The AREB transcription factor SaAREB6 promotes drought stress-induced santalol biosynthesis in sandalwood

Abstract

Sandalwood (Santalum album), a culturally significant and economically valuable horticultural species, is renowned for its heartwood and essential oils enriched with sesquiterpene compounds such as santalol. Despite progress in elucidating the biosynthetic pathway of these valuable metabolites, the transcriptional regulation of this process, particularly under abiotic stress conditions, remains largely unexplored. Under drought conditions, we observed a marked increase in SaAREB6 expression, paralleled by elevated levels of santalols. Moreover, we identified SaCYP736A167, a cytochrome P450 mono-oxygenase gene, as a direct target of SaAREB6. Using electrophoretic mobility shift assays (EMSAs), microscale thermophoresis assays (MSTs), and dual luciferase assays (DLAs), we validated the precise and specific interaction of SaAREB6 with the promoter region of SaCYP736A167. This interaction leads to the upregulation of SaCYP736A167, which in turn catalyzes the final steps in the conversion of sesquiterpene precursors to santalols, thereby reinforcing the connection between SaAREB6 activity and increased santalol production during drought. Collectively, our work illuminates the previously uncharacterized role of SaAREB6 in orchestrating a transcriptional regulation that facilitates drought-induced santalol biosynthesis in sandalwood, presenting opportunities for genetic engineering strategies to improve heartwood and essential oil yields in this economically vital species.

Acknowledgements

This research was supported by grants from the National Key R&D Program of China (2022YFD2202000), the National Natural Science Foundation of China (31722012, 31901304 and 32401636), the Natural Science Foundation of Guangdong Province, China (2019A1515011595) and the Basic and Applied Research Program of Guangzhou, Guangdong, China (SL2022A04J00577).

Author contributions

M.S., L.X., and L.N. performed the experiments. M.D. and L.J.K. conceived the project. Q.F.C., Y.S.Q., B.Z., and M.S. analyzed the experimental results. M.S. and L.J.K. wrote the paper.

Data availability

The supplementary material contains comprehensive data that substantiates the conclusions drawn from this study.

Conflict of interest statement

None declared.

Supplementary Data

Supplementary data is available at Horticulture Research online.

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