Expression conservation within the circadian clock of a monocot: natural variation at barley Ppd-H1 affects circadian expression of flowering time genes, but not clock orthologs.
Expression conservation within the circadian clock of a monocot: natural variation at barley Ppd-H1 affects circadian expression of flowering time genes, but not clock orthologs.
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DOI：
10.1186/1471-2229-12-97
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发表时间：
2012-06-21
影响因子：
5.3
通讯作者：
von Korff M
中科院分区：
文献类型：
--
作者：
Campoli C;Shtaya M;Davis SJ;von Korff M
生物钟是一种内源性机制，它使生物过程与环境的日常变化相协调。在植物中，昼夜节律对农业生产力和进化适应性都有贡献。在大麦中，光周期反应调节因子和开花时间基因Ppd - H1与拟南芥核心生物钟基因PRR7是直系同源基因。然而，对于Ppd - H1以及生物钟的其他成分在温带作物物种中的作用知之甚少。在这项研究中，我们鉴定了大麦生物钟的直系同源基因，并测试了Ppd - H1的自然遗传变异对生物钟以及光周期反应途径中的输出基因的昼夜和生物钟节律表达的影响。
大麦生物钟直系同源基因HvCCA1、HvGI、HvPRR1、HvPRR37（Ppd - H1）、HvPRR73、HvPRR59和HvPRR95与拟南芥相比，显示出高度的序列相似性以及昼夜和生物钟节律表达模式的保守性。Ppd - H1的自然突变并不影响大麦生物钟基因的昼夜或生物钟节律循环。然而，发现Ppd - H1突变体在自由运行条件下，光周期反应基因HvCO1、HvCO2以及MADS - box转录因子和春化反应基因Vrn - H1呈现无节律状态。
我们认为，所描述的真双子叶植物生物钟在单子叶植物大麦中基本是保守的。然而，基因家族内的遗传分化以及Ppd - H1功能的差异表明被子植物生物钟发生了进化修饰。我们的数据表明，Ppd - H1的自然变异不影响生物钟基因的表达水平，但控制光周期输出基因。大麦中Vrn - H1的生物钟控制表明，这个春化反应基因也受光周期反应途径控制。大麦生物钟的结构和功能特性将为未来研究小麦族物种生物钟的适应性意义奠定基础。
The circadian clock is an endogenous mechanism that coordinates biological processes with daily changes in the environment. In plants, circadian rhythms contribute to both agricultural productivity and evolutionary fitness. In barley, the photoperiod response regulator and flowering-time gene Ppd-H1 is orthologous to the Arabidopsis core-clock gene PRR7. However, relatively little is known about the role of Ppd-H1 and other components of the circadian clock in temperate crop species. In this study, we identified barley clock orthologs and tested the effects of natural genetic variation at Ppd-H1 on diurnal and circadian expression of clock and output genes from the photoperiod-response pathway. Barley clock orthologs HvCCA1, HvGI, HvPRR1, HvPRR37 (Ppd-H1), HvPRR73, HvPRR59 and HvPRR95 showed a high level of sequence similarity and conservation of diurnal and circadian expression patterns, when compared to Arabidopsis. The natural mutation at Ppd-H1 did not affect diurnal or circadian cycling of barley clock genes. However, the Ppd-H1 mutant was found to be arrhythmic under free-running conditions for the photoperiod-response genes HvCO1, HvCO2, and the MADS-box transcription factor and vernalization responsive gene Vrn-H1. We suggest that the described eudicot clock is largely conserved in the monocot barley. However, genetic differentiation within gene families and differences in the function of Ppd-H1 suggest evolutionary modification in the angiosperm clock. Our data indicates that natural variation at Ppd-H1 does not affect the expression level of clock genes, but controls photoperiodic output genes. Circadian control of Vrn-H1 in barley suggests that this vernalization responsive gene is also controlled by the photoperiod-response pathway. Structural and functional characterization of the barley circadian clock will set the basis for future studies of the adaptive significance of the circadian clock in Triticeae species.
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