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Effective use of high CO₂ efflux at the soil surface in a tropical understory plant.

Ishida A, Nakano T, Adachi M, Yoshimura K, Osada N, Ladpala P, Diloksumpun S, Puangchit L, Yoshimura J - Sci Rep (2015)

Bottom Line: We found a large difference in [CO2] between the partly closed space between the soil surface and the leaves (638 µmol mol(-1)) and the atmosphere at 20 cm above ground level (412 µmol mol(-1)).When ambient air [CO2] was experimentally increased from 400 to 600 μmol mol(-1), net photosynthetic rates increased by 45 to 48% under near light-saturated conditions.No significant increase was observed under low light conditions.

View Article: PubMed Central - PubMed

Affiliation: Center for Ecological Research, Kyoto University, Shiga 520-2113, Japan.

ABSTRACT
Many terrestrial plants are C3 plants that evolved in the Mesozoic Era when atmospheric CO2 concentrations ([CO2]) were high. Given current conditions, C3 plants can no longer benefit from high ambient [CO2]. Kaempferia marginata Carey is a unique understory ginger plant in the tropical dry forests of Thailand. The plant has two large flat leaves that spread on the soil surface. We found a large difference in [CO2] between the partly closed space between the soil surface and the leaves (638 µmol mol(-1)) and the atmosphere at 20 cm above ground level (412 µmol mol(-1)). This finding indicates that the plants capture CO2 efflux from the soil. Almost all of the stomata are located on the abaxial leaf surface. When ambient air [CO2] was experimentally increased from 400 to 600 μmol mol(-1), net photosynthetic rates increased by 45 to 48% under near light-saturated conditions. No significant increase was observed under low light conditions. These data demonstrate that the unique leaf structure enhances carbon gain by trapping soil CO2 efflux at stomatal sites under relatively high light conditions, suggesting that ambient air [CO2] can serve as an important selective agent for terrestrial C3 plants.

No MeSH data available.


Related in: MedlinePlus

Photosynthetic responses under high CO2 concentrations and high light conditions.(a) Photosynthetic light response curves (PPF-A curves) at 600 µmol mol−1 CO2 (closed circles) and 400 µmol mol−1 CO2 (open circles), where PPF represents the photosynthetic photon flux at the leaf surface and A is net C assimilation rate. Bars indicate 1 SD, (b) Photosynthetic ambient-air CO2 response curves (Ca-A curves) in a leaf blade at 500 µmol m−2 s−1 PPF (closed circles) and 40 µmol m−2 s−1 PPF (open circles), where Ca represents CO2 concentration in outlet gas stream in the LI-6400, i.e., ambient air CO2 concentration.
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f3: Photosynthetic responses under high CO2 concentrations and high light conditions.(a) Photosynthetic light response curves (PPF-A curves) at 600 µmol mol−1 CO2 (closed circles) and 400 µmol mol−1 CO2 (open circles), where PPF represents the photosynthetic photon flux at the leaf surface and A is net C assimilation rate. Bars indicate 1 SD, (b) Photosynthetic ambient-air CO2 response curves (Ca-A curves) in a leaf blade at 500 µmol m−2 s−1 PPF (closed circles) and 40 µmol m−2 s−1 PPF (open circles), where Ca represents CO2 concentration in outlet gas stream in the LI-6400, i.e., ambient air CO2 concentration.

Mentions: When the ambient-air [CO2] was artificially increased from 400 to 600 μmol mol−1, the A under near-light saturated conditions (800 µmol m−2 s−1 PPF: photosynthetic photon flux) increased from 5.8 to 8.2 μmol m−2 s−1, a 45% increase (Fig. 3A). In contrast, under low light conditions (less than 70 µmol m−2 s−1 PPF), no significant increase was detected in A after elevating [CO2] from 400 to 600 μmol mol−1. We also measured ambient-air CO2 response curves under 500 and 40 µmol m−2 s−1 PPFs. Both RuBP carboxylation and RuBP regeneration rates were reduced by the low PPF (Fig. 3B). When the ambient-air [CO2] was increased from 400 to 600 μmol mol−1, A increased by 48% under relatively strong sunlight (500 μmol m−2 s−1 PPF) and by 36% under reduced light (40 μmol m−2 s−1 PPF) conditions. The data indicate that a significant increase in A in response to elevated [CO2] was more pronounced under sunlit conditions compared with shaded conditions. Sunflecks must thus cooperate with rising [CO2] for enhancing of A1213.


