In sunny La Jolla, California, the founders of the Harnessing Plants Initiative (HPI) at the Salk Institute are thinking about the big question that connects agriculture, wetland restoration, and atmospheric climate change: How can we safely use plant pathways to capture and store carbon, while restoring our agricultural and coastal environments?
According to Joanne Chory, leading Lebanese American plant biologist and co-director of HPI, “If we can optimize plants’ natural ability to capture and store carbon, we can develop plants that not only have the potential to reduce carbon dioxide in the atmosphere but that can also help enrich soils and increase crop yields.”
How can we do that? The answer lies in a biomolecule called suberin, which is present in the cell walls of corky tissues of plant roots and stems. When suberin associates with cork, it becomes a tool for storing carbon. Scientists at the Salk Institute study the molecular tags that control whether suberin genes get turned on or off, as well as upregulation methods. However, for development of edible and reliable crops, it is unwise to just overexpress the genes to create high concentration of suberin. Plants also need to be bred to grow more extensive and deeper root systems to create a larger surface area for storing suberin.
Thankfully, deep plant roots are already a favored trait, especially in response to climate change because they increase plant stress resistance to drought, flooding, and disease. More extensive root systems are also beneficial for soil health because they attract soil microbiota and fauna and replenish the soil with organic carbon.
In 2019, the lab of Wolfgang Busch, the other co-director of HPI, identified a gene that helps regulate root system architecture. Manipulating this gene’s expression, in addition to that of the suberin genes, can lead to the development of “super plants” that have deep root systems and are good at storing carbon.
There is one more issue to solve: how can we make these super plants live longer? The Chory and Busch labs are in the midst of answering this question, testing ways to make the larger roots last longer and resist decomposition. Additionally, the greenhouses at the Salk Institute are filled with scientists using x-rays, machine learning, and many other tools to measure suberin content, root growth, and carbon storage at all stages of plant development.
Enhanced root growth of 5 or 6 economically important crops worldwide could devote 768 million hectares of land to carbon capture, and the only additional step would be for farmers to rotate in a new line of seeds.
HPI started studying roots with Arabidopsis thaliana and Lotus japonicus as their model species, and this year, they began their first experiments on more widely grown crops, like soy, rice, wheat and canola. Additionally, HPI is “developing wetland plants that hold carbon, purify water, preserve land and can thrive in challenging environments around the world,” since wetlands can store as much as 100 times more carbon per acre than dry land, but are rapidly eroding and emitting carbon into the atmosphere.
Counter arguments against this work concern the ethics of GMOs and the efficacy of carbon capture. Busch provides reassurance: the study is a safe and efficient effort towards the climate change solution, and we need to “reduce the amount of carbon dioxide in the atmosphere through many different means.”
The HPI report includes introducing these super plants into our wetlands and agricultural lands as one part of a larger land regeneration proposal, as well as emitting less carbon dioxide into the atmosphere. The focus of this work is bringing us closer to achieving consistent crop yields and ensuring food security for a growing global population.
This article was edited by Emi Krishnamurthy and Cat Kim.