Department of Biology, University of Florida, Gainesville, Florida, United States of America.
PLoS One. 2013;8(1):e53924. doi: 10.1371/journal.pone.0053924. Epub 2013 Jan 11.
Mediator is a conserved multi-protein complex that plays an important role in regulating transcription by mediating interactions between transcriptional activator proteins and RNA polymerase II. Much evidence exists that Mediator plays a constitutive role in the transcription of all genes transcribed by RNA polymerase II. However, evidence is mounting that specific Mediator subunits may control the developmental regulation of specific subsets of RNA polymerase II-dependent genes. Although the Mediator complex has been extensively studied in yeast and mammals, only a few reports on Mediator function in flowering time control of plants, little is known about Mediator function in floral organ identity. Here we show that in Arabidopsis thaliana, MEDIATOR SUBUNIT 18 (MED18) affects flowering time and floral organ formation through FLOWERING LOCUS C (FLC) and AGAMOUS (AG). A MED18 loss-of-function mutant showed a remarkable syndrome of later flowering and altered floral organ number. We show that FLC and AG mRNA levels and AG expression patterns are altered in the mutant. Our results support parallels between the regulation of FLC and AG and demonstrate a developmental role for Mediator in plants.
中介体是一种保守的多蛋白复合物，通过介导转录激活蛋白和 RNA 聚合酶 II 之间的相互作用，在调节转录中发挥重要作用。有大量证据表明，中介体在 RNA 聚合酶 II 转录的所有基因的转录中都发挥组成性作用。然而，越来越多的证据表明，特定的中介体亚基可能控制特定 RNA 聚合酶 II 依赖性基因亚群的发育调控。尽管中介体复合物在酵母和哺乳动物中已被广泛研究，但关于中介体在植物开花时间调控中的功能的报道很少，关于中介体在花器官身份形成中的功能知之甚少。在这里，我们表明在拟南芥中，MEDIATOR SUBUNIT 18（MED18）通过 FLOWERING LOCUS C（FLC）和 AGAMOUS（AG）影响开花时间和花器官形成。MED18 功能丧失突变体表现出明显的晚花和改变的花器官数量的综合征。我们表明突变体中 FLC 和 AG mRNA 水平和 AG 表达模式发生改变。我们的结果支持 FLC 和 AG 调控之间的平行关系，并证明了中介体在植物发育中的作用。
