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Allocation of freshly assimilated carbon into primary and secondary metabolites after in situ¹³C pulse labelling of Norway spruce (Picea abies)


Heinrich, Steffen; Dippold, Michaela A; Werner, Christiane; Wiesenberg, Guido L B; Kuzyakov, Yakov; Glaser, Bruno (2015). Allocation of freshly assimilated carbon into primary and secondary metabolites after in situ¹³C pulse labelling of Norway spruce (Picea abies). Tree Physiology, 35(11):1176-1191.

Abstract

Plants allocate carbon (C) to sink tissues depending on phenological, physiological or environmental factors. We still have little knowledge on C partitioning into various cellular compounds and metabolic pathways at various ecophysiological stages. We used compound-specific stable isotope analysis to investigate C partitioning of freshly assimilated C into tree compartments (needles, branches and stem) as well as into needle water-soluble organic C (WSOC), non-hydrolysable structural organic C (stOC) and individual chemical compound classes (amino acids, hemicellulose sugars, fatty acids and alkanes) of Norway spruce (Picea abies) following in situ ¹³C pulse labelling 15 days after bud break. The ¹³C allocation within the above-ground tree biomass demonstrated needles as a major C sink, accounting for 86% of the freshly assimilated C 6 h after labelling. In needles, the highest allocation occurred not only into the WSOC pool (44.1% of recovered needle ¹³C) but also into stOC (33.9%). Needle growth, however, also caused high ¹³C allocation into pathways not involved in the formation of structural compounds: (i) pathways in secondary metabolism, (ii) C-1 metabolism and (iii) amino acid synthesis from photorespiration. These pathways could be identified by a high ¹³C enrichment of their key amino acids. In addition, ¹³C was strongly allocated into the n-alkyl lipid fraction (0.3% of recovered ¹³C), whereby ¹³C allocation into cellular and cuticular exceeded that of epicuticular fatty acids. ¹³C allocation decreased along the lipid transformation and translocation pathways: the allocation was highest for precursor fatty acids, lower for elongated fatty acids and lowest for the decarbonylated n-alkanes. The combination of ¹³C pulse labelling with compound- specific ¹³C analysis of key metabolites enabled tracing relevant C allocation pathways under field conditions. Besides the primary metabolism synthesizing structural cell compounds, a complex network of pathways consumed the assimilated ¹³C and kept most of the assimilated C in the growing needles.

Abstract

Plants allocate carbon (C) to sink tissues depending on phenological, physiological or environmental factors. We still have little knowledge on C partitioning into various cellular compounds and metabolic pathways at various ecophysiological stages. We used compound-specific stable isotope analysis to investigate C partitioning of freshly assimilated C into tree compartments (needles, branches and stem) as well as into needle water-soluble organic C (WSOC), non-hydrolysable structural organic C (stOC) and individual chemical compound classes (amino acids, hemicellulose sugars, fatty acids and alkanes) of Norway spruce (Picea abies) following in situ ¹³C pulse labelling 15 days after bud break. The ¹³C allocation within the above-ground tree biomass demonstrated needles as a major C sink, accounting for 86% of the freshly assimilated C 6 h after labelling. In needles, the highest allocation occurred not only into the WSOC pool (44.1% of recovered needle ¹³C) but also into stOC (33.9%). Needle growth, however, also caused high ¹³C allocation into pathways not involved in the formation of structural compounds: (i) pathways in secondary metabolism, (ii) C-1 metabolism and (iii) amino acid synthesis from photorespiration. These pathways could be identified by a high ¹³C enrichment of their key amino acids. In addition, ¹³C was strongly allocated into the n-alkyl lipid fraction (0.3% of recovered ¹³C), whereby ¹³C allocation into cellular and cuticular exceeded that of epicuticular fatty acids. ¹³C allocation decreased along the lipid transformation and translocation pathways: the allocation was highest for precursor fatty acids, lower for elongated fatty acids and lowest for the decarbonylated n-alkanes. The combination of ¹³C pulse labelling with compound- specific ¹³C analysis of key metabolites enabled tracing relevant C allocation pathways under field conditions. Besides the primary metabolism synthesizing structural cell compounds, a complex network of pathways consumed the assimilated ¹³C and kept most of the assimilated C in the growing needles.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Language:English
Date:2015
Deposited On:26 Nov 2015 07:40
Last Modified:21 Nov 2017 18:06
Publisher:Oxford University Press
ISSN:0829-318X
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1093/treephys/tpv083
PubMed ID:26423131

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