Light Signaling and Cell Biology
Welcome to the site of the Light Signaling and Cell Biology group, led by Dr. Kasper van Gelderen at the Centre for Organismal Studies, Heidelberg, Germany. We investigate cell-biological aspects of plant light signaling; How photoreceptor complexes are organized in the nucleus and how the plant shoot can send signals to the root via mobile transcription factors.
Plant light perception through phytochromes
Plants need light to grow, so it makes a lot of sense that they can perceive the quantity and quality of light. To sense the shade of neighbouring plants, daylength, and even temperature and salinity, plants use the phytochrome photoreceptors. These receptors can be found in every cell of the plant and read out the amount of red and far-red light in the environment, which the plant uses as a cue for light quality. Phytochromes control a vast network of transcription factors that control growth, allowing the plant top respond to the environment
Phytochromes
Phytcochromes can be found throughout the tree of life where organisms use them to detect light. They are a dimeric protein with a pigment inside the structure absorbs the light, driving the structure into a new conformation, ready to initiate signalling events.
HY5 shoot-root signaling
Light perception in the shoot by phytochromes also affects root development through mobile signals. Plants need to balance shoot and root development with regard to available light and nutrients. We investigate how HY5, a key transcription factor, is transported from shoot to root, communicating over long distance.
Nuclear condensates and liquid phase separation
In the plant nucleus, photoreceptors, including phytochromes, coalesce into large protein condensates, phase-separating away from the rest of the nucleoplasm. These subnuclear compartments without membranes are flexible structures that integrate light perception and signalling. They can form and dissolve depending on the light environment, which is why they are called photobodies (see movie on the left). We want to understand how these compartments form, what they are made of, and how they function, in response to light