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Article|03 Aug 2022|OPEN
Apple U-box-type E3 ubiquitin ligase MdPUB23 reduces cold-stress tolerance by degrading the cold-stress regulatory protein MdICE1 
Da-Ru Wang1 ,† , Xiao-Wei Zhang1 ,† , Rui-Rui Xu2 , Gui-Luan Wang1 , Chun-Xiang You1 , and Jian-Ping An,1 ,
1State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, 271018, Shandong, China
2Key Laboratory of Biochemistry and Molecular Biology in Universities of Shandong, College of Biology and Oceanography, Weifang University, Weifang 261061, Shandong, China
*Corresponding author. E-mail: youchunxiang@sdau.edu.cn,anjianping@sdau.edu.cn
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhac171 (2022)
doi: https://doi.org/10.1093/hr/uhac171
Views: 86

Received: 16 Mar 2022
Accepted: 27 Jul 2022
Published online: 03 Aug 2022

Abstract

Cold stress limits plant growth, geographical distribution, and crop yield. The MYC-type bHLH transcription factor ICE1 is recognized as the core positive regulator of the cold-stress response. However, how ICE1 protein levels are regulated remains to be further studied. In this study, we observed that a U-box-type E3 ubiquitin ligase, MdPUB23, positively regulated the cold-stress response in apple. The expression of MdPUB23 increased at both the transcriptional and post-translational levels in response to cold stress. Overexpression of MdPUB23 in transgenic apple enhanced sensitivity to cold stress. Further study showed that MdPUB23 directly interacted with MdICE1, promoting the ubiquitination-mediated degradation of the MdICE1 protein through the 26S-proteasome pathway and reducing the MdICE1-improved cold-stress tolerance in apple. Our results reveal that MdPUB23 regulates the cold-stress response by directly mediating the stability of the positive regulator MdICE1. The PUB23–ICE1 ubiquitination module may play a role in maintaining ICE1 protein homeostasis and preventing overreactions from causing damage to plants. The discovery of the ubiquitination regulatory pathway of ICE1 provides insights for the further exploration of plant cold-stress-response mechanisms.