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Drought-Induced Oxidative Stress in Grassland Plants
Farfan-Vignolo, E.R. and Asard, H. 2012. Effect of elevated CO2 and temperature on the oxidative stress response to drought in Lolium perenne L. and Medicago sativa L. Plant Physiology and Biochemistry 59: 55-62.

The authors write that "grassland communities constitute an important fraction of the green surface of the earth, and are worldwide an important source of cattle-food (Carlier et al., 2009; Ciais et al., 2011)." And in light of these facts ...

What was done
... the pair of Belgian researchers investigated several physiological and molecular (antioxidant) responses to water deficit in two major grassland species (Lolium perenne L. and Medicago lupulina L.) under current ambient (A) and future elevated (E) atmospheric CO2 concentrations and air temperatures (T), where ECO2 = ACO2 + 375 ppm, and where ET = AT + 3°C.

What was learned
"Not surprisingly, in Farfan-Vignolo and Asard's words, "drought caused significant increases in oxidative damage, i.e., in protein oxidation and lipid peroxidation levels." But they found that "in both species the impact of drought on protein oxidation was reduced in future climate conditions [ECO2 and ET]." And speaking of the stress-reducing effect of ECO2, they say that "this 'CO2-protection effect' is reported for a variety of abiotic stress conditions and species," citing the studies of Schwanz and Polle (1998), Sgherri et al. (2000), Geissler et al. (2009), Perez-Lopez et al. (2009), Vurro et al. (2009) and Salazar-Parra et al. (2012), after which they indicate that they "find support for this effect at the level of oxidative cell damage and protein oxidation in water-deficit responses of L. perenne and M. lupulina." And, of course, they also found that even under drought stress, "elevated CO2 significantly affected shoot production in L. perenne (increase by 27-32%)," and that "also in M. lupulina a biomass increase was observed (26-38%)."

What it means
Atmospheric CO2 enrichment typically increases the quantity of grassland production, even when plants are stressed for water, while at the same time it additionally enhances the quality of what is produced, as it reduces drought-induced oxidative cell damage and protein oxidation.

Carlier, L., Rotar, I., Vlahova, M. and Vidican, R. 2009. Importance and functions of grasslands. Notulae Botanicae Horti Agrobotanici Cluj-Napoca 37: 25-30.

Ciais, P., Gervois, S., Vuichard, N., Piao, S.L. and Viovy, N. 2011. Effects of land use change and management on the European cropland carbon balance. Global Change Biology 17: 320-338.

Geissler, N., Hussin, S. and Koyro, H.-W. 2009. Elevated atmospheric CO2 concentration ameliorates effects of NaCl salinity on photosynthesis and leaf structure of Aster tripolium L. Journal of Experimental Botany 60: 137-151.

Perez-Lopez, U., Robredo, A., Lacuestra, M., Sgherri, C., Munoz-Rueda, A., Navari-Izzo, F. and Mena-Petite, A. 2009. The oxidative stress caused by salinity in two barley cultivars is mitigated by elevated CO2. Physiologia Plantarum 135: 29-42.

Salazar-Parra, C., Aguirreolea, J., Sanchez-Diaz, M., Irigoyen, J.J. and Morales, F. 2012. Climate change (elevated CO2, elevated temperature and moderate drought) triggers the antioxidant enzymes' response of grapevine cv. Tempranillo, avoiding oxidative damage. Physiologia Plantarum 144: 99-110.

Schwanz, P. and Polle, A. 1998. Antioxidative systems, pigment and protein contents in leaves of adult Mediterranean oak species (Quercus pubescens and Q. ilex) with lifetime exposure to elevated CO2. New Phytologist 140: 411-423.

Vurro, E., Bruni, R., Bianchi, A., and di Toppi, L.S. 2009. Elevated atmospheric CO2 decreases oxidative stress and increases essential oil yield in leaves of Thymus vulgaris grown in a mini-FACE system. Environmental and Experimental Botany 65: 99-106.

Reviewed 6 February 2013