Natural diversity of C3-C4 photosynthesis
Establishment of C4 photosynthesis requires considerable alterations in leaf architecture and biochemistry and evolves via intermediate states. Such intermediate photosynthetic mechanisms are characterised by increased CO2 concentration in the bundle sheath via a photorespiratory glycine pump and enhanced accumulation and arrangement of organelles. Glycine shuttles have evolved independently in different plant groups, and in our group we explore diversity of photorespiratory shuttles in the Brassicaceae, Asteraceae and Chenopodiaceae.
Cell specific gene regulatory networks
In C3-C4 photosynthesis, photorespiratory glycine decarboxylation is restricted to bundle sheath cells. This requires differential adjustments of carbon, nitrogen and energy metabolism in mesophyll and bundle sheath. Cell specific gene regulatory networks are investigated in our group by pangenome comparisons, single cell transcriptomes and genome engineering. We apply and develop deep learning tool predicting gene structure models and epigenetic states.
C3-C4 specific leaf anatomy
C3-C4 intermediates display C4-like leaf anatomical features thus differing from C3 leaf anatomy. To date, it is unknown how the characteristic leaf anatomy of C3-C4 intermediates is established and which gene-regulatory circuits govern this process. To unravel these intricate regulatory networks, the Brassicaceae family, with its five independent instances of the C3-C4 intermediate trait, will be used in conjunction with microscopy, cell biology, single-cell and computational biology approaches.
Facultative Crassulacean Acid Metabolism (CAM) in Talinum fruticosum
CAM has frequently and convergently evolved as the most water-use-efficient carbon-concentrating mechanism. By assimilating CO2 at night and temporal separation of their primary and secondary carbon assimilation, CAM plants can decrease their water loss. The facultative CAM plant Talinum fruticosum can reversibly reallocate its resources from C3 to CAM photosynthesis during drought and back to C3 upon rewatering. Mechanisms behind this switch are investigated by combining transcriptomics, genomics, bioinformatics, proteomics, and metabolomics.
Synthetic redesigning of plant photorespiration
C3 photosynthesis is performed by the vast majority of crop species and is limited by oxygenation reaction of Rubisco, which produces a toxic by-product which is neutralized in the photorespiratory pathway. Using synthetic biology approaches we aim to circumvent this process and redesign C3 photosynthesis by implementing heterologous or even new pathways such as the ß-hydroxyaspartate cycle (Roell et al., PNAS 2021) and the tartonyl-CoA pathway (Scheffen et al. Nature Catalysis 2021)
Ecology of C3-C4 intermediate Brassicaceae
Photosynthesis is the primary source of chemical energy for plants and, as such, crucial for plant fitness and ecology. Variation in leaf structure and anatomy influences the photosynthetic efficiency and carbon assimilation under different environmental conditions. In the TRR_341 project we will link intra- and inter-specific genetic variation in leaf traits with variation in photosynthetic efficiency. We aim at unravelling the contribution of leaf-trait-variation and photosynthetic performance to the genetic basis of ecological specialization in the Brassicaceae