Molecular Cloning and Functional Characterization of the GPDH Gene Family in the Green Microalga Chlamydomonas reinhardtii

Glycerol-3-phosphate dehydrogenase (GPDH) is an enzyme that catalyzes the reduction of dihydroxyacetone phosphate to glycerol-3-phosphate (G3P), which is an important precursor for the synthesis of glycerol and triacylglycerols (TAGs). Interestingly, the overexpression of a yeast GPDH gene (GPD1) in mature seeds of Brassica napus increased 40% the fatty acid content. Osmotic stress has been shown to induce glycerol and TAGs accumulation in C. reinhardtii. Recently, our research group identified three CrGPDH homologue genes in C. reinhardtii. Since the expression of both CrGPDH2 and CrGPDH3 was induced in response to 200 mM NaCl, we suggest that these genes could be involved in glycerol and TAGs synthesis in this microalga (Herrera-Valencia et al. 2012). In this study we are extending these previous findings by analyzing  1) the expression of the three CrGPDH genes in response to different NaCl concentrations and 2) the effect of overexpressing these genes on the levels of glycerol and TAGs in C. reinhardtii.