PARENT SESSION
Posters P6D Crop photosynthesis, agricultural biotechnology. Abstracts (742-753)

Towards the installation of a C4-like CO₂ fixation pathway in C3 plants. Teresa Sikora^*,1, Anna Czerednik¹, Heinz-Josef Hirsch¹, Thomas Rademacher², Sonja Töpsch¹, Christoph Peterhänsel¹, Fritz Kreuzaler¹, ¹ RWTH Aachen Institute for Biology I, Aachen, Germany² Fraunhofer IME, Aachen, Germany

ABSTRACT- C3 plants loose a significant part of the already fixed carbon and nitrogen in the process of photorespiration. C4 plants established an alternative CO2 fixation pathway capable of suppressing the oxygenase activity of Rubisco. They apply Phosphoenolpyruvate Carboxylase (PEPC) for the initial carbon fixation. We have previously shown that constitutive overexpression of a modified PEPC in potato redirects carbon flow from the production of sugars to organic acids. This enzyme was combined with a Phosphoenolpyruvate Carboxykinase (PCK) targeted to the chloroplast establishing a minimal C4-like cycle. Both transgenic activities can be detected in tobacco and Arabidopsis leaf extracts. These plants are currently analysed for metabolite concentrations and photosynthetic parameters. The PEPC enzyme was also expressed under light-induced promoter control. Our data indicate that the undesired effects of constitutive overexpression like the stunted growth of the plants can be relieved without affecting PEPC activity in the leaves.

KEY WORDS: C4-like, PCK, photosynthesis, PEPC