The Cell biology of light signaling – What is the function of nuclear photobodies?

• Applicant: Dr. Kasper van Gelderen
• Subject Area: Plant Cell and Developmental Biology ; Plant Biochemistry and Biophysics ; Plant Physiology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 500292960

Light perception and responses are essential for plant life and how light can be converted into a biochemical signal is a fundamental question in biology. Plants can see light through receptor proteins dedicated to particular colours. Different light cues can attract plants, cause them to grow taller, induce protective compounds, or make them flower earlier than normal. Phytochromes are the main red light sensors in plants and phytochromes form microscopically small (~40 nm) bodies within the plant cell nucleus. These subnuclear structures are called photobodies and they play an important role in the response to light. Photobodies also contain other proteins that are interacting with phytochromes to direct growth in response to light. Importantly, phytochrome B is not only required for light-, but also for temperature-sensing, suggesting that photobodies also play an important role in plant responses to ambient temperature changes. However, it remains unclear how photobodies aid phytochrome B signaling, and how they help the plant respond to light cues through developmental changes. To discover how the photobody helps light perception and signaling in plants, I propose to investigate the formation and responses of photobodies to light and temperature using microscopy, biochemistry and a chemical screen. I will 1) characterize how photobodies form, record the changes during light and temperature responses and track the assembly of helper proteins into the photobody by high resolution live imaging. 2) Decipher the composition of photobodies by isolating them with the help of fluorescent sorting techniques. Additionally, I will discover the proteins in and around the photobody by a technique called proximity labelling, where we ‘paint’ the protein environment with a specific tag. 3) Elucidate how photobodies help plant growth by discovering new compounds that can disturb the photobody. This will give us new tools to investigate photobody functioning and its effect on development. My proven skills in plant cell biology, plant photobiology and development, combined with expertise of the Heidelberg life-science community will give me an edge in the field of plant photobiology to create a vibrant research group and start my career as an independent scientist in Germany.

• DFG Programme: Independent Junior Research Groups