The impact of cold priming on the alerting phase of light and cold regulation of gene expression in Arabidopsis thaliana

We analysed the effect of a short 24 hours cold exposure (priming-stimulus) on gene regulation upon the first two hours of a second cold (4°C) stimulus (cold-triggering) and upon the first two hours of excess light exposure (800 µmol photons m-2 s-1, light triggering). The first and the second stress treatment was seperated by 5 days long lag-phase, which is long enough to reset most of the primary stress response. Several early light and early cold responsive genes showed however a altered transcript abundance in plants, which received five days befor the cold priming stimulus. Espicially JA responsive genes showed a common priming regulation within the cold and light exposure. Transcript levels were assessed in a transcriptome wide scale by peired end next generation sequencing (BGI-Seq-500). Half of the 4-week old Arabidopsis thaliana Col-0 plants were primed for 24 hours at 4 °C (cold-priming) and than retransferred to control conditions for addiotinal 5 days. Than rosette tissue of 20 % of the cold-primed and control non-primed plants were harvested two hours after the onset of the light period. The remaining 80% were split into two groups were either treated with second cold stimulus (4 °C) or were exposed to a 8-fold higher light intensity applied by heat-filtered halogen lamps. The cold treated and light treated plants were harvested after 30-, 60-, and 120 min of stress exposure. For each sample leave tissue of at least 5 plants were pooled and combined for cDNA library construction.