Limits...
The coordination of leaf photosynthesis links C and N fluxes in C3 plant species.

Maire V, Martre P, Kattge J, Gastal F, Esser G, Fontaine S, Soussana JF - PLoS ONE (2012)

Bottom Line: The resulting model linking leaf photosynthesis, stomata conductance and nitrogen investment provides testable hypotheses about the physiological regulation of these processes.A calibration by plant functional type of k(3) and J(fac) still leads to accurate model prediction of N(a), while SLA calibration is essentially required at species level.Observed variations in k(3) and J(fac) are partly explained by environmental and phylogenetic constraints, while SLA variation is partly explained by phylogeny.

View Article: PubMed Central - PubMed

Affiliation: INRA, UR874 UREP, Clermont-Ferrand, France. vmaire24@gmail.com

ABSTRACT
Photosynthetic capacity is one of the most sensitive parameters in vegetation models and its relationship to leaf nitrogen content links the carbon and nitrogen cycles. Process understanding for reliably predicting photosynthetic capacity is still missing. To advance this understanding we have tested across C(3) plant species the coordination hypothesis, which assumes nitrogen allocation to photosynthetic processes such that photosynthesis tends to be co-limited by ribulose-1,5-bisphosphate (RuBP) carboxylation and regeneration. The coordination hypothesis yields an analytical solution to predict photosynthetic capacity and calculate area-based leaf nitrogen content (N(a)). The resulting model linking leaf photosynthesis, stomata conductance and nitrogen investment provides testable hypotheses about the physiological regulation of these processes. Based on a dataset of 293 observations for 31 species grown under a range of environmental conditions, we confirm the coordination hypothesis: under mean environmental conditions experienced by leaves during the preceding month, RuBP carboxylation equals RuBP regeneration. We identify three key parameters for photosynthetic coordination: specific leaf area and two photosynthetic traits (k(3), which modulates N investment and is the ratio of RuBP carboxylation/oxygenation capacity (V(Cmax)) to leaf photosynthetic N content (N(pa)); and J(fac), which modulates photosynthesis for a given k(3) and is the ratio of RuBP regeneration capacity (J(max)) to V(Cmax)). With species-specific parameter values of SLA, k(3) and J(fac), our leaf photosynthesis coordination model accounts for 93% of the total variance in N(a) across species and environmental conditions. A calibration by plant functional type of k(3) and J(fac) still leads to accurate model prediction of N(a), while SLA calibration is essentially required at species level. Observed variations in k(3) and J(fac) are partly explained by environmental and phylogenetic constraints, while SLA variation is partly explained by phylogeny. These results open a new avenue for predicting photosynthetic capacity and leaf nitrogen content in vegetation models.

Show MeSH

Related in: MedlinePlus

Relationships between simulated photosynthetic leaf N content (Npac) (A), net photosynthesis (An) (B) and photosynthetic N use efficiency (PNUE) (C) and the photosynthetic traits k3 and Jfac under standard mean environmental conditions (PPFD  = 666 µmol m−2 s−1, Tg = 16.9°C, hs = 0.74).k3 is the ratio between  and Npa. Jfac is the ratio between Jmax and . A mesh of k3 values varying between 10 and 300 µmol g−1 N s−1 with 20 steps and of Jfac values varying between 1.75 and 3.5 with 0.05 steps was used. Figures D–E–F, relationships between (Npac) (D), net photosynthesis (An) (E) and photosynthetic N use efficiency (PNUE) (F) and the radiation (PPFD) and temperature (Tg) conditions during growth. Averages over the dataset of leaf photosynthetic parameters (k3, Jfac and SLA) are used (k3 = 59.1 µmol g−1Npa s−1, Jfac = 2.45, SLA  = 17.7 m2 kg−1 DM). The mesh for temperature is 0.5°C between 10 and 30°C and the mesh for radiation is 50 µmol m−2 s−1 between 300 and 1200 µmol m−2 s−1. The values of hs and Tg were fixed at 0.8 and 20°C, respectively. An was calculated with the coordinated leaf protein content and PNUE was calculated as the ratio between An and Npac.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3369925&req=5

