Experimental approaches to isolate drivers of variation in the carbon‐bound hydrogen isotope composition (δ2H) of plant cellulose are rare and current models are limited in their application. This is in part due to a lack in understanding of how 2H‐fractionations in carbohydrates differ between species. We analysed, for the first time, the δ2H of leaf sucrose along with the δ2H and δ18O of leaf cellulose and leaf and xylem water across seven herbaceous species and a starchless mutant of tobacco. The δ2H of sucrose explained 66% of the δ2H variation in cellulose (R2 = 0.66), which was associated with species differences in the 2H enrichment of sucrose above leaf water ( ε sucrose : −126% to −192‰) rather than by variation in leaf water δ2H itself. ε sucrose was positively related to dark respiration (R2 = 0.27), and isotopic exchange of hydrogen in sugars was positively related to the turnover time of carbohydrates (R2 = 0.38), but only when normalε sucrose was fixed to the literature accepted value of − 171 ‰. No relation was found between isotopic exchange of hydrogen and oxygen, suggesting large differences in the processes shaping post‐photosynthetic fractionation between elements. Our results strongly advocate that for robust applications of the leaf cellulose hydrogen isotope model, parameterization utilizing δ2H of sugars is needed.
<p>Plant organic compounds such as cellulose or <em>n</em>-alkanes are often utilized as recorders of oxygen (&#948;<sup>18</sup>O) or hydrogen (&#948;<sup>2</sup>H) isotopic signals to inform on past climate or environmental conditions, or on plant physiological changes. This is because these compounds can persist in the geologic record for decades to millennia or longer in select cases. Yet, large differences have often been observed among plant organic compound &#948;<sup>2</sup>H or &#948;<sup>18</sup>O values for species growing in a single location due to the balance between variable leaf water isotopic enrichment and variable biochemical isotopic effects among species. Distinguishing between these sources of variability and making use of these signals is an ongoing challenge, in part because of the limited number of studies that have explored the extent to which the different drivers influence the isotopic composition of each compound class and element within a single location.</p> <p>We present a detailed assessment of isotopic variation in relevant plant water pools and cellulose &#948;<sup>2</sup>H&#160;and &#948;<sup>18</sup>O&#160;values, in combination with <em>n</em>-alkane &#948;<sup>2</sup>H&#160;values in 192 eudicot species grown in a botanical garden in a single growing season, as well as year-to-year comparisons for consecutive years (2019-2020). Our results show that variation in leaf water &#948;<sup>2</sup>H values were not a strong driver for the observed variation in organic compound &#948;<sup>2</sup>H values across eudicot species. Additionally, while correlation between &#948;<sup>2</sup>H and &#948;<sup>18</sup>O values found in plant source water and leaf water was transferred to cellulose, the explanatory power of this correlation was strongly diminished. This indicates that additional biochemical isotope fractionation caused substantial variation in organic compound &#948;<sup>2</sup>H and/or &#948;<sup>18</sup>O values across species. Moreover, variation in cellulose &#948;<sup>2</sup>H values were poorly correlated with &#948;<sup>2</sup>H&#160;values from <em>n</em>-alkanes, suggesting that the biochemical pathways associated with different compounds were accompanied by varying isotope effects. Lastly, cellulose &#948;<sup>2</sup>H and &#948;<sup>18</sup>O values changed more than <em>n</em>-alkane &#948;<sup>2</sup>H&#160;values from one year to the next. This implies that, cellulose &#948;<sup>2</sup>H and &#948;<sup>18</sup>O values are more sensitive to environmental differences between growing seasons compared to &#948;<sup>2</sup>H&#160;values from <em>n</em>-alkanes, and thus that the environmental forcing effects on isotope values are not equal between compounds. Overall, we found that variation in organic compound &#948;<sup>2</sup>H, and possibly also &#948;<sup>18</sup>O, values across species and between growing seasons was substantially more strongly driven by biochemical isotope fractionation than by isotope values of plant water. Therefore, to the extent that it is possible, biochemical responses to environmental changes should be considered in interpretations of organic compound &#948;<sup>2</sup>H and &#948;<sup>18</sup>O values to reconstruct the past. Furthermore, there is potential to recover plant responses to environmental changes from plant organic compound &#948;<sup>2</sup>H and/or &#948;<sup>18</sup>O&#160;values when the measurements are incorporated into multi-compound or multi-proxy paleoenvironmental and paleophysiological inquiries.</p>
The European eel (Anguilla anguilla) is a thoroughly studied species, both for its role in aquaculture and its complicated lifecycle (Törlitz, 1922; Tesch, 2003). Anguilla comprises catadromous eel species that spend the majority of their lifecycle in freshwater but migrate back to the oceans for spawning only (Durif et al., 2009a). Hatching from their eggs in the Sargasso Sea, the Gulf Stream currents bring the larvae from their spawning grounds to the coastal waters of Europe and North Africa (van den Thillart et al., 2009). Reaching the
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.