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Miehe W, Czempik L, Klebl F, Lohaus G. Sugar concentrations and expression of SUTs suggest active phloem loading in tall trees of Fagus sylvatica and Quercus robur. TREE PHYSIOLOGY 2023; 43:805-816. [PMID: 36579830 DOI: 10.1093/treephys/tpac152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 12/15/2022] [Accepted: 12/23/2022] [Indexed: 05/13/2023]
Abstract
Phloem loading and sugar distribution are key steps for carbon partitioning in herbaceous and woody species. Although the phloem loading mechanisms in herbs are well studied, less is known for trees. It was shown for saplings of Fagus sylvatica L. and Quercus robur L. that the sucrose concentration in the phloem sap was higher than in the mesophyll cells, which suggests that phloem loading of sucrose involves active steps. However, the question remains whether this also applies for tall trees. To approach this question, tissue-specific sugar and starch contents of small and tall trees of F. sylvatica and Q. robur as well as the sugar concentration in the subcellular compartments of mesophyll cells were examined. Moreover, sucrose uptake transporters (SUTs) were analyzed by heterology expression in yeast and the tissue-specific expressions of SUTs were investigated. Sugar content in leaves of the canopy (11 and 26 m height) was up to 25% higher compared with that of leaves of small trees of F. sylvatica and Q. robur (2 m height). The sucrose concentration in the cytosol of mesophyll cells from tall trees was between 120 and 240 mM and about 4- to 8-fold lower than the sucrose concentration in the phloem sap of saplings. The analyzed SUT sequences of both tree species cluster into three types, similar to SUTs from other plant species. Heterologous expression in yeast confirmed that all analyzed SUTs are functional sucrose transporters. Moreover, all SUTs were expressed in leaves, bark and wood of the canopy and the expression levels in small and tall trees were similar. The results show that the phloem loading in leaves of tall trees of F. sylvatica and Q. robur probably involves active steps, because there is an uphill concentration gradient for sucrose. SUTs may be involved in phloem loading.
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Affiliation(s)
- Wiebke Miehe
- School of Mathematics and Natural Sciences, Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal 42119, Germany
| | - Laura Czempik
- School of Mathematics and Natural Sciences, Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal 42119, Germany
| | - Franz Klebl
- Department of Biology, Molecular Plant Physiology, University of Erlangen-Nürnberg, Erlangen 91058, Germany
| | - Gertrud Lohaus
- School of Mathematics and Natural Sciences, Molecular Plant Science/Plant Biochemistry, University of Wuppertal, Wuppertal 42119, Germany
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Noordally ZB, Trichtinger C, Dalvit I, Hofmann M, Roux C, Zamboni N, Pourcel L, Gas-Pascual E, Gisler A, Fitzpatrick TB. The coenzyme thiamine diphosphate displays a daily rhythm in the Arabidopsis nucleus. Commun Biol 2020; 3:209. [PMID: 32372067 PMCID: PMC7200797 DOI: 10.1038/s42003-020-0927-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/25/2020] [Indexed: 12/27/2022] Open
Abstract
In plants, metabolic homeostasis—the driving force of growth and development—is achieved through the dynamic behavior of a network of enzymes, many of which depend on coenzymes for activity. The circadian clock is established to influence coordination of supply and demand of metabolites. Metabolic oscillations independent of the circadian clock, particularly at the subcellular level is unexplored. Here, we reveal a metabolic rhythm of the essential coenzyme thiamine diphosphate (TDP) in the Arabidopsis nucleus. We show there is temporal separation of the clock control of cellular biosynthesis and transport of TDP at the transcriptional level. Taking advantage of the sole reported riboswitch metabolite sensor in plants, we show that TDP oscillates in the nucleus. This oscillation is a function of a light-dark cycle and is independent of circadian clock control. The findings are important to understand plant fitness in terms of metabolite rhythms. Noordally et al. show that the essential coenzyme thiamine diphosphate exhibits a daily rhythm in the Arabidopsis nucleus, which is driven by light-dark cycles and not by the circadian clock. This study provides insight into our understanding of the optimization of plant fitness.
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Affiliation(s)
- Zeenat B Noordally
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Celso Trichtinger
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Ivan Dalvit
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Manuel Hofmann
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Céline Roux
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Nicola Zamboni
- Institute of Molecular Systems Biology, ETH Zurich, 8093, Zurich, Switzerland
| | - Lucille Pourcel
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Elisabet Gas-Pascual
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Alexandra Gisler
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Teresa B Fitzpatrick
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland.
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