Light promotes asexual reproduction and mediates transcriptomic changes in Pediastrum duplex

The green alga Pediastrum duplex forms colonies through asexual reproduction and has a unique life cycle. To elucidate the mechanisms that regulate the asexual reproductive cycle in P. duplex, we analyzed the effects of light on the processes and gene expression involved in each step of the asexual reproductive cycle, revealing light irradiation to be essential for increasing the number of colonies. Among the processes in the asexual reproductive cycle, the transition from cell hypertrophy to zoospore formation could proceed even in the dark if glucose was added to the medium. Transcriptome analysis revealed that the expression of different groups of genes was significantly promoted or suppressed before and after the number of colonies increased. Our findings indicate that the asexual reproductive cycle of P. duplex includes a process promoted by photosynthesis. This study enhances our understanding of the growth characteristics of P. duplex and other microalgae.