PUB25 and PUB26 Promote Plant Freezing Tolerance by Degrading the Cold Signaling Negative Regulator MYB15

• Published in: Developmental cell Vol. 51; no. 2; pp. 222 - 235.e5
• Main Authors: Wang, Xi, Ding, Yanglin, Li, Zhuoyang, Shi, Yiting, Wang, Jinlong, Hua, Jian, Gong, Zhizhong, Zhou, Jian-Min, Yang, Shuhua
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 21.10.2019
• Subjects: Arabidopsis; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; CBF genes; cold response; Cold Temperature; E3 ligases PUB25/26; Gene Expression Regulation, Plant - genetics; MYB15; protein kinase OST1; Signal Transduction - physiology; Transcription Factors - metabolism; Ubiquitin-Protein Ligases - metabolism; protein kinase OST1; MYB15; E3 ligases PUB25/26; CBF genes; Arabidopsis; cold response
• ISSN: 1534-5807; 1878-1551; 1878-1551
• DOI: 10.1016/j.devcel.2019.08.008

Cold stress adversely affects plant growth, development, and crop productivity and quality. Plants employ cold acclimation strategy to protect them from cold damage. The transcription-factor-CBF-dependent cold signaling pathway plays a key role in plant cold acclimation. However, how this signaling pathway is dynamically and precisely regulated remains unknown. Here, we report that two U-box type E3 ubiquitin ligases, PUB25 and PUB26, positively regulate freezing tolerance in Arabidopsis thaliana. Both PUB25 and PUB26 poly-ubiquitinate MYB15, a transcriptional repressor of the CBF-dependent cold signaling pathway, leading to MYB15 degradation and thus enhanced CBF expression under cold stress. Furthermore, cold-activated OST1 specifically phosphorylates PUB25 and PUB26 at conserved threonine residues, enhancing their E3 activity and facilitating the cold-induced degradation of MYB15. Our results thus unravel the regulatory role of the OST1-PUB25/26 module in regulating the duration and amplitude of the cold response by controlling the homeostasis of the negative regulator MYB15. [Display omitted] •U-box E3 ligases PUB25 and PUB26 positively regulate freezing tolerance•PUB25 and PUB26 target MYB15 transcription factor for degradation under cold stress•Cold-activated OST1 phosphorylates PUB25 and PUB26 to enhance their E3 activity Wang et al. show that the U-box E3 ligases PUB25 and PUB26 are phosphorylated by OST1 to enhance their E3 activity. The ligases promote the degradation of MYB15, a key upstream negative regulator of CBF genes, thereby positively regulating freezing tolerance in plants.