Luo Xiaoning, Huang Sijie, Jiang Fangjun, Shi Qianqian, Wen Yafeng, Li Mengchen, Zhang Minhuan, Zhang Yanlong
College of Landscape Architecture, Central South University of Forestry and Technology, Hunan, Changsha, China.
College of Landscape Architecture and Art, Northwest A&F University, Shaanxi, Xianyang, China.
Front Plant Sci. 2025 Jun 23;16:1595014. doi: 10.3389/fpls.2025.1595014. eCollection 2025.
Tree peony is a traditional woody flower originating from China and possesses high ornamental value. The yellow cultivar is even more precious, known as the highest grade. However, the molecular mechanism underlying tree peony yellow flower formation is still unclear. Our present work identified two transcription factors (TFs), PsMYB4 and PsEGL3, which were highly expressed in yellow tree peony cultivar. Phylogenetic analysis indicates that PsMYB4 belonged to the R2R3-MYB repressor, while PsEGL3 was clustered into subgroup IIIf of bHLH family. Overexpression of and respectively in tobacco inhibited anthocyanin synthesis, with overexpressing lines being more pronounced and the expression levels of structural genes , , , and were significantly downregulated, while the expression levels of structural genes in transgenic lines showed no significant pattern. On the contrary, the expression of , , and increased in either or silencing tree peony petals, in which endogenous and genes were also inhibited to a certain extent. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays further confirmed PsMYB4 could interact with PsEGL3. Moreover, in dual-luciferase (LUC) assay, PsMYB4 and PsEGL3 synergistically suppressed the promoter activity of , , and , thus inhibiting anthocyanin biosynthesis branch and leading to a metabolic flow towards the flavonol synthesis branch. These findings provide a new perspective for revealing the molecular mechanism of the yellow flower formation in tree peony.
牡丹是一种原产于中国的传统木本花卉，具有很高的观赏价值。黄色品种更为珍贵，堪称极品。然而，牡丹黄花形成的分子机制仍不清楚。我们目前的研究鉴定出两个转录因子（TFs），即PsMYB4和PsEGL3，它们在黄色牡丹品种中高表达。系统发育分析表明，PsMYB4属于R2R3-MYB阻遏物，而PsEGL3聚类到bHLH家族的IIIf亚组。分别在烟草中过表达PsMYB4和PsEGL3抑制了花青素合成，其中PsMYB4过表达株系更为明显，结构基因CHS、CHI、F3H和DFR的表达水平显著下调，而PsEGL3转基因株系中结构基因的表达水平没有显著变化。相反，在PsMYB4或PsEGL3沉默的牡丹花瓣中，CHS、CHI、F3H和DFR的表达增加，其中内源性PsMYB4和PsEGL3基因也受到一定程度的抑制。酵母双杂交（Y2H）和双分子荧光互补（BiFC）分析进一步证实PsMYB4可以与PsEGL3相互作用。此外，在双荧光素酶（LUC）分析中，PsMYB4和PsEGL3协同抑制CHS、CHI和F3H的启动子活性，从而抑制花青素生物合成分支，并导致代谢流转向黄酮醇合成分支。这些发现为揭示牡丹黄花形成的分子机制提供了新的视角。
