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Oxygen isotope fractionations across individual leaf carbohydrates in grass and tree species
Author(s) -
Lehmann Marco M.,
Gamarra Bruno,
Kahmen Ansgar,
Siegwolf Rolf T.W.,
Saurer Matthias
Publication year - 2017
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12974
Subject(s) - fractionation , cellulose , sucrose , fructose , photosynthesis , oxygen isotope ratio cycle , sugar , stable isotope ratio , carbohydrate , chemistry , isotopes of oxygen , botany , oxygen , oxygen 18 , biology , food science , chromatography , biochemistry , organic chemistry , nuclear chemistry , physics , quantum mechanics
Abstract Almost no δ 18 O data are available for leaf carbohydrates, leaving a gap in the understanding of the δ 18 O relationship between leaf water and cellulose. We measured δ 18 O values of bulk leaf water (δ 18 O LW ) and individual leaf carbohydrates (e.g. fructose, glucose and sucrose) in grass and tree species and δ 18 O of leaf cellulose in grasses. The grasses were grown under two relative humidity (rH) conditions. Sucrose was generally 18 O‐enriched compared with hexoses across all species with an apparent biosynthetic fractionation factor ( ε bio ) of more than 27‰ relative to δ 18 O LW , which might be explained by isotopic leaf water and sucrose synthesis gradients. δ 18 O LW and δ 18 O values of carbohydrates and cellulose in grasses were strongly related, indicating that the leaf water signal in carbohydrates was transferred to cellulose ( ε bio = 25.1‰). Interestingly, damping factor p ex p x , which reflects oxygen isotope exchange with less enriched water during cellulose synthesis, responded to rH conditions if modelled from δ 18 O LW but not if modelled directly from δ 18 O of individual carbohydrates. We conclude that δ 18 O LW is not always a good substitute for δ 18 O of synthesis water due to isotopic leaf water gradients. Thus, compound‐specific δ 18 O analyses of individual carbohydrates are helpful to better constrain (post‐)photosynthetic isotope fractionation processes in plants.