Different type of photosynthesis may save temperate crops from climate change

Oct. 23 (UPI) — In many places, climate change is expected to bring hotter, drier weather. In a new study, published Friday in the journal The Plant Cell, scientists considered whether an alternative mode of photosynthesis, might yield more heat-tolerant and drought-resistant plants.

Most plants in arid and semi-arid environs use a photosynthesis method called Crassulacean acid metabolism, or CAM. Alternatively, plants in temperate environs, including crops, rely on a photosynthesis method called C3 carbon fixation.

Plants using C3 carbon fixation absorb CO2 through their leaves’ stomatal pores. The daytime process allows C3 plants to immediately convert sunlight into food. When conditions are especially hot and dry, C3 metabolism causes plants to lose too much water.

Conversely, CAM plants absorb CO2 through their stomatal pores at the night. The carbon gets stored in cells until daytime, when it is converted into food via photosynthesis. This alternative carbon fixation technique allows CAM plants to close their stomatal pores during the day to prevent excess water loss.

For the new study, researchers developed sophisticated biological models to determine whether C3 plants genetically engineered to perform CAM photosynthesis would fare better as hotter, drier weather becomes the norm.

Researchers tested their genetic engineering simulations across a variety of temperature and relative humidity conditions. The data showed that the benefits provided by a switch to CAM metabolism are influenced by the vacuolar storage capacity of a plant’s leaves, which is dictated by climate conditions.

“Moreover, our model identified an alternative CAM cycle involving mitochondrial isocitrate dehydrogenase as a potential contributor to initial carbon fixation at night,” researchers wrote in their paper. “Simulations across a range of environmental conditions show that the water-saving potential of CAM strongly depends on the daytime weather conditions.”

In other words, engineering CAM metabolism in temperature plants isn’t a cure-all. Still, authors of the new study suggest their findings will help plant scientists developed new strategies for engineering greater resiliency among C3 crops.

“Modelling is a powerful tool for exploring complex systems and it provides insights that can guide lab and field-based work,” lead study author Nadine Töpfer said in a news release.

“I believe that our results will provide encouragement and ideas for the researchers who aim to transfer the water-conserving trait of CAM plants into other species,” said Töpfer, a postdoctoral researcher at the Leibniz Institute of Plant Genetics and Crop Plant Research in Germany.

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