How Many Lumens Would You Like Your Plant?

Scientists seem to be insisting on creating plants that are able to shine spontaneously in the dark. New studies conducted by a team of scientists from Russia, Austria, and the UK focus on getting a better insight into how plant metabolism reacts to external factors, rather than aesthetic concerns. But still, seeing those experimental plants glittering in the dark illuminates both the imagination and aesthetic boundaries.

Until now, scientists carried out several studies to make plants that glow in the dark, so the issue is not new. With the help of some chemicals or nanoparticles, plants were programmed to sparkle for a certain time in the dark. This new study follows a different method, using a “fungal bioluminescence system” that converts a substance called caffeic acid, commonly found in all plants into a compound that enables luminescence in organisms. One significant point rendering this approach different from others is that it does not disrupt the natural functions of the plant in any way. In other words, it creates almost no change in the overall phenotype, chlorophyll and carotenoid content, or properties such as germination and flowering. Moreover, it provides luminescence throughout the entire life cycle of the plant, from germination to seeding. With this new method, it is possible to produce plants ten times brighter than those made with the old techniques.

Keith Wood, co-author of the study says that these new plants can provide “a much brighter and more steady glow, which is fully embodied within their genetic code,” adding the plants can produce over 1 billion photons per minute.

Bioluminescence in mushrooms depends on an organic molecule called caffeic acid. This molecule enables glowing through a metabolic cycle containing four different enzymes. Two of these turn caffeic acid into a precursor molecule, the third oxidizes it to produce photons, and the fourth converts the molecule back into caffeic acid to restart the cycle.

To transfer this system to plants, researchers borrowed DNA from fungi and transferred it to plants.

However, caffeic acid is also one of the basic building blocks of a polymer called lignin, which all plants use to build their cell walls and lignify their tissues (or, producing the “woody” bark as we know it). It is also an important component of the plant metabolism, a sine qua non for various compounds that determine colour, odour, and similar properties in plants. Therefore, a new configuration associating this molecule with bioluminescence may also be used as an indicator of the plant’s overall metabolism. Meaning, it can visualize both the physiological state of a plant and its response to external factors.

Although the main plant preferred in experiments was tobacco (due to its relatively simple genetic structure and rapid growth), trials were also made on more attractive plants such as petunia and roses.