Re-cycling of glycolate in C3-chloroplasts: Biochemical and physiological effects on plant metabolism

• Applicant: Professorin Dr. Veronica Maurino
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2002 to 2006
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5387331

The C2-cycle of photosynthetic carbon metabolism starts with the oxygenase reaction catalysed by ribulose 1.5-bisphosphate carxboxylase/oxygenase (Bubiosco). The prime function of the C2-pathway is to salvage glycolate 2-P by conversion to glycerate 3-P, which re-enters the C3-reductive cycle. Both CO2 and NH3 are released within the mitochondria, resulting in a loss of at least 25% of the CO2 fixed in abient air in C3-plants. We attempt to introduce two alternative and complete glycolate catabolic cycles into chloroplasts of the model plant A. thaliana (wild-type and a photorespiratory mutant) in order to release and re-fix the CO2 directly within the chloroplast thereby reducing the oxygenase activity of Rubisco by increasing the CO2/O2 ratio. Thus, an autoregulatory cycle would be created which results in an attenuation of the photorespiratory pathway and an expected improvement in the efficiency of CO2 assimilation. Analyses of transformants bearing single transgenes and those with fully operational glycolate cycles will generate data to complement our understanding of function and regulation of the photorespiratory pathway and its interaction with other processes such as the C3-cycle, the anaplerotic flow into organic acids an NH3 refixation.

• DFG Programme: Research Grants