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Communication Dans Un Congrès Année : 2023

Using 13C metabolic probes to assess carbon allocation processes within the central metabolism of Brassica napus source leaves

Résumé

Plant central carbon metabolism comprises several essential metabolic pathways, such as Calvin-Benson cycle, pentose phosphate pathway, photorespiration, glycolysis and tricarboxylic acid (TCA) cycle, that are acting together to support plant growth and yield establishment. The recent emergence of 13C-tracing dynamic approaches allowed to improve the identification of carbon allocation processes within this complex metabolic network in the model brassica specie Arabidopsis. However, some questions remained open for Brassica napus leaves, an economically relevant oleaginous crop experiencing sequential senescence during its vegetative growth. Notably, the supplying of the tricarboxylic acid (TCA) cycle in the light and its flux modes could be substantially different in source leaves in order to support remobilization processes. Here, we investigated these carbon fluxes by taking advantage of Brassica napus leaf discs to perform short-term incorporations of U-13C-pyruvate and U-13C-glucose (99% isotopic enrichment) under light and dark conditions. Indeed, leaf discs showed relatively similar photosynthetic and respiratory capacities compared to attached leaves. Isotopic enrichments were evaluated at both isotopologue and positional levels for some organic and amino acids by GC-MS. Mass spectrometry data and isotopologue network reconstruction revealed unique isotopic signatures for TCA cycle and suggested that: i) both cyclic and non-cyclic flux modes occurred in the light for the TCA cycle of B. napus source leaves ; ii) glycolysis rather than stored citrate was the major source of carbon for TCA cycle in the light; iii) TCA cycle derived-CO2 contributed to serine biosynthesis in the light and could be redirected to the TCA cycle through glycolysis. Overall, our results improved our understanding of central carbon metabolism and its metabolic connections in source leaves of Brassica napus. In the future, the integration of these results into recent INCA-based leaf metabolic models could help to infer a detailed map of absolute metabolic fluxes.
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Dates et versions

hal-04351791 , version 1 (18-12-2023)

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  • HAL Id : hal-04351791 , version 1

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Younes Dellero. Using 13C metabolic probes to assess carbon allocation processes within the central metabolism of Brassica napus source leaves. 2nd Workshop "Carbon allocation in plants": Advances in carbon allocation and acquisition, Nov 2023, Versailles, France. ⟨hal-04351791⟩
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