The impact of short-cutting photorespiration on carbon and nitrogen metabolism

点击翻译按钮获取中文摘要

We recently produced Arabidopsis plants engineered to oxidise glycolate inside the plastids. These plants showed beneficial effects on growth and had higher CO2 assimilation rates per unit area and chlorophyll. To achieve this, it was of radical importance to introduce catalase in the plastids to eliminate H2O2 produced by glycolate oxidase. Here, we propose to work further in the optimization of this original pathway using a glycolate dehydrogenase (GlcDH), without production of H2O2. To this end, we will follow two strategies, (i) the use of Micromonas GlcDH and (ii) the combined use of Synechocystis GlcD1 and GlcD2. Transgenic lines bearing the new pathways will be selected and the impact on plant performance will be analysed at different levels. Moreover, the kinetic properties of these activities enzymes will be thoroughly investigated. On the other hand, photorespiration has been clearly demonstrated to interact with other cellular processes. In this regard, our previous work indicated a light-dependent accumulation of 2-hydroxyglutarate (2HG) in the shm1-1 mutant, which was correlated with high levels of glycine, 2-ketoglutarate and many amino acids. Moreover, we showed for the first time that both enantiomeric forms of 2HG, D-and L-2HG can be found, although at extremely low levels, in wild-type leaf extracts of plants growing in normal conditions. Our group will thus specifically focus on the cross-talk of photorespiration with processes involving 2HG (e.g. senescence, metabolic repair). For this purpose a combination of genomic, biochemical, metabolomic and flux profiling approaches will be applied to a set of photorespiratory mutants, which accumulate glycine to different levels.