UNAM honorary doctor Joanne Chory has been working on a solution for carbon sequestration for more than a decade. It is based on the fact that plants can take carbon dioxide (CO2) from the air through photosynthesis and turn it into biomass. This is because the Earth's soils contain a lot of carbon - about 2,300 gigatons (Gt) of carbon at a depth of three meters, which is about three times the current CO2 reserve in the atmosphere.
It is thought that cropland and pasture soils, which cover about five billion hectares of land around the world, have a huge capacity to store carbon. This, along with the existing agricultural infrastructure, makes it possible to use genetics to improve traits related to plant-mediated carbon sequestration, he said in an interview.
Several plant traits are good candidates for helping to store carbon. One of these is root biomass, which determines root inputs and stores about five times more carbon than the same amount of above-ground litter, according to the 2020 winner of the Pearl Meister Greengard Prize.
"We decided that with this initiative we had to tap into some element of global distribution, and what we've done work with corn and rice seeds in their wild forms, but you can also work with soybeans, sorghum, and canola. "These species have a wide global distribution," the researcher explained.
Many plants could be used in the project, but they must have certain qualities. For example, they must have mechanisms that increase carbon sequestration, resist decomposition by soil microorganisms, and live longer in soils. This means that the final plants must be able to withstand a complex interaction between chemical composition, physical occlusion of carbon within soil aggregates, the formation of stable organo-mineral complexes, and the connectivity of the water flora.
"The modified plants are still in the research stage in the laboratory because there is still a long way to go before taking them to the field." "But we have tried to avoid GMOs (genetically modified organisms), and what we are trying to do is edit the chain using CRISPR sequencing techniques (a gene editing tool that "cuts" segments of a cell's DNA)," Chory explained.
Root biochemistry also plays a role in decomposition, and the amount of the natural product suberin in the roots is a major candidate trait. This is a lipophilic complex made up of long-chain fatty acids and polyaromatic compounds. It may be a good source for carbon sequestration because it is biochemically stable, interacts with soil minerals, and gets stuck in topsoil microaggregates.
Chory explains in a paper that was just published in the journal Plant Cell in 2022 that the best plant needs to store suberin in the cell walls of its root cells and grow a large root system. To do this, candidate genes affect how the root system is built and how many roots it has been chosen and put together with specific root promoters and genes that make suberin.
Using both traditional (breeding) and newer (editing the genome, genetic engineering) methods, the ideal plant is made by adding beneficial alleles and genes that increase root biomass and transgenes that increase suberin deposition in the root.
It is expected that, in addition to trapping more carbon, they will add carbon polymers that are hard to break down to carbon-depleted soils. The 2018 Gruber Genetics Award winner stressed that plant development is still in the lab stage for now.
Chory thinks that several tests are one of the problems that need to be solved before crops can be used to store carbon. At the moment, it is thought that the last plants will be able to take in up to 1.85 gigatons of carbon per year in just 30 cm of cropland. If the roots went deeper and had a different biochemical makeup, they could store more carbon.
Time is running out because every year that goes by without a big drop in carbon will hurt billions of people and reduce the variety of life on our planet. "We know this is not the only solution, but we are inviting creative people to come up with different ideas, and together we can do something different than what we are doing today."
Joanne Chory, who also won the 2019 Princess of Asturias Award for Technical and Scientific Research, said that the lack of progress shown at the last Conference of the Parties is disappointing because no country is meeting its goals.
Scientists and the general public must work together to solve this big problem because countries and governments haven't been able to cut their emissions. So, she wants to be in charge of the Plant Harnessing Initiative, which aims to remove carbon dioxide from the air.
The scientist from the Salk Institute explained: "We only have eight years left until 2030 to make a change, and all nations must work together to do it. The change will cause chaos, but eight years is not a long time, so we must act now. This is a global problem that we all need to work on. Scientists and politicians alike need to think about how they can help. It's time to check the box, so that's what we're doing ".