PDF(Pubmed)
Abstract：
The TTG2 transcription factor of Arabidopsis regulates a set of epidermal traits, including the differentiation of leaf trichomes, flavonoid pigment production in cells of the inner testa (or seed coat) layer and mucilage production in specialized cells of the outer testa layer. Despite the fact that TTG2 has been known for over twenty years as an important regulator of multiple developmental pathways, little has been discovered about the downstream mechanisms by which TTG2 co-regulates these epidermal features. In this study, we present evidence of phosphoinositide lipid signaling as a mechanism for the regulation of TTG2-dependent epidermal pathways. Overexpression of the AtPLC1 gene rescues the trichome and seed coat phenotypes of the ttg2-1 mutant plant. Moreover, in the case of seed coat color rescue, AtPLC1 overexpression restored expression of the TTG2 flavonoid pathway target genes, TT12 and TT13/AHA10. Consistent with these observations, a dominant AtPLC1 T-DNA insertion allele (plc1-1D) promotes trichome development in both wild-type and ttg2-3 plants. Also, AtPLC1 promoter:GUS analysis shows expression in trichomes and this expression appears dependent on TTG2. Taken together, the discovery of a genetic interaction between TTG2 and AtPLC1 suggests a role for phosphoinositide signaling in the regulation of trichome development, flavonoid pigment biosynthesis and the differentiation of mucilage-producing cells of the seed coat. This finding provides new avenues for future research at the intersection of the TTG2-dependent developmental pathways and the numerous molecular and cellular phenomena influenced by phospholipid signaling.
摘要：
拟南芥TTG2转录因子调控着一组表皮性状,包括叶片毛状体的分化，内种皮（或种皮）层细胞中黄酮类色素的产生和外种皮层专门细胞中粘液的产生。尽管TTG2作为多种发育途径的重要调节因子已有20多年的历史,关于TTG2共同调节这些表皮特征的下游机制几乎没有发现。在这项研究中,我们提供了磷酸肌醇脂质信号传导作为调节TTG2依赖性表皮途径的机制的证据。AtPLC1基因的过表达挽救了ttg2-1突变植物的毛状体和种皮表型。此外，在种皮颜色拯救的情况下，AtPLC1过表达恢复了TTG2类黄酮通路靶基因的表达,TT12和TT13/AHA10。与这些观察结果一致，显性AtPLC1T-DNA插入等位基因（plc1-1D）促进野生型和ttg2-3植物的毛状体发育。此外，AtPLC1启动子:GUS分析显示在毛状体中表达,并且该表达似乎依赖于TTG2。一起来看,TTG2和AtPLC1之间的遗传相互作用的发现表明磷酸肌醇信号在调节毛状体发育中的作用，类黄酮色素的生物合成和种皮粘液产生细胞的分化。这一发现为TTG2依赖性发育途径与磷脂信号传导影响的众多分子和细胞现象的交叉点的未来研究提供了新的途径。
