The Mediator kinase module serves as a positive regulator of salicylic acid accumulation and systemic acquired resistance
The Mediator kinase module serves as a positive regulator of salicylic acid accumulation and systemic acquired resistance
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DOI：
10.1111/tpj.14278
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发表时间：
2019-06-01
期刊：
影响因子：
7.2
通讯作者：
Li, Xin
中科院分区：
文献类型：
--
作者：
Huang, Jianhua;Sun, Yulin;Li, Xin
在植物中，钙调素结合转录激活因子（CAMTAs）在非生物和生物胁迫反应的转录调控中是必需的。其中CAMTA3在拟南芥中被广泛研究，并与CAMTA1和CAMTA2冗余作用，负性调节植物免疫。因此，由于自身免疫，camta1/2/3三重突变体表现出严重的侏儒症。在这里，通过camta1/2/3三重突变体的抑制因子筛选，我们发现细胞周期蛋白依赖性激酶8 （CDK8）的突变部分抑制camta1/2/3的侏儒症和组成抗性表型。CDK8正调控稳态水杨酸（SA）水平和系统必需抗性（SAR）。在未感染条件下，cdk8突变体中SA生物合成基因ICS1和EDS5的表达下调，表明cdk8参与了这些SA通路基因的转录调控。敲除另一个Mediator kinase模块成员MED12也会产生类似的缺陷，包括稳态SA水平下降和SAR受损，这表明整个Mediator kinase模块都参与了SA水平和SAR的转录调控。
In plants, the calmodulin-binding transcription activators (CAMTAs) are required for transcriptional regulation of abiotic and biotic stress responses. Among them, CAMTA3 in Arabidopsis has been intensively studied and shown to function redundantly with CAMTA1 and CAMTA2 to negatively regulate plant immunity. The camta1/2/3 triple mutant accordingly exhibits severe dwarfism due to autoimmunity. Here, through a suppressor screen using camta1/2/3 triple mutant, we found that a mutation in Cyclin-Dependent Kinase 8 (CDK8) partially suppresses the dwarfism and constitutive resistance phenotypes of camta1/2/3. CDK8 positively regulates steady-state salicylic acid (SA) levels and systemic required resistance (SAR). The expression of SA biosynthesis genes such as ICS1 and EDS5 is down-regulated in cdk8 mutants under uninfected conditions, suggesting that CDK8 contributes to the transcriptional regulation of these SA pathway genes. Knocking out another Mediator kinase module member MED12 yielded similar defects including decreased steady-state SA level and compromised SAR, suggesting that the whole Mediator kinase module contributes to the transcriptional regulation of SA levels and SAR.