How plants protect themselves against UV radiation
Plants also get harmed by the sun, especially by UV radiation. UV radiation damages not only their DNA, but also their proteins and lipids. Resulting in cell death, and wilting and yellowing of their leaves. It also leads to abnormal growth.
Enough reasons for plants to avoid this damage. And that is just what plants do. This starts with perception of UV-B, plants use for this the UVR8 photoreceptor. This receptor is always present. But when there is no UV-B two UVR8 receptors are closely bonded. But UV-B radiation breaks this bond. Enabling UVR8 to get into the nucleus and turn on UV-B defence genes. These activate the protection against UV-B.
UV-B protection consists of different parts. Firstly plants try to avoid damage. They do this by producing flavonoids, so called ‘sunscreen’ molecules, like anthocyanin and flavonol. This are pigments that absorb UV-B radiation, making it harmless in the process.
Second in line is the repair of the damage. For this the plant goes to DNA damage repair proteins. They, while temporary inhibiting DNA replication, make sure that the mistakes and breakages due to UV-radiation get repaired.
Why plants die from sunscreen
So plants make their own sunscreen. You don’t need to cover them with sunscreen to protect them. When you do that, ironically they die.
The reason is as follow: Sunscreen contains substances that block UV radiation. Only they also block visible light. Light that plants need for photosynthesis to make sugars. Without photosynthesis they starve. So when you smear plants in with sunscreen, you starve them, leading ultimately to their death.
Literature
Chen Shi, Hongtao Liu, How plants protect themselves from ultraviolet-B radiation stress, Plant Physiology, Volume 187, Issue 3, November 2021, Pages 1096–1103, https://doi.org/10.1093/plphys/kiab245
Tanaka, Y. , Parker, R. and Aganahi, A. (2023) Photoprotective Ability of Colored Iron Oxides in Tinted Sunscreens against Ultraviolet, Visible Light and Near-Infrared Radiation. Optics and Photonics Journal, 13, 199-208. doi: 10.4236/opj.2023.138018.
Plant en Zo 