Exogenously applied hydrogen peroxide modifies the course of the Chlamydomonas reinhardtii cell cycle

The interaction of NO and H₂O₂ in the regulation of plant development is well documented. We have recently shown that the content of NO and H₂O₂ changes in a characteristic way during the cell cycle of Chlamydomonas reinhardtii (Pokora et al., 2017), which implies participation of these molecules in the regulation of Chlamydomonas development. To verify this assumption, H₂O₂ was supplied at a concentration about 1.5 times higher than that determined in the control cells. Cells were synchronized by alternating the light/dark (10/14 h) regimen. H₂O₂ was added to zoospore suspensions, previously held in the dark, and cells growing for 3, 6, and 9 h in the light. The data indicate that, depending on the phase of the Chlamydomonas cell cycle, H₂O₂, via mild modification of redox homeostasis, may: a) accelerate or delay the duration of the cell cycle; b) increase the number of replication rounds occurring in one cell cycle; c) modify the biomass and cell volume of progeny cells and d) accelerate the liberation of daughter cells. This provides a tool to control the development of Chlamydomonas cell and thus offers the opportunity to obtain a population of cells with characteristics desired in biotechnology.