Anthocyanin biosynthesis is orchestrated by a well-conserved enzymatic pathway, but its regulation is anything but uniform across plant species. Ethylene, a gaseous phytohormone, has long been known to influence anthocyanin accumulation—but in maddeningly inconsistent ways. In some plants, ethylene promotes pigmentation; in others, it suppresses it. In apples and plums, ethylene turns color on; in Arabidopsis seedlings, pear fruits, and lily petals, it turns color off. This species-specific divergence has puzzled plant biologists for years, and the underlying molecular mechanisms in chrysanthemum—a genus with enormous horticultural and economic importance—remained almost entirely unexplored. Based on these challenges, a deeper investigation into how ethylene signaling interfaces with the anthocyanin pathway in chrysanthemum was urgently needed.
Now, researchers from Beijing Forestry University, the South China Botanical Garden, and the Zhejiang Academy of Agricultural Sciences have cracked the code. Publishing (DOI: 10.1093/hr/uhag132) on April 7, 2026, in Horticulture Research, the team reveals that ethylene triggers a CmERF3–CmMYB4 transcriptional cascade that directly suppresses three key late-stage anthocyanin biosynthetic genes. The work integrates time-ordered gene co-expression network analysis with molecular validation to trace the complete signaling path from hormone to pigment loss.
The study’s centerpiece is CmMYB4, a R2R3-MYB transcription factor that the team had previously implicated in anthocyanin repression. Here, they went much further. Overexpressing CmMYB4 in transgenic chrysanthemums produced ray florets with dramatically reduced pigmentation—and HPLC quantification confirmed a significant drop in total anthocyanin content. The team then demonstrated that CmMYB4 binds directly to the promoters of three late biosynthetic genes—CmDFR (dihydroflavonol 4-reductase), CmUFGT (UDP-glucose: flavonoid 3-O-glucosyltransferase), and Cm3MaT (anthocyanin 3-O-glucoside-6"-O-malonyltransferase)—and represses their transcription. But the real breakthrough came when they looked upstream. Using time-ordered gene co-expression networks built from transcriptomic data across five developmental stages, the researchers identified CmERF3 (ethylene response factor 3) as the hierarchical regulator sitting above CmMYB4. Exogenous ethylene treatment induced CmERF3 expression while simultaneously reducing anthocyanin accumulation. Functional assays confirmed that CmERF3 does double duty: it activates CmMYB4 transcription by binding to its promoter, and it directly represses CmDFR, CmUFGT, and Cm3MaT. This dual mechanism—indirect repression through a master switch and direct repression at the structural gene level—creates a potent inhibitory cascade.
“What surprised us most was the elegance of this two-pronged strategy,” the authors said. “CmERF3 doesn’t just turn on a repressor—it also directly silences the structural genes itself. It’s a one-two punch that ensures the pigment pathway stays off. This kind of layered regulation gives plants precise control over when and where color is produced, and it explains why ethylene has such a dramatic effect on petal color in chrysanthemums.”
The implications extend well beyond basic plant science. Chrysanthemums represent a multi-billion-dollar global industry, and flower color is arguably the single most important trait for marketability. Understanding exactly how ethylene suppresses pigmentation gives breeders a molecular toolkit for stabilizing or enhancing color across varieties and growing conditions. The CmERF3–CmMYB4 module could be targeted for gene editing to produce varieties with more vivid, longer-lasting blooms, or to prevent unwanted color loss during post-harvest handling—a major challenge in the cut-flower trade. More broadly, the study provides a blueprint for understanding how hormone signaling interfaces with specialized metabolism in ornamental plants, offering a framework that could be extended to other pigment pathways and other crops.
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References
DOI
10.1093/hr/uhag132
Original Source URL
https://doi.org/10.1093/hr/uhag132
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.