Eukaryotic algal phytochromes span the visible spectrum

Abstract

Significance Photosynthetic organisms exploit photosensory proteins to respond to changing light conditions. In land plants, phytochromes use the ratio of red to far-red light to detect shading by neighboring plants, leading to changes in growth and development. Light conditions can be more variable for algae because of the wavelength-dependent attenuation of light by water and because of ocean mixing. We studied phytochromes from taxonomically diverse eukaryotic algae from groups considered important for coastal ecosystems and the global carbon cycle. These proteins detect light throughout the visible spectrum (blue, green, orange, red, and far-red). Extensive spectral tuning has evolved within these algae, presumably reflecting aquatic light environments. These studies should ultimately facilitate engineering of crop plant species for diverse light environments.