Elevated atmospheric CO₂ decreases oxidative stress and increases essential oil yield in leaves of Thymus vulgaris grown in a mini-FACE system

Potted one-year-old plants of Thymus vulgaris L. (thyme, Lamiaceae, C3 metabolism), were grown for three months (10 June-10 September, 2004) in a “mini-free-air-CO₂-enrichment” (“mini-FACE”) system, under 500μmolmol⁻¹ and ambient concentrations of atmospheric carbon dioxide (CO₂). Compared to ambien...

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Bibliographic Details
Published in:Environmental and experimental botany 2009, Vol.65 (1), p.99-106
Main Authors: Vurro, Emanuela, Bruni, Renato, Bianchi, Alberto, Toppi, Luigi Sanità di
Format: Article
Language:English
Subjects:
Biological and medical sciences
carbon dioxide
catalase
crop yield
elevated atmospheric gases
enzyme activity
essential oils
free-air carbon dioxide enrichment
Fundamental and applied biological sciences. Psychology
glutathione
glutathione reductase (NADPH)
Lamiaceae
leaves
lipid peroxidation
monoterpenoids
oxidative stress
peroxidase
phenolic compounds
reactive oxygen species
seasonal variation
sesquiterpenoids
superoxide dismutase
thiobarbituric acid-reactive substances
thyme
Thymus
Thymus vulgaris
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Summary:Potted one-year-old plants of Thymus vulgaris L. (thyme, Lamiaceae, C3 metabolism), were grown for three months (10 June-10 September, 2004) in a “mini-free-air-CO₂-enrichment” (“mini-FACE”) system, under 500μmolmol⁻¹ and ambient concentrations of atmospheric carbon dioxide (CO₂). Compared to ambient CO₂, elevated CO₂ stimulated leaf superoxide dismutase (SOD, EC 1.15.1.1) activity only at the first sampling-time (July), followed by no variation or even a trend of decreased activity on the other two sampling-times (August and September). Under high CO₂, guaiacol peroxidase (GPX, EC 1.11.1.7) and catalase (CAT, EC 1.11.1.6) leaf activities showed no variation or drop throughout the duration of the experiment. By contrast, under elevated CO₂, leaf glutathione reductase (GR, EC 1.6.4.2) activity increased on all the sampling-times, and also a duration-dependent upward trend of glutathione (GSH) content was recorded, with this increase becoming significant - compared with ambient CO₂ - at the third sampling-time (September). Simultaneously, leaves from plants grown under high CO₂ showed a marked increase in essential oil yield, with slight increments in phenolic component and decrements in mono- and sesquiterpene components. Also, a drop in thiobarbituric acid reactive substances (TBARS) content under elevated CO₂ was displayed. Thus, in general, the results reported here point to a downregulation of leaf antioxidant enzymes under elevated CO₂, supporting the notion of reduced reactive oxygen species (ROS) formation under these circumstances. Relying instead on antioxidant-regenerating enzymes, namely GR, fairly high GSH content and essential oils, might be a 'low cost' life strategy for growth under elevated CO₂, not requiring synthesis/activation of energy-intensive and expensive metabolic processes.
ISSN:0098-8472
1873-7307
DOI:10.1016/j.envexpbot.2008.09.001