Unravelling post-transcriptional mechanisms governing the plant's response to high temperature

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Rising temperatures represent a major threat to food security. For each 1 degree C increase above optimal temperature, the yield of the two UK staple crops wheat and barley is reduced by 5-6%. Understanding how plants sense and respond to temperature is therefore vital to find ways to overcome these negative effects on crop yield.This project seeks to reveal the molecular mechanisms by which plants react to their temperature environment. It investigates how translation - the process by which proteins are synthesised - is regulated in a temperature-dependent manner and how this helps tailor a plant's growth to its surroundings. Messenger RNAs (mRNAs) provide essential instructions for the translation process. These molecules contain a coding sequence that specifies the sequence of amino acids required to assemble a specific protein and thereby function as "blueprints" for translation. Some mRNA molecules contain one or more short coding sequences - so-called upstream open reading frames (uORFs) - upstream of the main coding sequence that defines the major protein product. These uORFs can have regulatory function, controlling translation of the downstream sequence.In the model plant Arabidopsis, we find that uORFs in several transcripts are mainly translated at high temperature, raising the possibility that these features are major regulators of the plant's temperature response. With the proposed project, we aim to uncover the function of these temperature-sensitive uORFs and to gain comprehensive insight into how ambient temperature affects translation initiation, the first and rate-limiting step in protein synthesis. In order to do this, we will:(1) Characterise mRNAs with mutated uORF sequences to reveal a role for temperature-sensitive uORFs in plant temperature responses.(2) Investigate whether RNA structure affects uORF function at different temperatures and thereby define the functional relationship between these two features.(3) Generate a global, high-resolution dataset of translation initiation to track temperature effects on uORF and main ORF initiation rates with utmost precision.This research will provide us with a systems level understanding of how plants tailor translational processes to their temperature environment. It will allow us to better predict how plants will cope with challenging temperatures they are likely to encounter in the future and may ultimately help to create crops that can maintain high yields in a changing climate.