Brassinazole resistant 1 (BZR1)-dependent brassinosteroid signalling pathway leads to ectopic activation of quiescent cell division and suppresses columella stem cell differentiation.
Brassinazole resistant 1 (BZR1)-dependent brassinosteroid signalling pathway leads to ectopic activation of quiescent cell division and suppresses columella stem cell differentiation.
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DOI：
10.1093/jxb/erv316
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发表时间：
2015-08
影响因子：
6.9
通讯作者：
Kim SH
中科院分区：
文献类型：
--
作者：
Lee HS;Kim Y;Pham G;Kim JW;Song JH;Lee Y;Hwang YS;Roux SJ;Kim SH
拟南芥根中，类甾醇（BR）以BR浓度和BZR 1-/BES 1依赖的方式导致静止中心分裂的异位激活以及对柱干细胞分化的调节。先前的出版物已经表明，BRI 1 EMS抑制子1（BES 1），油菜素类固醇（BR）信号传导途径的正调控因子，增强静止中心（QC）的细胞分裂，并刺激小柱干细胞分化。在这里，它表明，BZR 1，一个BES 1同源物，也促进细胞分裂的QC，但它抑制小柱干细胞分化，相反的BES 1的作用。此外，BR及其BZR 1介导的信号通路被证明可以改变针形成（PIN）的表达/亚细胞分布，这可能导致生长素运动的变化。BR促进BZR 1在根尖区域的强烈核积累，以及BZR 1与几个根发育调节基因的启动子的结合，调节它们在根干细胞生态位区域的表达。这些BZR 1介导的信号级联反应可以解释QC细胞分裂的异位激活以及小柱干细胞分化的抑制。它们还可以通过拮抗生长素/WOX 5依赖性途径来抑制生长素依赖性远端干细胞分化。总之，BZR 1-/BES 1介导的BR信号通路对根顶端分生组织活动的维持表现出不同的影响：它们刺激异位QC分裂，而它们以BR浓度和BZR 1-/BES 1依赖的方式对远柱干细胞的分化表现出相反的影响。
Brassinosteroids (BRs) lead to ectopic activation of quiescent centre division as well as modulation of the columella stem cells differentiation in Arabidopsis roots in a BR concentration- and BZR1-/BES1-dependent manner. Previous publications have shown that BRI1 EMS suppressor 1 (BES1), a positive regulator of the brassinosteroid (BR) signalling pathway, enhances cell divisions in the quiescent centre (QC) and stimulates columella stem cell differentiation. Here, it is demonstrated that BZR1, a BES1 homologue, also promotes cell divisions in the QC, but it suppresses columella stem cell differentiation, opposite to the action of BES1. In addition, BR and its BZR1-mediated signalling pathway are shown to alter the expression/subcellular distribution of pin-formed (PINs), which may result in changes in auxin movement. BR promotes intense nuclear accumulation of BZR1 in the root tip area, and the binding of BZR1 to the promoters of several root development-regulating genes, modulating their expression in the root stem cell niche area. These BZR1-mediated signalling cascades may account for both the ectopic activation of QC cell divisions as well as the suppression of the columella stem cell differentiation. They could also inhibit auxin-dependent distal stem cell differentiation by antagonizing the auxin/WOX5-dependent pathway. In conclusion, BZR1-/BES1-mediated BR signalling pathways show differential effects on the maintenance of root apical meristem activities: they stimulate ectopic QC division while they show opposite effects on the differentiation of distal columella stem cells in a BR concentration- and BZR1-/BES1-dependent manner.