de Montaigu Amaury, Giakountis Antonis, Rubin Matthew, Tóth Réka, Cremer Frédéric, Sokolova Vladislava, Porri Aimone, Reymond Matthieu, Weinig Cynthia, Coupland George
Max Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany; and.
Department of Botany, University of Wyoming, Laramie, WY 82071.
Proc Natl Acad Sci U S A. 2015 Jan 20;112(3):905-10. doi: 10.1073/pnas.1422242112. Epub 2014 Dec 29.
Daily rhythms of gene expression provide a benefit to most organisms by ensuring that biological processes are activated at the optimal time of day. Although temporal patterns of expression control plant traits of agricultural importance, how natural genetic variation modifies these patterns during the day and how precisely these patterns influence phenotypes is poorly understood. The circadian clock regulates the timing of gene expression, and natural variation in circadian rhythms has been described, but circadian rhythms are measured in artificial continuous conditions that do not reflect the complexity of biologically relevant day/night cycles. By studying transcriptional rhythms of the evening-expressed gene gigantea (GI) at high temporal resolution and during day/night cycles, we show that natural variation in the timing of GI expression occurs mostly under long days in 77 Arabidopsis accessions. This variation is explained by natural alleles that alter light sensitivity of GI, specifically in the evening, and that act at least partly independent of circadian rhythms. Natural alleles induce precise changes in the temporal waveform of GI expression, and these changes have detectable effects on phytochrome interacting factor 4 expression and growth. Our findings provide a paradigm for how natural alleles act within day/night cycles to precisely modify temporal gene expression waveforms and cause phenotypic diversity. Such alleles could confer an advantage by adjusting the activity of temporally regulated processes without severely disrupting the circadian system.
基因表达的日常节律通过确保生物过程在一天中的最佳时间被激活，为大多数生物体带来益处。尽管表达的时间模式控制着具有农业重要性的植物性状，但自然遗传变异如何在白天改变这些模式以及这些模式如何精确地影响表型，目前还知之甚少。生物钟调节基因表达的时间，并且已经描述了昼夜节律的自然变异，但昼夜节律是在不反映生物相关昼夜循环复杂性的人工连续条件下测量的。通过在高时间分辨率和昼夜循环期间研究傍晚表达基因巨莲（GI）的转录节律，我们表明，在77个拟南芥种质中，GI表达时间的自然变异大多发生在长日照条件下。这种变异是由改变GI光敏感性的自然等位基因所解释的，特别是在傍晚，并且这些等位基因至少部分独立于昼夜节律起作用。自然等位基因会在GI表达的时间波形上引起精确变化，并且这些变化对光敏色素相互作用因子4的表达和生长有可检测到的影响。我们的研究结果为自然等位基因如何在昼夜循环中起作用以精确改变时间基因表达波形并导致表型多样性提供了一个范例。这些等位基因可以通过调整时间调节过程的活性而不严重破坏生物钟系统来赋予优势。
