Rubin Matthew J, Brock Marcus T, Davis Seth J, Weinig Cynthia
Department of Botany, University of Wyoming, Laramie, WY 82071
Program in Ecology, University of Wyoming, Laramie, WY 82071.
G3 (Bethesda). 2019 Apr 9;9(4):1131-1139. doi: 10.1534/g3.118.200770.
The circadian clock facilitates coordination of the internal rhythms of an organism to daily environmental conditions, such as the light-dark cycle of one day. Circadian period length (the duration of one endogenous cycle) and phase (the timing of peak activity) exhibit quantitative variation in natural populations. Here, we measured circadian period and phase in June, July and September in three recombinant inbred line populations. Circadian period and phase were estimated from bioluminescence of a genetic construct between a native circadian clock gene () and the reporter gene () after lines were entrained under field settings. Using a Bayesian mapping approach, we estimated the median number and effect size of genomic regions (Quantitative Trait Loci, QTL) underlying circadian parameters and the degree to which these regions overlap across months of the growing season. We also tested for QTL associations between the circadian clock and plant morphology. The genetic architecture of circadian phase was largely independent across months, as evidenced by the fact that QTL determining phase values in one month of the growing season were different from those determining phase in a second month. QTL for circadian parameters were shared with both cauline and rosette branching in at least one mapping population. The results provide insights into the QTL architecture of the clock under field settings, and suggest that the circadian clock is highly responsive to changing environments and that selection can act on clock phase in a nuanced manner.
生物钟有助于生物体的内部节律与日常环境条件相协调，比如一天的昼夜循环。昼夜周期长度（一个内源性周期的持续时间）和相位（峰值活动的时间）在自然种群中呈现出数量上的变化。在这里，我们在6月、7月和9月对三个重组自交系种群测量了昼夜周期和相位。在田间条件下对品系进行诱导后，根据一个天然生物钟基因（）与报告基因（）之间的基因构建体的生物发光来估计昼夜周期和相位。使用贝叶斯定位方法，我们估计了昼夜节律参数所对应的基因组区域（数量性状位点，QTL）的中位数数量和效应大小，以及这些区域在生长季节不同月份之间的重叠程度。我们还测试了生物钟与植物形态之间的QTL关联。昼夜相位的遗传结构在不同月份基本是独立的，这一事实表明，决定生长季节某一个月相位值的QTL与决定另一个月相位的QTL不同。在至少一个定位群体中，昼夜节律参数的QTL与茎生枝和莲座状分枝都有关联。这些结果为田间条件下生物钟的QTL结构提供了见解，并表明生物钟对不断变化的环境高度敏感，而且选择可以以一种微妙的方式作用于生物钟相位。
