Biochemistry and physiological importance of alternative photorespiratory pathways in higher plants

点击翻译按钮获取中文摘要

Besides oxidation of glycolate in peroxisomes as part of the main photorespiratory pathway, higher plants are also capable of converting glycolate in the chloroplast or the mitochondrium. Data from us and partners in the Promics network indicate that homologues to these additional pathways are found in cyanobacteria and green algae of the chlorophyte subclade, respectively. This suggests evolutionary conservation over a period of at least 400 Million years. However, the molecular regulation and biological importance of these two alternative opportunities for glycolate conversion in higher plants is mostly unknown. In this project, Arabidopsis genes encoding candidate components of the pathways will be overexpressed or suppressed and the effects on metabolite profiles, photorespiratory flow rates, and glycolate conversion in isolated organelles will be measured. Moreover, the activity of the three possible glycolate conversion pathways will be modulated in a combinatorial manner by genetic crossing of the generated lines. The resulting genotypes will be subjected to diverse stress conditions such as reduced CO2 supply, nitrogen depletion, or drought, and relative growth rates will be determined. This will allow new insights into the control of alternative glycolate oxidation reactions and the evolution of photorespiration.