Plants integrate widely fluctuating temperatures to monitor seasonal progression. Here, we investigate the temperature signals in field conditions that result in vernalisation, the mechanism by which flowering is aligned with spring. We find that multiple, distinct aspects of the temperature profile contribute to vernalisation. In autumn, transient cold temperatures promote transcriptional shutdown of Arabidopsis FLOWERING LOCUS C (FLC), independently of factors conferring epigenetic memory. As winter continues, expression of VERNALIZATION INSENSITIVE3 (VIN3), a factor needed for epigenetic silencing, is upregulated by at least two independent thermosensory processes. One integrates long-term cold temperatures, while the other requires the absence of daily temperatures above 15 °C. The lack of spikes of high temperature, not just prolonged cold, is thus the major driver for vernalisation. Monitoring of peak daily temperature is an effective mechanism to judge seasonal progression, but is likely to have deleterious consequences for vernalisation as the climate becomes more variable.
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机译：植物会整合温度波动较大的区域，以监控季节变化。在这里，我们调查田间条件下的温度信号，从而导致春化，即开花与春季对齐的机制。我们发现温度曲线的多个不同方面有助于春化。在秋天，短暂的低温促进拟南芥FLOERING LOCUS C（FLC）的转录关闭，而不受表观遗传记忆的影响。随着冬季的继续，至少两个独立的热感过程会上调表型遗传沉默所需的一个因子VERNALIZATION INSENSITIVE3（VIN3）。一种要求长期保持低温，而另一种要求没有高于15°C的每日温度。因此，缺乏高温的尖峰，而不仅仅是长时间的寒冷，是导致春化的主要原因。监测每日最高温度是判断季节变化的有效机制，但随着气候的变化，可能对春化产生有害影响。
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