Tobacco is not for smoking
Russian geneticists have grown glow-in-the-dark tobacco
Daria Spasskaya, N+1
For the first time, Russian geneticists have grown plants that can glow in the dark without adding any substances or ultraviolet irradiation. To do this, Nicotiana tabacum tobacco sprouts had to express four enzymes from the biosynthetic pathway of the glowing fungus, which the same team of scientists described earlier. The authors posted a preprint of the article with photos and videos on bioRxiv (Mitiouchkina et al., Plants with self-sustained luminescence).
Bioluminescence allows visible light to be emitted due to the oxidation of the substrate (luciferin) by a special enzyme luciferase. Some animals (such as worms and insects) and fungi have this system, but glowing plants do not exist in nature. A year ago, we told how a research group from The Institute of Bioorganic Chemistry of the Russian Academy of Sciences under the leadership of Ilya Yampolsky described the pathway of luciferin biosynthesis in the luminous fungus Neonotopanus nambi and identified the gene encoding mushroom luciferase. It turned out that mushroom luciferin is a derivative of caffeic acid — a common metabolite of plants.
In a new work, scientists from IBH RAS and Planta LLC inserted into the genome of tobacco plants (one of the favorite objects of genetic engineers) the mushroom genes missing for bioluminescence — two enzymes of biosynthesis of fungal luciferin (hispidin) from caffeic acid, a luciferase gene and an additional enzyme for converting oxidized luciferin back into caffeic acid. According to geneticists, the glow of GM plants is visible in the dark with the naked eye, while no additional substances or conditions for bioluminescence are required. The glow can be fixed on a "household" camera with shutter speed, and even on the camera of a good smartphone.
A luminous tobacco plant, taken in moderate light (a) and in the dark (b) on the camera of a Huawei P30 Pro smartphone with a shutter speed of 30 seconds. A drawing from an article in bioRxiv.
Apparently, the "built—in" luciferase in plants is a convenient reporter for monitoring a variety of biological processes. For example, the authors of the article showed that the glow of leaves increases with tissue damage and with the action of plant hormones. Besides, it's just beautiful. So far, the glow is rather weak, but theoretically it can be enhanced by "tuning" the expression of enzymes of the biosynthetic pathway. Scientists also suggest that this biosynthetic pathway can be recreated in animals if supplemented with a pair of enzymes for the synthesis of caffeic acid from the amino acid tyrosine.
In addition to bioluminescence, living organisms can glow due to fluorescence, that is, the reverse radiation of absorbed light. The most studied and used fluorophores in laboratories are fluorescent proteins, for example, the green fluorescent protein (GFP) of jellyfish. To see fluorescence, it must first be excited, as a rule, by ultraviolet irradiation. At the same time, no additional illumination is required for the detection of bioluminescence, which makes the described system a promising tool for research.
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