Connor Nehls-Ramos, Elizabete Carmo-Silva, Douglas J Orr

Crop yields can be improved through making photosynthesis more efficient. The regulation of the CO₂-fixing enzyme Rubisco during fluctuating light conditions limits productivity and is a target for improvement. Regulation in low light and darkness by accumulation of Rubisco inhibitors, predominantly via 2-carboxy-D-arabinitol 1-phosphate, has been known for over four decades but an explanation is still lacking for its physiological role and high variability across species. We compiled all published data for dark inhibition of Rubisco in flowering plants and investigated phylogenetic trends. Literature data for 157 species across 14 orders was compared and standardized, categorized into four dark inhibition levels, and analysed in the context of current phylogenetic information. We created a novel resource for Rubisco dark inhibition across flowering plants, highlighting clear gaps and biases in the available data, while also raising further questions on the evolution of this trait. Our work supports better understanding of the enigmatic process of photosynthetic regulation by Rubisco dark and low light inhibition and informs future efforts in enhancing photosynthesis in crops.