%0 Journal Article %1 kraemer2022interaction %A Kraemer, Konrad %A Brock, Judith %A Heyer, Arnd G. %D 2022 %J Frontiers in Plant Science %K environment metabolism myown %R 10.3389/fpls.2022.897924 %T Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2 %U https://www.frontiersin.org/article/10.3389/fpls.2022.897924 %V 13 %X It has been shown repeatedly that exposure to elevated atmospheric CO₂ causes an increased C/N ratio of plant biomass that could result from either increased carbon or – in relation to C acquisition - reduced nitrogen assimilation. Possible reasons for diminished nitrogen assimilation are controversial, but an impact of reduced photorespiration at elevated CO₂ has frequently been implied. Using a mutant defective in peroxisomal hydroxy-pyruvate reductase (hpr1-1) that is hampered in photorespiratory turnover, we show that indeed, photorespiration stimulates the glutamine-synthetase 2 (GS) / glutamine-oxoglutarate-aminotransferase (GOGAT) cycle, which channels ammonia into amino acid synthesis. However, mathematical flux simulations demonstrated that nitrate assimilation was not reduced at elevated CO₂, pointing to a dilution of nitrogen containing compounds by assimilated carbon at elevated CO₂. The massive growth reduction in the hpr1-1 mutant does not appear to result from nitrogen starvation. Model simulations yield evidence for a loss of cellular energy that is consumed in supporting high flux through the GS/GOGAT cycle that results from inefficient removal of photorespiratory intermediates. This causes a futile cycling of glycolate and hydroxy-pyruvate. In addition to that, accumulation of serine and glycine as well as carboxylates in the mutant creates a metabolic imbalance that could contribute to growth reduction.

@article{kraemer2022interaction, abstract = {It has been shown repeatedly that exposure to elevated atmospheric CO₂ causes an increased C/N ratio of plant biomass that could result from either increased carbon or – in relation to C acquisition - reduced nitrogen assimilation. Possible reasons for diminished nitrogen assimilation are controversial, but an impact of reduced photorespiration at elevated CO₂ has frequently been implied. Using a mutant defective in peroxisomal hydroxy-pyruvate reductase (hpr1-1) that is hampered in photorespiratory turnover, we show that indeed, photorespiration stimulates the glutamine-synthetase 2 (GS) / glutamine-oxoglutarate-aminotransferase (GOGAT) cycle, which channels ammonia into amino acid synthesis. However, mathematical flux simulations demonstrated that nitrate assimilation was not reduced at elevated CO₂, pointing to a dilution of nitrogen containing compounds by assimilated carbon at elevated CO₂. The massive growth reduction in the hpr1-1 mutant does not appear to result from nitrogen starvation. Model simulations yield evidence for a loss of cellular energy that is consumed in supporting high flux through the GS/GOGAT cycle that results from inefficient removal of photorespiratory intermediates. This causes a futile cycling of glycolate and hydroxy-pyruvate. In addition to that, accumulation of serine and glycine as well as carboxylates in the mutant creates a metabolic imbalance that could contribute to growth reduction.}, added-at = {2022-07-01T10:49:54.000+0200}, author = {Kraemer, Konrad and Brock, Judith and Heyer, Arnd G.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/25868968c416b01bbcb1b970ebd1303ac/arndheyer}, doi = {10.3389/fpls.2022.897924}, interhash = {12d451c11a348adfba758087698a59aa}, intrahash = {5868968c416b01bbcb1b970ebd1303ac}, journal = {Frontiers in Plant Science}, keywords = {environment metabolism myown}, month = {July}, timestamp = {2022-07-01T08:49:54.000+0200}, title = {Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2}, url = {https://www.frontiersin.org/article/10.3389/fpls.2022.897924}, volume = 13, year = 2022 }