Limits...
The acclimation of Phaeodactylum tricornutum to blue and red light does not influence the photosynthetic light reaction but strongly disturbs the carbon allocation pattern.

Jungandreas A, Schellenberger Costa B, Jakob T, von Bergen M, Baumann S, Wilhelm C - PLoS ONE (2014)

Bottom Line: Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated.The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation.Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Physiology, Institute of Biology, Faculty of Biosciences, Pharmacy and Psychology, University of Leipzig, Leipzig, Germany; Department of Computational Landscape Ecology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.

ABSTRACT
Diatoms are major contributors to the aquatic primary productivity and show an efficient acclimation ability to changing light intensities. Here, we investigated the acclimation of Phaeodactylum tricornutum to different light quality with respect to growth rate, photosynthesis rate, macromolecular composition and the metabolic profile by shifting the light quality from red light (RL) to blue light (BL) and vice versa. Our results show that cultures pre-acclimated to BL and RL exhibited similar growth performance, photosynthesis rates and metabolite profiles. However, light shift experiments revealed rapid and severe changes in the metabolite profile within 15 min as the initial reaction of light acclimation. Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated. Accordingly, on the time scale of hours the RL to BL shift led to a redirection of carbon into the synthesis of proteins, whereas during the BL to RL shift an accumulation of carbohydrates occurred. Thus, a vast metabolic reorganization of the cells was observed as the initial reaction to changes in light quality. The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation. Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool. Surprisingly, the RL to BL shift led to a severe inhibition of growth within the first 48 h which was not observed during the BL to RL shift. Furthermore, during the phase of growth arrest the photosynthetic performance did not change. We propose arguments that the growth arrest could have been caused by the reorganization of intracellular carbon partitioning.

No MeSH data available.


Related in: MedlinePlus

Long-term acclimation to light quality shifts.The acclimation process of P. tricornutum cultures was observed for 6 days after the light quality shift from BL to RL and RL to BL. Shown are (A) estimated gross oxygen evolution rates at growth light conditions, (B) growth rate per day, (C) maximum values of non-photochemical quenching and (D) concentration of the xanthophyll cycle pigment Ddx at growth light conditions. The NPQ values were measured at illumination with saturating light intensities, while all other values are measured at growth light conditions. The asterisks depict the p-values of the respective data point compared to the steady state (BL to RL shift is compared to RL steady state, RL to BL shift is compared to BL steady state). n = 4–5. The exact values are specified in Table S1.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4128583&req=5

pone-0099727-g001: Long-term acclimation to light quality shifts.The acclimation process of P. tricornutum cultures was observed for 6 days after the light quality shift from BL to RL and RL to BL. Shown are (A) estimated gross oxygen evolution rates at growth light conditions, (B) growth rate per day, (C) maximum values of non-photochemical quenching and (D) concentration of the xanthophyll cycle pigment Ddx at growth light conditions. The NPQ values were measured at illumination with saturating light intensities, while all other values are measured at growth light conditions. The asterisks depict the p-values of the respective data point compared to the steady state (BL to RL shift is compared to RL steady state, RL to BL shift is compared to BL steady state). n = 4–5. The exact values are specified in Table S1.

Mentions: No differences were observed in the oxygen-based photosynthesis rates during the entire period of observation (Figure 1 A). Hence, during the light shift experiments all P. tricornutum cultures showed comparable gross photosynthesis rates of ∼60 µmol O2 mg Chl a−1 h−1 irrespective of the incident light quality. This stands in contrast to the growth rates that were observed to be slightly reduced during the first 48 h after the light shift from BL to RL (∼0.3 d−1 compared to 0.42 d−1 in pre-acclimated cultures), whereas in the shift from RL to BL, the growth was completely arrested during the first 24 h of the light shift (Figure 1 B). Growth rates fully recovered to about 0.4 d−1 within the next 48 h until day 3 after the start of the light shift. This result was similar when the growth rates were calculated on the basis of the cell number or on the dry matter yield (data not shown).


