2H-enrichment of cellulose and n-alkanes in heterotrophic plants
2H-enrichment of cellulose and n-alkanes in heterotrophic plants
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DOI：
10.1007/s00442-019-04338-8
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发表时间：
2019-02-01
期刊：
影响因子：
2.7
通讯作者：
Kahmen, A.
中科院分区：
文献类型：
--
作者：
Cormier, M. -A.;Werner, R. A.;Kahmen, A.
植物有机化合物的氢(H)同位素很少用于生态学研究。如果是，则这些值被解释为指示植物来源和/或叶片水分。然而，最近的观察表明，在植物化合物(H-2-epsilon(BIO))的生物合成过程中发生的氢同位素分馏的变化在植物有机化合物的氢同位素组成(H-2值)中留下了有价值的代谢信息。在这里，我们展示了一系列自养/异养植物对异养植物中化合物的一致H-2富集性。我们认为，这是由于异养植物中Calvin和三羧酸循环中化合物的高度循环，这与C-结合H与周围富含H-2的叶水更完整地交换有关。有趣的是，我们发现异养植物对碳水化合物的H-2-富集量大于对脂肪的富集量，平均H-2-富集量在纤维素中为76+/-9，在正构烷烃中为23+/-23。我们认为，碳水化合物对H-2的富集度高于对脂肪的富集度，这要么是由于异养产生的NADPH产生的不同程度的H-2分馏，要么是由于异养植物对脂肪的潜在吸收。通过我们在这里介绍的工作，我们有助于更好地从机械上理解什么是将植物的碳水化合物动态与其H-2值相耦合的生化原理，并希望以此促进氢同位素在植物科学中的应用。
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 (H-2-epsilon(bio)) imprint valuable metabolic information into the hydrogen isotope composition (H-2 values) of plant organic compounds. Here we show a consistent H-2-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 H-2-enriched foliar water. Interestingly, we found that H-2-enrichment in heterotrophic plants was larger for carbohydrates than for lipids, with an average H-2-enrichment of 76 +/- 9 parts per thousand in -cellulose and 23 +/- 23 parts per thousand in n-alkanes. We propose that this systematically larger H-2-enrichment for carbohydrates than for lipids is either due to different level of H-2-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 H-2 values and hope to foster as such the application of H isotopes in plant sciences.