How fungi see the world: fungal photoreceptors and their role in the regulation of fungal biology

SUMMARYFungi use light as a signal for the regulation of development, to guide the growth of reproductive structures, and to protect the fungal cell from DNA damage produced by light and UV radiation. Light perception requires the activity of photoreceptors that relay the light signal through transduction pathways into the cellular response. Fungi can see and react to a wide range of colors, but most fungi use blue light as their primary signal to regulate its photobiology. Examples of fungal perception of UV, green, and red light, like plants, have been documented and, in most cases, the photoreceptors responsible for these responses have been identified. Blue light is perceived through the activity of light-regulated transcription factors, the WC proteins, first identified in Neurospora crassa. Red light is perceived by phytochromes, a photoreceptor characterized in detail in Aspergillus nidulans. A novel type of rhodopsin, rhodopsin guanylyl cyclase (RGS) has been identified in the zoosporic fungus Blastocladiella emersonii. These types of photoreceptors, together with the blue-light photoreceptor cryptochrome, are widespread in fungi, suggesting that the ancestor of the fungi could see a wide range of colors. Gene duplication and specialization have allowed specific use of fungal photoreceptors in the regulation of fungal biology.