Flowering time is a finely tuned process in plants, in part controlled by the age-regulated microRNA156 (miR156), which functions by suppressing the transcripts of SQUAMOSA-PROMOTER BINDING LIKE (SPL) transcription factors. ARGONAUTE (AGO) proteins are essential effectors of miRNA-mediated gene regulation. However, which AGO(s) mediate(s) the control of flowering time remains unclear. Here, we demonstrate a role of AGO5 in controlling flowering time by modulating the expression of SPL transcription factors. We show that AGO5 interacts physically and functionally with miR156 and that ago5 mutants present an early flowering phenotype in Arabidopsis. Furthermore, in ago5 mutants, the repression of flowering caused by miR156 overexpression is largely reversed, whereas leaf morphology remains unaffected. Our results thus indicate a specific role for AGO5 in mediating miR156 activity in meristematic, but not vegetative, tissue. As such, our data suggest a spatiotemporal regulation of the miR156 aging pathway mediated through different AGO proteins in different tissues.

中文翻译：

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ARGONAUTE5通过与拟南芥中miR156的物理和功能相互作用来抑制开花的年龄依赖性诱导。

开花时间是植物中的微调过程，部分受年龄调节的microRNA156（miR156）控制，其通过抑制SQUAMOSA-PROMOTER BINDING LIKE（SPL）转录因子的转录来发挥作用。ARGONAUTE（AGO）蛋白是miRNA介导的基因调控的重要效应子。然而，尚不清楚哪个AGO介导开花时间的控制。在这里，我们通过调节SPL转录因子的表达证明了AGO5在控制开花时间中的作用。我们显示，AGO5在物理和功能上与miR156相互作用，并且ago5突变体在拟南芥中表现出早期开花表型。此外，在ago5突变体中，miR156过表达引起的开花抑制在很大程度上被逆转，而叶片形态仍然不受影响。因此，我们的结果表明AGO5在分生组织而非营养组织中介导miR156活性的特定作用。因此，我们的数据表明通过不同组织中不同AGO蛋白介导的miR156衰老途径的时空调控。