Abstract
The identification and analysis of genes exhibiting large expression responses to several different types of stress may provide insights into the functional basis of multiple stress tolerance in plant species. This study considered whole-genome transcriptional profiles from Arabidopsis thaliana root and shoot organs under nine abiotic stress conditions (cold, osmotic stress, salt, drought, genotoxic stress, ultraviolet light, oxidative stress, wounding, and high temperature) and at six different time points of stress exposure (0.5, 1, 3, 6, 12, and 24 hr). In roots, genomewide correlations between transcriptional responses to different stress treatments peaked following 1 hr of stress exposure, while in shoots, correlations tended to increase following 6 hr of stress exposure. The generality of stress responses at the transcriptional level was therefore time and organ dependent. A total of 67 genes were identified as exhibiting a statistically significant pattern of gene expression characterized by large transcriptional responses to all nine stress treatments. Most genes were identified from early to middle (1-6 hr) time points of stress exposure. Analysis of this gene set indicated that cell rescue/defense/virulence, energy, and metabolism functional classes were overrepresented, providing novel insight into the functional basis of multiple stress tolerance in Arabidopsis.
Highlights
The identification and analysis of genes exhibiting large expression responses to several different types of stress may provide insights into the functional basis of multiple stress tolerance in plant species
Overviews of the nine environmental stress treatments are available at http://www.uni-tuebingen.de/plantphys/AFGN/ atgenextable2.htm, while complete descriptions can be obtained from The Arabidopsis Information Resource (TAIR)
Marker genes: The nine abiotic stress conditions induced significant expression responses of selected marker genes that had been found responsive to similar treatments in previous experiments. In both cold and drought treatments, for example, the DREB1A transcription factor was associated with significant differential expression at multiple points in the time course (P, 0.05), with greater than sevenfold induction under the cold stress treatment
Summary
The identification and analysis of genes exhibiting large expression responses to several different types of stress may provide insights into the functional basis of multiple stress tolerance in plant species. The mechanistic viewpoint has largely emerged from studies focusing on plant model systems, in which similarities between cellular responses to different types of stress have been explained in terms of the shared effects of different stress treatments on cellular water potential (Verslues et al 2006). This common effect has frequently been cited to explain associations found among cold, drought, and salinity stress responses in Arabidopsis and other plant species (e.g., Munns 2002; Denby and Gehring 2005; Verslues et al 2006). In the Arabidopsis model system, shared elements among drought, salinity, and temperature extreme response pathways have been identified, such as the DREB transcription factors and the phytohormone abscisic acid (ABA) (Liu et al 1998; Kim et al 2004; Mauch-Mani and Mauch 2005)
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