pone-0038345-g003: Relationships between simulated photosynthetic leaf N content (Npac) (A), net photosynthesis (An) (B) and photosynthetic N use efficiency (PNUE) (C) and the photosynthetic traits k3 and Jfac under standard mean environmental conditions (PPFD  = 666 µmol m−2 s−1, Tg = 16.9°C, hs = 0.74).k3 is the ratio between and Npa. Jfac is the ratio between Jmax and . A mesh of k3 values varying between 10 and 300 µmol g−1 N s−1 with 20 steps and of Jfac values varying between 1.75 and 3.5 with 0.05 steps was used. Figures D–E–F, relationships between (Npac) (D), net photosynthesis (An) (E) and photosynthetic N use efficiency (PNUE) (F) and the radiation (PPFD) and temperature (Tg) conditions during growth. Averages over the dataset of leaf photosynthetic parameters (k3, Jfac and SLA) are used (k3 = 59.1 µmol g−1Npa s−1, Jfac = 2.45, SLA  = 17.7 m2 kg−1 DM). The mesh for temperature is 0.5°C between 10 and 30°C and the mesh for radiation is 50 µmol m−2 s−1 between 300 and 1200 µmol m−2 s−1. The values of hs and Tg were fixed at 0.8 and 20°C, respectively. An was calculated with the coordinated leaf protein content and PNUE was calculated as the ratio between An and Npac.

Mentions: Under standard environmental conditions, Npac varied significantly with k3 and Jfac (Fig. 3A). Npac decreased with increasing k3 (Fig. 3A), which imposed a strong constraint on this physiological trait. For a given leaf Npac, high values of k3 did not affect An (Fig. 3B), but PNUE increased linearly with k3 (Fig. 3C). For a given k3 value, both Npac (Fig. 3A) and An (Fig. 3B) displayed saturating responses to increasing Jfac. As a consequence, PNUE was little affected by Jfac (Fig. 3C). In our model (Eqn 1), SLA and fns affected Nac, but did not affect Npac and consequently An and PNUE. Since SLA displayed a higher degree of variation, the leaf structural content per unit area and consequently the leaf N content were strongly dependent on SLA. Thus, the leaf structural N content per unit area and the leaf N content followed an inverse relationship as SLA increased.


The coordination of leaf photosynthesis links C and N fluxes in C3 plant species.

Maire V, Martre P, Kattge J, Gastal F, Esser G, Fontaine S, Soussana JF - PLoS ONE (2012)

Relationships between simulated photosynthetic leaf N content (Npac) (A), net photosynthesis (An) (B) and photosynthetic N use efficiency (PNUE) (C) and the photosynthetic traits k3 and Jfac under standard mean environmental conditions (PPFD  = 666 µmol m−2 s−1, Tg = 16.9°C, hs = 0.74).k3 is the ratio between  and Npa. Jfac is the ratio between Jmax and . A mesh of k3 values varying between 10 and 300 µmol g−1 N s−1 with 20 steps and of Jfac values varying between 1.75 and 3.5 with 0.05 steps was used. Figures D–E–F, relationships between (Npac) (D), net photosynthesis (An) (E) and photosynthetic N use efficiency (PNUE) (F) and the radiation (PPFD) and temperature (Tg) conditions during growth. Averages over the dataset of leaf photosynthetic parameters (k3, Jfac and SLA) are used (k3 = 59.1 µmol g−1Npa s−1, Jfac = 2.45, SLA  = 17.7 m2 kg−1 DM). The mesh for temperature is 0.5°C between 10 and 30°C and the mesh for radiation is 50 µmol m−2 s−1 between 300 and 1200 µmol m−2 s−1. The values of hs and Tg were fixed at 0.8 and 20°C, respectively. An was calculated with the coordinated leaf protein content and PNUE was calculated as the ratio between An and Npac.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369925&req=5

