The Complex Trait of C4 Photosynthesis Analyzed in Nine Independent Origins - Angiosperms

C4 photosynthesis confers high productivity to crop plants and the ability to thrive in marginal habitats. It is a biochemical supercharger for photosynthesis nearly eliminating photorespiration and thereby optimizing biomass gain vs. water and nitrogen use. Remarkably, it has independently evolved more than 60 times. We have RNA-seq’ed nine independent origins of C4 photosynthesis in monocots and dicots and their sister species without the trait in biological triplicates to characterize the complex trait in detail and trace the level of convergence to the single gene level. The ultimate goal is to rebuild the trait synthetically.

The phylogenetic analyses for the C4 cycle genes from nine species identify genes pre-disposed for the trait and their characteristics. There are instances where only one gene for a particular function is present in all species, instances where despite multiple genes for the function to choose from orthologous genes are co-opted in all species and instances where the co-opted genes are paralogous between different origins. The differences are explained based on the gene characteristics.

The meta-analysis of the RNA-seq data also identifies shared gene expression patterns for the nine C4 photosynthetic origins which includes transcriptional regulators.