From flower to fruit: How Camellia genes reshape tomato nutrition
image: Dual-platform transcriptomic analysis identifies genes with significant correlations to the concentration of key yellow pigments in C. nitidissima petals.
Credit: Horticulture Research
Scientists have decoded the molecular pathway behind the striking yellow petals of Camellia nitidissima and applied these insights to boost the nutritional profile of tomatoes. By pinpointing key flavonol pigments, particularly quercetin derivatives, and identifying critical biosynthetic genes such as CnFLS1, researchers successfully reconstructed the flavonol pathway in both tobacco and tomato plants. Engineered tomato lines accumulated a diverse range of Camellia-derived flavonols, including rare compounds like camelliaside A and C, which enhanced their antioxidant activity and imparted a yellow hue to the fruit flesh. This breakthrough highlights how unraveling ornamental plant pigmentation can fuel synthetic biology strategies to create healthier and more appealing crops.
Flower color diversity has fascinated scientists for centuries, yet the molecular mechanisms driving golden pigmentation in Camellias remained unresolved. Earlier studies disagreed on whether flavonoids or carotenoids dominated the yellow hues, leaving conservation and breeding efforts uncertain. At the same time, tomatoes, one of the world's most consumed vegetables, contain valuable carotenoids like lycopene but only trace levels of flavonols, mostly in the peel. Enriching flavonols in tomato flesh has long been a challenge for crop improvement programs. Based on these challenges, researchers needed to investigate golden Camellia pigmentation in depth and explore whether its biosynthetic genes could be leveraged to fortify tomato fruit with health-promoting flavonols.
A research team from Zhejiang University and collaborators published (DOI: 10.1093/hr/uhae308) their findings on November 7, 2024, in Horticulture Research. The study reveals how Camellia nitidissima synthesizes its distinctive yellow petals and demonstrates the successful transfer of this pathway into tomato fruits. By combining integrative transcriptomics, enzymatic assays, and transgenic plant experiments, the researchers identified CnFLS1 and associated genes as central to flavonol biosynthesis. Transgenic tomatoes enriched with Camellia-derived flavonols exhibited higher antioxidant capacity, offering new opportunities for crop nutrition and synthetic biology applications.
The study began with an analysis of 23 golden Camellia species, confirming that quercetin 7-O-glucoside (Qu7G) and quercetin 3-O-glucoside (Qu3G) are the dominant pigments responsible for the yellow coloration. Transcriptome profiling and weighted gene coexpression network analysis highlighted CnFLS1 as a hub gene, closely linked with CnCHS, CnF3'H, and CnUFGT. Enzyme kinetics revealed that CnFLS1 exhibited superior catalytic efficiency in converting dihydroquercetin into quercetin compared to homologs in tomato and Arabidopsis. To validate gene function, the team reconstructed the pathway in Nicotiana benthamiana leaves, where the stepwise addition of candidate genes produced expected flavonol intermediates and products. Extending the approach, they engineered tomato plants with multigene constructs under ripening-specific and early-activation promoters. The transgenic fruits accumulated not only rutin and Qu3G but also Camellia-specific flavonols such as camelliaside A and C. These compounds significantly enhanced the fruit's antioxidant capacity, confirmed by assays of total oxidation and free radical scavenging. The results underscore how ornamental plant genetics can be harnessed to elevate nutritional compounds in staple crops.
“Our work provides a rare example of translating ornamental plant traits into edible crop improvement,” said Dr. Pengxiang Fan, corresponding author of the study. “By dissecting the flavonol pathway in Camellia nitidissima, we not only resolved a long-standing puzzle in flower pigmentation but also developed a practical strategy to enrich tomatoes with valuable flavonols. These findings highlight the untapped potential of ornamental germplasm for synthetic biology and functional food development. The integration of plant systems biology with crop engineering paves the way for more nutritious and visually appealing foods.”
This research bridges ornamental horticulture and food crop improvement, offering both scientific and practical outcomes. For conservationists, the findings clarify the molecular basis of golden Camellia pigmentation, aiding efforts to protect and propagate endangered species. For agriculture and food science, the successful reconstruction of Camellia flavonol pathways in tomato demonstrates a new route to biofortified fruits with enhanced antioxidant capacity and potential health benefits. Such advances could contribute to healthier diets, extended shelf life, and increased consumer appeal. More broadly, the study exemplifies how synthetic biology can unlock hidden plant metabolic potential to diversify food systems and support human health.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhae308
Funding information
This study was funded by the Natural Science Foundation of Zhejiang province, China (Grant No. LZ22C150005) and the Starry Night Science Fund of Zhejiang University Shanghai Institute for Advanced Study (SN-ZJU-SIAS-0011).
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.