PP37 - Discovery of novel photorespiratory players by forward chemical and genetic approaches

Abstract

The high metabolic flux through photorespiration constitutes a significant part of the carbon cycle. Although the major enzymatic steps of the photorespiratory pathway are well characterized, little information is available on the functional significance of photorespiration beyond carbon recycling. Particularly important in this respect is the peroxisomal catalase activity which removes photorespiratory H 2 O 2 generated during the oxidation of glycolate to glyoxylate, thus maintaining the cellular redox homeostasis governing the perception, integration and execution of stress responses. We have previously performed a chemical screen that led to the identification of 34 small molecules that alleviate the negative effects of photorespiration in Arabidopsis thaliana mutants lacking peroxisomal catalase ( cat2 ). In parallel, we screened a mutagenized cat2 population and looked for second-site mutations that similarly attenuate the effects of photorespiratory conditions in cat2 plants. Currently, we characterize putative protein targets of some of the chemical hits and investigate the fine-tuning roles of the confirmed mutations on the photorespiratory phenotype of cat2 .