Survey of Photomotile Responses in Microorganisms

Abstract

As light is used as energy source in photosynthesis, plants and photosynthetic microorganisms have developed several different photosensing and photomotile systems, respectively. They enable them to find places of proper irradiances and to stay there, or to bring themselves or their organs into a position in which they can capture an optimal number of photons. Moreover, the same or other photosensing systems can be used to avoid places of too high irradiances and/or UV, this way preventing the cells from photodamage. Even some non-photosynthetic organisms can respond to light stimuli, e.g., the sporangiophores of some fungi as well as some colorless flagellates and other protozoa. In the latter case photomovement may have also a photoprotective function, whereas in fungi phototropic responses facilitate the propagation of spores whose germination is light-dependent.