A Novel Approach for Bypassing Photorespiration in C3 Plants

Metabolism of glycolate via the photorespiratory pathway in C3 plants consumes not only ATP and reducing equivalents but results also in approximately 25% loss of the carbon from glycolate.a novel bio­chemical pathway for the metabolism of glycolate was established in the chloroplast of Arabidopsis thaliana plants. The pathway is derived from E. coli and converts the glycolate formed during photorespi­ration into glycerate. Three enzymatic activities are required: glycolate dehydrogenase (GDH) glyoxylate carboligase (GCL) and tartronic semialdehyde reductase (TSR). Transgenic A. thaliana plants contai­ning the necessary genes for the novel pathway were generated. Variable amounts of foreign proteins as well as RNA were detected by Western blot and RT-PCR respectively. Enzymatic assays showed that the proteins are active in planta. Biochemical and physiological ana­lyses were performed under ambient and enhanced photorespiratory conditions for evaluating the impact of the novel pathway in planta.it can be concluded that the expression of the novel pathway in C3 plant chloroplasts does not only result in a reduction of photorespi­ration but it also enhances plant growth.