Auxin-induced WUS expression is essential for embryonic stem cell renewal during somatic embryogenesis in Arabidopsis.
Auxin-induced WUS expression is essential for embryonic stem cell renewal during somatic embryogenesis in Arabidopsis.
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生长素诱导的 WUS 表达对于拟南芥体细胞胚胎发生过程中胚胎干细胞的更新至关重要
DOI：
10.1111/j.1365-313x.2009.03880.x
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发表时间：
2009-08
期刊：
影响因子：
--
通讯作者：
Zhang XS
中科院分区：
文献类型：
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作者：
Su YH;Zhao XY;Liu YB;Zhang CL;O'Neill SD;Zhang XS
体细胞胚胎的发生需要生长素和茎尖分生组织的建立。在高等植物SAM中，WUSCHEL （WUS）是决定干细胞命运的关键基因。然而，生长素在体细胞胚胎发生过程中对WUS表达的调控尚不清楚。本研究表明，在拟南芥体细胞胚胎发生过程中，几个在合子胚胎发生中重要的调控基因的表达上调。有趣的是，当体细胞胚胎还不能在形态和分子上进行鉴定时，WUS在胚胎愈伤组织中被诱导表达。正确的us表达，由外源生长素的临界水平调节，是体细胞胚胎诱导所必需的。此外，还发现生长素梯度在特定区域建立，然后可以产生体细胞胚胎。生长素梯度的建立与诱导的WUS表达有关。此外，生长素梯度似乎激活了胚胎愈伤组织中PIN1的极性定位。极化的PIN1可能负责观察到的生长素在SAM和体细胞胚胎中的极性运输和生长素积累。WUS和PIN1基因的抑制表明，这两个基因通过调控下游基因的表达，是胚胎诱导所必需的。我们的研究结果表明，生长素梯度的建立和pin1介导的生长素极性运输对于WUS诱导和体细胞胚胎发生至关重要。这项研究揭示了生长素在体细胞胚胎发生过程中如何调控干细胞形成。
Somatic embryogenesis requires auxin and establishment of the shoot apical meristem (SAM). WUSCHEL (WUS) is critical for stem cell fate determination in the SAM of higher plants. However, regulation of WUS expression by auxin during somatic embryogenesis is poorly understood. Here, we show that expression of several regulatory genes important in zygotic embryogenesis were up-regulated during somatic embryogenesis of Arabidopsis. Interestingly, WUS expression was induced within the embryonic callus at a time when somatic embryos could not be identified morphologically or molecularly. CorrectWUS expression, regulated by a defined critical level of exogenous auxin, is essential for somatic embryo induction. Furthermore, it was found that auxin gradients were established in specific regions that could then give rise to somatic embryos. The establishment of auxin gradients was correlated with the induced WUS expression. Moreover, the auxin gradients appear to activate PIN1 polar localization within the embryonic callus. Polarized PIN1 is probably responsible for the observed polar auxin transport and auxin accumulation in the SAM and somatic embryo. Suppression of WUS and PIN1 indicated that both genes are necessary for embryo induction through their regulation of downstream gene expression. Our results reveal that establishment of auxin gradients and PIN1-mediated polar auxin transport are essential for WUS induction and somatic embryogenesis. This study sheds new light on how auxin regulates stem cell formation during somatic embryogenesis.