The acclimation of Phaeodactylum tricornutum to blue and red light does not influence the photosynthetic light reaction but strongly disturbs the carbon allocation pattern.

Jungandreas A, Schellenberger Costa B, Jakob T, von Bergen M, Baumann S, Wilhelm C - PLoS ONE (2014)

Long-term acclimation to light quality shifts.The acclimation process of P. tricornutum cultures was observed for 6 days after the light quality shift from BL to RL and RL to BL. Shown are (A) estimated gross oxygen evolution rates at growth light conditions, (B) growth rate per day, (C) maximum values of non-photochemical quenching and (D) concentration of the xanthophyll cycle pigment Ddx at growth light conditions. The NPQ values were measured at illumination with saturating light intensities, while all other values are measured at growth light conditions. The asterisks depict the p-values of the respective data point compared to the steady state (BL to RL shift is compared to RL steady state, RL to BL shift is compared to BL steady state). n = 4–5. The exact values are specified in Table S1.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128583&req=5

pone-0099727-g001: Long-term acclimation to light quality shifts.The acclimation process of P. tricornutum cultures was observed for 6 days after the light quality shift from BL to RL and RL to BL. Shown are (A) estimated gross oxygen evolution rates at growth light conditions, (B) growth rate per day, (C) maximum values of non-photochemical quenching and (D) concentration of the xanthophyll cycle pigment Ddx at growth light conditions. The NPQ values were measured at illumination with saturating light intensities, while all other values are measured at growth light conditions. The asterisks depict the p-values of the respective data point compared to the steady state (BL to RL shift is compared to RL steady state, RL to BL shift is compared to BL steady state). n = 4–5. The exact values are specified in Table S1.
Mentions: No differences were observed in the oxygen-based photosynthesis rates during the entire period of observation (Figure 1 A). Hence, during the light shift experiments all P. tricornutum cultures showed comparable gross photosynthesis rates of ∼60 µmol O2 mg Chl a−1 h−1 irrespective of the incident light quality. This stands in contrast to the growth rates that were observed to be slightly reduced during the first 48 h after the light shift from BL to RL (∼0.3 d−1 compared to 0.42 d−1 in pre-acclimated cultures), whereas in the shift from RL to BL, the growth was completely arrested during the first 24 h of the light shift (Figure 1 B). Growth rates fully recovered to about 0.4 d−1 within the next 48 h until day 3 after the start of the light shift. This result was similar when the growth rates were calculated on the basis of the cell number or on the dry matter yield (data not shown).

Bottom Line: Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated.The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation.Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Physiology, Institute of Biology, Faculty of Biosciences, Pharmacy and Psychology, University of Leipzig, Leipzig, Germany; Department of Computational Landscape Ecology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.

ABSTRACT
Diatoms are major contributors to the aquatic primary productivity and show an efficient acclimation ability to changing light intensities. Here, we investigated the acclimation of Phaeodactylum tricornutum to different light quality with respect to growth rate, photosynthesis rate, macromolecular composition and the metabolic profile by shifting the light quality from red light (RL) to blue light (BL) and vice versa. Our results show that cultures pre-acclimated to BL and RL exhibited similar growth performance, photosynthesis rates and metabolite profiles. However, light shift experiments revealed rapid and severe changes in the metabolite profile within 15 min as the initial reaction of light acclimation. Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated. Accordingly, on the time scale of hours the RL to BL shift led to a redirection of carbon into the synthesis of proteins, whereas during the BL to RL shift an accumulation of carbohydrates occurred. Thus, a vast metabolic reorganization of the cells was observed as the initial reaction to changes in light quality. The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation. Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool. Surprisingly, the RL to BL shift led to a severe inhibition of growth within the first 48 h which was not observed during the BL to RL shift. Furthermore, during the phase of growth arrest the photosynthetic performance did not change. We propose arguments that the growth arrest could have been caused by the reorganization of intracellular carbon partitioning.

No MeSH data available.


Related in: MedlinePlus