Schuler, Philipp, Rehmann, Oliver, Vitali, Valentina, Saurer, Matthias, Oettli, Manuela, Cernusak, Lucas A., Gessler, Arthur, Buchmann, Nina, and Lehmann, Marco (2024) Hydrogen isotope fractionation in plants with C3, C4, and CAM CO2 fixation. New Phytologist, 244 (2). pp. 477-495.

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Abstract

Measurements of stable isotope ratios in organic compounds are widely used tools for plant ecophysiological studies. However, the complexity of the processes involved in shaping hydrogen isotope values (δ2H) in plant carbohydrates has limited its broader application.

To investigate the underlying biochemical processes responsible for 2H fractionation among water, sugars, and cellulose in leaves, we studied the three main CO2 fixation pathways (C3, C4, and CAM) and their response to changes in temperature and vapor pressure deficit (VPD).

We show significant differences in autotrophic 2H fractionation (εA) from water to sugar among the pathways and their response to changes in air temperature and VPD. The strong 2H depleting εA in C3 plants is likely driven by the photosynthetic H+ production within the thylakoids, a reaction that is spatially separated in C4 and strongly reduced in CAM plants, leading to the absence of 2H depletion in the latter two types. By contrast, we found that the heterotrophic 2H-fractionation (εH) from sugar to cellulose was very similar among the three pathways and is likely driven by the plant's metabolism, rather than by isotopic exchange with leaf water.

Our study offers new insights into the biochemical drivers of 2H fractionation in plant carbohydrates.

Item ID:	85347
Item Type:	Article (Research - C1)
ISSN:	1469-8137
Copyright Information:	© 2024 The Author(s). New Phytologist Ó 2024 New Phytologist Foundation. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Date Deposited:	06 May 2025 01:45
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