Fang Hailing, Wan Yan, Liu Huiping, Qi Xiwu, Yu Xu, Chen Zequn, Liu Qun, Li Li, Bai Yang, Liu Dongmei, Liang Chengyuan
Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, China; Nanjing University of Chinese Medicine, Nanjing 210023, China.
Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, China; Nanjing University of Chinese Medicine, Nanjing 210023, China.
Plant Sci. 2025 Oct;359:112654. doi: 10.1016/j.plantsci.2025.112654. Epub 2025 Jul 11.
Lonicera japonica Thunb., commonly known as honeysuckle, is a significant medicinal plant in Asia, with its flowers, stems, and leaves widely utilized in traditional Chinese medicine due to their rich bioactive constituents. Among these, flavonoids are of particular importance for their pharmacological properties. While previous studies have shown that light significantly induces flavonoid accumulation, the molecular mechanisms remain poorly understood. In this study, we isolated and characterized a novel R2R3-MYB transcription factor, LjaMYB305, from honeysuckle. Expression analysis revealed a strong correlation between LjaMYB305 transcription and flavonoid accumulation in flowers following light treatment. Functional characterization showed that the LjaMYB305 promoter is transcriptionally activated by light. Transient overexpression in honeysuckle leaves and stable ectopic expression in transgenic tobacco both significantly upregulated key flavonoid biosynthesis genes and increased flavonoid content. Conversely, virus-induced gene silencing (VIGS) of LjaMYB305 in honeysuckle led to significantly reduced flavonoid levels, accompanied by downregulation of flavonoid pathway genes. Mechanistic studies demonstrated that LjaMYB305 directly binds to and activates the promoters of Lja4CL2 and LjaCHS3, as validated by yeast one-hybrid (Y1H) and dual-luciferase (Dual-LUC) assays. Additionally, yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC), Dual-LUC assays and transient co-overexpression assays revealed that LjaMYB305 interacts with LjaHY5 to form a transcriptional module, synergistically enhancing the expression of Lja4CL2 and LjaCHS3. Overall, our findings establish that LjaMYB305 acts as a key regulator of flavonoid biosynthesis, functioning both independently and in conjunction with LjaHY5 to activate the expression of Lja4CL2 and LjaCHS3. This study provides new insights into the light-responsive regulatory network governing flavonoid production in honeysuckle.
忍冬，俗称金银花，是亚洲一种重要的药用植物，其花、茎和叶因其丰富的生物活性成分而在传统中药中被广泛应用。其中，黄酮类化合物因其药理特性而尤为重要。虽然先前的研究表明光照能显著诱导黄酮类化合物的积累，但其分子机制仍知之甚少。在本研究中，我们从金银花中分离并鉴定了一个新的R2R3-MYB转录因子LjaMYB305。表达分析表明，光照处理后，金银花中LjaMYB305转录与花中黄酮类化合物积累之间存在很强的相关性。功能表征表明，LjaMYB305启动子受光照转录激活。在金银花叶片中瞬时过表达以及在转基因烟草中稳定异位表达均显著上调了关键黄酮类生物合成基因并增加了黄酮类化合物含量。相反，金银花中LjaMYB305的病毒诱导基因沉默（VIGS）导致黄酮类化合物水平显著降低，同时黄酮类途径基因下调。机制研究表明，通过酵母单杂交（Y1H）和双荧光素酶（Dual-LUC）分析验证，LjaMYB305直接结合并激活Lja4CL2和LjaCHS3的启动子。此外，酵母双杂交（Y2H）、双分子荧光互补（BiFC）、Dual-LUC分析和瞬时共过表达分析表明，LjaMYB305与LjaHY5相互作用形成转录模块，协同增强Lja4CL2和LjaCHS3的表达。总体而言，我们的研究结果表明，LjaMYB305作为黄酮类生物合成的关键调节因子，既能独立发挥作用，也能与LjaHY5共同激活Lja4CL2和LjaCHS3的表达。本研究为金银花中黄酮类化合物生产的光响应调控网络提供了新的见解。
