The phosphoinositide dependent-phospholipase C pathway differentially controls the basal expression of DREB1 and DREB2 genes

We recently showed that-in Arabidopsis thaliana suspension cells-phosphoinositide dependent-phospholipase C (PI-PLC) and diacylglycerol kinase (DGK) negatively regulated the basal expression of most DREB2 genes. DREB2 genes encode transcription factors that bind to Drought Responsive Elements (DRE). Those elements are also bound by DREB1 factors. While DREB2 factors are mostly involved in drought and heat responses, DREB1s are induced in the response to chilling. We here show that the pharmacological inhibition of PIPLC or DGK leads to the basal induction of DREB1 genes. However, the induction is much less marked for the DREB1 genes than that of DREB2A, a member of the DREB2 family. This illustrates that DREB1 and DREB2 genes, while having the same targets, are not submitted to the same transcription regulation, and that lipid signaling might in part explain these differences in the regulation of the DREB genes.