Blue honeysuckle is one of the hardiest fruit crops on Earth, surviving temperatures as low as -50°C without damage and ripening earlier than apples, raspberries, or blueberries. Native to high-latitude regions of the Northern Hemisphere, it produces deep blue berries rich in anthocyanins—pigments with potent antioxidant properties—and iridoids, bitter-tasting compounds with anti-inflammatory and antiviral activities. However, exactly how this plant coordinates the production of these two compound classes to survive cold stress while delivering palatable fruit has remained largely unexplored. Due to these challenges, the need for an in-depth investigation into the regulatory mechanisms orchestrating these competing metabolic demands has been critical for both understanding plant adaptation and guiding future breeding efforts.
Now, researchers from Beijing Forestry University, China Agricultural University, and the Chinese Academy of Sciences have assembled a chromosome-level genome for wild blue honeysuckle from the Changbai Mountain region. Publishing (DOI: 10.1093/hr/uhag198) their findings in Horticulture Research on August 19, 2026, the team used multi-omics approaches—integrating genomics, transcriptomics, and metabolomics—to reveal how two key metabolic pathways are dynamically regulated to support both cold tolerance and fruit quality.
The genome, spanning 806 megabases across nine chromosomes, showed expansions in gene families linked to cold adaptation, anthocyanin biosynthesis, and iridoid production—notably 11 DREB1 genes and multiple copies of enzymes like LcF3GT and LcSLAS. Under -4°C cold stress, the plant rapidly increased accumulation of both anthocyanins and iridoids. Two regulatory modules were activated: the LcODO1/LcMYB15-LcSLAS pathway drove iridoid production, while the LcbHLH62/LcMYB3R5-LcF3GT module stimulated anthocyanin biosynthesis. This coordinated response provided both antioxidant protection and chemical defense. Yet during fruit maturation, a dramatic metabolic shift occurred: total anthocyanins surged from 3.33 to 465.84 mg/100 g in the pulp, while bitter iridoids markedly declined in edible tissues—though they remained high in the peel, suggesting continued defensive roles. The study also identified over 100 other bitter compounds, including chlorogenic acid and various flavonoids, indicating that blue honeysuckle's flavor emerges from a synergistic blend rather than a single source of bitterness.
“This plant has evolved a remarkable ability to switch between defense and reward modes,” the authors said. “When temperatures drop, both anthocyanin and iridoid pathways are activated—it's a double layer of protection. But as the fruit develops, the plant selectively reduces bitter compounds in the pulp while allowing anthocyanins to accumulate, making the fruit more attractive to seed dispersers. It's a sophisticated resource-allocation strategy shaped by millions of years of evolution in harsh northern climates. Understanding this balance gives us new tools for breeding varieties that are both resilient and palatable.”
The findings offer immediate practical value for blue honeysuckle breeding programs. By targeting the identified regulatory genes—LcbHLH62, LcMYB3R5, LcMYB15, and LcODO1—breeders could potentially enhance cold hardiness or fine-tune bitterness levels in the pulp while maintaining protective compounds in the peel. For growers in cold regions, this research also provides genomic resources to select wild germplasm with superior stress tolerance from the Changbai Mountain “genetic treasure trove.” Beyond agriculture, the study's insights into iridoid biosynthesis could inform pharmaceutical applications, as these compounds are valued for their anti-inflammatory and antiviral properties. Ultimately, this work demonstrates that survival and quality are not opposing forces in nature—they can be masterfully integrated.
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References
DOI
10.1093/hr/uhag198
Original Source URL
https://doi.org/10.1093/hr/uhag198
Funding information
This work was supported by the National Key R&D Program of China (2022YFD2200603 and 2023YFD2201801), National Natural Science Foundation of China (32271831), Science and Technology Innovation Programs of Beijing Forestry University (2025ZLXD02), and Engineering Research & Innovation Team Project of Beijing Forestry University (BLRC2023C01).
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.