Yin Mengmeng, Wei Changhe, Du Hanmei, Lyu Tengfei, Luo Fan, Zhang Wenfeng, Zhou Xiaoli, Wang Chengbosen, Chen Lijuan, Lee Dongsun
Rice Research Institute, Yunnan Agricultural University, Kunming 650201, China; College of Agricultural Science, Panxi Crop Improvement Key Laboratory of Sichuan Province, Xichang University, Liangshan 615013, China.
College of Agricultural Science, Panxi Crop Improvement Key Laboratory of Sichuan Province, Xichang University, Liangshan 615013, China.
Plant Sci. 2025 Aug 23;360:112732. doi: 10.1016/j.plantsci.2025.112732.
R2R3-MYB transcription factors (TFs) are key regulators of plant development, stress responses, and secondary metabolism, with a central role in anthocyanin biosynthesis. However, a comprehensive understanding of the R2R3-MYB TFs involved in anthocyanin accumulation in rice (Oryza sativa L.) remains limited. In this study, we identified 105 R2R3-MYB TFs in the rice genome and performed extensive analyses of their phylogenetic relationships, conserved motifs, gene structures, and syntenic conservation across species. Integrating phylogenetic and expression profiling data, OsMYB1-belonging to subfamily 4 (S4) and homologous to AtMYB4-emerged as a key negative regulator of anthocyanin biosynthesis. Subcellular localization analysis confirmed that OsMYB1 is localized predominantly in the nucleus. Functional assays demonstrated that OsMYB1 binds to the promoters of OsDFR and OsANS, repressing their transcription. Moreover, OsMYB1 interacts with core components of the MYB-bHLH-WD40 (MBW) activation complex, specifically OsB2 and OsPAC1, to modulate anthocyanin biosynthesis via a negative feedback mechanism. CRISPR-Cas9-mediated knockout of OsMYB1 in purple rice varieties led to a marked increase in anthocyanin accumulation in pericarps and leaves, accompanied by upregulation of key biosynthetic genes such as OsF3'H, OsDFR, and OsANS. These findings establish OsMYB1 as a pivotal transcriptional repressor orchestrating anthocyanin biosynthesis in rice, providing valuable insights into the regulatory networks governing flavonoid pathways. This work offers promising genetic targets for biofortification and crop improvement strategies aimed at enhancing nutritional quality and stress resilience in cereal crops.
R2R3-MYB转录因子（TFs）是植物发育、应激反应和次生代谢的关键调节因子，在花青素生物合成中起核心作用。然而，对参与水稻（Oryza sativa L.）花青素积累的R2R3-MYB TFs的全面了解仍然有限。在本研究中，我们在水稻基因组中鉴定出105个R2R3-MYB TFs，并对它们的系统发育关系、保守基序、基因结构以及跨物种的共线性保守性进行了广泛分析。整合系统发育和表达谱数据，属于第4亚家族（S4）且与AtMYB4同源的OsMYB1成为花青素生物合成的关键负调节因子。亚细胞定位分析证实OsMYB1主要定位于细胞核。功能分析表明，OsMYB1与OsDFR和OsANS的启动子结合，抑制它们的转录。此外，OsMYB1与MYB-bHLH-WD40（MBW）激活复合体的核心组分，特别是OsB2和OsPAC1相互作用，通过负反馈机制调节花青素生物合成。在紫稻品种中利用CRISPR-Cas9介导敲除OsMYB1导致果皮和叶片中花青素积累显著增加，同时关键生物合成基因如OsF3'H、OsDFR和OsANS上调。这些发现确立了OsMYB1作为水稻花青素生物合成中关键转录抑制因子的地位，为调控类黄酮途径的网络提供了有价值的见解。这项工作为旨在提高谷类作物营养品质和抗逆性的生物强化和作物改良策略提供了有前景的遗传靶点。
