The 30th International Conference on Arabidopsis Research (ICAR 2019)

631 / 2019-04-26 14:44:01

Signaling pathways and adaptation to abiotic stress conditions

abiotic stress, osmotic stress, heat, transcriptional network, protein stability

Plenary track > Abiotic Stress

Drought, heat, and freezing are environmental conditions that cause adverse effects on plant growth and productivity. Expression of many genes is induced by these stresses in plants. We have shown that a cis-acting element DRE/CRT plays an important role in regulating gene expression in response to these stresses. We isolated two type DRE-binding proteins, DREB1/CBF and DREB2. DREB2A acts as a key transcription factor in both drought and heat stress tolerance in Arabidopsis and induces the expression of many stress-inducible genes. Although DREB2A expression is induced by stress, the posttranslational regulation of DREB2A is required for its activity. The deletion of an integral negative regulatory domain (NRD) transforms DREB2A into a stable and constitutively active form (DREB2A CA). We identified BPMs, substrate adaptors of the CUL3-based E3 ligase, as DREB2A interacting proteins. Genetic analysis indicated that BPM-CUL3 E3 ligase is the factor responsible for the destabilization of DREB2A via the NRD. Furthermore, we found that Ser/Thr residues in the NRD are phosphorylated under nonstress growth conditions and that their phosphorylation decreases in response to heat. This phosphorylation is likely mediated by casein kinase 1 and is essential for the NRD-dependent, proteasomal degradation of DREB2A. These observations suggest that inhibition of NRD phosphorylation stabilizes and activates DREB2A in response to stresses to enhance plant stress tolerance.