Department of Plant Sciences, University of Cambridge, Cambridge, UK.
Department of Pathology, University of Cambridge, Cambridge, UK.
Nat Plants. 2020 May;6(5):522-532. doi: 10.1038/s41477-020-0633-3. Epub 2020 Apr 13.
Temperature is a major environmental cue affecting plant growth and development. Plants often experience higher temperatures in the context of a 24 h day-night cycle, with temperatures peaking in the middle of the day. Here, we find that the transcript encoding the bHLH transcription factor PIF7 undergoes a direct increase in translation in response to warmer temperature. Diurnal expression of PIF7 transcript gates this response, allowing PIF7 protein to quickly accumulate in response to warm daytime temperature. Enhanced PIF7 protein levels directly activate the thermomorphogenesis pathway by inducing the transcription of key genes such as the auxin biosynthetic gene YUCCA8, and are necessary for thermomorphogenesis to occur under warm cycling daytime temperatures. The temperature-dependent translational enhancement of PIF7 messenger RNA is mediated by the formation of an RNA hairpin within its 5' untranslated region, which adopts an alternative conformation at higher temperature, leading to increased protein synthesis. We identified similar hairpin sequences that control translation in additional transcripts including WRKY22 and the key heat shock regulator HSFA2, suggesting that this is a conserved mechanism enabling plants to respond and adapt rapidly to high temperatures.
温度是影响植物生长和发育的主要环境线索。在 24 小时的昼夜循环中，植物经常经历更高的温度，温度在中午达到峰值。在这里，我们发现编码 bHLH 转录因子 PIF7 的转录本直接响应温暖的温度增加翻译。PIF7 转录本的昼夜表达门控这种反应，允许 PIF7 蛋白在温暖的白天温度下快速积累。增强的 PIF7 蛋白水平通过诱导生长素生物合成基因 YUCCA8 等关键基因的转录直接激活热形态发生途径，并且对于在温暖的循环白天温度下发生热形态发生是必需的。PIF7 信使 RNA 的温度依赖性翻译增强是由其 5'非翻译区中 RNA 发夹的形成介导的，该发夹在较高温度下采用替代构象，导致蛋白质合成增加。我们在包括 WRKY22 和关键热休克调节剂 HSFA2 在内的其他转录本中鉴定了类似的发夹序列，这些序列控制翻译，这表明这是一种保守机制，使植物能够快速响应和适应高温。
