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13C and 15N allocations of two alpine species from early and late snowmelt locations reflect their different growth strategies.

Baptist F, Tcherkez G, Aubert S, Pontailler JY, Choler P, Nogués S - J. Exp. Bot. (2009)

Bottom Line: Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment.Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs.These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire d'Ecologie Alpine, UMR CNRS-UJF 5553, Université de Grenoble, BP 53, F-38041 Grenoble Cedex 09, France. florence.baptist@ujf-grenoble.fr

ABSTRACT
Intense efforts are currently devoted to disentangling the relationships between plant carbon (C) allocation patterns and soil nitrogen (N) availability because of their consequences for growth and more generally for C sequestration. In cold ecosystems, only a few studies have addressed whole-plant C and/or N allocation along natural elevational or topographical gradients. (12)C/(13)C and (14)N/(15)N isotope techniques have been used to elucidate C and N partitioning in two alpine graminoids characterized by contrasted nutrient economies: a slow-growing species, Kobresia myosuroides (KM), and a fast-growing species, Carex foetida (CF), located in early and late snowmelt habitats, respectively, within the alpine tundra (French Alps). CF allocated higher labelling-related (13)C content belowground and produced more root biomass. Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment. Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs. These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

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Labelling-derived 15N content in whole-plant dry matter (μg 15N g-1 DW) after amendment with [15N]-NO3– (a), [15N]-NH4+ (b), or [15N]-glycine (c) in K. myosuroides (grey bar) and C. foetida (white bar). Circle graphs, percentage allocation of the total labelling-derived 15N mass recovered in the leaves (white), new roots (grey), and old roots (black) (μg 15N μg-1 15N in whole-plant dry matter). Values are the mean ±SE (n=3). ns, not significant, * indicates significant differences between both species (P <0.05). See text for further statistical details.
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fig4: Labelling-derived 15N content in whole-plant dry matter (μg 15N g-1 DW) after amendment with [15N]-NO3– (a), [15N]-NH4+ (b), or [15N]-glycine (c) in K. myosuroides (grey bar) and C. foetida (white bar). Circle graphs, percentage allocation of the total labelling-derived 15N mass recovered in the leaves (white), new roots (grey), and old roots (black) (μg 15N μg-1 15N in whole-plant dry matter). Values are the mean ±SE (n=3). ns, not significant, * indicates significant differences between both species (P <0.05). See text for further statistical details.

Mentions: The nitrogen allocation after 24 h 15N labelling with [15N]-nitrate, [15N]-ammonium, or [15N]-glycine is indicated in Fig. 4. Clearly, CF was more 15N-labelled than KM at the whole-plant level, no matter which labelling molecule was applied. In other words, CF had a higher nitrogen uptake efficiency (NupE) than KM: the recovery of 15N from the labelling solution was 13.7±2.5% glycine, 19.8±3.1% NO3–, 2.9±1.2% NH4+ for CF; and 4.6±0.5% glycine, 10.4±3.8% NO3–, and 1.8±0.4% NH4+ for KM. For nitrate, the CF/KM ratio of NupE was then as high as 1.9.


13C and 15N allocations of two alpine species from early and late snowmelt locations reflect their different growth strategies.

Baptist F, Tcherkez G, Aubert S, Pontailler JY, Choler P, Nogués S - J. Exp. Bot. (2009)

Labelling-derived 15N content in whole-plant dry matter (μg 15N g-1 DW) after amendment with [15N]-NO3– (a), [15N]-NH4+ (b), or [15N]-glycine (c) in K. myosuroides (grey bar) and C. foetida (white bar). Circle graphs, percentage allocation of the total labelling-derived 15N mass recovered in the leaves (white), new roots (grey), and old roots (black) (μg 15N μg-1 15N in whole-plant dry matter). Values are the mean ±SE (n=3). ns, not significant, * indicates significant differences between both species (P <0.05). See text for further statistical details.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2692016&req=5

fig4: Labelling-derived 15N content in whole-plant dry matter (μg 15N g-1 DW) after amendment with [15N]-NO3– (a), [15N]-NH4+ (b), or [15N]-glycine (c) in K. myosuroides (grey bar) and C. foetida (white bar). Circle graphs, percentage allocation of the total labelling-derived 15N mass recovered in the leaves (white), new roots (grey), and old roots (black) (μg 15N μg-1 15N in whole-plant dry matter). Values are the mean ±SE (n=3). ns, not significant, * indicates significant differences between both species (P <0.05). See text for further statistical details.
Mentions: The nitrogen allocation after 24 h 15N labelling with [15N]-nitrate, [15N]-ammonium, or [15N]-glycine is indicated in Fig. 4. Clearly, CF was more 15N-labelled than KM at the whole-plant level, no matter which labelling molecule was applied. In other words, CF had a higher nitrogen uptake efficiency (NupE) than KM: the recovery of 15N from the labelling solution was 13.7±2.5% glycine, 19.8±3.1% NO3–, 2.9±1.2% NH4+ for CF; and 4.6±0.5% glycine, 10.4±3.8% NO3–, and 1.8±0.4% NH4+ for KM. For nitrate, the CF/KM ratio of NupE was then as high as 1.9.

Bottom Line: Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment.Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs.These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire d'Ecologie Alpine, UMR CNRS-UJF 5553, Université de Grenoble, BP 53, F-38041 Grenoble Cedex 09, France. florence.baptist@ujf-grenoble.fr

ABSTRACT
Intense efforts are currently devoted to disentangling the relationships between plant carbon (C) allocation patterns and soil nitrogen (N) availability because of their consequences for growth and more generally for C sequestration. In cold ecosystems, only a few studies have addressed whole-plant C and/or N allocation along natural elevational or topographical gradients. (12)C/(13)C and (14)N/(15)N isotope techniques have been used to elucidate C and N partitioning in two alpine graminoids characterized by contrasted nutrient economies: a slow-growing species, Kobresia myosuroides (KM), and a fast-growing species, Carex foetida (CF), located in early and late snowmelt habitats, respectively, within the alpine tundra (French Alps). CF allocated higher labelling-related (13)C content belowground and produced more root biomass. Furthermore, assimilates transferred to the roots were preferentially used for growth rather than respiration and tended to favour N reduction in this compartment. Accordingly, this species had higher (15)N uptake efficiency than KM and a higher translocation of reduced (15)N to aboveground organs. These results suggest that at the whole-plant level, there is a compromise between N acquisition/reduction and C allocation patterns for optimized growth.

Show MeSH
Related in: MedlinePlus