In 2022, nearly 30% of the global population faced food shortages, and over 10% grappled with severe food insecurity, as reported by the UN Food and Agriculture Organisation.
To address this pressing issue, enhancing crop yields represents a key solution. While significant progress has been made in increasing crop yields, such as tripling maize production over the last century, it has come at the cost of heightened water usage.
“We need to be able to increase productivity without increasing further demand, particularly in terms of water,” says Prof Steve Long of the University of Illinois.
One critical facet of plant growth that has lagged behind is photosynthetic efficiency – the ability of plants to convert solar radiation into biomass. Notably, photosynthesis in crops like wheat and soybeans has seen minimal improvement over the years.
Professor Stephen Long is at the forefront of a groundbreaking initiative known as “Realizing Increased Photosynthetic Efficiency (RIPE),” which aims to augment crop yields by enhancing photosynthetic capacity through genetic modifications.
Photosynthesis in crop plants currently operates well below its theoretical maximum, but influencing it has been challenging due to its intricate nature. The process involves over 100 steps, governed by numerous genes, resulting in millions of potential permutations.
To overcome this complexity, Prof. Long’s team has harnessed the power of powerful computers to construct a digital twin of the photosynthesis process, capable of exploring millions of potential adjustments.
“We then engineered these into crops, and if that results in an improvement in the glasshouse, then we take it to our experimental farm and test it in a real-world environment,” says Prof Long.
This approach has yielded promising results, with soybean plants displaying over 20% yield improvements in controlled environments.
Field trials are now underway to validate these findings. A particular focus has been on altering the way plants respond to changes in light levels, with the introduction of gene modifications that enable plants to adapt more swiftly to varying light conditions.
Meanwhile, other research teams worldwide are actively engaged in boosting photosynthesis. For instance, Wild Bioscience, a spinout from Oxford University, is concentrating on increasing the photosynthetic capacity of each leaf by enhancing the expression of a specific gene found in wild plants. This process involves sophisticated computational biology and aims to replicate natural photosynthetic enhancements seen in the wild.
The process involves sophisticated computational biology: “What we’re doing is trying to reverse engineer the naturally occurring upgrades to photosynthesis that are out there in the wild, so we can copy them in crops,” says co-founder Ross Hendron.
Often, that gene is already present in the plant, and can be activated in different areas.
“We can look at wheat and find that gene is already in the wheat genome, it’s just on in the wrong place,” says Mr Hendron. “So when we want to improve this particular process in this part of the plant, what we need to do is flick on a switch and turn that gene on in that location.”
The company’s efforts span wheat, soybeans, and maize, with gains of over 20% in seed biomass achieved in field trials. These crop varieties may potentially become commercially available by around 2030 or 2031.
Both the RIPE project and Wild BioScience employ gene editing techniques, which entail modifying gene expression by adding or removing DNA. It is distinct from genetic modification (GM), which involves the introduction of genes from different species. The regulatory landscape for gene-edited and GM crops varies from one country to another, with the European Union having some of the most stringent rules.
In the UK, recent regulatory changes have eased the path for commercial cultivation of gene-edited crops in England. Nevertheless, there is resistance from certain quarters, including those opposed to both GM and gene-edited crops.
“This unproven science offers only a potential short-term relief of the symptoms of an unsustainable farming industry. In the meantime, it is diverting time, investment and attention away from real and already-proven solutions,” Friends of the Earth Europe said in a report, titled Editing the Truth.
Researchers at Imperial College London are in the early stages of exploring the possibility of engineering plants to photosynthesise using far-red light of lower energy instead of visible light. This novel approach holds potential for more sustainable and efficient crop production.
“There is potential under some circumstances, but we are still in the early phases of working out how it works and what are the pros and cons,” says Prof Bill Rutherford of the Department of Life Sciences.
However, not all scientists are entirely convinced of the transformative impact of enhanced photosynthesis on field crops. Some, like Matthew Paul of Rothamsted Research, caution that increasing a leaf’s photosynthetic capability could lead to smaller leaves and potentially greater water loss, necessitating more irrigation.
“For any GM or gene editing approach to have widespread impact it would need to be reproduced in varieties grown in different regions. Subtleties of expression control and interaction with genetic background of each variety will make this tricky,” he says.
As the research is still in its nascent stages, the full extent to which commercial crop yields can be improved through photosynthetic enhancements remains uncertain.
Nonetheless, proponents of this research, such as Ross Hendron of Wild BioScience, believe that combining various techniques may yield even more significant benefits, offering hope for a future where agriculture can address the pressing global challenge of food security.
“We know these are stackable improvements that can drive further and further increases,” he says.
So there will be other technologies out there – Ripe will be one of them – so we can say both of us are doing this individually, but how much more powerful is this in combination?”
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