What Plants Glow?

Certain fungi and fireflies are naturally bioluminescent, and other plants are being modified by researchers to glow in the dark. Bioluminescent organisms produce and emit light through biological processes. The mechanism that produces the glow is due to an enzymatic chemical reaction.

Bioluminescent organisms produce and emit light through an enzymatic reaction. There are many organisms that are naturally bioluminescent, including fireflies and a variety of aquatic creatures. Certain fungi are also bioluminescent, although there is some disagreement as to whether fungi qualify as plants. Aside from fungi, there are no plants that can produce light naturally. However, researchers have recently found ways to create glowing plants through genetic engineering and plant nanobiotics.

Naturally bioluminescent fungi include more than 80 different species. Among the brightest bioluminescent fungi are strains of Panellus stipticus (bitter oyster), which grow in the eastern part of North America, but various species of glowing fungus are widely distributed throughout the world.

The mechanism that creates the greenish glow in fungus starts with the enzyme luciferase, which interacts with oxidized luciferin (a small-molecule substrate) to create oxyluciferin. The chemical reaction that occurs in this process also releases energy in the form of light. This is the same process that allows bioluminescent sea creatures and fireflies to light up. All known bioluminescent fungi light up at wavelengths from 520-530 nanometers, meaning they all have a consistent green color.

An Evolutionary Edge

The evolutionary advantage that led certain fungus species to develop glow-in-the-dark capability is not clear, but there are several theories. One popular idea is that the glowing light attracts insects to the mushrooms, which then help to disperse their spores. An opposing theory is that the glow actually discourages grazing animals from feeding on the mushrooms.

Scientists have an interest in using glowing plants to benefit humans in the future and for the clues they can provide about how the plants function. Bioluminescence has always been of great interest to people, as you can see from the crowds that flock to beaches lit up with glowing plankton and the fascination children have with fireflies. But scientists have other reasons to pay close attention to the ways that different organisms can glow in the dark.

Creating Light with Plants

Artificial lighting allows us to extend our working and leisure hours, but lighting also consumes about 20% of all energy usage currently. Glowing plants could replace some light sources, both indoors and outdoors, without using any resources. In fact, plants produce their own energy and are self-healing, making them a much more sustainable resource than other light sources.

The first efforts to create bioluminescent plants were carried out in the 1980s. Early attempts to create glowing plants relied on genetic engineering to create tobacco plants that could produce luciferase, the enzyme that acts on luciferin that causes light to be produced through oxidation. These efforts used the chemicals from fireflies to allow the plants to emit light. However, genetically engineering plants is a difficult process, and the results in this case were technically successful but the plants only produced a dim light.

Since then, researchers have continued to develop techniques to make their bioluminescent plants glow longer and brighter, while being less difficult to produce. They are now using nanoparticles, containing luciferase embedded inside plant leaves, to allow the plant to produce light. Newer glow-in-the-dark plants are 10 times brighter than earlier experimental plants, and are also able to maintain their bioluminescence throughout the plants’ lifespans.

While researchers have not yet developed a glowing houseplant that is bright enough to replace artificial lighting in our homes or on the street, they are getting closer to reaching that goal with each new development.