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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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The concentration of pyruvate (a), citrate (b), and 2-OG (c) in the leaf tissue of WT and MSC16 plants. Leaf samples were collected after 8 h of darkness (gray bars) or after 6 h of illumination (white bars). Values are means from 3–5 replicates ± SD. Bars with different letters were significantly different at α ≤ 0.05
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Fig2: The concentration of pyruvate (a), citrate (b), and 2-OG (c) in the leaf tissue of WT and MSC16 plants. Leaf samples were collected after 8 h of darkness (gray bars) or after 6 h of illumination (white bars). Values are means from 3–5 replicates ± SD. Bars with different letters were significantly different at α ≤ 0.05

Mentions: Suppression of dark respiration by light can result in changes in concentration of TCA cycle intermediates. During night pyruvate is probably the main substrate entering the TCA cycle. Under darkness, pyruvate levels in the leaves of MSC16 plants were similar to those in WT leaves (Fig. 2a). Illumination resulted in a great increase (almost 3-times) in pyruvate concentration in WT leaves (Fig. 2a) probably indicating its lower utilization in TCA cycle but in MSC16 leaves pyruvate concentrations were not affected by the light conditions (Fig. 2a). Moreover, the activity and protein level of pyruvate dehydrogenase complex (PDC) in mitochondria of MSC16 plants were higher compared with WT mitochondria (about 100 and 40%, respectively; Fig. 3a).Fig. 2


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)

The concentration of pyruvate (a), citrate (b), and 2-OG (c) in the leaf tissue of WT and MSC16 plants. Leaf samples were collected after 8 h of darkness (gray bars) or after 6 h of illumination (white bars). Values are means from 3–5 replicates ± SD. Bars with different letters were significantly different at α ≤ 0.05
© Copyright Policy
Related In: Results  -  Collection

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

Fig2: The concentration of pyruvate (a), citrate (b), and 2-OG (c) in the leaf tissue of WT and MSC16 plants. Leaf samples were collected after 8 h of darkness (gray bars) or after 6 h of illumination (white bars). Values are means from 3–5 replicates ± SD. Bars with different letters were significantly different at α ≤ 0.05
Mentions: Suppression of dark respiration by light can result in changes in concentration of TCA cycle intermediates. During night pyruvate is probably the main substrate entering the TCA cycle. Under darkness, pyruvate levels in the leaves of MSC16 plants were similar to those in WT leaves (Fig. 2a). Illumination resulted in a great increase (almost 3-times) in pyruvate concentration in WT leaves (Fig. 2a) probably indicating its lower utilization in TCA cycle but in MSC16 leaves pyruvate concentrations were not affected by the light conditions (Fig. 2a). Moreover, the activity and protein level of pyruvate dehydrogenase complex (PDC) in mitochondria of MSC16 plants were higher compared with WT mitochondria (about 100 and 40%, respectively; Fig. 3a).Fig. 2

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