The Diamond of the Plant World

June 29, 2022

Creating 1000+ year biological carbon storage with sporopollenin

Plants are constantly drawing down huge amounts of carbon, but much of this carbon returns to the atmosphere each year as the plants grow, die, and decay. At times, however, conditions have been right for plant biomass to be naturally preserved and keep carbon locked away for thousands or millions of years. 

It is not unprecedented for plants to store carbon indefinitely, but we can’t wait millions of years for these conditions to happen again. The “holy grail” of carbon removal is to develop plants that achieve both the self-replicating nature of biology and the durability of engineered solutions - using only sunlight and water.  Before more extreme solutions such as solar radiation management become a real possibility, it is essential to push the limits of nature-based solutions to durably sequester large amounts of carbon.

Enter sporopollenin

Sporopollenin is the main component of exine, the outer coating of most pollen grains and spores. Referred to as “the diamond of the plant world”, sporopollenin is the toughest biopolymer nature has ever produced. Scientists have found samples of this biopolymer in sedimentary rocks that are over 500 million years old! It is naturally produced in the reproductive tissues of terrestrial plants, as well as the outer cell walls of certain algae species. 

Sporopollenin does not require any special mode of storage or processing to prevent decay.  It is incredibly resistant to chemical and physical degradation and can be found everywhere in soils and sediments. If plants could produce more of this long-lasting biopolymer - perhaps even in other parts of the plant besides pollen and spores - we believe this would be a step change in carbon removal.  

Living Carbon is undertaking a discovery project to increase the production of sporopollenin for carbon sequestration over 10- to 100-fold longer durations compared to other nature-based solutions. We are excited to announce that Stripe is supporting our research as part of its Spring 2022 funding commitments. We are excited to partner with Stripe to demonstrate the role synthetic biology and advanced biotechnology can play in carbon removal. You can read the full announcement here.

Our project: 

Increasing the production of sporopollenin in any plant cell system would be a breakthrough that opens the possibility of growing any plant for durable carbon sequestration. We are choosing to focus initially on microalgae due to their high photosynthetic efficiency and growth rate compared to terrestrial plants, and the fact that sporopollenin has already been discovered in the cell walls of species such as Auxenochlorella protothecoides

Engineering microalgae to express even more sporopollenin in their cell walls would increase the percentage of the biomass that can be used for durable carbon removal without any energy-intensive post-processing. Instead, algae can be dried out using solar power and stored as an inert dust where the sporopollenin component will remain long after the rest of the biomass degrades. 

Our initial plan was to focus on sporopollenin production in trees or other woody tissues of plants, however, this support from Stripe enables us to research a wider variety of organisms and prioritize those that require less arable land. 

We’ve already produced a photosynthesis-enhanced tree which can store more carbon on less land and we are in the process of developing a metal hyper-accumulation trait to increase the durability of stored carbon by slowing the rate of decomposition. We believe engineering durable carbon storage as part of our portfolio of traits is one of the most groundbreaking applications of plant biotechnology to the climate crisis. We are also growing our research team in this area - view our open positions here

Now is the launch window for large-scale carbon removal solutions. We don’t have millions of years to wait for the perfect combination of factors. It’s this urgency that drives us and gives us hope. Biotechnology has made it possible to take the best lessons from millions of years of evolution on our side and apply them with precision and speed. The future is sporopollenin and it starts today.

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