Dr. Kasper van Gelderen, Universität Heidelberg

Phytochrome B is a crucial red and far-red light sensor in plants, which controls plant development and environmental responses to light and temperature. In the nucleus, phyB forms phase separated condensates, also called photobodies, consisting of various transcriptional regulators and transcription factors. phyB photobodies can form or disperse depending on the amount of light, the light quality, or ambient temperature. However, the biological relevance for forming photobodies is still unclear. Here, we hypothesize that the formation of phyB photobodies and the associated sequestration of signaling molecules allows for the formation of cell-type specific memory about light conditions, and smoothen the light signalling output in changing condtions. Using a combination of live- and fixed seedling imaging of photobodies with single nucleus transcriptomics and proximity labelling we shed new light on the formation, composition and function of phytochrome B photobodies.