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Lima VF, Erban A, Daubermann AG, Freire FBS, Porto NP, Cândido-Sobrinho SA, Medeiros DB, Schwarzländer M, Fernie AR, Dos Anjos L, Kopka J, Daloso DM. Establishment of a GC-MS-based 13 C-positional isotopomer approach suitable for investigating metabolic fluxes in plant primary metabolism. Plant J 2021; 108:1213-1233. [PMID: 34486764 DOI: 10.1111/tpj.15484] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/20/2021] [Accepted: 08/30/2021] [Indexed: 06/13/2023]
Abstract
13 C-Metabolic flux analysis (13 C-MFA) has greatly contributed to our understanding of plant metabolic regulation. However, the generation of detailed in vivo flux maps remains a major challenge. Flux investigations based on nuclear magnetic resonance have resolved small networks with high accuracy. Mass spectrometry (MS) approaches have broader potential, but have hitherto been limited in their power to deduce flux information due to lack of atomic level position information. Herein we established a gas chromatography (GC) coupled to MS-based approach that provides 13 C-positional labelling information in glucose, malate and glutamate (Glu). A map of electron impact (EI)-mediated MS fragmentation was created and validated by 13 C-positionally labelled references via GC-EI-MS and GC-atmospheric pressure chemical ionization-MS technologies. The power of the approach was revealed by analysing previous 13 C-MFA data from leaves and guard cells, and 13 C-HCO3 labelling of guard cells harvested in the dark and after the dark-to-light transition. We demonstrated that the approach is applicable to established GC-EI-MS-based 13 C-MFA without the need for experimental adjustment, but will benefit in the future from paired analyses by the two GC-MS platforms. We identified specific glucose carbon atoms that are preferentially labelled by photosynthesis and gluconeogenesis, and provide an approach to investigate the phosphoenolpyruvate carboxylase (PEPc)-derived 13 C-incorporation into malate and Glu. Our results suggest that gluconeogenesis and the PEPc-mediated CO2 assimilation into malate are activated in a light-independent manner in guard cells. We further highlight that the fluxes from glycolysis and PEPc toward Glu are restricted by the mitochondrial thioredoxin system in illuminated leaves.
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Affiliation(s)
- Valéria F Lima
- LabPLant, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza-CE, 60451-970, Brazil
| | - Alexander Erban
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, D-14476, Germany
| | - André G Daubermann
- Departamento de Biologia, Setor de Fisiologia Vegetal, Universidade Federal de Lavras, Lavras-MG, 37200-900, Brazil
| | - Francisco Bruno S Freire
- LabPLant, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza-CE, 60451-970, Brazil
| | - Nicole P Porto
- LabPLant, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza-CE, 60451-970, Brazil
| | - Silvio A Cândido-Sobrinho
- LabPLant, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza-CE, 60451-970, Brazil
| | - David B Medeiros
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, D-14476, Germany
| | - Markus Schwarzländer
- Institute of Plant Biology and Biotechnology, Westfälische-Wilhelms-Universität Münster, Münster, D-48143, Germany
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, D-14476, Germany
| | - Leticia Dos Anjos
- Departamento de Biologia, Setor de Fisiologia Vegetal, Universidade Federal de Lavras, Lavras-MG, 37200-900, Brazil
| | - Joachim Kopka
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, D-14476, Germany
| | - Danilo M Daloso
- LabPLant, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza-CE, 60451-970, Brazil
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