Deep roots, edited genes and a plan to fight climate change with supercharged plants
There are quite a few ways we could benefit from tweaking the genetic makeup of plants. Scientists making breakthroughs in this area hail exciting new possibilities around improved crop security, new kinds of naturally sourced medicines, and hey, maybe just pretty new-colored flowers. Researchers at the Salk Institute are approaching this technology with some very big-picture thinking, looking to edit the genes of humankind's most commonly sown crops so they store more carbon dioxide underground as a way of fighting climate change. And in a paper published last week, they describe their first big breakthrough.
The Harnessing Plants Initiative is a team of scientists from California's Salk Institute who hope to leverage gene-editing technologies so that plants can help stem the tide of global warming. But not just any plants. Corn, soybean, rice, wheat, cotton and rapeseed are the species in the scientists' sights as they probe the molecular mysteries of plant life. And with very good reason, as team member Wolfgang Busch, explains.
"We are interested in achieving the biggest impact on storing carbon in the soil," Busch, a molecular biologist and author on the new study, tells New Atlas. "To make a meaningful impact on atmospheric CO2 levels is a massive challenge. Agriculture is one of the most enormous human activities and performed on vast scales. These six species are among the most prevalent crops and are grown on almost 800 million hectares of land worldwide. That means that the impact that can be achieved by focusing on these six crops is potentially enormous if, on a significant fraction of the land that is occupied by these crops, carbon-sequestration-enhanced varieties of these crop plants can be grown."
The scientists working on the Harnessing Plants Initiative are coming at this problem from three different, but closely-related angles. One of their objectives is to boost the amount of a substance called suberin within a plant, which occurs naturally and does a great job of absorbing carbon. Another goal is to cultivate plant species that produce many more roots. Another is to make those roots run deeper.
"Most of the root dry mass consists of carbon," Busch tells us. "This carbon is usually degraded by soil microorganisms. The deeper roots grow, the slower their degradation is as the microbial activity decreases with increasing soil depth. The root-derived carbon in deeper soil is therefore stored longer than that close to the surface."
A deep dive
The pursuit of deeper roots led Busch and his colleagues to a plant hormone called auxin, which plays an important role in root system architecture. Though scientists understood this much, the exact mechanisms underpinning its influence were relatively unknown. By splicing a thale cress plant in half as a model for study, the team was then able to gain a clearer view of how tweaking certain genes produced different results.
"We knew that one of the most important plant hormones, auxin, is involved in shaping the way roots grow," Busch says. "This includes the tendency of roots to grow downwards towards the center of the Earth. We therefore looked for genes and their variants that changed the way roots grow when we disturbed the auxin balance. The gene and its variants that we then found caused the roots to be slower in correcting their growth when they didn't grow downwards. We also found that it affected the whole root system in the soil."
The team describes this discovery, that they can alter a gene to produce deeper roots, as "incredibly exciting" and its first on the road to achieving its goals. The breakthrough centers on a gene called EXOCYST70A3, which appeared to have a direct connection with the development of the plant's root system by shaping the distribution of a key protein in auxin transport.
"Biological systems are incredibly complex, so it can be difficult to connect plants' molecular mechanisms to an environmental response," says first author of the study Takehiko Ogura. "By linking how this gene influences root behavior, we have revealed an important step in how plants adapt to changing environments through the auxin pathway."
Beyond the lab
This singular gene represents one small piece of the puzzle the Harnessing Plants Initiative is aiming to solve, and an even smaller one in the overall picture of climate change. But greenery has always played a huge role in sequestering carbon dioxide and keeping the Earth's climate balanced, so if small, generic tweaks can be applied on large scales, they certainly have the potential to move the needle.
The thale cress plant the team used as a model for its experiments isn't likely to fit the mold, but the scientists are optimistic the lessons learned here can be applied elsewhere. The endgame is what the team calls the Salk Ideal Plant, which would feature deeper and more robust root systems that stow away carbon underground for longer. It says these improved root systems will also make the plants more durable in the face of climate change and make the soil richer.
Turning these early results into supercharged crops that fight climate change, produce greater yields and help ensure food security for a growing population will take some doing. But because of the parallels between the model used in their study and most plant species, the team feels it has taken a small, but significant step in the right direction.
"For increasing rooting depth in crop plants, we aim to identify similar genes to what we found in this study with the same function," says Busch. "This is most likely possible because the gene or highly similar genes to the one we found in our study occur in all plant species, including crop species. We are also systematically searching for other genes and gene variants that make roots grow deep."
The research has been published in the journal Cell, and you can hear from the scientists involved in the video below.
Source: Salk Institute