Single gene boosts climate resilience, yield and carbon capture in crops

Scientists at Oak Ridge National Laboratory have discovered a single gene that simultaneously boosts plant growth and tolerance for stresses such as drought and salt, all while tackling the root cause of climate change by enabling plants to pull more carbon dioxide from the atmosphere.

As climate change triggers more frequent and longer-lasting droughts, water scarcity concerns are escalating. Only about 3% of the world’s water is freshwater, and much of that is frozen in ice or otherwise unavailable to use. Agriculture is the biggest freshwater consumer worldwide, which emphasizes the need for hardier plants that can withstand drier conditions and use non-potable water containing higher levels of salt.

With the aim of engineering more productive and drought-tolerant bioenergy crops, ORNL scientists at the Center for Bioenergy Innovation, or CBI, have been studying the mechanisms that allow desert plants, such as agave and kalanchoe, to thrive in dry conditions.

Desert plants use a form of photosynthesis known as crassulacean acid metabolism, or CAM, to hold carbon dioxide in their cells overnight to be turned into sugars in the daylight hours. To survive extreme desert temperatures, CAM plants only open their stomata, or leaf pores, to capture carbon dioxide during the night and keep them closed during the heat of day, avoiding water loss.

An ORNL team identified the key genes for CAM photosynthesis in 2017 using the laboratory’s Titan supercomputer. Building on that study, researchers homed in on a novel variant of an important enzyme and found that it triggers two pathways simultaneously — one for carbon fixation and plant growth and another that produces proline, a key amino acid known to increase stress tolerance. Their results are published in the journal Cells.

“It is unusual to find that a single genetic modification can have multiple benefits,” said ORNL’s Xiaohan Yang, a plant systems and synthetic biologist who led the study. “This is different than the classic model of one gene and one protein affecting one trait. We are seeing more examples of this phenomenon where a single gene acts as a master regulator that turns on many other genes both upstream and downstream from it.”

“Anything we can do to make bioenergy crops more drought tolerant and grow quickly has positive economic value,” CBI Director Jerry Tuskan said. “We are looking at dedicated energy crops that do not compete with food production. To do that, we’ll need to grow these crops on marginal lands that experience drought.”