Breaking winter into “Bits”: how plants sense the cold

Plants integrate complex information from their environment to control their development and maximise their fitness. One key signal that plants use is temperature, which has a clear seasonal trend, but is also very variable across a single day and between different years. To understand seasonal temperature sensing, we studied the floral repressor gene FLOWERING LOCUS C (FLC) and its regulators in Arabidopsis thaliana. Specifically, we studied their temperature responses in field and lab conditions. We discovered that plants responded to seasonal temperatures through multiple mechanisms including long-term averages and daily extremes. These analyses highlighted the importance of temperature fluctuations, which had been largely ignored in previous models. They also identified the additional dangers posed by more variable temperatures due to climate change. In my work, I used mathematical modelling to investigate cold sensing at multiple different timescales. We found that temperature sensing over hours to months involves distinct molecular machineries, such as epigenetic regulators, the circadian clock and the plant growth rate.

To understand this in the context of adaptation, we compared temperature responses between different field sites and among different natural accessions of Arabidopsis, focusing on ones from Sweden. Most variation in FLC expression levels occurred in autumn, suggesting prevention of precocious flowering at this time was under strong selective pressure. With climate change causing more unpredictable and variable temperatures and endangering food security, it is now more important than ever to understand the underlying mechanisms of temperature sensing to breed the plants of the future.

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