Characterization of the Lonicera japonica R2R3-MYB transcription factor gene LjaMYB305 that promotes the flavonoid biosynthesis

Hailing Fang; Yan Wan; Huiping Liu; Xiwu Qi; Xu Yu; Zequn Chen; Qun Liu; Li Li; Yang Bai; Dongmei Liu; Chengyuan Liang

doi:10.1016/j.plantsci.2025.112654

Characterization of the Lonicera japonica R2R3-MYB transcription factor gene LjaMYB305 that promotes the flavonoid biosynthesis

Plant Sci. 2025 Jul 11:112654. doi: 10.1016/j.plantsci.2025.112654. Online ahead of print.

Authors

Hailing Fang¹, Yan Wan², Huiping Liu³, Xiwu Qi⁴, Xu Yu⁴, Zequn Chen⁴, Qun Liu⁴, Li Li⁴, Yang Bai⁴, Dongmei Liu⁴, Chengyuan Liang¹

Affiliations

¹ 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. Electronic address: liangcy618@cnbg.net.
² 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.
³ Nanjing University of Chinese Medicine, Nanjing 210023, China.
⁴ Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, China.

PMID: 40653171
DOI: 10.1016/j.plantsci.2025.112654

Abstract

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.

Keywords: Flavonoid biosynthesis; LjaMYB305; Lonicera japonica Thunb.; R2R3-MYB transcription factor.