背景回顾：SALT OVERLY SENSITIVE1 (SOS1) is a key component of plant salt tolerance. 

提出问题：However, how SOS1 transcription is dynamically regulated in plant response to different salinity conditions remains elusive. 

主要发现：Here, we report that C-type Cyclin1; 1 (CycC1; 1) negatively regulates salt tolerance by interfering with WRKY75-mediated transcriptional activation of SOS1 in Arabidopsis (Arabidopsis thaliana). 

结果1-CycC1; 1-SOS1-盐耐受性：Disruption of CycC1; 1 promotes SOS1 expression and salt tolerance in Arabidopsis because CycC1; 1 interferes with RNA polymerase II recruitment by occupying the SOS1 promoter. Enhanced salt tolerance of the cycc1; 1 mutant was completely compromised by an SOS1 mutation. 

结果2-CycC1; 1-WRKY75、WRKY75-SOS1-盐耐受性：Moreover, CycC1; 1 physically interacts with the transcription factor WRKY75, which can bind to the SOS1 promoter and activate SOS1 expression. In contrast to the cycc1; 1 mutant, the wrky75 mutant has attenuated SOS1 expression and salt tolerance, whereas overexpression of SOS1 rescues the salt sensitivity of wrky75. 

结果3-CycC1; 1-WRKY75-SOS1-盐耐受性：Intriguingly, CycC1; 1 inhibits WRKY75-mediated transcriptional activation of SOS1 via their interaction. Thus, increased SOS1 expression and salt tolerance in cycc1; 1 was abolished by WRKY75 mutation. 

结论：Our findings demonstrate that CycC1; 1 forms a complex with WRKY75 to inactivate SOS1 transcription under low salinity conditions. By contrast, under high salinity conditions, SOS1 transcription and plant salt tolerance is activated at least partially by increased WRKY75 expression but decreased CycC1; 1 expression.

SOS1是植物耐盐的关键组分。但是，SOS1基因转录在植物响应不同程度盐胁迫时的转录调控仍不清楚。本文中，作者报道了细胞周期蛋白CycC1; 1通过干扰WRKY75介导的SOS1转录激活，负调控植物的耐盐性。通过扰乱CycC1; 1能够促进拟南芥中SOS1的表达和耐盐性，原因是CycC1; 1通过占据SOS1启动子阻碍RNA聚合酶II的招募。通过在cycc1; 1突变体中突变SOS1能够完全去除cycc1; 1突变体的强耐盐能力。此外，CycC1; 1能够与WRKY75转录因子互作，而WRKY75则是SOS1基因的直接转录激活因子。与cycc1; 1突变体相反，wrky75突变体会减弱SOS1的表达和耐盐性，而过表达SOS1能够拯救wrky75突变体的盐敏感性。有趣的是，CycC1; 1能够通过与WRKY75的互作，抑制由WRKY75介导的SOS1转录激活。因此，通过在cycc1; 1突变体中突变WRKY75基因，能够废除cycc1; 1突变体中SOS1表达的增加和耐盐能力的提高。本文的研究结果揭示了在低盐条件下，CycC1; 1和WRKY75形成复合体，以防止SOS1的转录激活。相反，在高盐条件下，WRKY75表达水平的上调和CycC1; 1基因表达水平的下调，部分地激活了SOS1基因的转录和植物的耐盐能力。

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