OfWRKY33 binds to the promoter of key linalool synthase gene OfTPS7 to stimulate linalool synthesis in Osmanthus fragrans flowers

Abstract

Volatile aroma compounds make significant contributions to human perception of flowers. Osmanthus fragrans is a famous aroma plant, and linalool is proved to be the dominant aroma active compound. Although some terpene synthases have been characterized, a comprehensive study of the hub metabolic gene and its transcriptional regulation remain to be revealed. Here, we selected a specific cultivar Boyeyingui with the highest content of linalool among 20-wide-cultivated cultivars for genome and transcriptome sequencings. Among the 25 new putative OfTPSs, only OfTPS6, OfTPS7 could exclusively produce linalool in planta. Biochemical analysis demonstrated that OfTPS6, OfTPS7 were able to catalyze geranyl diphosphate into linalool and a small proportion of other monoterpenes in vitro. Spatial and temporal correlation analysis further confirmed the expression level of OfTPS7 was strongly correlated with linalool content in a panel of 20 cultivars, suggesting OfTPS7 was the essential linalool synthase gene. Combined with yeast one-hybrid screen and weighted correlation network analysis, a nucleus-localized transcriptional factor OfWRKY33 was identified as a prospective modulator. Y1H, LUC, and EMSA demonstrated that OfWRKY33 directly bound to the W-box of OfTPS7 promoter to stimulate its transcription. OfWRKY33 could coordinately induce the expressions of OfTPS7 and 1-deoxy-d-xylulose 1, thereby promoting the linalool formation. The results first identified the key linalool synthase gene OfTPS7 and a novel transcription factor playing a role in the complex regulatory network of linalool biosynthesis in O. fragrans flowers.

Acknowledgments

We thank Prof. Deng Xiuxin (Huazhong Agricultural University, Wuhan, China) for providing informative guide for this study. This work was funded by the National Natural Science Foundation of China (32172621) and Fundamental Research Funds for the Central Universities (2662024YLPY006 and 2662024FW013).

Author Contributions

R.Z. conceived and coordinated this project. W.X. and R.Z. designed the research. W.X. performed the experiments and analyzed the data with contributions from L.Z., X.Z. M.J. H.J., Q.Y., T.Y., and W.X. wrote the original manuscript, R.Z. and C.W. reviewed and improved the manuscript. All the authors read and approved the final manuscript.

Data availability statement

Raw sequencing reads of all Osmanthus fragrans accessions reported in this study have been deposited into the public database of the National Center of Biotechnology Information (NCBI) BioProject under the accession number PRJNA1141249. All data in this study are provided in the article and its supplementary materials

Conflict of interests

The authors declare that they have no competing interests.

Supplementary information

Supplementary data is available at Horticulture Research online.

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