Genome-wide analyses of early translational responses to elevated temperature and high salinity in Arabidopsis thaliana.

Abiotic stress influences the translation of mRNAs in plants. To gain a global view of the early translational response to abiotic stress, we investigated genome-wide changes in mRNA translation in Arabidopsis thaliana suspension cell cultures exposed to brief periods of two types of stress: elevated temperature (37 degrees C) and high salinity (200 mM NaCl). Microarray analyses revealed that polysome association of most transcripts, which were monitored by using polysomal- and non-polysomal-associated RNA pools, was variably depressed by both stresses within 10 min. We also inspected coordination of changes in translational profiles with transcriptional profiles, and found no simple correlations between the changes in these two processes under both stresses. In addition, we uncovered that the 10 min heat- and salt-inducible changes in polysome association of individual transcripts affected specific biological functions differently; some functional classes were recalcitrant to the overall depression, while others were hypersensitive to it. Heat and salt stresses imposed similar, but not identical, changes in polysome association of individual transcripts, and the functional categories with differential responses from all other genes (i.e. recalcitrant or hypersensitive functional categories) displayed some overlap between the two stresses, suggesting similar underlying mechanisms. Our results highlight the importance of dynamic changes in mRNA translation, which include selective translation and extensive repression of a subset of transcripts, in plant abiotic stress responses.