For farmers who cultivate Camellia drupifera, a woody oilseed tree prized across southern China for its edible seed oil, the difference between a bumper harvest and a disappointing season can be written months before a single flower opens. Well-developed floral buds are the raw material of yield, yet the biochemical choreography that turns a dormant bud into a fully formed flower has remained largely hidden. Now, a team at Zhongkai University of Agriculture and Engineering in Guangzhou has lifted that curtain, combining proteomics, metabolomics and classic physiological measurements to map how these buds rewire their chemistry as they mature. The study, published in Biochemical Genetics, offers the most integrated picture to date of the molecular machinery driving late-stage flower bud development in this economically important species.
The researchers tracked floral buds through three final developmental stages, designated GZI, GZII and GZIII, and measured how four major classes of plant hormones shifted across this window. The results were striking. Levels of indole-3-acetic acid, the principal auxin, dropped sharply between GZI and the later two stages, as did abscisic acid and 1-aminocyclopropane-1-carboxylic acid, the immediate precursor of the gaseous hormone ethylene. Gibberellin 3, by contrast, held relatively steady in GZII before falling significantly in GZIII. According to the authors, this coordinated decline in hormone abundance may serve a specific developmental purpose: removing the brakes on the growth and differentiation of stamens and pistils, the reproductive organs at the heart of every flower.
Hormone changes were only one thread of the story. The team also measured a battery of physiological indicators and found that as buds progressed through development, their relative water content, superoxide dismutase activity, soluble sugar content and soluble protein content all declined significantly. At the same time, hydrogen peroxide accumulated. This shift toward oxidative conditions is not necessarily a sign of distress; reactive oxygen species such as hydrogen peroxide are increasingly recognized as signaling molecules that help steer plant reproduction and developmental transitions. The falling antioxidant defenses and nutrient reserves suggest that the buds were reallocating resources and committing to a terminal developmental program rather than maintaining the flexible, proliferative state of earlier stages.
To understand what drove these physiological changes, the researchers turned to mass spectrometry-based profiling of the metabolome and proteome, identifying differentially accumulated metabolites and differentially expressed proteins between stages. Integrating the two datasets revealed a central role for energy metabolism. Proteins operating in glycolysis and the tricarboxylic acid cycle were upregulated in later stages, including pyruvate kinase, citrate synthase, succinate dehydrogenase, aldolase and hexokinase. Together, these enzymes accelerate the conversion of sugars into adenosine triphosphate, the universal cellular energy currency. The authors argue that this surge in ATP production is critical for the entire floral development process, supplying the power not only for tissue growth but also for the energy-intensive biosynthesis of plant hormones themselves.
The proteomic data also explained why auxin levels fell so precipitously. Indole-3-acetic acid is synthesized through tryptophan-dependent pathways, and the team observed downregulation of enzymes embedded in tryptophan metabolism, including aldehyde dehydrogenase, the 3-dehydroquinate dehydratase and shikimate dehydrogenase activities known as aroDE, and chorismate mutase and prephenate dehydratase activities known as aroH. Because chorismate sits at a key branching point of the shikimate pathway that feeds aromatic amino acid and hormone synthesis, dialing down these enzymes effectively throttles the raw material supply for auxin. In other words, the bud appears to actively suppress its own auxin production machinery at the protein level, matching the hormonal decline seen in the metabolite measurements.
A single enzyme emerged as a likely regulator of two more hormones at once. 4-hydroxy-3-methylbut-2-enyl diphosphate reductase, or ispH, catalyzes the final step of the methylerythritol phosphate pathway that produces isopentenyl diphosphate, the building block for a vast family of isoprenoid compounds, including the precursors of both abscisic acid and gibberellins. When ispH protein abundance declined in the developing buds, the researchers found that ABA and GA3 contents were correspondingly affected. This observation links plastidial isoprenoid biosynthesis directly to the hormonal landscape of the flower bud and suggests that ispH could be a bottleneck worth targeting in future efforts to manipulate flowering and bud retention.
Perhaps the most visually telling finding concerned anthocyanins, the pigments that lend many flowers their red, purple and blue hues and that double as antioxidant metabolites protecting plant tissues from oxidative damage. Anthocyanin contents dropped significantly in both GZII and GZIII, and the proteomic analysis pinpointed the cause: downregulation of a suite of key enzymes in the anthocyanin biosynthesis pathway, including 4-coumarate-CoA ligase, flavonoid 3′-hydroxylase, flavanone 3-hydroxylase, flavonol synthase and anthocyanidin synthase. As the capacity to produce these protective pigments waned, hydrogen peroxide climbed, consistent with the emerging picture of a bud that is shifting from protected growth to a committed, energetically driven maturation phase in which antioxidant pigments are no longer a priority.
