Systematic identification and characterization of novel genes in the regulation and biogenesis of photosynthetic machinery

Photosynthesis is central to food production and the Earth’s biogeochemistry, yet the molecular basis for its regulation remains poorly understood. Here, using high-throughput genetics in the model eukaryotic alga Chlamydomonas reinhardtii, we identify 115 genes required for photosynthesis, 70 of which were previously uncharacterized. We initiate functional characterization of the novel genes by determining the proteomes of mutant strains lacking these genes. The data allow assignment of 34 of the novel genes to the biogenesis or regulation of one or more specific photosynthetic complexes. Additional analysis uncovers at least seven novel critical regulatory proteins, including five Photosystem I mRNA maturation factors and two master regulators: MTF1, which impacts chloroplast gene expression directly; and PMR1, which impacts expression via nuclear-expressed factors. Our work provides a rich resource identifying novel regulatory and functional genes and placing them into pathways, thereby opening the door to a system-level understanding of photosynthesis.