Malate metabolism and reactions of oxidoreduction in cold-hardened winter rye (Secale cereale L.) leaves
In cold-hardened leaves (CHL) of winter rye (Secale cereale L.) much higher levels of malate were detected by (13)C-NMR than in non-hardened leaves (NHL). As this was not observed previously, malate metabolism of CHL was studied in more detail by biochemical assays. The activities of several enzymes...
| Veröffentlicht in: | Journal of experimental botany. - 1985. - 54(2003), 384 vom: 02. März, Seite 1075-83 |
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| Weitere Verfasser: | , |
| Format: | Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2003
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| Zugriff auf das übergeordnete Werk: | Journal of experimental botany |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Carbon Isotopes Malates Carbon Dioxide 142M471B3J Malate Dehydrogenase EC 1.1.1.37 malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) EC 1.1.1.40 mehr... |
| Zusammenfassung: | In cold-hardened leaves (CHL) of winter rye (Secale cereale L.) much higher levels of malate were detected by (13)C-NMR than in non-hardened leaves (NHL). As this was not observed previously, malate metabolism of CHL was studied in more detail by biochemical assays. The activities of several enzymes of malate metabolism, NADP-malate dehydrogenase, NAD-malate dehydrogenase, phosphoenolpyruvate carboxylase, and NADP-malic enzyme, were also increased in CHL. Short exposures to low temperature of 1-3 d did not induce increases in the malate content or in the activities of enzymes of malate metabolism in mature NHL. The malate content and the enzyme activities declined within 1-2 d after a transfer of CHL from their growing temperature of 4 degrees C to 22 degrees C. The malate content was further increased when CHL were exposed to a higher light intensity at 4 degrees C. In CO(2)-free air the malate content of CHL strongly declined at 4 degrees C. Malate may thus serve as an additional carbon sink and as a CO(2)-store in CHL. It may further function as a vacuolar osmolyte balancing increased concentrations of soluble sugars previously observed in the cytosol of CHL. Malate was not used as a source of reductants when CHL were exposed to photo-oxidative stress by treatment with paraquat. However, the activities of enzymes of the oxidative pentose phosphate pathway were markedly increased in CHL and may serve as non-photosynthetic sources of NADPH and thus contribute to the previously observed superior capacity of CHL of winter rye to maintain their antioxidants in a reduced state in the presence of paraquat |
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| Beschreibung: | Date Completed 15.05.2003 Date Revised 13.05.2019 published: Print Citation Status MEDLINE |
| ISSN: | 1460-2431 |