Discrete redox signaling pathways regulate photosynthetic light-harvesting and chloroplast gene transcription.

In photosynthesis in chloroplasts, two related regulatory processes balance the actions of photosystems I and II. These processes are short-term, post-translational redistribution of light-harvesting capacity, and long-term adjustment of photosystem stoichiometry initiated by control of chloroplast DNA transcription. Both responses are initiated by changes in the redox state of the electron carrier, plastoquinone, which connects the two photosystems.

Energy transduction anchors genes in organelles.

The work of mitochondria and chloroplasts is energy transduction in respiration and photosynthesis. The physico-chemical mechanisms of bioenergetics do not directly involve genes and heredity, and furthermore, redox chemistry is intrinsically mutagenic. Thus the small, functional genomes of mitochondria and chloroplasts are an oddity.