Nimmo Hugh G, Laird Janet
Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom.
Front Plant Sci. 2021 Oct 15;12:750367. doi: 10.3389/fpls.2021.750367. eCollection 2021.
The core of the plant circadian clock involves multiple interlocking gene expression loops and post-translational controls along with inputs from light and metabolism. The complexity of the interactions is such that few specific functions can be ascribed to single components. In previous work, we reported differences in the operation of the clocks in Arabidopsis shoots and roots, including the effects of mutations of key clock components. Here, we have used luciferase imaging to study mutants expressing CCA1::LUC and GI::LUC markers. In mature shoots expressing CCA1::LUC, loss of PRR7 radically altered behaviour in light:dark cycles and caused loss of rhythmicity in constant light but had little effect on roots. In contrast, in mature plants expressing GI::LUC, loss of PRR7 had little effect in light:dark cycles but in constant light increased the circadian period in shoots and reduced it in roots. We conclude that most or all of the circadian input to the CCA1 promoter in shoots is mediated by PRR7 and that loss of PRR7 has organ-specific effects. The results emphasise the differences in operation of the shoot and root clocks, and the importance of studying clock mutants in both light:dark cycles and constant light.
植物生物钟的核心涉及多个相互关联的基因表达环和翻译后调控，以及来自光和代谢的输入。这些相互作用的复杂性使得很少有特定功能能归因于单个组件。在之前的工作中，我们报道了拟南芥地上部和根部生物钟运行的差异，包括关键生物钟组件突变的影响。在这里，我们利用荧光素酶成像技术研究了表达CCA1::LUC和GI::LUC标记的突变体。在表达CCA1::LUC的成熟地上部中，PRR7的缺失在光暗循环中彻底改变了其行为，并在持续光照下导致节律性丧失，但对根部影响很小。相比之下，在表达GI::LUC的成熟植株中，PRR7的缺失在光暗循环中影响很小，但在持续光照下，地上部的昼夜周期延长，而根部的昼夜周期缩短。我们得出结论，地上部中CCA1启动子的大部分或所有生物钟输入由PRR7介导，并且PRR7的缺失具有器官特异性效应。这些结果强调了地上部和根部生物钟运行的差异，以及在光暗循环和持续光照下研究生物钟突变体的重要性。
