Variation in hydrogen stable isotopes in cellulose and n-alkanes: phylogenetic signal and related traits

Abstract

<p>Hydrogen (H) stable isotope analysis of specific plant organic compounds has become of interest as a tool for ecological, environmental and palaeoclimatological studies. Aside from the influence of leaf water evaporative enrichment on the δ<sup>2</sup>H composition of organic compounds, hydrogen isotope fractionation occurs during carbon metabolism in the plant (ε<sub>bio</sub>). To get a better understanding of the metabolic signal recorded in ε<sub>bio</sub>, we explored the variation of δ<sup>2</sup>H in cellulose and n-alkanes, and its relationship with phylogeny and other plant traits. Leaf material of a large set of species in the eudicot clade was collected in the botanical garden at the University of Basel, cellulose and n-alkanes were extracted, δ<sup>2</sup>H in both compounds and δ<sup>18</sup>O in cellulose were analysed. It was found that modelled leaf water differences only explain part of the observed variation of δ<sup>2</sup>H in organic compounds. δ<sup>2</sup>H appears to be related to phylogeny and a wider assessment of trait data is currently being undertaken to test for signal associations with physiological traits. This study helps address at which taxonomic level the variation of δ<sup>2</sup>H is found; illuminate plant physiological traits that can be responsible for shaping species specific δ<sup>2</sup>H values in organic compounds; as well as, provide novel insights into the δ<sup>2</sup>H covariation between cellulose and n-alkanes.</p>