Anaplerotic flux into the Calvin-Benson cycle : hydrogen isotope evidence for in vivo occurrence in C3 metabolism
© 2022 The Authors New Phytologist © 2022 New Phytologist Foundation.
| Veröffentlicht in: | The New phytologist. - 1979. - 234(2022), 2 vom: 12. Apr., Seite 405-411 |
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| Weitere Verfasser: | , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2022
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| Zugriff auf das übergeordnete Werk: | The New phytologist |
| Schlagworte: | Journal Article Calvin-Benson cycle flux estimation glucose-6-phosphate shunt hydrogen stable isotopes nitrogen assimilation oxidative pentose phosphate pathway plant carbon metabolism source-sink balance Isotopes mehr... |
| Zusammenfassung: | © 2022 The Authors New Phytologist © 2022 New Phytologist Foundation. As the central carbon uptake pathway in photosynthetic cells, the Calvin-Benson cycle is among the most important biochemical cycles for life on Earth. A carbon flux of anaplerotic origin (i.e. through the chloroplast-localized oxidative branch of the pentose phosphate pathway) into the Calvin-Benson cycle was proposed recently. Here, we measured intramolecular deuterium abundances in leaf starch of Helianthus annuus grown at varying ambient CO2 concentrations, Ca . Additionally, we modelled deuterium fractionations expected for the anaplerotic pathway and compared modelled with measured fractionations. We report deuterium fractionation signals at H1 and H2 of starch glucose. Below a Ca change point, these signals increase with decreasing Ca consistent with modelled fractionations by anaplerotic flux. Under standard conditions (Ca = 450 ppm corresponding to intercellular CO2 concentrations, Ci , of 328 ppm), we estimate negligible anaplerotic flux. At Ca = 180 ppm (Ci = 140 ppm), more than 10% of the glucose-6-phosphate entering the starch biosynthesis pathway is diverted into the anaplerotic pathway. In conclusion, we report evidence consistent with anaplerotic carbon flux into the Calvin-Benson cycle in vivo. We propose the flux may help to: maintain high levels of ribulose 1,5-bisphosphate under source-limited growth conditions to facilitate photorespiratory nitrogen assimilation required to build-up source strength; and counteract oxidative stress |
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| Beschreibung: | Date Completed 31.03.2022 Date Revised 31.07.2022 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1469-8137 |
| DOI: | 10.1111/nph.17957 |