Now Cavanagh and her colleagues are testing if, and how, the tweak to the oxygen-recycling pathway would work on crop plants like soybeans and cowpea in their lab. Another question they hope to answer is whether the modified crops have a different nutritional value than their unaltered kin, because the genetic modification will essentially feed the plant more CO2. “One of the things we do know is that more carbon dioxide produces less nutritious grains,” Cavanagh says. That is a chief concern of food security in the climate-change era: higher CO2 concentrations in the atmosphere can make plants grow more, yes, but research has also shown that more CO2 means lower concentrations of nutrients. In one 2018 study, higher CO2 levels translated to rice crops with lower concentrations of protein, B-vitamins, and important minerals like zinc and iron.

Paul South, of the United States Department of Agriculture and the lead author on the paper, collects samples of modified tobacco plants.
Paul South, of the United States Department of Agriculture and the lead author on the paper, collects samples of modified tobacco plants.
Image: Claire Benjamin/RIPE Project

But Cavanagh is hopeful, and notes that as the global climate warms, finding a way to solve for photorespiration will be ever more dire: Right now, plants are absorbing around one-third of the excess carbon dioxide humans are pumping into the atmosphere, and turning it into sugars to grow. As carbon dioxide levels rose, global photosynthesis ramped up. But as temperatures rise, plants will start to offset less and less carbon dioxide, and probably already have. That’s because as the air warms, plants are less able to discern between oxygen and carbon dioxide, and photorespiration rates go up. Our warming planet will surely result in more yield losses to this “glitch,” and less of a plant buffer to our carbon emissions, too.

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