Deciphering the role of translation in temperature-controlled development

环境温度对植物发育的几乎所有方面都有深远的影响，从种子萌发、幼苗形成到开花结果。因此，温度对作物品质和产量也有很大影响。随着气候变化的进程，温带地区的植物面临着更频繁的热浪和环境温度整体上升的挑战。因此，深入了解植物对温度的反应对于充分了解气候变化将如何影响未来植物的生长和发育至关重要，也可能指出减轻温度上升对作物生产的负面影响的方法。我们最近使用核糖体分析（Ribo-seq）在全球水平上量化了温暖温度对模式植物拟南芥翻译动力学的影响。这使我们能够识别在温暖的温度下进行增强翻译的转录本，例如编码植物温度信号传导关键角色的PIF7转录本。此外，这种方法还允许我们识别转录本主要开放阅读框（ORF）上游的序列，这些序列经过翻译。这种上游开放阅读框架（uorf）最近在许多生物系统中引起了人们的注意。虽然它们的确切机制仍然知之甚少，但经常发现uorf作为主要ORF翻译的控制元件。在植物中，已在24-30%的转录本中发现了uorf，但仅确定了其中少数的功能，与形态发生、代谢和抗病的控制有关。在我们的核糖核酸序列数据中，我们发现了多个拟南芥uorf，其翻译以温度依赖的方式变化。本项目将采用遗传和分子生物学方法揭示几种候选uorf在植物发育和非生物胁迫反应中的功能，特别强调温度敏感过程。它还将解决是否以及如何这些uORFs影响基因功能的问题，使用体外和体内生化分析。这些候选基因聚焦的方法将被翻译起始的转录组分析所补充，旨在揭示在一系列环境温度下uORF翻译的精确动态。总之，这些方法将提供温度调节的uORF景观的详细视图，并揭示温度敏感的uORF在拟南芥中的新功能。

Ambient temperature has profound effects on almost all aspects of plant development, from the onset of seed germination and seedling establishment to flower and fruit production. Consequently, temperature also strongly impacts crop quality and yield. With the progression of climate change, plants in temperate regions are challenged by more frequent heat waves as well as an overall rise in ambient temperature. Gaining insight into a plant's response to temperature is thus vital to fully understand how climate change will affect plant growth and development in the future and may also indicate ways to mitigate negative effects of rising temperatures on crop production. We recently used Ribosome Profiling (Ribo-seq) to quantify the effect of warm temperature on translation dynamics in the model plant Arabidopsis thaliana at a global level. This allowed us to identify transcripts that undergo enhanced translation at warmer temperature, for instance the PIF7 transcript that encodes a key player in plant temperature signalling. In addition, this approach also allowed us to identify sequences upstream of a transcript's main open reading frame (ORF) that undergo translation. Such upstream open reading frames (uORFs) have recently attracted attention in many biological systems. While their precise mechanism still remains poorly understood, uORFs were often found to act as control elements for translation of the main ORF. In plants, uORFs have been found in 24-30% of transcripts, but a function has only been identified for few of them, linked to the control of morphogenesis, metabolism and disease resistance. In our Ribo-seq data, we identified multiple Arabidopsis uORFs whose translation changes in a temperature-dependent manner. This project will employ genetic and molecular biology approaches to reveal the functions of several candidate uORFs in plant development and abiotic stress responses, with a particular emphasis on temperature-sensitive processes. It will also tackle the question whether and how these uORFs affect gene function, using in vitro and in vivo biochemical assays. These candidate gene-focused approaches will be complemented by transcriptome-wide analysis of translation initiation, aiming to reveal precise dynamics of uORF translation across a range of ambient temperatures. Together, these approaches will provide a detailed view of the temperature-regulated uORF landscape and reveal novel functions of temperature-sensitive uORFs in Arabidopsis.