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Influence of mitochondrial genome rearrangement on cucumber leaf carbon and nitrogen metabolism.

Szal B, Jastrzębska A, Kulka M, Leśniak K, Podgórska A, Pärnik T, Ivanova H, Keerberg O, Gardeström P, Rychter AM - Planta (2010)

Bottom Line: We have shown that the mitochondrial dysfunction in MSC16 plants had no effect on photosynthetic CO(2) assimilation, but the concentration of soluble carbohydrates and starch was higher in leaves of MSC16 plants.Impaired mitochondrial respiratory chain activity was associated with the perturbation of mitochondrial TCA cycle manifested, e.g., by lowered decarboxylation rate.Enhanced incorporation of ammonium group into amino acids structures in mutated plants has resulted in decreased concentration of organic acids and accumulation of Glu.

View Article: PubMed Central - PubMed

Affiliation: Institute of Experimental Plant Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. szal@biol.uw.edu.pl

ABSTRACT
The MSC16 cucumber (Cucumis sativus L.) mitochondrial mutant was used to study the effect of mitochondrial dysfunction and disturbed subcellular redox state on leaf day/night carbon and nitrogen metabolism. We have shown that the mitochondrial dysfunction in MSC16 plants had no effect on photosynthetic CO(2) assimilation, but the concentration of soluble carbohydrates and starch was higher in leaves of MSC16 plants. Impaired mitochondrial respiratory chain activity was associated with the perturbation of mitochondrial TCA cycle manifested, e.g., by lowered decarboxylation rate. Mitochondrial dysfunction in MSC16 plants had different influence on leaf cell metabolism under dark or light conditions. In the dark, when the main mitochondrial function is the energy production, the altered activity of TCA cycle in mutated plants was connected with the accumulation of pyruvate and TCA cycle intermediates (citrate and 2-OG). In the light, when TCA activity is needed for synthesis of carbon skeletons required as the acceptors for NH(4) (+) assimilation, the concentration of pyruvate and TCA intermediates was tightly coupled with nitrate metabolism. Enhanced incorporation of ammonium group into amino acids structures in mutated plants has resulted in decreased concentration of organic acids and accumulation of Glu.

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Nitrate concentration (a), maximal nitrate reductase activity (b), ammonium concentration (c), the activity of glutamine synthetase (d), and GS1 and GS2 protein levels (e) in illuminated WT and MSC16 leaves. Signal intensities of bands corresponding to the GS1 and GS2 were estimated using Quantity One 4.6.2 software after correcting for background. Results are expressed relative to control; the amount of protein (GS1 or GS2) in WT mitochondria is set as 100. Representative results are shown. Values are means from 3–10 replicates ± SD. *Significant differences (α ≤ 0.05)
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Fig4: Nitrate concentration (a), maximal nitrate reductase activity (b), ammonium concentration (c), the activity of glutamine synthetase (d), and GS1 and GS2 protein levels (e) in illuminated WT and MSC16 leaves. Signal intensities of bands corresponding to the GS1 and GS2 were estimated using Quantity One 4.6.2 software after correcting for background. Results are expressed relative to control; the amount of protein (GS1 or GS2) in WT mitochondria is set as 100. Representative results are shown. Values are means from 3–10 replicates ± SD. *Significant differences (α ≤ 0.05)

Mentions: The difference in concentrations of TCA-cycle intermediates between WT and MSC16 leaves could result from restricted availability of substrates for mitochondrial respiration (which was not the case in MSC16 plants) or altered utilization. In the light the concentrations of TCA intermediates are tightly connected with nitrate assimilation (Hanning and Heldt 1993). The concentration of nitrate in light was lower in MSC16 leaves by about 25% (Fig. 4a), and a significant decrease (about 45%) in NR activity was observed (Fig. 4b). Ammonium concentrations were about 50% higher in MSC16 leaf compared with WT (Fig. 4c), but GS activities and protein levels were unchanged (Fig. 4d, e).Fig. 4


Influence of mitochondrial genome rearrangement on cucumber leaf carbon and nitrogen metabolism.

