Osmanthus fragrans is prized not only as an ornamental tree, but also as an economically important source of floral volatiles used in fragrance, food, and related industries. Among its many aroma compounds, linalool stands out as a dominant and commercially valuable monoterpene. Previous studies had already identified OfTPS2 as a linalool synthase gene and showed that the transcription factor OfMYB21 can activate its expression. At the same time, jasmonic acid is widely known to regulate plant secondary metabolism, yet its precise role in controlling linalool formation in sweet osmanthus remained unclear. Based on these challenges, deeper research was needed into how jasmonic acid signaling regulates linalool biosynthesis in Osmanthus fragrans.
Researchers from Zhejiang Agriculture and Forestry University and Anhui Agricultural University reported (DOI: 10.1093/hr/uhaf321) on November 25, 2025, in Horticulture Research that the OfJAZ3-OfMYB21 module mediates jasmonic acid signaling to regulate linalool biosynthesis in Osmanthus fragrans, revealing how hormone-triggered protein degradation releases the expression of OfTPS2 and promotes floral scent formation.
The team began by tracking hormone levels and linalool accumulation across three flowering stages of sweet osmanthus. They found that jasmonic acid was the only tested endogenous hormone whose pattern closely matched the rise in linalool and OfTPS2 expression. When flowers were treated with methyl jasmonate, OfTPS2 transcription increased and linalool production rose, confirming that jasmonate positively regulates scent formation. The researchers then turned to mechanism. Dual-luciferase and EMSA assays showed that OfMYB21 activates OfTPS2, but OfJAZ3 interferes with this process by interacting with OfMYB21 and weakening its binding to the OfTPS2 promoter. Functional tests strengthened the case: overexpressing OfJAZ3 reduced linalool biosynthesis not only in sweet osmanthus, but also in transgenic Arabidopsis thaliana and Nicotiana tabacum. The story did not end there. Additional experiments showed that jasmonate promotes degradation of OfJAZ3 through the 26S proteasome pathway, thereby restoring OfMYB21 activity. The team further identified OfCOI1 as the F-box protein that interacts with OfJAZ3, enhances its ubiquitination, and helps release the repression on OfTPS2. Together, these results outline a dynamic signaling circuit in which jasmonate removes a repressor so floral scent biosynthesis can proceed.
Rather than simply showing that jasmonic acid is associated with fragrance, this work explains how the signal is translated into scent at the molecular level. The study positions OfJAZ3 as a brake, OfMYB21 as an activator, and OfCOI1 as the machinery that removes repression when jasmonate levels rise. This gives the field a much more precise model for understanding how floral volatiles are controlled in sweet osmanthus. It also strengthens the broader idea that conserved jasmonate signaling modules can be repurposed across species to regulate economically important terpenoid pathways.
The implications of this work extend beyond a single ornamental species. Because linalool is widely used in fragrance, food, and consumer products, identifying the OfJAZ3-OfMYB21-OfCOI1 regulatory module offers potential targets for metabolic engineering and aroma improvement. In horticulture, the findings could support the breeding of sweet osmanthus cultivars with stronger or more stable fragrance. In biotechnology, they may help guide new strategies to increase terpene production in plants or engineered systems. More broadly, the study offers a framework for linking hormone signaling, transcriptional regulation, and volatile metabolism, making it valuable for future efforts to design plants with customized scent traits and higher industrial value.
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References
DOI
10.1093/hr/uhaf321
Original Source URL
https://doi.org/10.1093/hr/uhaf321
Funding information
This work was supported by National Natural Science Foundation of China (nos 32501723 and 32472782), Scientific Research Foundation of Zhejiang A&F University (no. 2024LFR117), Anhui Provincial Education Department (no. 2022AH050903), and Leading Talent Project for Scientific and Technological Innovation of Zhejiang Province (no. 2022R52026).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.