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

First author: Xi Wang; Affiliations: China Agricultural University (中国农业大学): Beijing, China

Corresponding author: Shuhua Yang

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.

全低温胁迫对于植物生长、发育以及作物产量和品质都具有不利的影响。植物通过低温适应来自保从而免受低温的伤害。转录因子CBF依赖型低温信号转导途径在植物的低温适应过程中发挥关键作用。然而，有关该通路是如何动态、精确调控的还不是很清楚。本文中，作者报道了两个U-box类E3泛素连接酶PUB25和PUB26正向调控拟南芥的低温抗性。PUB25和PUB26都能多泛素化一个CBF依赖型低温信号转导途径的抑制转录因子MYB15，导致该蛋白的降解，从而增强CBF基因在低温胁迫时的表达。此外，低温激活的OST1蛋白会特定磷酸化PUB25和PUB26保守的苏氨酸残基，增强他们的E3活性，促进低温诱导的MYB15降解。本文的结果揭示了一个OST1-PUB25/26调控模块，其通过控制负调控子MYB15的内稳态作用于植物低温响应的持续时间与强度。

通讯：杨淑华  (http://cbs.cau.edu.cn/art/2018/9/14/art_31816_594296.html)

个人简介：1987-1991年，南开大学，学士；1991-1994年，南开大学，硕士；1998-2002年，新加坡国立大学，博士；2002-2004年，美国康奈尔大学，博士后。

研究方向：植物感知和响应低温胁迫的分子机理。

doi: https://doi.org/10.1016/j.devcel.2019.08.008

Journal: Developmental Cell

Published date: September 19, 2019