During my PhD I was fortunate enough to collaborate with some brilliant scientists. I’m so pleased that two projects that I contributed towards published this year12. These papers nicely exemplify the ingenuity needed to figure out how plants work. Congratulations to the lead authors and everyone involved!
These papers dive deep into photosynthesis. So with their publication I’d like to explain why I’ve been obsessing about this planet-shaping process.
“Photosynthesis is the engine of plant growth.”
I first heard this expression from my PhD supervisor, later co-founder, Prof Steve Kelly. The idea of the photosynthetic engine stayed with me for a couple of reasons.
The word photosynthesis often conjures up images of chalkboard chemistry. A magical arrow combines carbon dioxide, water, and sunlight. The outputs are two of the most important molecules for breathing life into our planet. Glucose – the fuel, and oxygen – which functionally combusts that fuel to generate energy.
Instead, I find it more helpful to think of photosynthesis as an engine. No abstract arrows, we’re looking at a machine. This machine has thousands of high performance components. Each part is energetic and working in coordination to power growth.
Unlike mechanical engines, the photosynthesis engine is the product of engineering by evolution. Thanks to advances in sequencing, ML/AI, and gene editing, today we have an amazing opportunity to understand that evolution. And to use that knowledge to supercharge the performance of this engine.
The good – quantum-powered before it was cool.
The term photosynthesis was coined in 1893, though the process was being investigated before then3. Despite its long research history, our fundamental knowledge about photosynthesis continues to deepen. We’re even still learning more about the first step of the process.
To start doing photosynthesis, a plant needs to split a water molecule into a proton and oxygen. This is hard because the atoms in a water molecule stick together by stable covalent bonds. To solve this, plants capture photons from sunlight and direct this energy to split water.
Solar energy is captured in a specialised pigment-protein structure called the light-harvesting complex. Then this relays energy to a reaction centre complex where water is waiting.
It now seems that there is near-perfect energy transfer between these components. And that this is achieved by exploiting quantum coherence4 [5]. The energy carrier (exciton) samples all travel paths at once to find the route of minimal energy loss. Incredibly, this coherence seems to hold in warm, wet, noisy cells5.
Human engineering is still at the early stages of leveraging quantum mechanics. This is most obviously exemplified today with quantum computers. However, most types of quantum computer need extreme cooling to maintain quantum coherence.
But it turns out a dandelion on a roadside is doing this same trick for its lunch. Nonchalant about whether it’s the hottest or coldest day of the year. It’s an extraordinary example of how much more we have to learn from nature.
The bad – there’s a lot of room for improvement.
>More output please.
Photosynthesis is far from optimised. For every 100 joules of solar energy that hits a leaf, no more than 12 joules can turn into chemical energy6. This is a fundamental limit imposed by the reactions of photosynthesis. But this ceiling only accounts for chemistry constraints. When proteins have to coordinate in real world conditions, the conversion is closer to 2.2-3 joules7.
Even a small improvement in this conversion efficiency could unlock major productivity gains. And there is a lot of scope to dream bigger than a small improvement.
>Fewer inputs please.
Photosynthetic inefficiency is costing the planet. Two massively expensive inputs being:
Water, for splitting. Agriculture is the world’s number one consumer of freshwater at 70% of global supply. Water stress is rising as agricultural demands deplete this resource. India’s consumption doubled between 1975 and 2010; >90% of supply supports its large agricultural output. Our world in data has a nice visualisation of the scale of this challenge8.
and
Nitrogen, for building. I summarised this in a previous article9. Fertilizers are expensive, require energy, and are polluting. In return, they enable photosynthesis and make the proteins we need desperately.
Boosting photosynthetic efficiency could improve both water use efficiency and Nitrogen use efficiency. This would enable more sustainable growing practices while also safeguarding yields. This makes photosynthesis a path to aligning two critically-important and often misaligned objectives. Looking after people, and looking after the planet.
Can we really supercharge crop productivity through photosynthesis?
Today there are no options for farmers to grow step-change photosynthesis-boosted crops. There have been 4,000 regulatory approvals for biotech crops over the past 30 years. None contained photosynthesis traits10. It has proven to be a very difficult technical challenge.
However, there is genuine cause for optimism when looking at the evolutionary record.
There are many ways to build a mechanical engine. Likewise plants have built different types of photosynthetic engines all over the planet. Just as you would take different equipment to explore a forest, desert, mountain, and or even Antarctica, so do plants. These upgrades persist because they enhance survival in the harsh conditions of the wild. So they should hold up in the comparatively gentle arable fields our crop enjoy.
This is an evolutionary approach to engineering. It transforms a scientifically-risky design problem into a simple optimisation exercise. We don’t need to re-invent the wheel, just recreate the stuff we already know works.
And what happens when we do achieve photosynthetic gain? The Free-Air CO2 Enrichment (FACE) experiments have asked this question for decades. This research increases carbon dioxide availability around crops to artificially boost photosynthesis11.
After 250 trials spanning five continents and diverse crops, the authors came to an important conclusion. Running the photosynthetic engine harder reliably results in more yield. Not by single percentages, but by double digits. This even holds true in both water-limited and Nitrogen-limited conditions12.
In a vast and fragmented agricultural system facing diverse challenges, photosynthesis stands out as a powerful lever. Boosting this engine offers a scalable path to improve sustainability and efficiency together. The more we understand it, the more precisely we can supercharge it. Time to look under the hood.
- Lambret Frotte, Buarque de Gusmão, et al., 2025, New Phytol. ↩︎
- Cackett et al., 2025, Plant Physiol. ↩︎
- Gest, 2002, Photosynthesis Research ↩︎
- Engel et al., 2007, Nature ↩︎
- Panitchayangkoon et al., 2010, PNAS ↩︎
- Ying & Struik, 2015, J. Exp. Bot. ↩︎
- Ying & Struik, 2015, J. Exp. Bot. ↩︎
- Our World in Data – Water Use and Stress ↩︎
- Lightning in a biological bottle – Ross Hendron ↩︎
- AgbioInvestor-GM – GM Approvals Database ↩︎
- Ainsworth & Long, 2020, Glob. Change Biol. ↩︎
- Ainsworth & Long, 2020, Glob. Change Biol. ↩︎