Hydrogen (H) isotopes of plant organic compounds are rarely employed in ecological studies. If so, these values are interpreted as being indicative of the plant source and/or leaf water. Recent observations suggest, however, that variations in hydrogen isotope fractionation that occur during the biosynthesis of plant compounds ( 2 H-ε bio ) imprint valuable metabolic information into the hydrogen isotope composition (δ 2 H values) of plant organic compounds. Here we show a consistent 2 H-enrichment of compounds in heterotrophically growing plants across a series of autotrophic/heterotrophic plant pairs. We suggest that this is due to a higher recycling of compounds in the Calvin and tricarboxylic acid cycles in heterotrophic plants that is associated with a more complete exchange of C-bound H with the surrounding 2 H-enriched foliar water. Interestingly, we found that 2 H-enrichment in heterotrophic plants was larger for carbohydrates than for lipids, with an average 2 H-enrichment of 76 ± 9‰ in α-cellulose and 23 ± 23‰ in n-alkanes. We propose that this systematically larger 2 H-enrichment for carbohydrates than for lipids is either due to different level of 2 H-fractionation associated with heterotrophically produced NADPH, or to the potential uptake of lipids by heterotrophic plants. With the work we present here, we contribute to a better mechanistic understanding of what the biochemical principles are that couple the carbohydrate dynamics of plants to their δ 2 H values and hope to foster as such the application of H isotopes in plant sciences.
CITATION STYLE
Cormier, M. A., Werner, R. A., Leuenberger, M. C., & Kahmen, A. (2019). 2 H-enrichment of cellulose and n-alkanes in heterotrophic plants. Oecologia, 189(2), 365–373. https://doi.org/10.1007/s00442-019-04338-8
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