Diversity of C3-C4 intermediate photosynthesis
The establishment of C4 photosynthesis requires considerable alterations in leaf architecture and biochemistry and evolves via intermediate states. The Brassicaceae family contains several species with a C3-C4 intermediate architecture and a limited CO2 concentration in the bundle sheath via a photorespiratory glycine pump. In the Asteraceae intermediate forms can also be found close to C4 species.
C3-C4 species can be distinguished so far by their CO2 compensation point and their bundle sheath anatomy. Within the Brassicaceae we investigate the diversity of such glycine pump mechanisms in by parallel analysis of the genome, the anatomy and physiology in a large panel of species. The gained knowledge will help us to introduce a C3-C4 like phenotype into the C3 species Arabidopsis by a synthetic biology approach.
C3-C4 intermediate leaves differ from C3 leaves by alterations in metabolic balance between the mesophyll and bundle sheath cells. The shift of photorespiratory glycine decarboxylation to the bundle sheath causes changes in cell biochemistry, organelle distribution and metabolite transport between cells. In this multiplexed project we aim at elucidation of leaf cell fate control using optogenetic tools.
Molecular mechanisms of facultative Crassulacean Acid Metabolism (CAM)
CAM plants can be found in warm and seasonally dry environments, where they can survive due to their efficient mode of photosynthesis regarding water-use efficiency. Some plants, such as Talinum fruticosum can switch between C3 and CAM photosynthesis if conditions are (not) favorable. We are working on understanding this mechanism by using approaches in the fields of synthetic biology, proteomics, trancriptomics, metabolomics and genomics.
Maximising C4 photosynthesis in maize
Maize is an important C4 crop plant with high light, nitrogen and water use efficiency. In intensively managed maize cultures the photosynthetic performance is however still short of its theoretical maximum. In the Fullthrottle project we explore the natural photosynthetic diversity of maize lines in the field and the factors potentially lowering the efficiency of C4 photosynthesis.
Measurements of photosynthetic performance are still laborious and time-consuming. The potential of leaf reflectance spectroscopy for regression model based estimation of different photosynthetically relevant parameters such as maximal assimilation, chlorophyll and nitrogen content is investigated. In the BMBF funded Fullthrottle project we collaborate with the Schön group at TUM, the Stitt and Fernie groups at MPIMP Golm, the Nikoloski group at University of Potsdam and the KWS.