Qi Tiancheng, Wu Mengbo, Wang Sijie, Yuan Ying, Xu Xin, Zhang Qiongdan, Jian Yongfei, Qiu Dan, Cheng Yulin, Huang Baowen, Li Zhengguo, Zhang Weiqing, Deng Wei
Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing, China.
Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing, China; Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, China.
J Biol Chem. 2025 Mar;301(3):108313. doi: 10.1016/j.jbc.2025.108313. Epub 2025 Feb 13.
Trichomes are specialized epidermal outgrowths serving as protective barriers for plants against various stresses such as herbivore attacks. MYB-bHLH-WD40 complex is of great significance for unicellular trichome formation in Arabidopsis, whereas its role in the formation of multicellular trichomes in tomatoes remains largely unknown. In the present study, we identified that the R2R3-type MYB transcription factor SlMYB72 promotes the formation of type II, V, and VI trichomes by inhibiting the expression of SlCycB2, a repressor of trichome initiation. SlMYB75 is a negative regulator of trichome formation and positively regulates SlCycB2 expression. Interaction analyses showed that SlMYB72 and SlMYB75 can form MYB-bHLH-WD40 complexes with SlbHLH150 and SlTTG1, respectively, through mutual interactions. The dual-luciferase assay demonstrated that the regulatory functions of SlMYB72 and SlMYB75 in SlCycB2 expression can be enhanced by their corresponding MYB-bHLH-WD40 complexes. Interestingly, yeast-three-hybrid assay indicated that SlMYB75 competes with SlMYB72 for SlbHLH150 and SlTTG1, and counterbalances the down-regulation of SlCycB2 expression controlled by SlMYB72 alone, which is further confirmed by genetic hybrid experiments. These results reveal that SlMYB72 and SlMYB75 antagonistically regulate trichome formation and SlCycB2 expression through MYB-bHLH-WD40 complexes. These findings provide a novel perspective and theoretical basis for the formation of multicellular trichomes in tomatoes and the development of highly resistant plants.
毛状体是特化的表皮附属物，可作为植物抵御各种胁迫（如食草动物攻击）的保护屏障。MYB-bHLH-WD40复合体对拟南芥单细胞毛状体的形成具有重要意义，而其在番茄多细胞毛状体形成中的作用仍 largely unknown。在本研究中，我们鉴定出R2R3型MYB转录因子SlMYB72通过抑制毛状体起始抑制因子SlCycB2的表达来促进II型、V型和VI型毛状体的形成。SlMYB75是毛状体形成的负调控因子，并正向调控SlCycB2的表达。相互作用分析表明，SlMYB72和SlMYB75可分别通过相互作用与SlbHLH150和SlTTG1形成MYB-bHLH-WD40复合体。双荧光素酶测定表明，SlMYB72和SlMYB75在SlCycB2表达中的调控功能可被其相应的MYB-bHLH-WD40复合体增强。有趣的是，酵母三杂交测定表明，SlMYB75与SlMYB72竞争SlbHLH150和SlTTG1，并抵消由SlMYB72单独控制的SlCycB2表达的下调，这在遗传杂交实验中得到了进一步证实。这些结果表明，SlMYB72和SlMYB75通过MYB-bHLH-WD40复合体拮抗调节毛状体形成和SlCycB2表达。这些发现为番茄多细胞毛状体的形成和高抗性植物的培育提供了新的视角和理论基础。
