 |
| Titel |
Nitrogen control of 13C enrichment in heterotrophic organs relative to leaves in a landscape-building desert plant species |
| VerfasserIn |
J. Zhang, L. Gu, F. Bao, Y. Cao, Y. Hao, J. He, J. Li, Y. Li, Y. Ren, F. Wang, R. Wu, B. Yao, Y. Zhao, G. Lin, B. Wu, Q. Lu, P. Meng |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 1 ; Nr. 12, no. 1 (2015-01-05), S.15-27 |
| Datensatznummer |
250117756
|
| Publikation (Nr.) |
 copernicus.org/bg-12-15-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| A longstanding puzzle in isotope studies of C3 plant species is that
heterotrophic plant organs (e.g., stems, roots, seeds, and fruits) tend to be
enriched in 13C compared to the autotrophic organ (leaves) that provides
them with photosynthate. Our inability to explain this puzzle suggests key
deficiencies in understanding post-photosynthetic metabolic processes. It
also limits the effectiveness of applications of stable carbon isotope
analyses in a variety of scientific disciplines ranging from plant physiology
to global carbon cycle studies. To gain insight into this puzzle, we
excavated whole plant architectures of Nitraria tangutorum Bobrov,
a C3 species that has an exceptional capability of fixing sands and
building sand dunes, in two deserts in northwestern China. We systematically
and simultaneously measured carbon isotope ratios and nitrogen and
phosphorous contents of different parts of the excavated plants. We also
determined the seasonal variations in leaf carbon isotope ratios on nearby
intact plants of N. tangutorum. We found, for the first time, that
higher nitrogen contents in heterotrophic organs were significantly
correlated with increased heterotrophic 13C enrichment compared to
leaves. However, phosphorous contents had no effect on the enrichment. In
addition, new leaves had carbon isotope ratios similar to roots but were
progressively depleted in 13C as they matured. We concluded that a
nitrogen-mediated process, hypothesized to be the refixation of respiratory
CO2 by phosphoenolpyruvate (PEP) carboxylase, was responsible for the
differences in 13C enrichment among different heterotrophic organs, while
processes such as fractionating foliar metabolism and preferentially loading
into phloem of 13C-enriched sugars may contribute to the overall
autotrophic–heterotrophic difference in carbon isotope compositions. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|