OST1 Kinase Modulates Freezing Tolerance by Enhancing ICE1 Stability in Arabidopsis

• Published in: Developmental cell Vol. 32; no. 3; pp. 278 - 289
• Main Authors: Ding, Yanglin, Li, Hui, Zhang, Xiaoyan, Xie, Qi, Gong, Zhizhong, Yang, Shuhua
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 09.02.2015
• Subjects: Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Freezing; Gene Expression Regulation, Plant - physiology; Genes, Plant - genetics; Plants, Genetically Modified - metabolism; Protein Kinases - metabolism; Signal Transduction - genetics; Signal Transduction - physiology; Transcription Factors - metabolism
• ISSN: 1534-5807; 1878-1551; 1878-1551
• DOI: 10.1016/j.devcel.2014.12.023

Cold stress is a major environmental factor that limits plant growth and development. The C-repeat-binding factor (CBF)-dependent cold signaling pathway is extensively studied in Arabidopsis; however, the specific protein kinases involved in this pathway remain elusive. Here we report that OST1 (OPEN STOMATA 1), a well-known Ser/Thr protein kinase in ABA signaling, acts upstream of CBFs to positively regulate freezing tolerance. The ost1 mutants show freezing hypersensitivity, whereas transgenic plants overexpressing OST1 exhibit enhanced freezing tolerance. The OST1 kinase is activated by cold stress. Moreover, OST1 interacts with both the transcription factor ICE1 and the E3 ligase HOS1 in the CBF pathway. Cold-activated OST1 phosphorylates ICE1 and enhances its stability and transcriptional activity. Meanwhile, OST1 interferes with the interaction between HOS1 and ICE1, thus suppressing HOS1-mediated ICE1 degradation under cold stress. Our results thus uncover the unexpected roles of OST1 in modulating CBF-dependent cold signaling in Arabidopsis. [Display omitted] •OST1 is a positive regulator in CBF-dependent cold signaling•OST1 interacts with and phosphorylates the ICE1 protein•OST1 interferes with the interaction between ICE1 and HOS1•OST1 suppresses HOS1-mediated ICE1 degradation The ICE1 transcription factor integrates different signals to regulate cold tolerance in Arabidopsis. Ding et al. demonstrate that the protein kinase OST1, a key component in ABA signaling, is also activated by cold stress. In response to cold, OST1 phosphorylates and stabilizes ICE1, promoting the expression of downstream cold-tolerance genes.