A gene trio that shapes floral scent in peony

Floral scent is a defining trait for many ornamental plants, yet the genetic logic behind fragrance production often remains unclear. A new study uncovers how a coordinated group of transcription factors controls the biosynthesis of geraniol, a key compound responsible for the rose-like scent of herbaceous peony flowers. Researchers show that three MYB proteins act together as a regulatory complex to activate a single terpene synthase gene, dramatically increasing geraniol accumulation. By revealing how multiple regulators cooperate at the molecular level, the work clarifies a long-standing question in plant scent biology and offers a new framework for understanding how plants fine-tune the production of valuable volatile compounds.

Geraniol is a widely valued floral volatile that contributes to fragrance, pollinator attraction, and plant–environment interactions. In ornamental species, especially herbaceous peony, geraniol dominates the scent profile of strongly fragrant cultivars. Although enzymes responsible for geraniol biosynthesis have been identified, far less is known about how their expression is precisely controlled. Previous research has shown that terpene biosynthesis is often regulated by transcription factors, yet most studies focus on single regulators or non-volatile compounds. The lack of a clear transcriptional framework for volatile scent formation has limited both basic understanding and practical manipulation. Based on these challenges, it is necessary to conduct in-depth research into the coordinated regulation of geraniol biosynthesis.

Researchers from Northwest A&F University report that a trio of MYB transcription factors works together to control floral scent formation in herbaceous peony. Published (DOI: 10.1093/hr/uhaf141) on May 29, 2025, in Horticulture Research, the study demonstrates that PlMYB73, PlMYB70, and PlMYB108 form a functional complex that activates the geraniol synthase gene PlTPS1. Through transcriptome analysis, gene silencing, overexpression, and molecular interaction assays, the team reveals how this complex drives the production of geraniol, the dominant scent compound in fragrant peony cultivars.

The study began by tracking geraniol emission across flower developmental stages and tissues, revealing that scent release peaks at full bloom and is concentrated in petals. By integrating these data with transcriptome profiles from multiple cultivars, the researchers identified three MYB transcription factors whose expression closely matched geraniol accumulation patterns. Functional tests confirmed their roles: silencing any of the three genes sharply reduced PlTPS1 expression and geraniol content, while transient overexpression produced the opposite effect.

Molecular assays showed that two of the MYB proteins directly bind to specific motifs in the PlTPS1 promoter, switching on gene transcription. The third protein does not bind DNA itself but instead interacts with the other two, strengthening promoter activation. Protein–protein interaction analyses demonstrated that all three factors assemble into a single regulatory complex within the nucleus. When all three were co-expressed, PlTPS1 activity and geraniol production increased far more than with any single factor alone.

Importantly, the regulatory effect was highly specific: other terpene synthase genes and unrelated scent compounds were largely unaffected. Together, these results reveal a previously unknown MYB–MYB transcriptional complex that precisely controls a key floral scent pathway.

“Our findings show that floral scent regulation is not driven by isolated switches, but by coordinated regulatory teams,” said the study's lead researcher. “By uncovering how three MYB transcription factors assemble into a single complex to control one critical enzyme, we provide a clear molecular explanation for why certain peony cultivars are so strongly fragrant. This kind of cooperative regulation may be more common than previously thought, especially for volatile compounds that require tight spatial and temporal control.”

Understanding how floral scent is genetically regulated opens new possibilities for both ornamental breeding and plant biotechnology. The MYB regulatory complex identified in this study offers a precise molecular target for enhancing or modifying fragrance without broadly altering plant metabolism. Beyond peony, the findings suggest that similar transcriptional strategies may govern scent formation in other crops and ornamentals. Geraniol is also widely used in perfumes, cosmetics, and flavor industries, raising the prospect of engineering plants or biological systems for improved natural production. More broadly, the work provides a blueprint for decoding complex regulatory networks that control economically valuable plant metabolites.

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References

DOI

10.1093/hr/uhaf141

Original Source URL

https://doi.org/10.1093/hr/uhaf141

Funding information

This work was supported by the National Natural Science Foundation of China (No. 32271950) and the Open Fund of Shanghai Key Laboratory of Plant Functional Genomics and Resources (PFGR202301).

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.