Circadian clock gene LATE ELONGATED HYPOCOTYL directly regulates the timing of floral scent emission in Petunia
Circadian clock gene LATE ELONGATED HYPOCOTYL directly regulates the timing of floral scent emission in Petunia
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DOI：
10.1073/pnas.1422875112
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发表时间：
2015-08-04
影响因子：
11.1
通讯作者：
Imaizumi, Takato
中科院分区：
文献类型：
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作者：
Fenske, Myles P.;Hazelton, Kristen D. Hewett;Imaizumi, Takato
花呈现出一种复杂的信号显示，以吸引传粉者，包括花挥发物的排放。挥发物的排放受到高度管制，许多物种将排放限制在一天中的特定时间。这种有节奏的气味散发是由生物钟调节的;然而，其机制仍然未知。在矮牵牛中，挥发性物质的排放主要是由花挥发性苯类/苯丙烷类（FVBP）代谢途径的产物。在这里，我们证明了生物钟基因P. hybrida LATE ELLONGATED HYPOCOTYL（LHY; PhLHY）调节FVBP途径基因和花挥发物产生的日常表达模式。PhLHY表达在早晨达到峰值，与主要气味调节剂ODORANT 1（ODO1）和许多其他晚上表达的FVBP基因的表达相反。PhLHY在拟南芥中的过表达表型引起了一个生物钟表型，这类似于LHY过表达的表型。在矮牵牛中，PhLHY的组成型表达抑制了PhGI、ODO 1、evening-expressed FVBP途径基因的表达水平和花中FVBP的排放。此外，在其中PhLHY表达降低的矮牵牛品系中，PhGI、ODO 1和FVBP途径基因的峰值表达的时间提前到早晨。此外，PhLHY蛋白结合到ODO 1和其他FVBP基因启动子中存在的称为夜晚元件的顺式调节元件。因此，我们的研究结果表明，PhLHY直接设置花挥发性物质排放的时间限制ODO1和其他FVBP基因的表达到晚上在矮牵牛。
Flowers present a complex display of signals to attract pollinators, including the emission of floral volatiles. Volatile emission is highly regulated, and many species restrict emissions to specific times of the day. This rhythmic emission of scent is regulated by the circadian clock; however, the mechanisms have remained unknown. In Petunia hybrida, volatile emissions are dominated by products of the floral volatile benzenoid/phenylpropanoid (FVBP) metabolic pathway. Here we demonstrate that the circadian clock gene P. hybrida LATE ELONGATED HYPOCOTYL (LHY; PhLHY) regulates the daily expression patterns of the FVBP pathway genes and floral volatile production. PhLHY expression peaks in the morning, antiphasic to the expression of P. hybrida GIGANTEA (PhGI), the master scent regulator ODORANT1 (ODO1), and many other evening-expressed FVBP genes. Overexpression phenotypes of PhLHY in Arabidopsis caused an arrhythmic clock phenotype, which resembles those of LHY overexpressors. In Petunia, constitutive expression of PhLHY depressed the expression levels of PhGI, ODO1, evening-expressed FVBP pathway genes, and FVBP emission in flowers. Additionally, in the Petunia lines in which PhLHY expression was reduced, the timing of peak expression of PhGI, ODO1, and the FVBP pathway genes advanced to the morning. Moreover, PhLHY protein binds to cis-regulatory elements called evening elements that exist in promoters of ODO1 and other FVBP genes. Thus, our results imply that PhLHY directly sets the timing of floral volatile emission by restricting the expression of ODO1 and other FVBP genes to the evening in Petunia.