Life in a city goes on long after the sun sets, with nightclubs and fast food joints that stay open past midnight. The rows of streetlights lining up the streets make the vibrant nightlife of a city possible, but at a high cost. Street lighting reduces the amount of crime in a city by up to 15%, but it can also account for up to 40% of a city’s budget. Therefore, a more economical way of keeping the city lit during the night is needed. Some scientists are looking to nature as an alternative to electric lighting, by creating trees that glow in the dark.
Luciferin: the key behind the glow
Many living organisms have the ability to glow, from summer fireflies to algae living in the ocean. This ability comes from their ability to produce certain types of compounds known as luciferins. While each organism produces their own kind of luciferin, they all react with the enzyme luciferase to emit visible light. Scientists theorize that if some variation of the compound and the enzyme could be added into a tree, the tree will then gain the ability to glow.
One way of adding these compounds into a tree is by taking another organism’s luciferin-producing gene and inserting it into a tree’s genes. Genes from fireflies and algae have been used, and this ensures the tree will continue to produce luciferin throughout its life without additional retreatment. Another way is by implanting nanoparticles that contain the compound and the enzyme into the tree via diffusion through its leaves, which eliminates the need to genetically modify the tree. However, once the compound is all used up, more nanoparticles need to be implanted into the tree to maintain its glow.
Potential benefits and issues:
So what are the benefits of using these glowing tree as opposed to electric streetlights? Trees don’t require electricity like lights do, so a city’s electric bills will drop as a result of the substitution. Furthermore, trees do not need to be maintained by electricians the way streetlights do, so the cost of maintenance would also be lower if trees are used. There are also the additional benefits that come with having more greenery in a city in general (improved air quality, habitat for urban wildlife, etc.) which add to the value of using glowing trees instead of electric streetlights. Globally, these trees could help provide light for the 1.3 billion people around the world that currently live without electricity.
However, there are still a lot of questions to be answered before we can start replacing streetlights with trees because of how new this technology is. If we go with the genetic modification route, the effects of genetically modifying trees to produce luciferin on the surrounding ecosystem have not been investigated. Studies have shown that the barriers against cross-pollination between different plant species are limited, so the possibility of the glowing tree passing its luciferin-making genes to other plants in its ecosystem seems low. If we go with the nanoparticle implant method, researchers are still looking into how to reduce the frequency of retreatment while still maintaining a consistent level of brightness. Right now, this treatment can produce about 0.5μW of light, which is less than one-thousandth the amount of light we need to read by. In both cases, luciferin in high concentrations has been found to be toxic to plant cells, so there might be negative long-term effects on the trees themselves. Current experiments are being conducted on small plants, so it will be a while before we get to see the first glow-in-the-dark tree.
If you have any questions or would like to know if we can help you with your innovation challenge, please contact our Natural Resources lead, Eric Joyce at ejoyce@prescouter.com.
