School of Life Sciences, Tsinghua University, Beijing, China.
Plant Cell. 2011 May;23(5):1795-814. doi: 10.1105/tpc.111.083261. Epub 2011 May 6.
Jasmonates (JAs) mediate plant responses to insect attack, wounding, pathogen infection, stress, and UV damage and regulate plant fertility, anthocyanin accumulation, trichome formation, and many other plant developmental processes. Arabidopsis thaliana Jasmonate ZIM-domain (JAZ) proteins, substrates of the CORONATINE INSENSITIVE1 (COI1)-based SCF(COI1) complex, negatively regulate these plant responses. Little is known about the molecular mechanism for JA regulation of anthocyanin accumulation and trichome initiation. In this study, we revealed that JAZ proteins interact with bHLH (Transparent Testa8, Glabra3 [GL3], and Enhancer of Glabra3 [EGL3]) and R2R3 MYB transcription factors (MYB75 and Glabra1), essential components of WD-repeat/bHLH/MYB transcriptional complexes, to repress JA-regulated anthocyanin accumulation and trichome initiation. Genetic and physiological evidence showed that JA regulates WD-repeat/bHLH/MYB complex-mediated anthocyanin accumulation and trichome initiation in a COI1-dependent manner. Overexpression of the MYB transcription factor MYB75 and bHLH factors (GL3 and EGL3) restored anthocyanin accumulation and trichome initiation in the coi1 mutant, respectively. We speculate that the JA-induced degradation of JAZ proteins abolishes the interactions of JAZ proteins with bHLH and MYB factors, allowing the transcriptional function of WD-repeat/bHLH/MYB complexes, which subsequently activate respective downstream signal cascades to modulate anthocyanin accumulation and trichome initiation.
茉莉酸（JAs）介导植物对昆虫攻击、创伤、病原体感染、胁迫和 UV 损伤的反应，并调节植物的生殖力、花青素积累、毛状体形成和许多其他植物发育过程。拟南芥茉莉酸 ZIM 结构域（JAZ）蛋白是 CORONATINE INSENSITIVE1（COI1）为基础的 SCF（COI1）复合物的底物，负调控这些植物反应。关于茉莉酸调控花青素积累和毛状体起始的分子机制知之甚少。在本研究中，我们揭示了 JAZ 蛋白与 bHLH（Transparent Testa8、Glabra3 [GL3]和 Enhancer of Glabra3 [EGL3]）和 R2R3 MYB 转录因子（MYB75 和 Glabra1）相互作用，这些因子是 WD-repeat/bHLH/MYB 转录复合物的必需成分，抑制 JA 调节的花青素积累和毛状体起始。遗传和生理证据表明，JA 以 COI1 依赖的方式调节 WD-repeat/bHLH/MYB 复合物介导的花青素积累和毛状体起始。MYB 转录因子 MYB75 和 bHLH 因子（GL3 和 EGL3）的过表达分别恢复了 coi1 突变体中的花青素积累和毛状体起始。我们推测，JA 诱导的 JAZ 蛋白降解消除了 JAZ 蛋白与 bHLH 和 MYB 因子的相互作用，使 WD-repeat/bHLH/MYB 复合物的转录功能得以发挥，进而激活各自的下游信号级联，以调节花青素积累和毛状体起始。
