The bHLH genes GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3) specify epidermal cell fate in the Arabidopsis root
The bHLH genes GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3) specify epidermal cell fate in the Arabidopsis root
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DOI：
10.1242/dev.00880
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发表时间：
2003-12-01
期刊：
影响因子：
4.6
通讯作者：
Schiefelbein, J
中科院分区：
文献类型：
--
作者：
Bernhardt, C;Lee, MM;Schiefelbein, J
拟南芥根表皮中毛细胞和非毛细胞类型的位置依赖特征为研究植物细胞命运决定提供了一个简单的模型。已知几个假定的转录调节因子影响细胞命运的决定。来自玉米R基因研究的间接证据表明bHLH转录因子也参与了这一过程。我们发现编码bHLH蛋白的两个拟南芥基因，GLABRA3 （GL3）和GLABRA3的增强子（EGL3），以部分冗余的方式指定根表皮细胞命运。两个基因纯合子突变的植物不能确定非毛细胞类型，而过表达任何一个基因的植物产生异位的非毛细胞。我们还发现这些基因是非毛特异基因GL2和毛细胞特异基因CPC的适当转录所必需的，这表明GL3和EGL3都影响表皮细胞的命运。此外，我们发现这些bHLH蛋白需要一个功能性的WER MYB蛋白才能发挥作用，并且它们在酵母双杂交实验中与WER和CPC发生物理相互作用。这些结果表明，GL3和EGL3在N细胞位置与WER一起作用，促进非毛细胞的命运，而它们在H位置与不完整的MYB蛋白CPC相互作用，阻断非毛通路，导致毛细胞的命运。
The position-dependent specification of the hair and non-hair cell types in the Arabidopsis root epidermis provides a simple model for the study of cell fate determination in plants. Several putative transcriptional regulators are known to influence this cell fate decision. Indirect evidence from studies with the maize R gene has been used to suggest that a bHLH transcription factor also participates in this process. We show that two Arabidopsis genes encoding bHLH proteins, GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3), act in a partially redundant manner to specify root epidermal cell fates. Plants homozygous for mutations in both genes fail to specify the non-hair cell type, whereas plants overexpressing either gene produce ectopic non-hair cells. We also find that these genes are required for appropriate transcription of the non-hair specification gene GL2 and the hair cell specification gene CPC, showing that GL3 and EGL3 influence both epidermal cell fates. Furthermore, we show that these bHLH proteins require a functional WER MYB protein for their action, and they physically interact with WER and CPC in the yeast two-hybrid assay. These results suggest a model in which GL3 and EGL3 act together with WER in the N cell position to promote the non-hair cell fate, whereas they interact with the incomplete MYB protein CPC in the H position, which blocks the non-hair pathway and leads to the hair cell fate.