San Diego scientists are advancing an effort to turn plants into allies in the battle to slow global warming. Researchers at the Salk Institute of Biological Studies are working to turn the world’s major crops into carbon-capture superheroes.
“Here you can see a fully grown pennycress plant,” said Wolfgang Busch as he pointed to a tangle of roots inside a transparent pot.
He was inside a Salk greenhouse, where his team does the meticulous work of growing different plants, measuring root systems, and finding plants that show a propensity for growing longer, deeper roots.
The effort is squarely aimed at reducing the amount of carbon that’s pushing up temperatures around the planet.
“So, plants are the world record holders for … getting carbon dioxide out of the air that causes the greenhouse effect and thereby climate change,” Busch said. “And they grow everywhere.”
Plants draw in carbon dioxide, extract the carbon and expel oxygen. That carbon is used to grow stems, leaves and roots. And the root systems have the attention of Salk researchers.
“Now the deeper you put that carbon into the root system the slower the decomposition gets,” Busch said. “So, carbon that is below 30 centimeters. Below a foot in the soil is much, much more stable, and will hang around much longer in the soil.”
And roots that push carbon deeper can lock up the greenhouse gases, make plants more drought resistant, and even boost crop yields.
Salk researchers have already identified more than 100 genes that guide the creation of deep and robust root systems.
Researchers hope to either breed those traits into food crops like rice, wheat, corn or soy, or use modern gene splicing technology to give those abilities to the most commonly grown plants.
“If you just take five major crops, the most prevalent crops and you would pool the growth area it would cover the whole subcontinent of India,” Busch said. “That’s so much soil being covered by these plants, and even if a plant will do very little on its own, the massive scale of agriculture can make a dramatic impact.”
The Harnessing Plants Initiative was an idea germinated by Salk researcher Joanne Chory. The award-winning biologist remains keen on the enormous potential of plants.
“I think we could take out ten gigatons (of carbon) by this method. That’s not the whole amount we need to take out every year, but we could make a big contribution to the whole,” Chory said.
Ten gigatons is about a quarter of the carbon dioxide humans put into the air each year. And she is optimistic that, when brought to scale, plants can be an important tool.
“We have too much carbon dioxide already up there, warming the earth,” Chory said. “So, we have to pull some down that's already up as well. So, it could be hundreds of billions of tons of carbon dioxide that we have to take out in order to bring the planet back to equilibrium.”
One particular plant of interest is Typha, better known as cattails. The freshwater plant is common, robust and produces a prodigious amount of seeds.
“There are a lot of recent events that suggest that we need to be moving fast. And some of the solutions that we’re talking about are 10, 20 years out. But we need to be working on them now because this is really what technology is really about. Right?”Todd Michael, Salk Institute of Biological Studies
“It’s one of the three species that grows almost in all wetlands,” said Todd Michael, a Salk Institute researcher.
Michael handles a mature cattail plant that he grew in a pot outside his lab. He points to the tightly wound ball of roots.
“And the roots grow so fast. This is an amazing plant. It’s like a machine sucking up nutrients,” Michael said.
The plant is one of the best at moving carbon into a corked molecule known as suberin. Cattails create thick strings of suberin in their root ball.
Michael hopes giving other plants that ability could be a key to trapping more carbon in the ground. He is working to isolate the genetic characteristics that allow cattails to do that, and the hope is that those abilities can be transferred to other plants.
“They grab onto the surrounding substrate and they build,” Michael said. “So, they are basically building land. And you can see that they’re sort of tight. And this is actually what’s capturing the carbon and this becomes oxygen free.”
And sealing out the oxygen keeps the roots from decomposing. It essentially locks the carbon inside the root ball.
Two years of sequencing Typha genomes has pointed researchers in encouraging directions, but the overarching goal of an army of plants fighting global warming remains out of immediate reach.
“There are a lot of recent events that suggest that we need to be moving fast. And some of the solutions that we’re talking about are 10, 20 years out. But we need to be working on them now because this is really what technology is really about. Right?” Michael said.
The solution to slowing temperature rise will not come from just one thing.
“We need to be working on every angle,” Michael said. “So not just carbon scrubbers but how do we use plants? We need to cut down on emissions. All of these solutions come together.”
The idea has attracted plenty of supporters. Energy companies like the Hess Corporation and Sempra Energy are investing money. So is the Bezos Earth Fund and the Bill and Melinda Gates Foundation.
All hope to leverage their investments into strategies that will keep the planet from heating up.