Coordination of robust single cell rhythms in the Arabidopsis circadian clock via spatial waves of gene expression.
Coordination of robust single cell rhythms in the Arabidopsis circadian clock via spatial waves of gene expression.
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DOI：
10.7554/elife.31700
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发表时间：
2018-04-26
期刊：
影响因子：
7.7
通讯作者：
Locke JC
中科院分区：
文献类型：
--
作者：
Gould PD;Domijan M;Greenwood M;Tokuda IT;Rees H;Kozma-Bognar L;Hall AJ;Locke JC
拟南芥的昼夜生物钟在昼夜周期中协调基因调控。尽管多反馈回路电路已被证明可以产生24小时节律，但尚不清楚单个电池的时钟有多稳健，也不清楚整个工厂的时钟定时是如何协调的。在这里，我们研究了在恒定环境条件下，拟南芥幼苗在单细胞水平上几天的时钟活动。我们的数据显示了强劲的单细胞振荡，尽管是不同步的。特别是，我们观察到两波时钟活动；一波向下，一波向上。我们还发现了时钟细胞间耦合的证据，特别是在根尖。一个简单的模型表明，细胞间的耦合和我们测量的细胞之间的周期差可以产生观察到的波。我们的结果揭示了植物时钟的空间结构，并表明与集中式哺乳动物时钟不同，拟南芥的时钟有多个协调点。昼夜循环决定了地球上大多数生命的生存节奏。作为回应，许多生物体进化出了与光明和黑暗的节奏同步的内部生物钟。多亏了这个“生物钟”，动植物可以预测黎明和黄昏的开始，并将生物过程安排到一天中的特定时间。每个细胞都有自己的生物钟，它由一个复杂的基因和蛋白质网络组成，这些基因和蛋白质沿着24小时的周期被激活。这就提出了一个问题：这些细胞如何协调，在整个生物体的水平上创造一个生物钟？在哺乳动物中，这种同步化的发生要归功于大脑中的一种结构，但对植物中这种同步是如何发生的知之甚少。这在一定程度上是因为很少有研究专注于测量单个植物细胞的时钟。在这里，古尔德，多米扬等人。在持续几天和恒定的环境条件下，监测一种名为拟南芥的植物幼苗中单细胞的昼夜生物钟。为了做到这一点，他们使用延时显微镜和遗传方法来查看时钟的核心基因之一何时何地被开启。结果表明，在植物水平上，拟南芥有两波时钟基因表达，一波向上，一波向下。此外，植物的不同部分的昼夜节律略有不同--例如，根尖的时钟更快。在整个植物的单个细胞中也可以检测到强劲的时钟节律。相邻细胞中的时钟被发现相互通信以跟踪时间，这可能有助于这种健壮性。数学模拟表明，当各个时钟相互作用时，它们会在整个植物中产生时钟活动模式，这解释了根中基因表达的两个波。植物的昼夜节律控制着对农业至关重要的性状，如生长、产量、抗病能力和开花时间。了解并最终控制这些时钟的复杂齿轮，有朝一日可能会让科学家创造出表现更好的作物。
The Arabidopsis circadian clock orchestrates gene regulation across the day/night cycle. Although a multiple feedback loop circuit has been shown to generate the 24-hr rhythm, it remains unclear how robust the clock is in individual cells, or how clock timing is coordinated across the plant. Here we examine clock activity at the single cell level across Arabidopsis seedlings over several days under constant environmental conditions. Our data reveal robust single cell oscillations, albeit desynchronised. In particular, we observe two waves of clock activity; one going down, and one up the root. We also find evidence of cell-to-cell coupling of the clock, especially in the root tip. A simple model shows that cell-to-cell coupling and our measured period differences between cells can generate the observed waves. Our results reveal the spatial structure of the plant clock and suggest that unlike the centralised mammalian clock, the Arabidopsis clock has multiple coordination points. The cycle of day and night sets the pace for the existence of most life on Earth. In response, many organisms have evolved internal biological clocks which are synchronized with the rhythm of light and dark. Thanks to this ‘circadian clock’, plants and animals can predict the onset of dawn and dusk, and schedule biological processes to specific times of the day. Each cell possesses its own circadian clock, which is formed of a complex network of genes and proteins that get activated along a 24-hour cycle. This raises the question: how do these cells coordinate to create a body clock at the level of the entire organism? In mammals, this synchronisation happens thanks to a structure in the brain, but much less is known about how this occurs in plants. This is partly because few studies exist that focus on measuring the clocks of individual plant cells. Here, Gould, Domijan et al. monitor the circadian clock of single cells in seedlings of a plant called Arabidopsis thaliana across several days and under constant environmental conditions. To do so, they use time-lapse microscopy and genetic methods to see when and where one of the clock’s core genes is switched on. The results show that, at the level of the plant, Arabidopsis has two waves of clock gene expression, one that goes up and one that goes down the root. In addition, the various parts of the plant have slightly different circadian rhythms – for instance, the tip of the root has a faster clock. Robust clock rhythms are also detected in individual cells across the plant. Clocks in neighbouring cells are found to communicate with each other to keep track of time, which might be contributing to this robustness. Mathematical simulations show that, when the individual clocks interact, they generate patterns of clock activity across the plant, which explains the two waves of gene expression in the root. Plant circadian rhythms control traits that are crucial for agriculture, such as growth, yield, disease resistance and flowering time. Understanding, and ultimately controlling, the intricate cogs of these clocks may one day allow scientists to create better performing crops.