Editor L. De Kok
Metabolic-dependent changes in plant cell redox power after ozone exposure
Article first published online: 23 SEP 2009
© 2009 German Botanical Society and The Royal Botanical Society of the Netherlands
Special Issue: Plant Functioning in a Changing Global Environment.
Volume 11, Issue Supplement s1, pages 35–42, November 2009
How to Cite
Dizengremel, P., Le Thiec, D., Hasenfratz-Sauder, M.-P., Vaultier, M.-N., Bagard, M. and Jolivet, Y. (2009), Metabolic-dependent changes in plant cell redox power after ozone exposure. Plant Biology, 11: 35–42. doi: 10.1111/j.1438-8677.2009.00261.x
Conflicts of interest The authors have declared no conflicts of interest.
- Issue published online: 23 SEP 2009
- Article first published online: 23 SEP 2009
- Received: 25 March 2009; Accepted: 11 August 2009
- effective dose;
- indicator of risk;
- NADP-dependent enzymes;
- ozone uptake;
- reducing power
The tropospheric level of the phytotoxic air pollutant ozone has increased considerably during the last century, and is expected to continue to rise. Long-term exposure of higher plants to low ozone concentrations affects biochemical processes prior to any visible symptoms of injury. The current critical level of ozone used to determine the threshold for damaging plants (biomass loss) is still based on the seasonal sum of the external concentration above 40 nl·l−1 (AOT40). Taking into account stomatal conductance and the internal capacity of leaf defences, a more relevant concept should be based upon the ‘effective ozone flux’, the balance between the stomatal flux and the intensity of cellular detoxification. The large decrease in the Rubisco/PEPc ratio reflects photosynthetic damage from ozone, and a large increase in activity of cytosolic PEPc, which allows increased malate production. Although the direct detoxification of ozone (and ROS produced from its decomposition) is carried out primarily by cell wall ascorbate, the existing level of this antioxidant is not sufficient to indicate the degree of cell sensitivity. In order to regenerate ascorbate, NAD(P)H is needed as the primary supplier of reducing power. It is hypothesised that increased activity of the catabolic pathways and associated shunts (glucose-6-phosphate dehydrogenase, NADP-dependent glyceraldehyde-3-phosphate dehydrogenase, isocitrate dehydrogenase and malic enzyme) can provide sufficient NAD(P)H to maintain intracellular detoxification. Thus, measurement of the level of redox power would contribute to determination of the ‘effective ozone dose’, serving ultimately to improve the ozone risk index for higher plants.