Research in my laboratory focuses on the phytochrome superfamily, light sensing biliproteins that are widespread in eukaryotes (plants, algae, fungi, oomycetes and diatoms) and prokaryotes (both photosynthetic and non-photosynthetic species). Phytochromes and cyanobacteriochromes are light-switches whose function depends on the light color. Plants, algae and cyanobacteria use these pigmented protein sensors to regulate photosynthesis-associated gene expression for optimum photosynthesis under the ambient light conditions and for regulation of growth, movement or reproduction to avoid suboptimal light conditions. Our studies utilize representative species from all lineages of oxygenic photosynthetic organisms, including cyanobacteria, green alga and plants. Mainly biochemical in nature, our research focuses on structure-function and molecular evolution of these optogenetic light sensors. Ongoing research seeks to leverage this knowledge for synthetic biological applications that seek to optimize yield and agronomic performance of photosynthetic species for food, fiber and energy production.