ARGONAUTE1 Acts in Arabidopsis Root Radial Pattern Formation Independently of the SHR/SCR Pathway
ARGONAUTE1 Acts in Arabidopsis Root Radial Pattern Formation Independently of the SHR/SCR Pathway
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DOI：
10.1093/pcp/pcp020
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发表时间：
2009-03-01
影响因子：
4.9
通讯作者：
Nakajima, Keiji
中科院分区：
文献类型：
--
作者：
Miyashima, Shunsuke;Hashimoto, Takashi;Nakajima, Keiji
径向对称组织模式的形成是维管植物发育过程中最基本的过程之一。在拟南芥中，植物特异性的GRAS型转录因子，短根（SHR）和SCARECROW（SCR），需要不对称的细胞分裂，分离两个基本组织细胞层，内皮层和皮层，以及内胚层细胞命运的规范。虽然SHR或SCR的丧失导致单层的基础组织，但仍然保持径向对称的细胞模式，这表明未知的调节机制独立于SHR/SCR依赖性通路起作用。在本研究中，我们发现了一个新的根辐射型突变体，并发现它是一个新的argonaute 1（ago 1）等位基因。多个ago 1突变等位基因包含多余的地面组织细胞层缺乏同心组织，而SHR和SCR的表达模式没有受到影响，揭示了以前未报道的AGO 1在根地面组织图案的作用。对ago 1 scr双突变体的分析表明，与单突变体相比，这两条途径的同时缺失导致细胞组织和基本组织特性的显著降低。基于这些结果，我们建议，高度对称的根地面组织模式保持两个独立的途径，一个使用AGO 1介导的转录后调节和其他使用SHR/SCR转录调节的行动。
The formation of radially symmetric tissue patterns is one of the most basic processes in the development of vascular plants. In Arabidopsis thaliana, plant-specific GRAS-type transcription factors, SHORT-ROOT (SHR) and SCARECROW (SCR), are required for asymmetric cell divisions that separate two ground tissue cell layers, the endodermis and cortex, as well as for endodermal cell fate specification. While loss of SHR or SCR results in a single-layered ground tissue, radially symmetric cellular patterns are still maintained, suggesting that unknown regulatory mechanisms act independently of the SHR/SCR-dependent pathway. In this study, we identified a novel root radial pattern mutant and found that it is a new argonaute1 (ago1) allele. Multiple ago1 mutant alleles contained supernumerary ground tissue cell layers lacking a concentric organization, while expression patterns of SHR and SCR were not affected, revealing a previously unreported role for AGO1in root ground tissue patterning. Analyses of ago1 scr double mutants demonstrated that the simultaneous loss of the two pathways caused a dramatic reduction in cellular organization and ground tissue identity as compared with the single mutants. Based on these results, we propose that highly symmetric root ground tissue patterns are maintained by the actions of two independent pathways, one using post-transcriptional regulation mediated by AGO1 and the other using the SHR/SCR transcriptional regulator.