Regulation of AUXIN RESPONSE FACTOR3 by TAS3 ta-siRNA affects developmental timing and patterning in Arabidopsis
Regulation of AUXIN RESPONSE FACTOR3 by TAS3 ta-siRNA affects developmental timing and patterning in Arabidopsis
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DOI：
10.1016/j.cub.2006.03.065
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发表时间：
2006-05-09
期刊：
影响因子：
9.2
通讯作者：
Carrington, James C.
中科院分区：
文献类型：
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作者：
Fahlgren, Noah;Montgomery, Talowa A.;Carrington, James C.
植物中的微小RNA（miRNAs）和反式作用siRNA（tasiRNAs）通过不同的途径形成，尽管它们通过类似的机制作为mRNA靶点的负调节剂发挥作用[1-7]。在拟南芥中已知三个ta-siRNA基因家族（TAS 1、TAS 2和TAS 3）。靶向编码几种生长素应答因子（包括ARF 3/ETTIN和ARF 4 [1，8]）的mRNA的TAS 3 ta-siRNA的生物发生涉及miR 390引导的初级转录物加工、通过RNA依赖性RNA聚合酶6（RDR 6）活性将前体转化为dsRNA以及连续的DICER-LIKE 4（DCL 4）介导的切割事件。我们发现，青少年到成人的相位转换通常被抑制TAS 3 ta-siRNA，在一个ARGONAUTE 7依赖的方式，通过负调节ARF 3 mRNA。在野生型背景下表达非靶向的ARF 3突变体（ARF 3 mut）再现了在rdr 6 -15和dc 14 -2突变体中检测到的相变表型，这些突变体丢失了所有ta-siRNA。无论是ARF 3或ARF 3 mut的表达在rdr 6 -15植物，其中内源性和转基因的ARF 3拷贝被去阻遏，导致进一步加速的相位变化和严重的形态和图案缺陷的叶和花器官。鉴于ARF 3和ARF 4在器官不对称性中的功能，这些数据揭示了TAS 3 ta-siRNA介导的ARF基因调控在发育时机和模式中的多种作用。
MicroRNAs (miRNAs) and trans-acting siRNAs (tasiRNAs) in plants form through distinct pathways, although they function as negative regulators of mRNA targets by similar mechanisms [1-7]. Three ta-siRNA gene families (TAS1, TAS2, and TAS3) are known in Arabidopsis thaliana. Biogenesis of TAS3 ta-siRNAs, which target mRNAs encoding several AUXIN RESPONSE FACTORs (including ARF3/ETTIN and ARF4 [1, 8]) involves miR390-guided processing of primary transcripts, conversion of a precursor to dsRNA through RNA-DEPENDENT RNA POLYMERASE6 (RDR6) activity, and sequential DICER-LIKE4 (DCL4)-mediated cleavage events. We show that the juvenile-to-adult phase transition is normally suppressed by TAS3 ta-siRNAs, in an ARGONAUTE7-dependent manner, through negative regulation of ARF3 mRNA. Expression of a nontargeted ARF3 mutant (ARF3mut) in a wild-type background reproduced the phase-change phenotypes detected in rdr6-15 and dc14-2 mutants, which lose all ta-siRNAs. Expression of either ARF3 or ARF3mut in rdr6-15 plants, in which both endogenous and transgenic copies of ARF3 were derepressed, resulted in further acceleration of phase change and severe morphological and patterning defects of leaves and floral organs. In light of the functions of ARF3 and ARF4 in organ asymmetry, these data reveal multiple roles for TAS3 ta-siRNA-mediated regulation of ARF genes in developmental timing and patterning.