Four unmodified plants (left) grow beside four plants (right) engineered with alternate routes for photorespiration, which allow them to reinvest their energy and resources to boost productivity by 40 percent. Claire Benjamin/RIPE Project
Scientists have found a way to boost crop growth by as much as 40 percent by fixing a glitch in the photosynthesis process, according to a new study published in the journal Science. With current techniques to improve yields largely optimized — including using more pesticides, fertilizers, and irrigation — the scientists argue that the new findings offer a breakthrough way for farmers to feed more people on less land.
The yield-costing inefficiency lies within the process of photorespiration. Plants use the enzyme Rubisco and sunlight to turn carbon dioxide and water into sugars that fuel plant growth and yield. But Rubisco is unable to reliably distinguish between CO2 and oxygen, and will mistakenly grab oxygen 20 percent of the time, resulting in a plant-toxic compound that must be recycled through the process of photorespiration. This process, however, is uses energy and reduces photosynthetic efficiency – a key determinant of yield potential – of some of the planet’s most important crops by 20 to 50 percent.
“We could feed up to 200 million additional people with the calories lost to photorespiration in the Midwestern U.S. each year,” the study’s co-author, Donald Ort — a professor of plant and crop Sciences at Illinois’ Carl R. Woese Institute for Genomic Biology — said in a statement. “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.”
Photorespiration typically goes through three compartments in a plant cell. Ort and his colleagues engineered a shortcut for the process that saves enough resources to boost plant growth by 40 percent. They tested the alternate route in replicated field studies of tobacco plants over a two year period because tobacco is hardy, an easy crop to genetically manipulate, and has bountiful seed production. The scientists are now testing the newly engineered pathway in soybean, cowpea, rice, potato, tomato, and eggplant.
The research is part of a larger international scientific endeavor to engineer crops to photosynthesize more efficiently and improve crop yields, known as the Realizing Increased Photosynthetic Efficiency (RIPE) project. A booming global population and climate change makes fixing this yield-costing glitch all the more important right now.
“Rubisco has even more trouble picking out carbon dioxide from oxygen as it gets hotter, causing more photorespiration,” co-author Amanda Cavanagh, an Illinois postdoctoral researcher working on the RIPE project, said in a statement. “Our goal is to build better plants that can take the heat today and in the future, to help equip farmers with the technology they need to feed the world.”