Differential gene expression in senescing leaves of two silver birch genotypes in response to elevated CO2 and tropospheric ozone.
Long-term effects of elevated CO(2) and O(3) 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 CO(2) and/or O(3) 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 CO(2) and O(3). 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 CO(2) and O(3). Elevated CO(2) delayed leaf senescence and reduced associated transcriptional changes, whereas elevated O(3) advanced leaf senescence because of increased oxidative stress. The combined treatment demonstrated that elevated CO(2) only temporarily alleviated the negative effects of O(3). Gene expression data alone were insufficient to explain the O(3) response in birch, and additional physiological and biochemical data were required to understand the true O(3) sensitivity of these clones.
Suonenjoki Research Unit, Finnish Forest Research Institute, 77600 Suonenjoki, Finland. sari.kontunen-soppela@joensuu.fi
Sari
S
Kontunen-Soppela
Johanna
J
Riikonen
Hanna
H
Ruhanen
Mikael
M
Brosché
Panu
P
Somervuo
Petri
P
Peltonen
Jaakko
J
Kangasjärvi
Petri
P
Auvinen
Lars
L
Paulin
Markku
M
Keinänen
Elina
E
Oksanen
Elina
E
Vapaavuori
D001272:Atmosphere / Q000737:chemistry; D029662:Betula / Q000166:cytology / Q000187:drug effects / Q000235:genetics*; D002245:Carbon Dioxide / Q000494:pharmacology*; D016922:Cellular Senescence / Q000187:drug effects / Q000235:genetics*; D002999:Clone Cells; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant / Q000235:genetics; D005838:Genotype; D009693:Nucleic Acid Hybridization / Q000235:genetics; D010126:Ozone / Q000494:pharmacology*; D010802:Phylogeny; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000235:genetics*; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
D002245:Carbon Dioxide; D010126:Ozone