Szal B, Jastrzębska A, Kulka M, Leśniak K, Podgórska A, Pärnik T, Ivanova H, Keerberg O, Gardeström P, Rychter AM - Planta (2010)

Nitrate concentration (a), maximal nitrate reductase activity (b), ammonium concentration (c), the activity of glutamine synthetase (d), and GS1 and GS2 protein levels (e) in illuminated WT and MSC16 leaves. Signal intensities of bands corresponding to the GS1 and GS2 were estimated using Quantity One 4.6.2 software after correcting for background. Results are expressed relative to control; the amount of protein (GS1 or GS2) in WT mitochondria is set as 100. Representative results are shown. Values are means from 3–10 replicates ± SD. *Significant differences (α ≤ 0.05)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2957574&req=5

Fig4: Nitrate concentration (a), maximal nitrate reductase activity (b), ammonium concentration (c), the activity of glutamine synthetase (d), and GS1 and GS2 protein levels (e) in illuminated WT and MSC16 leaves. Signal intensities of bands corresponding to the GS1 and GS2 were estimated using Quantity One 4.6.2 software after correcting for background. Results are expressed relative to control; the amount of protein (GS1 or GS2) in WT mitochondria is set as 100. Representative results are shown. Values are means from 3–10 replicates ± SD. *Significant differences (α ≤ 0.05)
Mentions: The difference in concentrations of TCA-cycle intermediates between WT and MSC16 leaves could result from restricted availability of substrates for mitochondrial respiration (which was not the case in MSC16 plants) or altered utilization. In the light the concentrations of TCA intermediates are tightly connected with nitrate assimilation (Hanning and Heldt 1993). The concentration of nitrate in light was lower in MSC16 leaves by about 25% (Fig. 4a), and a significant decrease (about 45%) in NR activity was observed (Fig. 4b). Ammonium concentrations were about 50% higher in MSC16 leaf compared with WT (Fig. 4c), but GS activities and protein levels were unchanged (Fig. 4d, e).Fig. 4

Bottom Line: We have shown that the mitochondrial dysfunction in MSC16 plants had no effect on photosynthetic CO(2) assimilation, but the concentration of soluble carbohydrates and starch was higher in leaves of MSC16 plants.Impaired mitochondrial respiratory chain activity was associated with the perturbation of mitochondrial TCA cycle manifested, e.g., by lowered decarboxylation rate.Enhanced incorporation of ammonium group into amino acids structures in mutated plants has resulted in decreased concentration of organic acids and accumulation of Glu.

View Article: PubMed Central - PubMed

Affiliation: Institute of Experimental Plant Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. szal@biol.uw.edu.pl

ABSTRACT
The MSC16 cucumber (Cucumis sativus L.) mitochondrial mutant was used to study the effect of mitochondrial dysfunction and disturbed subcellular redox state on leaf day/night carbon and nitrogen metabolism. We have shown that the mitochondrial dysfunction in MSC16 plants had no effect on photosynthetic CO(2) assimilation, but the concentration of soluble carbohydrates and starch was higher in leaves of MSC16 plants. Impaired mitochondrial respiratory chain activity was associated with the perturbation of mitochondrial TCA cycle manifested, e.g., by lowered decarboxylation rate. Mitochondrial dysfunction in MSC16 plants had different influence on leaf cell metabolism under dark or light conditions. In the dark, when the main mitochondrial function is the energy production, the altered activity of TCA cycle in mutated plants was connected with the accumulation of pyruvate and TCA cycle intermediates (citrate and 2-OG). In the light, when TCA activity is needed for synthesis of carbon skeletons required as the acceptors for NH(4) (+) assimilation, the concentration of pyruvate and TCA intermediates was tightly coupled with nitrate metabolism. Enhanced incorporation of ammonium group into amino acids structures in mutated plants has resulted in decreased concentration of organic acids and accumulation of Glu.

Show MeSH