Limits...
High intraspecific ability to adjust both carbon uptake and allocation under light and nutrient reduction in Halimium halimifolium L.

Wegener F, Beyschlag W, Werner C - Front Plant Sci (2015)

Bottom Line: Despite the 57% light reduction the total biomass production was not affected in the Low L treatment.The plants probably compensated light reduction by an improvement of their ability to fix C.Finally, our results indicate that growing heterotrophic tissues strongly reduce the C reflux from storage and structural C pools and therefore enhance the fraction of recent assimilates allocated to respiration.

View Article: PubMed Central - PubMed

Affiliation: Ecosystem Physiology, University of Freiburg Freiburg, Germany ; AgroEcosystem Research, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth Bayreuth, Germany.

ABSTRACT
The allocation of recently assimilated carbon (C) by plants depends on developmental stage and on environmental factors, but the underlying mechanisms are still a matter of debate. In the present study, we investigated the regulation of C uptake and allocation and their adjustments during plant growth. We induced different allocation strategies in the Mediterranean shrub Halimium halimifolium L. by a reduction of light (Low L treatment) and nutrient availability (Low N treatment) and analyzed allocation parameters as well as morphological and physiological traits for 15 months. Further, we conducted a (13)CO2 pulse-labeling and followed the way of recently assimilated carbon to eight different tissue classes and respiration for 13 days. The plant responses were remarkably distinct in our study, with mainly morphological/physiological adaptions in case of light reduction and adjustment of C allocation in case of nutrient reduction. The transport of recently assimilated C to the root system was enhanced in amount (c. 200%) and velocity under nutrient limited conditions compared to control plants. Despite the 57% light reduction the total biomass production was not affected in the Low L treatment. The plants probably compensated light reduction by an improvement of their ability to fix C. Thus, our results support the concept that photosynthesis is, at least in a medium term perspective, influenced by the C demand of the plant and not exclusively by environmental factors. Finally, our results indicate that growing heterotrophic tissues strongly reduce the C reflux from storage and structural C pools and therefore enhance the fraction of recent assimilates allocated to respiration. We propose that this interruption of the C reflux from storage and structural C pools could be a regulation mechanism for C translocation in plants.

No MeSH data available.


Related in: MedlinePlus

δ13CO2 of leaves (A) and rhizosphere (B) during the chase period after pulse labeling. δ13C of leaf respiration (n = 3 ± SE, after day 3 n = 2) was measured via in-tube incubation technique (Werner et al., 2007). Rhizosphere respired CO2 was measured in the soil compartment of one whole plant gas-exchange chamber per treatment. Gray areas indicate dark periods.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4528176&req=5

Figure 3: δ13CO2 of leaves (A) and rhizosphere (B) during the chase period after pulse labeling. δ13C of leaf respiration (n = 3 ± SE, after day 3 n = 2) was measured via in-tube incubation technique (Werner et al., 2007). Rhizosphere respired CO2 was measured in the soil compartment of one whole plant gas-exchange chamber per treatment. Gray areas indicate dark periods.

Mentions: After 15 months we conducted a 4-h 13CO2 pulse labeling with a 13 days chase period. Five hour after labeling leaf respired CO2 was strongly enriched in 13C followed by a decrease of about 80% within 30 h with minor differences between treatments (Figure 3A). In contrast, differences between treatments were pronounced in 13C dynamics of rhizosphere respiration during the first 3 days after labeling (Figure 3B). Low L and the Low N plants rhizosphere respiration reached a first 13C peak in the first night and a second peak of similar size was measured 24 and 29 h after labeling, respectively. No distinct double peak was found in the control treatment, which showed the highest δ13CO2 values 33 h after labeling (Figure 3B). The half-life time of labeled C in leaf respiration substrate (estimated by δ13CO2 exponential decay functions) ranged between 11 and 14 h, whereas those from rhizosphere respiration ranged between 26 and 31 h (Table 2).


