Photosensory Adaptation in Plants

Photosensory adaptation (range adjustment) is of great importance in plants (including fungi and various microorganisms) that operate in large intensity ranges. The adaptation mechanisms of plants have some features in common with those of vertebrates and invertebrates. As with those systems, plants have biphasic exponential dark‐adaptation kinetics, that are much slower than the corresponding light adaptation kinetics. One needs to distinguish between sensor adaptation, which regulates range adjustment, and effector adaptation (habituation), which regulates the motor apparatus of the organism (flagellar movement or cell wall growth). InPhycomyces, and perhapsStentor, sensor adaptation is mediated by the photoreceptor system. In contrast to vertebrates and invertebrates, dark adaptation can be controlled in some plants by special photoreceptors. InPhycomyces, these can be either photo‐products of the actinic photoreceptor(s) or not yet identified receptor pigments. In higher plants phytochrome can alter the state of adaptation.