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First published online November 30, 2007; 10.1104/pp.107.112060 Plant Physiology 146:748-761 (2008) © 2008 American Society of Plant Biologists OPEN ACCESS ARTICLE
Core Genome Responses Involved in Acclimation to High Temperature1,[C],[W],[OA]Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, Arizona 85721
Plants can acclimate rapidly to environmental conditions, including high temperatures. To identify molecular events important for acquired thermotolerance, we compared viability and transcript profiles of Arabidopsis thaliana treated to severe heat stress (45°C) without acclimation or following two different acclimation treatments. Notably, a gradual increase to 45°C (22°C to 45°C over 6 h) led to higher survival and to more and higher-fold transcript changes than a step-wise acclimation (90 min at 38°C plus 120 min at 22°C before 45°C). There were significant differences in the total spectrum of transcript changes in the two treatments, but core components of heat acclimation were apparent in the overlap between treatments, emphasizing the importance of performing transcriptome analysis in the context of physiological response. In addition to documenting increases in transcripts of specific genes involved in processes predicted to be required for thermotolerance (i.e. protection of proteins and of translation, limiting oxidative stress), we also found decreases in transcripts (i.e. for programmed cell death, basic metabolism, and biotic stress responses), which are likely equally important for acclimation. Similar protective effects may also be achieved differently, such as prevention of proline accumulation, which is toxic at elevated temperatures and which was reduced by both acclimation treatments but was associated with transcript changes predicted to either reduce proline synthesis or increase degradation in the two acclimation treatments. Finally, phenotypic analysis of T-DNA insertion mutants of genes identified in this analysis defined eight new genes involved in heat acclimation, including cytosolic ascorbate peroxidase and the transcription factors HsfA7a (heat shock transcription factor A7a) and NF-X1.
1 This work was supported by the National Science Foundation (grant no. IBN–0213128) and by the U.S. Department of Agriculture (grant no. NRICGP 99–351007618 to E.V.). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Elizabeth Vierling (vierling{at}email.arizona.edu). [C] Some figures in this article are displayed in color online but in black and white in the print edition. [W] The online version of this article contains Web-only data. [OA] Open Access articles can be viewed online without a subscription. www.plantphysiol.org/cgi/doi/10.1104/pp.107.112060 * Corresponding author; e-mail vierling{at}email.arizona.edu. Received November 1, 2007; accepted November 19, 2007; published November 30, 2007. This article has been cited by other articles:
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