LAUSR

As in metazoans, life in oxygenic photosynthetic organisms relies on the accurate regulation of cell death. During development and in response to the environment, photosynthetic cells activate and execute cell death pathways that culminate in the death of a specific group of cells, a process known as regulated cell death (RCD). RCD control is instrumental, as its mis regulation can lead to growth penalties and even the death of the entire organism. Intracellular molecules released during cell demise may act as "survival" or "death" signals and control the propagation of cell death to surrounding cells, even in unicellular organisms. This review explores different signals involved in cell-cell communication and systemic signaling in photosynthetic organisms, in particular Ca 2+, ROS, lipid derivates, NO and eATP. We discuss their possible mode-of-action as either "survival" and "death" molecules and their potential role in determining cell fate in neighboring cells. By comparing the knowledge available across the taxonomic spectrum of this coherent phylogenetic group, from cyanobacteria to vascular plants, we aim at contributing to the identification of conserved mechanisms that control cell death propagation in oxygenic photosynthetic organisms.