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Marc-André Cormier


Last Name

Cormier

First Name

Marc-André

ORCID

0000-0001-7645-1375

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2017 - 201932020 - 20243
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Publications 1 - 6 of 6
  • Influence of starch deficiency on photosynthetic and post-photosynthetic carbon isotope fractionations
    Item type: Journal Article
    Lehmann, Marco M.; Ghiasi, Shiva; George, Gavin M.; et al. (2019)
    Journal of Experimental Botany
    Carbon isotope (^13C) fractionations occurring during and after photosynthetic CO_2 fixation shape the carbon isotope composition (δ^13C) of plant material and respired CO_2. However, responses of ^13C fractionations to diel variation in starch metabolism in the leaf are not fully understood. Here we measured δ^13C of organic matter (δ^13COM), concentrations and δ^13C of potential respiratory substrates, δ^13C of dark-respired CO_2 (δ^13CR), and gas exchange in leaves of starch-deficient plastidial phosphoglucomutase (pgm) mutants and wild-type plants of four species (Arabidopsis thaliana, Mesembryanthemum crystallinum, Nicotiana sylvestris, and Pisum sativum). The strongest δ^13C response to the pgm-induced starch deficiency was observed in N. sylvestris, with more negative δ^13COM, δ^13CR, and δ^13C values for assimilates (i.e. sugars and starch) and organic acids (i.e. malate and citrate) in pgm mutants than in wild-type plants during a diel cycle. The genotype differences in δ^13C values could be largely explained by differences in leaf gas exchange. In contrast, the PGM-knockout effect on post-photosynthetic ^13C fractionations via the plastidic fructose-1,6-bisphosphate aldolase reaction or during respiration was small. Taken together, our results show that the δ^13C variations in starch-deficient mutants are primarily explained by photosynthetic ^13C fractionations and that the combination of knockout mutants and isotope analyses allows additional insights into plant metabolism.
  • Isotopes—Terminology, Definitions and Properties
    Item type: Book Chapter
    Werner, Roland Anton; Cormier, Marc-André (2022)
    Tree Physiology ~ Stable Isotopes in Tree Rings: Inferring Physiological, Climatic and Environmental Responses
    The intention of this chapter is to give insight into the properties and peculiarities of the stable isotopes of the bioelements. Following an overview about the terminology and ʻtechnical jargonʼ used in stable isotope sciences, methods to calculate and express isotopic abundances are presented. Subsequently, a short description of the physicochemical basis of equilibrium and kinetic (mass-dependent) isotope effects (EIEs and KIEs) as origin of isotope fractionation in chemical and biological systems is given. Further, measures for calculation and presentation of isotope fractionation are introduced and the corresponding properties of these quantities are critically discussed. Finally, examples for equilibrium and kinetic isotope fractionation in biochemical reactions are presented in more details and subsequent effects and consequences including the relationship between EIEs and KIEs are reviewed.
  • A high temperature water vapor equilibration method to determine non‐exchangeable hydrogen isotope ratios of sugar, starch, and cellulose
    Item type: Journal Article
    Schuler, Philipp; Cormier, Marc-André; Werner, Roland A.; et al. (2022)
    Plant, Cell & Environment
    The analysis of the non-exchangeable hydrogen isotope ratio (δ2Hne) in carbohydrates is mostly limited to the structural component cellulose, while simple high-throughput methods for δ2Hne values of non-structural carbohydrates (NSC) such as sugar and starch do not yet exist. Here, we tested if the hot vapor equilibration method originally developed for cellulose is applicable for NSC, verified by comparison with the traditional nitration method. We set up a detailed analytical protocol and applied the method to plant extracts of leaves from species with different photosynthetic pathways (i.e., C3, C4 and CAM). δ2Hne of commercial sugars and starch from different classes and sources, ranging from −157.8 to +6.4‰, were reproducibly analysed with precision between 0.2‰ and 7.7‰. Mean δ2Hne values of sugar are lowest in C3 (−92.0‰), intermediate in C4 (−32.5‰) and highest in CAM plants (6.0‰), with NSC being 2H-depleted compared to cellulose and sugar being generally more 2H-enriched than starch. Our results suggest that our method can be used in future studies to disentangle 2H-fractionation processes, for improving mechanistic δ2Hne models for leaf and tree-ring cellulose and for further development of δ2Hne in plant carbohydrates as a potential proxy for climate, hydrology, plant metabolism and physiology.
