Most crops on earth don’t photosynthesize efficiently; they use a wasteful cellular pathway called photorespiration, dramatically impacting their potential yield. Now, scientists at the University of Illinois and U.S. Department of Agriculture Agricultural Research Service have found that when crops are engineered to use a photorespiratory shortcut, they are around forty percent more productive. The findings were reported in the journal Science.
"We could feed up to 200 million additional people with the calories lost to photorespiration in the Midwestern U.S. each year," noted the principal investigator of the work Donald Ort, the Robert Emerson Professor of Plant Science and Crop Sciences at Illinois' Carl R. Woese Institute for Genomic Biology. "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 enzyme called Rubisco is critical to photosynthesis. It has generated an atmosphere rich in oxygen, but it also can’t really tell the difference between oxygen and carbon dioxide. That means it grabs oxygen instead of carbon dioxide about one out of five times, which creates a toxic compound that plants have to recycle through photorespiration.
"Photorespiration is anti-photosynthesis," explained the lead author of the study Paul South, a research molecular biologist with the Agricultural Research Service, who works on the RIPE project at Illinois. "It costs the plant precious energy and resources that it could have invested in photosynthesis to produce more growth and yield."
The research team has now engineered three different ways to shortcut the native pathway. After lengthy field tests, they developed plants that grew faster and larger, with around 40 percent more biomass.