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Elevated O3 (elevated + o3)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Do elevated atmospheric CO2 and O3 affect food quality and performance of folivorous insects on silver birch?

GLOBAL CHANGE BIOLOGY, Issue 3 2010
PETRI A. PELTONEN
Abstract The individual and combined effects of elevated CO2 and O3 on the foliar chemistry of silver birch (Betula pendula Roth) and on the performance of five potential birch-defoliating insect herbivore species (two geometrid moths, one lymantrid moth and two weevils) were examined. Elevated CO2 decreased the water concentration in both short- and long-shoot leaves, but the effect of CO2 on the concentration of nitrogen and individual phenolic compounds was mediated by O3 treatment, tree genotype and leaf type. Elevated O3 increased the total carbon concentration only in short-shoot leaves. Bioassays showed that elevated CO2 increased the food consumption rate of juvenile Epirrita autumnata and Rheumaptera hastata larvae fed with short- and long-shoot leaves in spring and mid-summer, respectively, but had no effect on the growth of larvae. The contribution of leaf quality variables to the observed CO2 effects indicate that insect compensatory consumption may be related to leaf age. Elevated CO2 increased the food preference of only two tested species: Phyllobius argentatus (CO2 alone) and R. hastata (CO2 combined with O3). The observed stimulus was dependent on tree genotype and the measured leaf quality variables explained only a portion of the stimulus. Elevated O3 decreased the growth of flush-feeding young E. autumnata larvae, irrespective of CO2 concentration, apparently via reductions in general food quality. Therefore, the increasing tropospheric O3 concentration could pose a health risk for juvenile early-season birch folivores in future. In conclusion, the effects of elevated O3 were found to be detrimental to the performance of early-season insect herbivores in birch whereas elevated CO2 had only minor effects on insect performance despite changes in food quality related foliar chemistry. [source]

Species-specific responses to atmospheric carbon dioxide and tropospheric ozone mediate changes in soil carbon

ECOLOGY LETTERS, Issue 11 2009
Alan F. Talhelm
Abstract We repeatedly sampled the surface mineral soil (0,20 cm depth) in three northern temperate forest communities over an 11-year experimental fumigation to understand the effects of elevated carbon dioxide (CO2) and/or elevated phyto-toxic ozone (O3) on soil carbon (C). After 11 years, there was no significant main effect of CO2 or O3 on soil C. However, within the community containing only aspen (Populus tremuloides Michx.), elevated CO2 caused a significant decrease in soil C content. Together with the observations of increased litter inputs, this result strongly suggests accelerated decomposition under elevated CO2. In addition, an initial reduction in the formation of new (fumigation-derived) soil C by O3 under elevated CO2 proved to be only a temporary effect, mirroring trends in fine root biomass. Our results contradict predictions of increased soil C under elevated CO2 and decreased soil C under elevated O3 and should be considered in models simulating the effects of Earth's altered atmosphere. [source]

Do elevated atmospheric CO2 and O3 affect food quality and performance of folivorous insects on silver birch?

Effects of elevated ozone on photosynthesis and stomatal conductance of two soybean varieties: a case study to assess impacts of one component of predicted global climate change

PLANT BIOLOGY, Issue 2009
E. Singh
Abstract Global climatic change scenarios predict a significant increase in future tropospheric ozone (O3) concentrations. The present investigation was done to assess the effects of elevated O3 (70 and 100 ppb) on electron transport, carbon fixation, stomatal conductance and pigment concentrations in two tropical soybean (Glycine max L.) varieties, PK 472 and Bragg. Plants were exposed to O3 for 4 h·day,1 from 10:00 to 14:00 from germination to maturity. Photosynthesis of both varieties were adversely affected, but the reduction was higher in PK 472 than Bragg. A comparison of chlorophyll a fluorescence kinetics with carbon fixation suggested greater sensitivity of dark reactions than light reactions of photosynthesis to O3 stress. The O3 -induced uncoupling between photosynthesis and stomatal conductance in PK 472 suggests the reduction in photosynthesis may be attributed to a factor other than reduced stomatal conductance. An increase in internal CO2 concentration in both O3 -treated soybean varieties compared suggests that the reduction in photosynthesis was due to damage to the photosynthetic apparatus, leading to accumulation of internal CO2 and stomatal closure. The adverse impact of O3 stress increased at higher O3 concentrations in both soybean varieties leading to large reductions in photosynthesis. This study suggests that O3 -induced reductions in photosynthesis in tropical and temperate varieties are similar. [source]

Differential gene expression in senescing leaves of two silver birch genotypes in response to elevated CO2 and tropospheric ozone

PLANT CELL & ENVIRONMENT, Issue 6 2010
SARI KONTUNEN-SOPPELA
ABSTRACT Long-term effects of elevated CO2 and O3 concentrations on gene expression in silver birch (Betula pendula Roth) leaves were studied during the end of the growing season. Two birch genotypes, clones 4 and 80, with different ozone growth responses, were exposed to 2× ambient CO2 and/or O3 in open-top chambers (OTCs). Microarray analyses were performed after 2 years of exposure, and the transcriptional profiles were compared to key physiological characteristics during leaf senescence. There were genotypic differences in the responses to CO2 and O3. Clone 80 exhibited greater transcriptional response and capacity to alter metabolism, resulting in better stress tolerance. The gene expression patterns of birch leaves indicated contrasting responses of senescence-related genes to elevated CO2 and O3. Elevated CO2 delayed leaf senescence and reduced associated transcriptional changes, whereas elevated O3 advanced leaf senescence because of increased oxidative stress. The combined treatment demonstrated that elevated CO2 only temporarily alleviated the negative effects of O3. Gene expression data alone were insufficient to explain the O3 response in birch, and additional physiological and biochemical data were required to understand the true O3 sensitivity of these clones. [source]

Transcriptional profiling reveals elevated CO2 and elevated O3 alter resistance of soybean (Glycine max) to Japanese beetles (Popillia japonica)

PLANT CELL & ENVIRONMENT, Issue 4 2008
CLARE L. CASTEEL
ABSTRACT The accumulation of CO2 and O3 in the troposphere alters phytochemistry which in turn influences the interactions between plants and insects. Using microarray analysis of field-grown soybean (Glycine max), we found that the number of transcripts in the leaves affected by herbivory by Japanese beetles (Popillia japonica) was greater when plants were grown under elevated CO2, elevated O3 and the combination of elevated CO2 plus elevated O3 than when grown in ambient atmosphere. The effect of herbivory on transcription diminished strongly with time (<1% of genes were affected by herbivory after 3 weeks), and elevated CO2 interacted more strongly with herbivory than elevated O3. The majority of transcripts affected by elevated O3 were related to antioxidant metabolism. Constitutive levels and the induction by herbivory of key transcripts associated with defence and hormone signalling were down-regulated under elevated CO2; 1-aminocyclopropane-1-carboxylate (ACC) synthase, lipoxygenase (LOX), allene oxide synthase (AOS), allene oxide cyclase (AOC), chalcone synthase (CHS), polyphenol oxidase (PPO) and cysteine protease inhibitor (CystPI) were lower in abundance compared with levels under ambient conditions. By suppressing the ability to mount an effective defence, elevated CO2 may decrease resistance of soybean to herbivory. [source]