State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, People's Republic of China.
School of Advanced Agricultural Sciences, Peking University, Beijing 100871, People's Republic of China.
Plant Physiol. 2021 May 27;186(1):434-451. doi: 10.1093/plphys/kiab053.
Trichomes are specialized epidermal cells that act as barriers against biotic and abiotic stresses. Although the formation of trichomes on hairy organs is well studied, the molecular mechanisms of trichome inhibition on smooth organs are still largely unknown. Here, we demonstrate that the CINCINNATA (CIN)-like TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors inhibit the formation of trichomes on cotyledons in Arabidopsis (Arabidopsis thaliana). The tcp2/3/4/5/10/13/17 septuple mutant produces cotyledons with ectopic trichomes on the adaxial sides. The expression patterns of TCP genes are developmentally regulated during cotyledon development. TCP proteins directly interact with GLABRA3 (GL3), a key component of the MYB transcription factor/basic helix-loop-helix domain protein/WD40-repeat proteins (MYB-bHLH-WD40, MBW) complex essential for trichome formation, to interfere with the transactivation activity of the MBW complex in cotyledons. TCPs also disrupt the MBW complex-R3 MYB negative feedback loop by directly promoting the expression of R3 MYB genes, which enhance the repression of the MBW complex. Our findings reveal a molecular framework in which TCPs suppress trichome formation on adaxial sides of cotyledons by repressing the activity of the MBW complex at the protein level and the transcripts of R3 MYB genes at the transcriptional level.
表皮毛是一种特化的表皮细胞，可作为抵抗生物和非生物胁迫的屏障。虽然毛状器官上表皮毛的形成已得到充分研究，但光滑器官上表皮毛抑制的分子机制在很大程度上仍然未知。在这里，我们证明 CINCINNATA（CIN）样 TEOSINTE BRANCHED1/CYCLOIDEA/PCF（TCP）转录因子抑制拟南芥（Arabidopsis thaliana）子叶上表皮毛的形成。tcp2/3/4/5/10/13/17 七突变体的子叶在腹侧产生异位表皮毛。TCP 基因的表达模式在子叶发育过程中受到发育调控。TCP 蛋白直接与 GLABRA3（GL3）相互作用，GL3 是 MYB 转录因子/碱性螺旋-环-螺旋结构域蛋白/WD40 重复蛋白（MYB-bHLH-WD40，MBW）复合物的关键组成部分，对于表皮毛的形成是必不可少的，以干扰 MBW 复合物在子叶中的转录激活活性。TCP 还通过直接促进 R3 MYB 基因的表达来破坏 MBW 复合物-R3 MYB 负反馈环，从而增强对 MBW 复合物的抑制作用。我们的研究结果揭示了一个分子框架，即 TCP 通过在蛋白质水平和 R3 MYB 基因转录本水平上抑制 MBW 复合物的活性和 R3 MYB 基因的转录本来抑制子叶腹侧表皮毛的形成。
