Correlation between citric acid and nitrate metabolisms during CAM cycle in the atmospheric bromeliad Tillandsia pohliana
Copyright © 2010 Elsevier GmbH. All rights reserved.
| Veröffentlicht in: | Journal of plant physiology. - 1979. - 167(2010), 18 vom: 15. Dez., Seite 1577-83 |
|---|---|
| 1. Verfasser: | |
| Weitere Verfasser: | , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2010
|
| Zugriff auf das übergeordnete Werk: | Journal of plant physiology |
| Schlagworte: | Journal Article Citric Acid 2968PHW8QP Nitrate Reductase EC 1.7.99.4 |
| Zusammenfassung: | Copyright © 2010 Elsevier GmbH. All rights reserved. Crassulacean acid metabolism (CAM) confers crucial adaptations for plants living under frequent environmental stresses. A wide metabolic plasticity can be found among CAM species regarding the type of storage carbohydrate, organic acid accumulated at night and decarboxylating system. Consequently, many aspects of the CAM pathway control are still elusive while the impact of this photosynthetic adaptation on nitrogen metabolism has remained largely unexplored. In this study, we investigated a possible link between the CAM cycle and the nitrogen assimilation in the atmospheric bromeliad Tillandsia pohliana by simultaneously characterizing the diel changes in key enzyme activities and metabolite levels of both organic acid and nitrate metabolisms. The results revealed that T. pohliana performed a typical CAM cycle in which phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase phosphorylation seemed to play a crucial role to avoid futile cycles of carboxylation and decarboxylation. Unlike all other bromeliads previously investigated, almost equimolar concentrations of malate and citrate were accumulated at night. Moreover, a marked nocturnal depletion in the starch reservoirs and an atypical pattern of nitrate reduction restricted to the nighttime were also observed. Since reduction and assimilation of nitrate requires a massive supply of reducing power and energy and considering that T. pohliana lives overexposed to the sunlight, we hypothesize that citrate decarboxylation might be an accessory mechanism to increase internal CO₂ concentration during the day while its biosynthesis could provide NADH and ATP for nocturnal assimilation of nitrate. Therefore, besides delivering photoprotection during the day, citrate might represent a key component connecting both CAM pathway and nitrogen metabolism in T. pohliana; a scenario that certainly deserves further study not only in this species but also in other CAM plants that nocturnally accumulate citrate |
|---|---|
| Beschreibung: | Date Completed 25.02.2011 Date Revised 30.09.2020 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1618-1328 |
| DOI: | 10.1016/j.jplph.2010.06.002 |