Plants produce their own chemical sunscreens, known as flavonoids, which shield them from the harmful effects of UV-B radiation. Exposure to UV-B light stimulates a doughnut-shaped photoreceptor protein called UVR8, which in turn activates genes that produce flavonoids.
This ‘sun block’ is then deposited on the outer tissues of leaves, where it absorbs UV-B rays, preventing them from entering deeper into the leaf. Exposure to UV-B light also stimulates the production of enzymes that repair damage to DNA, to minimise any harmful effects of the UV-B rays.
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