Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2
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 controvers...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-07-01
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| Series: | Frontiers in Plant Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fpls.2022.897924/full |
| _version_ | 1811317874451546112 |
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| author | Konrad Krämer Judith Brock Arnd G. Heyer |
| author_facet | Konrad Krämer Judith Brock Arnd G. Heyer |
| author_sort | Konrad Krämer |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-04-13T12:15:56Z |
| format | Article |
| id | doaj.art-3dc9e7a5d69e4617a6d55f0f7c986361 |
| institution | Directory Open Access Journal |
| issn | 1664-462X |
| language | English |
| last_indexed | 2024-04-13T12:15:56Z |
| publishDate | 2022-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Plant Science |
| spelling | doaj.art-3dc9e7a5d69e4617a6d55f0f7c9863612022-12-22T02:47:21ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2022-07-011310.3389/fpls.2022.897924897924Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2Konrad KrämerJudith BrockArnd G. HeyerIt 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.https://www.frontiersin.org/articles/10.3389/fpls.2022.897924/fullphotorespirationnitrate assimilationelevated CO2hydroxypyruvate reductaseArabidopsis |
| spellingShingle | Konrad Krämer Judith Brock Arnd G. Heyer Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2 Frontiers in Plant Science photorespiration nitrate assimilation elevated CO2 hydroxypyruvate reductase Arabidopsis |
| title | Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2 |
| title_full | Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2 |
| title_fullStr | Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2 |
| title_full_unstemmed | Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2 |
| title_short | Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2 |
| title_sort | interaction of nitrate assimilation and photorespiration at elevated co2 |
| topic | photorespiration nitrate assimilation elevated CO2 hydroxypyruvate reductase Arabidopsis |
| url | https://www.frontiersin.org/articles/10.3389/fpls.2022.897924/full |
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