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

Summary: 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 2x 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.

Data repository: ArrayExpress  (Accession number A-MEXP-1042) (http://www.ebi.ac.uk/microarray-as/aer/entry)

​

Reference: KONTUNEN‐SOPPELA, S.A.R.I., Riikonen, J., Ruhanen, H., Brosche, M., Somervuo, P., Peltonen, P., Kangasjärvi, J., Auvinen, P., Paulin, L., Keinänen, M. and Oksanen, E., 2010. Differential gene expression in senescing leaves of two silver birch genotypes in response to elevated CO2 and tropospheric ozone. Plant, cell & environment, 33(6),