Periodic Reporting for period 3 - EXECUT.ER (Dissecting the molecular mechanisms that execute developmental programmed cell death in plants)
Reporting period: 2023-09-01 to 2025-02-28
Programmed Cell Death (PCD) is fundamental to the development and health of multicellular organisms. However, our knowledge on developmentally controlled PCD in plants remains fragmentary, despite its undoubted significance for plant growth and reproduction. Developmental PCD in plants is for instance a critical step in the formation of water conducting tissue, and indispensable for several aspects of successful plant reproduction. As our food supply directly and indirectly depends on growing and reproducing plants, understanding PCD as a fundamental principle of plant development will be important to obtain information that can help us to identify novel strategies to develop novel more stress resilient crop plant varieties.
My team has established the Arabidopsis root cap as a novel model system for developmental PCD in plants. This model has enabled us to identify a gene regulatory network controlling the preparation of PCD. However, the molecular processes that terminate the vital functions of a plant cell during the final steps of PCD execution remain unknown. The overall objective of EXECUT.ER is to understand the cellular and subcellular processes that occur during developmental PCD in plants. On the one hand this entails to describe the dynamic modifications that plant cells undergo in terms of cell biology, transcriptome, and proteome during PCD execution. On the other hand, we aim to identify the genes and proteins, as well as their operating mechanisms, that are critical to execute cell death in the right time and in the right place.
My team has established the Arabidopsis root cap as a novel model system for developmental PCD in plants. This model has enabled us to identify a gene regulatory network controlling the preparation of PCD. However, the molecular processes that terminate the vital functions of a plant cell during the final steps of PCD execution remain unknown. The overall objective of EXECUT.ER is to understand the cellular and subcellular processes that occur during developmental PCD in plants. On the one hand this entails to describe the dynamic modifications that plant cells undergo in terms of cell biology, transcriptome, and proteome during PCD execution. On the other hand, we aim to identify the genes and proteins, as well as their operating mechanisms, that are critical to execute cell death in the right time and in the right place.
Exploiting the accessibility of the root cap for live-cell analysis of PCD execution, we revealed a succession of distinct membrane permeabilization events in which certain cellular compartments are dissociated. This stepwise decompartmentalization can liberate and activate cell death executing proteins from save storage locations. Therefore, we hypothesize that this sequential de-compartmentalization is the mechanism underlying the irreversible and orderly execution of PCD.
Recent advances in several key technologies provide unprecedented opportunities to test this hypothesis and make a quantum leap in our understanding of the mechanisms carrying out PCD execution. We are applying super-resolution as well as correlative light and electron microscopy to analyse PCD execution in unparalleled spatial and temporal resolution. RNA sequencing of single cells at the onset of PCD execution will provide information on the genes that are required for this rapid process. Advanced proteomics techniques will provide a direct route to identify proteins acting on membrane permeabilization during PCD execution. Lastly, multiplex and tissue-specific mutagenesis via innovative CRISPR screens will enable us to overcome genetic redundancy and lethality in the PCD context.
Recent advances in several key technologies provide unprecedented opportunities to test this hypothesis and make a quantum leap in our understanding of the mechanisms carrying out PCD execution. We are applying super-resolution as well as correlative light and electron microscopy to analyse PCD execution in unparalleled spatial and temporal resolution. RNA sequencing of single cells at the onset of PCD execution will provide information on the genes that are required for this rapid process. Advanced proteomics techniques will provide a direct route to identify proteins acting on membrane permeabilization during PCD execution. Lastly, multiplex and tissue-specific mutagenesis via innovative CRISPR screens will enable us to overcome genetic redundancy and lethality in the PCD context.
Application of latest technologies will push the boundaries of our knowledge on plant PCD. At the end of the project, we want to have made a decisive progress in our understanding of developmentally PCD processes in plants. Identification of hitherto unknown proteins and their operating mechanisms will be the first steps for a detailed understanding of plant PCD execution mechanisms. The insights generated by this research program will shed light on a fundamental principle of plant development and open new avenues for crop improvement and protection.