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Media type:
E-Article
Title:
Oxygen isotope fractionations across individual leaf carbohydrates in grass and tree species
Contributor:
Lehmann, Marco M.;
Gamarra, Bruno;
Kahmen, Ansgar;
Siegwolf, Rolf T.W.;
Saurer, Matthias
imprint:
Wiley, 2017
Published in:Plant, Cell & Environment
Language:
English
DOI:
10.1111/pce.12974
ISSN:
1365-3040;
0140-7791
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title><jats:p>Almost no δ<jats:sup>18</jats:sup>O data are available for leaf carbohydrates, leaving a gap in the understanding of the δ<jats:sup>18</jats:sup>O relationship between leaf water and cellulose. We measured δ<jats:sup>18</jats:sup>O values of bulk leaf water (δ<jats:sup>18</jats:sup>O<jats:sub>LW</jats:sub>) and individual leaf carbohydrates (e.g. fructose, glucose and sucrose) in grass and tree species and δ<jats:sup>18</jats:sup>O of leaf cellulose in grasses. The grasses were grown under two relative humidity (rH) conditions. Sucrose was generally <jats:sup>18</jats:sup>O‐enriched compared with hexoses across all species with an apparent biosynthetic fractionation factor (<jats:italic>ε</jats:italic><jats:sub>bio</jats:sub>) of more than 27‰ relative to δ<jats:sup>18</jats:sup>O<jats:sub>LW</jats:sub>, which might be explained by isotopic leaf water and sucrose synthesis gradients. δ<jats:sup>18</jats:sup>O<jats:sub>LW</jats:sub> and δ<jats:sup>18</jats:sup>O values of carbohydrates and cellulose in grasses were strongly related, indicating that the leaf water signal in carbohydrates was transferred to cellulose (<jats:italic>ε</jats:italic><jats:sub>bio</jats:sub> = 25.1‰). Interestingly, damping factor <jats:italic>p</jats:italic><jats:sub>ex</jats:sub><jats:italic>p</jats:italic><jats:sub>x</jats:sub>, which reflects oxygen isotope exchange with less enriched water during cellulose synthesis, responded to rH conditions if modelled from δ<jats:sup>18</jats:sup>O<jats:sub>LW</jats:sub> but not if modelled directly from δ<jats:sup>18</jats:sup>O of individual carbohydrates. We conclude that δ<jats:sup>18</jats:sup>O<jats:sub>LW</jats:sub> is not always a good substitute for δ<jats:sup>18</jats:sup>O of synthesis water due to isotopic leaf water gradients. Thus, compound‐specific δ<jats:sup>18</jats:sup>O analyses of individual carbohydrates are helpful to better constrain (post‐)photosynthetic isotope fractionation processes in plants.</jats:p>