Fig. 8.

The involvement of reactive electrophile species (RES) in the Jekyll and Hyde high light stress responses of C. reinhardtii. Excess light increases the formation of singlet oxygen (¹O₂) from PSII, which can induce lipid peroxidation of the thylakoid membrane lipids in the chloroplast (green). Lipid peroxides decay to release RES (yellow) that attack photosystems, contributing to photoinhibition, but are also sensed by specific nuclear transcription factors, such as SOR1, to affect transcription in the nucleus (red), whereby RES act as chloroplast-to-nucleus ‘retrograde’ signals. Up-regulated transcripts (white italics) are involved in helping mitigate excess light energy (LHCSR1, PSBS1), or contribute to photosystem assembly (ELI1, ELI3). The pathway, modified with permission from Roach et al. (2018) is superimposed over a false-coloured electron micrograph of an algal cell. The non-coloured region is the cytosol.