in regions continuously exposed to sunlight, uv rays can cause biochemical damage to plants, and eventually lead to dna mutations and damages in the long run. when one of the main molecules involved in photosynthesis, photosystem ii (psii) is damaged by uv rays, it induces responses in the plant, leading to the synthesis of protectant molecules such as flavonoids and more wax. flavonoids are uv-absorbing and act like sunscreen for the plant.