Unravelling the role of 1-aminocyclopropane-1-carboxylic acid (ACC) as a signalling molecule in land plant evolution

• Applicant: Dr. Alisa Keyl
• Subject Area: Evolution and Systematics of Plants and Fungi ; Plant Biochemistry and Biophysics ; Plant Physiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 557916995

The colonisation of land by plants about 450 million years ago marks a pivotal event in the history of Earth, giving rise to the broad diversity of land plants observed today. The transition from aquatic to terrestrial environments exposed the first land plants to a broad array of environmental stressors, including drought, high ultraviolet radiation, fluctuations in temperature as well as pathogenic microbes. One key component in the adaption to terrestrial conditions was the capacity to produce phytohormones, low-molecular-weight metabolites that regulate various aspects of plant growth, development, or stress responses. The volatile plant hormone ethylene plays a crucial role in those processes and probably played a crucial role in land plant evolution. In seed plants, the canonical ethylene biosynthesis pathway consists of two enzymatic reactions, where 1-aminocyclopropane-1-carboxylic acid (ACC) is used as the direct precursor for ethylene production catalysed by ACC oxidases (ACOs). However, genome sequencing and phylogenetic studies have shown that non-seed plants do not have homologs for canonical ACO enzymes but still produce both ACC and ethylene. Therefore, non-seed plants must have an ACC-independent ethylene biosynthesis pathway that remains to be investigated. In addition, recent studies have shown that ACC itself can act as a signalling molecule, independent of ethylene, to control plant development throughout the streptophyte lineage. However, it remains unknown how ACC is perceived, the details of its signalling pathway, and which downstream responses are triggered. To understand the origin and evolution of the alternative ethylene biosynthesis and the ACC signalling pathway, I will use the liverwort Marchantia polymorpha as a model system for non-seed plants. Using functional genetics and multiple omics approaches, this project will characterise the non-canonical ethylene biosynthesis pathway as well as ACC signalling and ACC-mediated processes to understand the role of both ethylene and ACC in the evolution of land plants.

• DFG Programme: WBP Fellowship
• International Connection: Belgium
• Host: Professor Dr.-Ing. Bram van de Poel