Effects of perturbation of redox state on postfertilization development and spore differentiation in the red alga Bostrychia moritziana

The correct development of an organism is critical for its survival and reproduction, especially the early stages of establishment. Early developmental stages require close control and careful signaling between cells and genetic networks. Red algae also undergo critical developmental stages, but very little is known about these processes or their control. An important developmental signal is the redox state of a cell. The complex life cycle of red algae also involves the intricate development of the fertilized egg to produce diploid spores (carpospores). We examined the effect of redox perturbation on the life cycle of Bostrychia moritziana, focusing on critical stages of spore development, the formation of meiospores (tetraspores), and the development of the diploid carposporophytes. Our results showed that spore development follows a distinct pattern of asymmetrical division and differentiation, regulated by reactive oxygen species (ROS) signaling. Reactive oxygen species were observed to accumulate specifically at the dividing plane of the central cell, suggesting their importance in cell division. Treatments with various redox-altering compounds, including hydrogen peroxide, antioxidants, and inhibitors of NADPH oxidase and calcium signaling, significantly impacted spore development, carposporophyte formation, and the development of tetrasporangial branches. Our results demonstrated that short-term redox perturbations during critical developmental stages can have far-reaching consequences on the morphogenesis of B. moritziana, affecting both immediate growth patterns and long-term developmental trajectories.