesis," explains Paul South, lead author on the new research. "It costs the plant precious energy and resources that it could have invested in photosynthesis to produce more growth and yield."

In food crops such as soybean, rice and wheat, it's estimated that photorespiration can take up anywhere from 20 to 50 percent of a plant's photosynthetic energy. So it is no surprise that scientists have been working hard to find ways to lower the energy cost of photorespiration.

Realizing Increased Photosynthetic Efficiency (RIPE) is an international research project founded in 2012 with the primary goal of developing ways to increase food crop yields by engineering more efficient photosynthesis techniques. The project is primarily funded by the Bill and Melinda Gates Foundation, and earlier this year it revealed an exciting simple genetic breakthrough that resulted in crops needing 25 percent less water to produce a regular yield.

To battle the energy cost of photorespiration, a team of scientists worked to engineer more efficient and significantly shorter photorespiratory pathways. The incredible work essentially created alternate routes within a plant cell so the toxic byproducts could be more efficiently removed using less energy.

"Much like the Panama Canal was a feat of engineering that increased the efficiency of trade, these photorespiratory shortcuts are a feat of plant engineering that prove a unique means to greatly increase the efficiency of photosynthesis," says RIPE Director Stephen Long.

The new process was subsequently tested using tobacco crops, a common target for crop research due to its fast lifecycle and ease of modification. Over two years of real-world testing, the engineered crops were found to grow taller, faster and develop up to 40 percent more biomass than their regular counterparts.

The next stage of the research will apply this technique to more common food crops such as soybean, rice, potato, and tomato with the hopes it will boost those crop's yields. The researchers suspect it will be well over a decade before this breakthrough can be applied in real-world conditions.

There is bound to be a regulatory battle to establish safety profiles before such a genetically modified food crop is widely grown. Nevertheless, one of RIPE's fundamental commitments is that these food engineering innovations will be freely available to smallholder famers so these technological breakthroughs can help feed growing populations in third-world nations.

"We could feed up to 200 million additional people with the calories lost to photorespiration in the Midwestern U.S. each year," suggests principal investigator Donald Ort, on the benefits the breakthrough could have in the United States. "Reclaiming even a portion of these calories across the world would go a long way to meeting the 21st Century's rapidly expanding food demands—driven by population growth and more affluent high-calorie diets."

The new research was published in the journal Science.

Source: University of Illinois