Wei Weilin, Lin-Wang Kui, Chen Guosong, Espley Richard V, Allan Andrew C, Cao Beibei, Qin Mengfan, Sha Shoufeng, Li Juncai, Wang Runze, Li Jiaming, Wu Jun
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Weigang Road No.1, Xuanwu District, Nanjing, Jiangsu 210095, China.
The New Zealand Institute for Plant & Food Research Ltd, Mt Albert Research Centre, Private Bag, Auckland 92169, New Zealand.
Hortic Res. 2025 Mar 3;12(6):uhaf071. doi: 10.1093/hr/uhaf071. eCollection 2025 Jun.
Anthocyanins are important specialized fruit metabolites and major pigments, whose abundance depends on co-regulation of activators and repressors, primarily transcription factors (TFs) of the MYB family. Herein, a KANADI-like TF PuKAN4 was characterized in pear. This TF could be transcriptionally up-regulated by the anthocyanin-related R2R3-MYBs PuMYB10/PuMYB114 and exhibited high expression within red-skinned pears. Interestingly, repressed anthocyanin biosynthesis in transiently overexpressed pear fruit, and stable transformation in pear calli and tobacco plants. The PuKAN4 had a conserved EAR repression domain in C-terminal while the repression function of PuKAN4 could be offset by a transcription activation domain VP64. The dual luciferase analysis proved that PuMYB114/PuMYB10 up-regulated expression of Furthermore, the PuKAN4 could physically interact with PuMYB10/PuMYB114 and did not affect the combination of MYB10/MYB114-bHLH3, as demonstrated by Y2H, pull-down and firefly luciferase complementation. Thus, the PuKAN4 should play the role of active repressor, the formation of PuKAN4-PuMYB10/PuMYB114-PubHLH3 complex inhibited pear anthocyanin biosynthesis. Our findings unveiled an activator-and-repressor feedback loop between PuMYB114/PuMYB10 and PuKAN4, which possibly balance biosynthesis activity and prevents over-accumulation of phenylpropanoids.
花青素是重要的果实特异性代谢产物和主要色素，其含量取决于激活因子和抑制因子的共同调控，主要是MYB家族的转录因子（TFs）。在此，在梨中鉴定了一种类KANADI转录因子PuKAN4。该转录因子可被花青素相关的R2R3-MYBs PuMYB10/PuMYB114转录上调，并在红皮梨中高表达。有趣的是，它在瞬时过表达的梨果实中抑制花青素生物合成，并在梨愈伤组织和烟草植株中稳定转化。PuKAN4在C端有一个保守的EAR抑制结构域，而PuKAN4的抑制功能可被转录激活结构域VP64抵消。双荧光素酶分析证明PuMYB114/PuMYB10上调了……的表达。此外，如酵母双杂交、下拉和萤火虫荧光素酶互补实验所示，PuKAN4可与PuMYB10/PuMYB114发生物理相互作用，且不影响MYB10/MYB114-bHLH3的结合。因此，PuKAN4应发挥活性抑制因子的作用，PuKAN4-PuMYB10/PuMYB114-PubHLH3复合物的形成抑制了梨花青素的生物合成。我们的研究结果揭示了PuMYB114/PuMYB10与PuKAN4之间的激活因子-抑制因子反馈环，这可能平衡了生物合成活性并防止苯丙烷类物质过度积累。
