Cold stress is a major environmental stress that severely affects plant growth and crop productivity. Arabidopsis (Arabidopsis thaliana) HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE15 (HOS15) is a substrate receptor of the CULLIN4-based CLR4 ubiquitin E3 ligase complex, which epigenetically regulates cold tolerance by degrading HISTONE DEACETYLASE2C (HD2C) to switch from repressive to permissive chromatin structure in response to cold stress. In this study, we characterized a HOS15-binding protein, POWERDRESS (PWR), and analyzed its function in the cold stress response. PWR loss-of-function plants (pwr) showed lower expression of cold-regulated (COR) genes and sensitivity to freezing. PWR interacts with HD2C through HOS15, and cold-induced HD2C degradation by HOS15 is diminished in the pwr mutant. The association of HOS15 and HD2C to promoters of cold-responsive COR genes was dependent on PWR. Consistent with these observations, the high acetylation levels of histone H3 by cold-induced and HOS15-mediated HD2C degradation were significantly reduced in pwr under cold stress. PWR also interacts with C-repeat element-binding factor transcription factors to modulate their cold-induced binding to the promoter of COR genes. Collectively, our data signify that the PWR-HOS15-HD2C histone-modifying complex regulates the expression of COR genes and the freezing tolerance of plants.

冷胁迫是严重影响植物生长和作物生产力的主要环境胁迫。拟南芥 ( Arabidopsis thaliana ) 高表达渗透响应基因 15 (HOS15) 是基于 CULLIN4 的 CLR4 泛素 E3 连接酶复合物的底物受体，该复合物通过降解组蛋白去乙酰化酶 2C (HD2C) 从抑制性染色质结构转变为许可性染色质结构，从而在表观遗传上调节耐冷性。对冷应激的反应。在这项研究中，我们表征了 HOS15 结合蛋白 POWERDRESS (PWR)，并分析了其在冷应激反应中的功能。 PWR 功能丧失植物 ( pwr ) 显示出较低的冷调节 ( COR ) 基因表达和对冷冻的敏感性。 PWR 通过 HOS15 与 HD2C 相互作用，并且 HOS15 冷诱导的 HD2C 降解在pwr突变体中减弱。 HOS15 和 HD2C 与冷响应COR基因启动子的关联取决于 PWR。与这些观察结果一致，冷诱导和 HOS15 介导的 HD2C 降解导致的组蛋白 H3 的高乙酰化水平在冷应激下的pwr中显着降低。 PWR 还与 C 重复元件结合因子转录因子相互作用，调节其冷诱导的与COR基因启动子的结合。总的来说，我们的数据表明 PWR-HOS15-HD2C 组蛋白修饰复合物调节COR基因的表达和植物的耐冻性。