How plants could become decorative lamps

How plants could become decorative lamps

This genetically modified petunia emits a continuous glow. The light is generated by genes isolated from bioluminescent fungi and introduced into the plant. © Light Bio, Inc.

Instead of using electricity-powered light bulbs or LEDs, apartments and gardens could in future be illuminated by glowing plants. A newly discovered plant gene enables researchers to use the naturally occurring bioluminescence of fungi in plants more effectively than before. The gene converts energy from plant metabolism into light and occurs in different variants in different species. The first luminous plant developed in this way shines 100 times more strongly than without the newly discovered gene. But the mechanism is not only decorative, but can also be used in the future to research molecular processes in plants.

Some living things naturally have the ability to produce light and glow in the dark. This bioluminescence is known from various animal species such as jellyfish, fish and fireflies, but also occurs in fungi. Researchers have been trying for some time to transfer this natural radiance to plants. They are based on the molecular metabolic processes of bioluminescent fungi because, as previous studies have shown, these are physiologically similar to those of plants. The researchers mimicked these processes in plants by transferring five fungal genes into plants. However, this is time-consuming and has so far only resulted in plants with low luminosity.

Plant gene enhances luminosity of transgenic plants

This has changed now. A research team led by Kseniia Palkina from the Russian research institute Planta LLC had scoured previous studies for evidence of a plant's own gene that could contribute to bioluminescence. In fact, they found what they were looking for: they found such a gene in a total of twelve different plants from very different genera. It codes for an enzyme, a hispidin synthase. The enzyme produced in these plants and fungi catalyzes the most complicated of the various chemical reactions that cause the mushrooms to glow, the tests revealed. The gene occurs in different variants in different plant species, as Palkina and her colleagues found.

genetically modified luminous chrysanthemum
By using the hispidin synthase signaling pathway in plants, scientists have created, among other things, chrysanthemums that glow in the dark. © LightBio

This discovery is the first indication that bioluminescence could also occur naturally in plants. In experiments with the model plant Nicotiana benthamiana, the team also succeeded in combining this newly discovered plant luminescence gene with the already known fungal genes. This means that it is sufficient if only three fungal genes are introduced into the plants instead of the previous five. The new gene served as a bridge between the lighting mechanism of fungi and plants and at the same time as a bridge between the energy metabolism of the tobacco plant and its bioluminescence. As a result, the genetically modified plants began to glow brighter than in all previous approaches, as Palkina and her colleagues report. This was also achieved with other plant species.

However, the researchers successfully integrated the hybrid lighting mechanism consisting of the plant gene for hispidin synthase and the three remaining fungal genes not only into various plants, but also into yeast cells and human cells. The yeast cells then glowed even brighter than when the “classic” glow mechanism made from fireflies was installed. However, in human cells, Palkina and her team's new hybrid mechanism only produced a faint glow.

Luminous petunia will soon be available for purchase in the USA

Overall, the gene reduces the technical effort required to make plants visibly glow because it is smaller than the two previously used fungal genes and no longer requires any modifications after installation. The US company Light Bio is already using this technology and has developed a type of petunia that, according to the company, shines as brightly “as moonlight”. Thanks to the new genetic engineering, their radiance is 100 times stronger than without the plant's own gene. The cultivation of the glowing petunia has already been approved in the USA and, according to the company, it will be sold there from April for $29. Demand is already high in advance. In the future, other plant species with even greater luminosity will follow.

In addition to commercial exploitation, research also provides fundamental insights into plant metabolism. The method makes molecular processes visible and can serve as a reporter signal through clever linking: “This technology is a plug-and-play tool for visualizing practically every molecular metabolic process at the organism level in real time,” says Palkina’s colleague and senior author Karen Sarkisyan. In the future, the technique could be used, for example, to identify molecular stress responses in plants. As a result, more resistant plant varieties could be developed that can cope better with stress factors such as drought or pathogens. In addition, the researchers want to investigate whether plants have other genes that enable bioluminescent reactions.

Source: Kseniia Palkina (Planta LLC) et al., Science Advances, doi: 10.1126/sciadv.adk1992

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