Plants have evolved to grow under prominently fluctuating environmental conditions. In experiments under controlled conditions, temperature is often set to artificial, binary regimes with constant values at day and at night. This study investigated how such a diel (24 hr) temperature regime affects leaf growth, carbohydrate metabolism and gene expression, compared to a temperature regime with a field-like gradual increase and decline throughout 24 hr. Soybean (Glycine max) was grown under two contrasting diel temperature treatments. Leaf growth was measured in high temporal resolution. Periodical measurements were performed of carbohydrate concentrations, carbon isotopes as well as the transcriptome by RNA sequencing. Leaf growth activity peaked at different times under the two treatments, which cannot be explained intuitively. Under field-like temperature conditions, leaf growth followed temperature and peaked in the afternoon, whereas in the binary temperature regime, growth increased at night and decreased during daytime. Differential gene expression data suggest that a synchronization of cell division activity seems to be evoked in the binary temperature regime. Overall, the results show that the coordination of a wide range of metabolic processes is markedly affected by the diel variation of temperature, which emphasizes the importance of realistic environmental settings in controlled condition experiments.

中文翻译：

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重新思考温度对叶片生长、基因表达和代谢的影响：昼夜变化很重要


植物已经进化到可以在显着波动的环境条件下生长。在受控条件下的实验中，温度通常被设置为人工的二元状态，在白天和晚上都有恒定值。本研究调查了这种昼夜（24 小时）温度制度如何影响叶片生长、碳水化合物代谢和基因表达，与在 24 小时内呈场状逐渐升高和下降的温度制度相比。大豆 ( Glycine max ) 在两种对比鲜明的昼夜温度处理下生长。以高时间分辨率测量叶子生长。通过 RNA 测序定期测量碳水化合物浓度、碳同位素以及转录组。两种处理下叶片生长活性在不同时间达到峰值，这无法直观地解释。在类似田间的温度条件下，叶片生长随温度变化，并在下午达到峰值，而在二元温度条件下，生长在夜间增加，白天减少。差异基因表达数据表明细胞分裂活动的同步似乎是在二元温度条件下引起的。总体而言，结果表明，各种代谢过程的协调受到昼夜温度变化的显着影响，这强调了受控条件实验中真实环境设置的重要性。