pone-0038345-g003: Relationships between simulated photosynthetic leaf N content (Npac) (A), net photosynthesis (An) (B) and photosynthetic N use efficiency (PNUE) (C) and the photosynthetic traits k3 and Jfac under standard mean environmental conditions (PPFD  = 666 µmol m−2 s−1, Tg = 16.9°C, hs = 0.74).k3 is the ratio between and Npa. Jfac is the ratio between Jmax and . A mesh of k3 values varying between 10 and 300 µmol g−1 N s−1 with 20 steps and of Jfac values varying between 1.75 and 3.5 with 0.05 steps was used. Figures D–E–F, relationships between (Npac) (D), net photosynthesis (An) (E) and photosynthetic N use efficiency (PNUE) (F) and the radiation (PPFD) and temperature (Tg) conditions during growth. Averages over the dataset of leaf photosynthetic parameters (k3, Jfac and SLA) are used (k3 = 59.1 µmol g−1Npa s−1, Jfac = 2.45, SLA  = 17.7 m2 kg−1 DM). The mesh for temperature is 0.5°C between 10 and 30°C and the mesh for radiation is 50 µmol m−2 s−1 between 300 and 1200 µmol m−2 s−1. The values of hs and Tg were fixed at 0.8 and 20°C, respectively. An was calculated with the coordinated leaf protein content and PNUE was calculated as the ratio between An and Npac.
Mentions: Under standard environmental conditions, Npac varied significantly with k3 and Jfac (Fig. 3A). Npac decreased with increasing k3 (Fig. 3A), which imposed a strong constraint on this physiological trait. For a given leaf Npac, high values of k3 did not affect An (Fig. 3B), but PNUE increased linearly with k3 (Fig. 3C). For a given k3 value, both Npac (Fig. 3A) and An (Fig. 3B) displayed saturating responses to increasing Jfac. As a consequence, PNUE was little affected by Jfac (Fig. 3C). In our model (Eqn 1), SLA and fns affected Nac, but did not affect Npac and consequently An and PNUE. Since SLA displayed a higher degree of variation, the leaf structural content per unit area and consequently the leaf N content were strongly dependent on SLA. Thus, the leaf structural N content per unit area and the leaf N content followed an inverse relationship as SLA increased.

Bottom Line: The resulting model linking leaf photosynthesis, stomata conductance and nitrogen investment provides testable hypotheses about the physiological regulation of these processes.A calibration by plant functional type of k(3) and J(fac) still leads to accurate model prediction of N(a), while SLA calibration is essentially required at species level.Observed variations in k(3) and J(fac) are partly explained by environmental and phylogenetic constraints, while SLA variation is partly explained by phylogeny.

View Article: PubMed Central - PubMed

Affiliation: INRA, UR874 UREP, Clermont-Ferrand, France. vmaire24@gmail.com

ABSTRACT
Photosynthetic capacity is one of the most sensitive parameters in vegetation models and its relationship to leaf nitrogen content links the carbon and nitrogen cycles. Process understanding for reliably predicting photosynthetic capacity is still missing. To advance this understanding we have tested across C(3) plant species the coordination hypothesis, which assumes nitrogen allocation to photosynthetic processes such that photosynthesis tends to be co-limited by ribulose-1,5-bisphosphate (RuBP) carboxylation and regeneration. The coordination hypothesis yields an analytical solution to predict photosynthetic capacity and calculate area-based leaf nitrogen content (N(a)). The resulting model linking leaf photosynthesis, stomata conductance and nitrogen investment provides testable hypotheses about the physiological regulation of these processes. Based on a dataset of 293 observations for 31 species grown under a range of environmental conditions, we confirm the coordination hypothesis: under mean environmental conditions experienced by leaves during the preceding month, RuBP carboxylation equals RuBP regeneration. We identify three key parameters for photosynthetic coordination: specific leaf area and two photosynthetic traits (k(3), which modulates N investment and is the ratio of RuBP carboxylation/oxygenation capacity (V(Cmax)) to leaf photosynthetic N content (N(pa)); and J(fac), which modulates photosynthesis for a given k(3) and is the ratio of RuBP regeneration capacity (J(max)) to V(Cmax)). With species-specific parameter values of SLA, k(3) and J(fac), our leaf photosynthesis coordination model accounts for 93% of the total variance in N(a) across species and environmental conditions. A calibration by plant functional type of k(3) and J(fac) still leads to accurate model prediction of N(a), while SLA calibration is essentially required at species level. Observed variations in k(3) and J(fac) are partly explained by environmental and phylogenetic constraints, while SLA variation is partly explained by phylogeny. These results open a new avenue for predicting photosynthetic capacity and leaf nitrogen content in vegetation models.

Show MeSH
Related in: MedlinePlus