• 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>
  • Access State: Open Access