UV-B promotes flavonoid biosynthesis in Ginkgo biloba by inducing the GbHY5-GbMYB1-GbFLS module

Abstract

Ginkgo biloba (ginkgo) leaves have medicinal value due to their high levels of secondary metabolites, such as flavonoids. We found that the flavonoid content in ginkgo leaves increases significantly at high altitudes (Qinghai-Tibet Plateau). Considering that high UV-B radiation is among the key environmental characteristics of the Qinghai-Tibet Plateau, we carried out simulated UV-B treatments on ginkgo seedlings and found that the flavonoid content of the leaves increased significantly following the treatments. Combined with results from our previous studies, we determined that the transcription factor GbHY5 may play a key role in responses to UV-B radiation. Overexpression of GbHY5 significantly promoted the accumulation of flavonoids in both ginkgo callus and Arabidopsis thaliana. Furthermore, yeast two-hybrid and real-time quantitative PCR showed that GbHY5 promoted the expression of GbMYB1 by interacting with GbMYB1 protein. Overexpression of GbMYB1 in ginkgo callus and A. thaliana also significantly promoted flavonoid biosynthesis. GbFLS encodes a key enzyme in flavonoid biosynthesis, and its promoter has binding elements of GbHY5 and GbMYB1. A dual-luciferase reporter assay indicated that while GbHY5 and GbMYB1 activated the expression of GbFLS individually, their co-expression achieved greater activation. Our analyses reveal the molecular mechanisms by which the UV-B-induced GbHY5- GbMYB1- GbFLS module promotes flavonoid biosynthesis in ginkgo, and they provide insight into the use of UV-B radiation to enhance the flavonoid content of ginkgo leaves.

Acknowledgements

This project was supported by grants from the National Natural Science Foundation of China (grant nos. 31871408, 32001341 and 31971686), Central Financial Projects of Forestry Sci-Tech Promotion (SU[2022]TG09), and the Jiangsu Agriculture Science and Technology Innovation Fund (grant no. CX(21)3047).

Author contributions

W.L. and Li.W. designed the project. S.L, X.G, Y.J., Lu.W., N.X. and Y.C. performed the experiments. S.L and X.G performed data analysis. S.L. drafted the manuscript. B.J., W.L., and Li.W. reviewed and revised the manuscript.

Data availability

The sequencing data are available at the NCBI SRA database under accession number PRJNA960813.

Conflict of interest

The authors declare that they have no conflicts of interest.

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