The DELLA-independent interactome of GID1 in the regulation of shade avoidance

• Applicant: Dr. Putri Prasetyaningrum
• Subject Area: Plant Physiology ; Plant Cell and Developmental Biology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 540959978

Plants compete for available light and resources and they can detect each other via the reflection of far-red light from their competitors' leaves, lowering the red:far-red ratio. This elicits a response that consists of stem elongation, leaf elevation and early flowering and is called the shade avoidance response. Gibberellin (GA) is one of the important phytohormones in regulating the shade avoidance response and is perceived by the receptor GIBBERELLIN-INSENSITIVE DWARF1 (GID1). Arabidopsis has three gibberellin receptors, GID1A, GID1B and GID1C which are localized in the nucleus and cytoplasm. Upon GA binding, GID1 recruits a group of growth inhibitor proteins called DELLAs. This complex then interacts with the ubiquitination machinery, leading to DELLA degradation, thus releasing DELLA suppression of growth. The role of GA in shade avoidance is mainly described via DELLA degradation by GA-GID1. However, the result of my preliminary experiments indicates that DELLA-independent GA perception plays a role in shade avoidance. This effect likely occurs through GID1 interacting with non-DELLA proteins that regulate plant growth and the shade avoidance response. However, these DELLA-independent GID1 interactions have been poorly investigated and understood molecularly. This highlights the necessity to revisit and redefine GA perception, and how it affects the shade avoidance mechanism. Therefore, I propose to investigate the interactome of GID1 in shade avoidance and its potential role in the under-explored DELLA-independent pathway of GA perception. I will 1) investigate the temporal regulation and protein accumulation of GID1 A, B and C in the shade avoidance response, 2) identify the unknown GID1 interacting proteins using proximity labelling, and 3) confirm these interactions and characterise the GID1-interacting proteins in the shade avoidance response. This will give us new insights into the under-explored non-canonical GA perception and how this regulates shade avoidance. I propose to carry out this project in the research group of Prof. Andreas Hiltbrunner at the University of Freiburg (host group), which has excellent facilities and field-leading expertise on light-regulated growth and protein-protein interactions. I have excellent knowledge of the temporal and spatial regulation of GA biosynthesis and plant growth and thus will add a new research topic to the host group, ensuring excellent two-way knowledge transfer and most importantly, a great chance to bring this project into a success.

• DFG Programme: WBP Position