Priming the chromatin in response to heat stress in Arabidopsis thaliana – The role of Mediator in transcriptional memory

中度热胁迫（HS）使植物准备好随后承受高温，该高温对处于初始状态的植物是致命的。在恢复到无应激温度后，启动状态维持了几天，这种记忆在遗传上与热启动是分开的。HS记忆的基本机制，即：e. HS后预处理状态的保持还没有得到很好的理解。这个项目解决了染色质和转录调控在HS记忆中的作用。先前，我们发现HS记忆与两种类型的转录记忆相关，持续诱导（I型）和复发HS后增强的再诱导（II型）。从II型转录记忆的修饰筛选，我们已经确定了几个涉及HS诱导的转录记忆中的介体共激活复合物的突变体。介体是一种高度保守的多亚基共激活因子复合物，它将基因特异性转录因子的信号传导连接到RNA聚合酶II和一般的转录机制。在本研究项目中，我们将使用全基因组转录和表观基因组分析以及蛋白质相互作用研究来研究中介体在HS诱导的转录记忆中的机制基础。除了深入了解HS诱导的转录记忆机制之外，该研究项目的发现还将对我们对植物与环境相互作用中介体功能的了解产生更广泛的影响，并最终可能为提高作物HS弹性提供新的途径。

Moderate heat stress (HS) primes a plant to subsequently withstand high temperatures that are lethal to a plant in the naïve state. After returning to non-stress temperatures the primed state is maintained over several days, and this memory is genetically separable from thermopriming. The underlying mechanism of HS memory, i. e. the maintenance of the primed state after HS, is not well understood. This project addresses the role of chromatin and transcriptional regulation in HS memory. Previously, we found that HS memory is associated with two types of transcriptional memory, sustained induction (type I) and enhanced re-induction upon recurring HS (type II). From a modifier screen for type II transcriptional memory we have identified several mutants that implicate the Mediator co-activator complex in HS-induced transcriptional memory. Mediator is a highly conserved multi-subunit co-activator complex that bridges signalling from gene-specific transcription factors to RNA polymerase II and the general transcriptional machinery. In this research project, we will study the mechanistic basis of Mediator in HS-induced transcriptional memory using genome-wide transcription and epigenomic profiling as well as protein interaction studies. Beyond insights into the mechanism of HS-induced transcriptional memory, the findings of this research project will have wider implications for our knowledge of Mediator function in plant-environment interactions and may ultimately provide new avenues for improving HS resilience in crop plants.