Assessing the effect of light stress on Chlamydomonas reinhardtii using metabolomics

Maria Davis (Correia)1, Oliver Fiehn2 and Dion G Durnford1

1) Biology Department, University of New Brunswick, Fredericton, NB E3B 5A3, Canada 2) Davis Genome Center, University of California, Davis, CA 95616, USA

Although light is essential for photosynthesis, high-light intensity causes photo-oxidative damage to photosynthetic cells. Photosynthetic organisms have evolved various photo-protective responses to cope with changes in incident light intensity. These responses have been studied extensively, but the signaling pathways that trigger stress responses are not well understood. Our previous data suggests that metabolites may act as sensors of the energy status of cells. Changes in metabolite concentration or flux through pathways may thus initiate compensatory changes in gene expression during stressful conditions. Our current study examines metabolic changes occurring in C. reinhardtii during light stress. Metabolic fingerprinting was used to study short and long term changes in intracellular metabolite concentrations due to high light exposure. Metabolic fingerprints were obtained using mass spectrometry (MS) and nuclear magnetic resonance (NMR) and these data are being analyzed in detail to identify light stress related biomarkers. Metabolic fingerprints are also correlated to changes in the transcriptional profiles of five genes involved in mitochondrial and plastid metabolism. Correlation of metabolic changes to observed physiological responses will aid the identification of key pathways affected by short-term light stress. Characterizing metabolic changes will contribute to providing a comprehensive view of high irradiance stress in C. reinhardtii and how the organism is able to sense and acclimate to light stress.

e-mail address of presenting author: Maria.Correia@unb.ca