High intraspecific ability to adjust both carbon uptake and allocation under light and nutrient reduction in Halimium halimifolium L.

Wegener F, Beyschlag W, Werner C - Front Plant Sci (2015)

δ13CO2 of leaves (A) and rhizosphere (B) during the chase period after pulse labeling. δ13C of leaf respiration (n = 3 ± SE, after day 3 n = 2) was measured via in-tube incubation technique (Werner et al., 2007). Rhizosphere respired CO2 was measured in the soil compartment of one whole plant gas-exchange chamber per treatment. Gray areas indicate dark periods.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4528176&req=5

Figure 3: δ13CO2 of leaves (A) and rhizosphere (B) during the chase period after pulse labeling. δ13C of leaf respiration (n = 3 ± SE, after day 3 n = 2) was measured via in-tube incubation technique (Werner et al., 2007). Rhizosphere respired CO2 was measured in the soil compartment of one whole plant gas-exchange chamber per treatment. Gray areas indicate dark periods.
Mentions: After 15 months we conducted a 4-h 13CO2 pulse labeling with a 13 days chase period. Five hour after labeling leaf respired CO2 was strongly enriched in 13C followed by a decrease of about 80% within 30 h with minor differences between treatments (Figure 3A). In contrast, differences between treatments were pronounced in 13C dynamics of rhizosphere respiration during the first 3 days after labeling (Figure 3B). Low L and the Low N plants rhizosphere respiration reached a first 13C peak in the first night and a second peak of similar size was measured 24 and 29 h after labeling, respectively. No distinct double peak was found in the control treatment, which showed the highest δ13CO2 values 33 h after labeling (Figure 3B). The half-life time of labeled C in leaf respiration substrate (estimated by δ13CO2 exponential decay functions) ranged between 11 and 14 h, whereas those from rhizosphere respiration ranged between 26 and 31 h (Table 2).

Bottom Line: Despite the 57% light reduction the total biomass production was not affected in the Low L treatment.The plants probably compensated light reduction by an improvement of their ability to fix C.Finally, our results indicate that growing heterotrophic tissues strongly reduce the C reflux from storage and structural C pools and therefore enhance the fraction of recent assimilates allocated to respiration.

View Article: PubMed Central - PubMed

Affiliation: Ecosystem Physiology, University of Freiburg Freiburg, Germany ; AgroEcosystem Research, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth Bayreuth, Germany.

ABSTRACT
The allocation of recently assimilated carbon (C) by plants depends on developmental stage and on environmental factors, but the underlying mechanisms are still a matter of debate. In the present study, we investigated the regulation of C uptake and allocation and their adjustments during plant growth. We induced different allocation strategies in the Mediterranean shrub Halimium halimifolium L. by a reduction of light (Low L treatment) and nutrient availability (Low N treatment) and analyzed allocation parameters as well as morphological and physiological traits for 15 months. Further, we conducted a (13)CO2 pulse-labeling and followed the way of recently assimilated carbon to eight different tissue classes and respiration for 13 days. The plant responses were remarkably distinct in our study, with mainly morphological/physiological adaptions in case of light reduction and adjustment of C allocation in case of nutrient reduction. The transport of recently assimilated C to the root system was enhanced in amount (c. 200%) and velocity under nutrient limited conditions compared to control plants. Despite the 57% light reduction the total biomass production was not affected in the Low L treatment. The plants probably compensated light reduction by an improvement of their ability to fix C. Thus, our results support the concept that photosynthesis is, at least in a medium term perspective, influenced by the C demand of the plant and not exclusively by environmental factors. Finally, our results indicate that growing heterotrophic tissues strongly reduce the C reflux from storage and structural C pools and therefore enhance the fraction of recent assimilates allocated to respiration. We propose that this interruption of the C reflux from storage and structural C pools could be a regulation mechanism for C translocation in plants.

No MeSH data available.


Related in: MedlinePlus