  • Trace element and organic matter mobility impacted by Fe3O4-nanoparticle surface coating within wetland soil
    Item type: Journal Article
    Al-Sid-Cheikh, Maya; Pédrot, Mathieu; Dia, Aline; et al. (2019)
    Environmental Science: Nano
  • Biochemical and metabolic effects on hydrogen isotope composition of organic compounds in plants
    Item type: Doctoral Thesis
    Cormier, Marc-André (2017)
    Despite a large unexplained variability in the values, the analysis of the hydrogen (H) isotope composition (δ2H) of plant organic compounds is confidently applied to assess ecohydrological processes in the environment. This is possible because most studies that use the stable H isotopes from plant-derived biomarkers consider the H isotope fractionation that occurs during the biosynthesis of any given compound (2H-εbio) to be constant within a species. Consequently, 2H values in plant organic compounds are assumed to be mainly driven by the plant’s source water 2H values and the leaf water evaporative 2H-enrichment. There are, however, several indications that 2H-εbio of plant organic compounds can vary and that the δ2H values are also related to the plant’s metabolism. In this thesis, the elucidate the puzzling variability in the δ2H values of plant organic compounds, the influence of the plant’s metabolism on the variability of 2H-εbio is specifically explored with regards to the possible biochemical mechanisms underlying this variability. In a first study, based on empirical data produced in two separate experiments, it is shown that the 2H-εbio of different compounds in plants is tightly coupled to a plant’s carbon and energy metabolism. Based on these data, we develop a conceptual biochemical model that explains how and where 2H-fractionation occurs in the biosynthesis of major plant organic compound classes such as carbohydrates and lipids and what the isotope fractionation processes are that introduce a metabolic signal in δ2H values to these compounds. In a second study, with δ2H analyses from heterotrophic plants, it is shown that the hydrogen isotope fractionation occurring during the biosynthesis of different organic compounds in plants can explain part of the variability observed in δ2H values across species. Metabolic effects on 2H values between heterotrophic plants and their autotrophic host plants differed for different compound classes. The remarkable consistency of the compound specific isotope effects between autotrophic host or reference plants and the heterotrophic parasitic or mycoheterotrophic plants points towards a general physiological mechanism that determines these effects and support the model developed in the first study. Finally, with this model, it is mechanistically illustrated that information recorded in the δ2H values of plant organic compounds goes beyond hydrological signals, but also contains important information on the carbon and energy metabolism of a plant. As such we provide the mechanistic basis to introduce hydrogen isotopes in plant organic compounds as new metabolic proxy for the carbon and energy metabolism of plants. Such a new metabolic proxy has the potential to be applied in a broad range of disciplines, including plant and ecosystem physiology, plant breeding, biogeochemistry, paleoecology and Earth system sciences.
  • Biochemical and biophysical drivers of the hydrogen isotopic composition of carbohydrates and acetogenic lipids
    Item type: Journal Article
    Lehmann, Marco M.; Schuler, Philipp; Werner, Roland Anton; et al. (2024)
    Science Advances
    The hydrogen isotopic composition (δ²H) of plant compounds is increasingly used as a hydroclimatic proxy; however, the interpretation of δ²H values is hampered by potential coeffecting biochemical and biophysical processes. Here, we studied δ²H values of water and carbohydrates in leaves and roots, and of leaf n-alkanes, in two distinct tobacco (Nicotiana sylvestris) experiments. Large differences in plant performance and biochemistry resulted from (a) soil fertilization with varying nitrogen (N) species ratios and (b) knockout-induced starch deficiency. We observed a strong ²H-enrichment in sugars and starch with a decreasing performance induced by increasing NO₃⁻/NH₄⁺ ratios and starch deficiency, as well as from leaves to roots. However, δ²H values of cellulose and n-alkanes were less affected. We show that relative concentrations of sugars and starch, interlinked with leaf gas exchange, shape δ²H values of carbohydrates. We thus provide insights into drivers of hydrogen isotopic composition of plant compounds and into the mechanistic modeling of plant cellulose δ²H values.
Publications 1 - 6 of 6