Plants have evolved efficient mechanisms for adapting to temperature fluctuations, known as heat stress response and heat stress memory. Although the transcriptional regulatory network of plant heat stress response has been established, little is known about the genome‐wide transcriptional changes occurring within the first several minutes after heat shock. Here, we investigated the nascent RNA and mature messenger RNA (mRNA) from plant leaf tissues exposed to 5 min of heat shock treatment using global run‐on sequencing and RNA sequencing methods. Only a small group of genes were up‐ or downregulated at both the nascent RNA and mRNA levels. Primed plants that were already exposed to mild heat stress exhibited a more drastic alteration at multiple transcriptional steps than naïve plants that had not experienced heat stress. Upon heat shock, we also observed the following: (i) engaged RNA polymerase II accumulated downstream of transcription start sites; (ii) 5′ pausing release was a rate‐limiting step for the induction of some heat shock protein genes; (iii) numerous genes switched transcription modes; (iv) pervasive read‐through was induced at terminators; and (v) heat stress memory occurs at multiple steps of the transcription cycle, such as at Pol II recruitment, 5′ pausing, elongation, and termination.

中文翻译：

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拟南芥叶片对热激的即时转录反应

植物已经开发出适应温度波动的有效机制，称为热应激响应和热应激记忆。尽管已经建立了植物热应激反应的转录调控网络，但对热休克后最初几分钟内发生的全基因组转录变化了解甚少。在这里，我们使用全局运行测序和RNA测序方法研究了暴露于热激处理5分钟的植物叶片组织中的新生RNA和成熟信使RNA（mRNA）。在新生的RNA和mRNA水平上，只有一小部分基因被上调或下调。与没有经历过热胁迫的纯朴植物相比，已经暴露于轻度热胁迫的初生植物在多个转录步骤表现出更大的改变。受热冲击时 我们还观察到以下情况：（i）参与的RNA聚合酶II积累在转录起始位点的下游；（ii）5'暂停释放是诱导某些热激蛋白基因的限速步骤；（iii）众多基因转换了转录模式；（iv）在终止子处引起普遍的通读；（v）热应激记忆发生在转录循环的多个步骤，例如在Pol II募集，5'暂停，延长和终止时。