Gene expression patterns of trembling aspen trees following long-term exposure to interacting elevated CO < inf> 2 and tropospheric O < inf> 3

Document Type

Article

Publication Date

7-1-2005

Abstract

Expression of 4600 poplar expressed sequence tags (ESTs) was studied over the 2001-2002 growing seasons using trees of the moderately ozone (O 3)-tolerant trembling aspen (Populus tremuloides) clone 216 exposed to elevated CO2 and/or O3 for their entire 5-yr life history. Based on replication of the experiment in years 2001 and 2002, 238 genes showed qualitatively similar expression in at least one treatment and were retained for analysis. Of these 238 genes, 185 were significantly regulated (1.5-fold) from one year to the other in at least one treatment studied. Less than 1% of the genes were regulated 2-fold or more. In the elevated CO 2 treatment, relatively small numbers of genes were upregulated, whereas in the O3 treatment, higher expression of many signaling and defense-related genes and lower expression of several photosynthesis and energy-related genes were observed. Senescence-associated genes (SAGs) and genes involved in the flavanoid pathway were also up-regulated under O3, with or without CO2 treatment. Interestingly, the combined treatment of CO2 plus O3 resulted in the differential expression of genes that were not up-regulated with individual gas treatments. This study represents the first investigation into gene expression following long-term exposure of trees to the interacting effects of elevated CO2 and O3 under field conditions. Patterns of gene-specific regulation described in this study correlated with previously published physiological responses of aspen clone 216. © New Phytologist (2005).

Publication Title

New Phytologist

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