Plants exhibit phototropism, the ability to move towards light, primarily through the action of the pigment riboflavin, which serves as a photoreceptor. When light is detected, the plant hormone auxin is redistributed from the illuminated side of the stem to the shaded side. This uneven distribution of auxin causes the cells on the shady side to elongate more than those on the bright side, resulting in the bending of the plant towards the light source. The exact mechanism of how light reception triggers auxin production remains unclear. Auxin also plays a critical role in other plant processes, including gravitropism, apical dominance, and the development of roots and seeds.
