title: Effects of leaf water evaporative2H-enrichment and biosynthetic fractionation on leaf wax n-alkane δ2H values in C3 and C4 grasses.
abstract: Leaf wax n-alkane δ2H values carry important information about environmental and ecophysiological processes in plants. However, the physiological and biochemical drivers that shape leaf wax n-alkane δ2H values are not completely understood. It is particularly unclear why n-alkanes in grasses are typically2H-depleted compared with plants from other taxonomic groups such as dicotyledonous plants and why C3 grasses are2H-depleted compared with C4 grasses. To resolve these uncertainties, we quantified the effects of leaf water evaporative2H-enrichment and biosynthetic hydrogen isotope fractionation on n-alkane δ2H values for a range of C3 and C4 grasses grown in climate-controlled chambers. We found that only a fraction of leaf water evaporative2H-enrichment is imprinted on the leaf wax n-alkane δ2H values in grasses. This is interesting, as previous studies have shown in dicotyledonous plants a nearly complete transfer of this2H-enrichment to the n-alkane δ2H values. We thus infer that the typically observed2H-depletion of n-alkanes in grasses (as opposed to dicots) is because only a fraction of the leaf water evaporative2H-enrichment is imprinted on the δ2H values. Our experiments also show that differences in n-alkane δ2H values between C3 and C4 grasses are largely the result of systematic differences in biosynthetic fractionation between these two plant groups, which was on average -198‰ and-159‰ for C3 and C4 grasses, respectively.
authors.affiliation: Department of Environmental Systems Sciences, ETH Zürich, 8092, Zurich, Switzerland. bruno.gamarra@usys.ethz.ch.|Department of Environmental Sciences - Botany, University of Basel, 4003, Basel, Switzerland. bruno.gamarra@usys.ethz.ch.
authors.forename: B
authors.initials: B
authors.lastname: Gamarra
authors.affiliation: Institut für Erd- und Umweltwissenschaften, Universität Potsdam, 144969, Potsdam, Germany.|Section 5.1: Geomorphology, Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences, 14473, Potsdam, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Sachse
authors.affiliation: Department of Environmental Sciences - Botany, University of Basel, 4003, Basel, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Kahmen
mesh_terms: D000473:Alkanes / Q000032:analysis / Q000737:chemistry; D003903:Deuterium / Q000032:analysis* / Q000737:chemistry; D006813:Humidity; D018515:Plant Leaves / Q000378:metabolism; D006109:Poaceae / Q000378:metabolism*; D014867:Water / Q000378:metabolism*; D014885:Waxes / Q000737:chemistry
chemical_list: D000473:Alkanes; D014885:Waxes; D014867:Water; D003903:Deuterium
keywords: C3 and C4 grasses; biosynthetic fractionation; deuterium; leaf water evaporative 2H-enrichment; leaf wax n-alkanes