HD-Zip Proteins GL2 and HDG11 Have Redundant Functions in Arabidopsis Trichomes, and GL2 Activates a Positive Feedback Loop via MYB23
HD-Zip Proteins GL2 and HDG11 Have Redundant Functions in Arabidopsis Trichomes, and GL2 Activates a Positive Feedback Loop via MYB23
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DOI：
10.1105/tpc.113.120360
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发表时间：
2014-05-01
期刊：
影响因子：
11.6
通讯作者：
Schrick, Kathrin
中科院分区：
文献类型：
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作者：
Khosla, Aashima;Paper, Janet M.;Schrick, Kathrin
IV类同源结构域亮氨酸拉链转录因子GLABRA 2（GL 2）在调节拟南芥毛状体分化的复杂调节回路中起作用。我们描述了一种与HOMEODOMAIN GLABROUS 11（HDG 11）的遗传相互作用，HDG 11以前被鉴定为毛状体分支的负调节因子。G12 HDG 11双突变体显示增强的毛状体细胞类型分化缺陷。使用GL 2启动子的HDG 11的转基因表达部分抑制了gl 2毛状体表型。反之亦然，表达GL 2的控制下，其天然启动子部分补充hdg 11异位分支。由于gl 2 hdg 11和gl 2 myb 23双突变体和三重突变体显示类似的毛状体分化缺陷，我们研究了R2 R3-MYB转录因子MYB 23的连接。我们表明，MYB 23转录水平显着降低芽从GL 2突变体和GL 2可以驱动表达的MYB 23启动子融合（n）的绿色荧光蛋白。酵母单杂交，染色质免疫沉淀，并在植物报告基因的实验表明，在MYB 23启动子的L1盒作为GL 2结合位点。两者合计，我们的研究结果揭示了GL 2和HDG 11之间的功能冗余，这两个同源结构域亮氨酸拉链转录因子先前被认为在毛状体形态发生中介导相反的功能。提出了一种模型，其中GL 2转录水平通过涉及MYB 23的GL 2激活的正反馈回路来维持。
The class IV homeodomain leucine zipper transcription factor GLABRA2 (GL2) acts in a complex regulatory circuit that regulates the differentiation of trichomes in Arabidopsis thaliana. We describe a genetic interaction with HOMEODOMAIN GLABROUS11 (HDG11), previously identified as a negative regulator of trichome branching. gl2 hdg11 double mutants display enhanced trichome cell-type differentiation defects. Transgenic expression of HDG11 using the GL2 promoter partially suppresses gl2 trichome phenotypes. Vice versa, expression of GL2 under the control of its native promoter partially complements hdg11 ectopic branching. Since gl2 hdg11 and gl2 myb23 double mutants and the triple mutant display similar trichome differentiation defects, we investigated a connection to the R2R3-MYB transcription factor MYB23. We show that MYB23 transcript levels are significantly reduced in shoots from gl2 mutants and that GL2 can drive the expression of a MYB23-promoter fusio(n) to green fluorescent protein. Yeast one-hybrid, chromatin immunoprecipitation, and in planta reporter gene experiments indicate that an L1-box in the MYB23 promoter acts as a GL2 binding site. Taken together, our findings reveal a functional redundancy between GL2 and HDG11, two homeodomain leucine zipper transcription factors previously thought to mediate opposing functions in trichome morphogenesis. A model is proposed in which GL2 transcript levels are maintained through a positive feedback loop involving GL2 activation of MYB23.