Effective use of high CO₂ efflux at the soil surface in a tropical understory plant.

Ishida A, Nakano T, Adachi M, Yoshimura K, Osada N, Ladpala P, Diloksumpun S, Puangchit L, Yoshimura J - Sci Rep (2015)

Photosynthetic responses under high CO2 concentrations and high light conditions.(a) Photosynthetic light response curves (PPF-A curves) at 600 µmol mol−1 CO2 (closed circles) and 400 µmol mol−1 CO2 (open circles), where PPF represents the photosynthetic photon flux at the leaf surface and A is net C assimilation rate. Bars indicate 1 SD, (b) Photosynthetic ambient-air CO2 response curves (Ca-A curves) in a leaf blade at 500 µmol m−2 s−1 PPF (closed circles) and 40 µmol m−2 s−1 PPF (open circles), where Ca represents CO2 concentration in outlet gas stream in the LI-6400, i.e., ambient air CO2 concentration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4355870&req=5

f3: Photosynthetic responses under high CO2 concentrations and high light conditions.(a) Photosynthetic light response curves (PPF-A curves) at 600 µmol mol−1 CO2 (closed circles) and 400 µmol mol−1 CO2 (open circles), where PPF represents the photosynthetic photon flux at the leaf surface and A is net C assimilation rate. Bars indicate 1 SD, (b) Photosynthetic ambient-air CO2 response curves (Ca-A curves) in a leaf blade at 500 µmol m−2 s−1 PPF (closed circles) and 40 µmol m−2 s−1 PPF (open circles), where Ca represents CO2 concentration in outlet gas stream in the LI-6400, i.e., ambient air CO2 concentration.
Mentions: When the ambient-air [CO2] was artificially increased from 400 to 600 μmol mol−1, the A under near-light saturated conditions (800 µmol m−2 s−1 PPF: photosynthetic photon flux) increased from 5.8 to 8.2 μmol m−2 s−1, a 45% increase (Fig. 3A). In contrast, under low light conditions (less than 70 µmol m−2 s−1 PPF), no significant increase was detected in A after elevating [CO2] from 400 to 600 μmol mol−1. We also measured ambient-air CO2 response curves under 500 and 40 µmol m−2 s−1 PPFs. Both RuBP carboxylation and RuBP regeneration rates were reduced by the low PPF (Fig. 3B). When the ambient-air [CO2] was increased from 400 to 600 μmol mol−1, A increased by 48% under relatively strong sunlight (500 μmol m−2 s−1 PPF) and by 36% under reduced light (40 μmol m−2 s−1 PPF) conditions. The data indicate that a significant increase in A in response to elevated [CO2] was more pronounced under sunlit conditions compared with shaded conditions. Sunflecks must thus cooperate with rising [CO2] for enhancing of A1213.

Bottom Line: We found a large difference in [CO2] between the partly closed space between the soil surface and the leaves (638 µmol mol(-1)) and the atmosphere at 20 cm above ground level (412 µmol mol(-1)).When ambient air [CO2] was experimentally increased from 400 to 600 μmol mol(-1), net photosynthetic rates increased by 45 to 48% under near light-saturated conditions.No significant increase was observed under low light conditions.

View Article: PubMed Central - PubMed

Affiliation: Center for Ecological Research, Kyoto University, Shiga 520-2113, Japan.

ABSTRACT
Many terrestrial plants are C3 plants that evolved in the Mesozoic Era when atmospheric CO2 concentrations ([CO2]) were high. Given current conditions, C3 plants can no longer benefit from high ambient [CO2]. Kaempferia marginata Carey is a unique understory ginger plant in the tropical dry forests of Thailand. The plant has two large flat leaves that spread on the soil surface. We found a large difference in [CO2] between the partly closed space between the soil surface and the leaves (638 µmol mol(-1)) and the atmosphere at 20 cm above ground level (412 µmol mol(-1)). This finding indicates that the plants capture CO2 efflux from the soil. Almost all of the stomata are located on the abaxial leaf surface. When ambient air [CO2] was experimentally increased from 400 to 600 μmol mol(-1), net photosynthetic rates increased by 45 to 48% under near light-saturated conditions. No significant increase was observed under low light conditions. These data demonstrate that the unique leaf structure enhances carbon gain by trapping soil CO2 efflux at stomatal sites under relatively high light conditions, suggesting that ambient air [CO2] can serve as an important selective agent for terrestrial C3 plants.

No MeSH data available.


Related in: MedlinePlus