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- Podgórska, Anna, et al.
(författare)
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Short-term ammonium supply induces cellular defence to prevent oxidative stress in Arabidopsis leaves
- 2017
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 160:1, s. 65-83
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Tidskriftsartikel (refereegranskat)abstract
- Plants can assimilate nitrogen from soil pools of both ammonium and nitrate, and the relative levels of these two nitrogen sources are highly variable in soil. Long-term ammonium nutrition is known to cause damage to Arabidopsis that has been linked to mitochondrial oxidative stress. Using hydroponic cultures, we analysed the consequences of rapid shifts between nitrate and ammonium nutrition. This did not induce growth retardation, showing that Arabidopsis can compensate for the changes in redox metabolism associated with the variations in nitrogen redox status. During the first 3h of ammonium treatment, we observed distinct transient shifts in reactive oxygen species (ROS), low-mass antioxidants, ROS-scavenging enzymes, and mitochondrial alternative electron transport pathways, indicating rapid but temporally separated changes in chloroplastic, mitochondrial and cytosolic ROS metabolism. The fast induction of antioxidant defences significantly lowered intracellular H2O2 levels, and thus protected Arabidopsis leaves from oxidative stress. On the other hand elevated extracellular ROS production in response to ammonium supply may be involved in signalling. The response pattern displays an intricate plasticity of Arabidopsis redox metabolism to minimise stress in responses to nutrient changes.
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| 3. |
- Szal, Bożena, et al.
(författare)
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Influence of mitochondrial genome rearrangement on cucumber leaf carbon and nitrogen metabolism
- 2010
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Ingår i: Planta. - : Springer. - 0032-0935 .- 1432-2048. ; 232:6, s. 1371-1382
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Szal, Bozena, et al.
(författare)
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Changes in energy status of leaf cells as a consequence of mitochondrial genome rearrangement
- 2008
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Ingår i: Planta. - : Springer. - 0032-0935 .- 1432-2048. ; 227:3, s. 697-706
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Tidskriftsartikel (refereegranskat)abstract
- The MSC16 cucumber (Cucumis sativus L.) mutant with lower activity of mitochondrial Complex I was used to study the influence of mitochondrial metabolism on whole cell energy and redox state. Mutant plants had lower content of adenylates and NADP(H) whereas the NAD(H) pool was similar as in wild type. Subcellular compartmentation of adenylates and pyridine nucleotides were studied using the method of rapid fractionation of protoplasts. The data obtained demonstrate that dysfunction of mitochondrial respiratory chain decreased the chloroplastic ATP pool. No differences in NAD(H) pools in subcellular fractions of mutated plants were observed; however, the cytosolic fraction was highly reduced whereas the mitochondrial fraction was more oxidized in MSC16, as compared to WTc. The NADP(H) pool in MSC16 protoplasts was greatly decreased and the chloroplastic NADP(H) pool was more reduced, whereas the extrachloroplastic pool was much more oxidized, than in WTc protoplast. Changes in nucleotides distribution in cucumber MSC16 mutant were compared to changes found in tobacco (Nicotiana sylvestris) CMS II mitochondrial mutant. In contrast to MSC16 cucumber, the content of adenylates in tobacco mutant was much higher than in tobacco wild type. The differences were more pronounced in leaf tissue collected after darkness than in the middle of the photoperiod. Results obtained after tobacco protoplast fractionating showed that the increase in CMS II adenylate content was mainly due to a higher level in extrachloroplast fraction. Both mutations have a negative effect on plant growth through perturbation of chloroplast/mitochondrial interactions.
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