Expression data from A. thaliana WT and gnat2 under control conditions and after 2 h treatment with high light or darkness

We used microarrays to detail the response of A. thaliana WT and gnat2 to high light and darkness treatments and identified distinct classes of regulated genes during this process. In wildtype, the expression of 1,808 of 27,826 analysed transcripts was significantly (>2-fold, p<0.05) altered after high light treatment. Of those 1,808 transcripts, 943 were up- and 865 were downregulated. A similar response to high light was observed in gnat2, where 2,083 transcripts (1,126 up and 957 down) were significantly regulated upon high light stress. Similarly, lack of light resulted in an altered expression of 2,042 transcripts. Of those 2,042 transcripts, 979 were up- and 1,063 were downregulated. The gnat2 mutant responded similarly with 2,361 transcripts (1,195 up and 1,166 down) significantly regulated upon darkness. Under control conditions, only 38 transcripts except GNAT2 were differentially regulated between WT and gnat2. Overall the transcriptional responses of the WT and gnat2 to unexpected short-term darkness and high light were similar. Arabidopsis thaliana ecotype Co-0 and gnat2 mutants (SALK_033944) were grown on soil under short-day conditions (8 h light, 120 µmol m-2s-1 photon flux density, 23 °C and 50 % humidity). After 4.5 weeks, the plants were subjected to different light regimes interrupting the short-day light cycle. Two hours after the regular onset of light, the plants were treated with either high light illumination (HL, 1000 µmol m-2s-1) or darkness (D) for two hours. The control group (C) continued growth at 120 µmol m-2s-1. Immediately after treatment, the rosettes were harvested.