The practical stakes of this work are considerable. Flower abscission, the premature shedding of flowers before fruit set, is a persistent problem in Camellia drupifera cultivation and a major constraint on seed oil yield. By identifying the metabolites and enzymes that gate late-stage bud development, the study provides a molecular framework for understanding why some buds fail to complete their program and drop off. The researchers note that their findings lay a theoretical foundation for solving the flower abscission problem, potentially through breeding or management strategies that maintain favorable hormone balance and energy supply during the critical GZII-to-GZIII transition.
The study also demonstrates the power of multi-omics integration in a crop that has received far less molecular attention than its famous relatives, tea (Camellia sinensis) and oil-tea camellia (Camellia oleifera). Neither the proteome nor the metabolome alone could have told the full story. The metabolomics revealed what changed, the proteomics explained how it changed, and the physiological assays tied both to the visible biology of the developing bud. The convergence of independent evidence, such as the match between declining ispH protein and falling isoprenoid-derived hormones, lends particular confidence to the proposed regulatory model.
To support further investigation, the team has deposited its proteomics data in the National Genomics Data Center under accession OMIX014577, giving other laboratories open access to the protein-level evidence. The work was funded by the Guangdong Provincial Forestry Science and Technology Innovation Project, the Guangdong Provincial Universities Innovation Team Project and a postgraduate innovation fund from Zhongkai University of Agriculture and Engineering. For a species whose value rests on the promise locked inside each unopened bud, this integrated atlas of hormones, enzymes and metabolites transforms a long-standing agricultural mystery into a tractable biochemical question, one that plant scientists and breeders can now begin to answer gene by gene and enzyme by enzyme.
Beyond its immediate agricultural relevance, the study adds to a growing body of literature showing that floral transition in woody perennials operates under rules quite different from those established in annual model plants such as Arabidopsis. Trees like Camellia drupifera must coordinate bud development with seasonal cycles and with the substantial carbon reserves stored in branches and roots, which may explain why the observed decline in soluble sugars and soluble proteins coincides with, rather than precedes, the energetic push driven by upregulated glycolytic and tricarboxylic acid cycle enzymes. The bud appears to consume its own reserves even as it ramps up ATP generation, a pattern consistent with a sink tissue approaching reproductive maturity.
The accumulation of hydrogen peroxide alongside falling superoxide dismutase activity deserves particular attention. Superoxide dismutase converts superoxide radicals into hydrogen peroxide, so its decline would ordinarily be expected to reduce hydrogen peroxide production. The simultaneous rise in hydrogen peroxide therefore implies additional sources, such as mitochondrial electron transport or cell wall peroxidase activity, and suggests that the redox environment of the bud is being actively remodeled rather than passively deteriorating. Because hydrogen peroxide can act as a second messenger influencing transcription factors involved in floral organogenesis, this oxidative shift may be an instructive signal rather than a byproduct of senescence.
The anthocyanin findings also connect to broader questions in Camellia biology. The same phenylpropanoid pathway that produces anthocyanins feeds flavonol and lignin synthesis, and the downregulation of 4-coumarate-CoA ligase in particular touches a metabolic node shared by multiple branches. Reduced flux through this pathway during late bud stages could free up precursors for other demands, or it could simply reflect the diminished need for photoprotection in buds that are no longer expanding green tissue. Distinguishing between these possibilities will require isotope tracing experiments that the current study did not perform.
Methodologically, the work illustrates why paired omics approaches are becoming standard in non-model crops. Metabolite measurements capture the net result of synthesis, degradation and transport, while protein abundance reveals which enzymatic steps are being adjusted. The concordance observed here between enzyme downregulation and product decline, seen for auxin, gibberellins, abscisic acid and anthocyanins alike, strengthens causal interpretation in a system where genetic transformation remains technically challenging. Future studies building on this dataset could validate candidate enzymes such as ispH through transient expression systems or correlate protein abundance with natural variation in flower retention across cultivars, translating the molecular atlas into markers that breeders can use to select trees with more reliable fruit set.
Subject of Research: Integrated proteomics and metabolomics analysis of the hormonal, energetic and biosynthetic regulation of flower bud development in Camellia drupifera.
Article Title: Integrated Proteomics and Metabolomics Analysis Reveals Regulatory Mechanisms Underlying Flower Bud Development in Camellia drupifera
Article References: Wang, Y., Chen, X., Chen, Y., Liao, B., Zhang, H., & Li, Y. (2026). Integrated Proteomics and Metabolomics Analysis Reveals Regulatory Mechanisms Underlying Flower Bud Development in Camellia drupifera. Biochemical Genetics. https://doi.org/10.1007/s10528-026-11448-5
Image Credits: AI Generated
DOI: 10.1007/s10528-026-11448-5
Keywords: Camellia drupifera, flower bud development, proteomics, metabolomics, plant hormones, auxin, abscisic acid, gibberellin, ATP, anthocyanins, energy metabolism, flower abscission
Cite Scienmag News
APA
MLA
Chicago
Drew Townsend. (September 12, 2026). Hormones, Energy and Anthocyanins: How an Oil-Rich Camellia Builds Its Flower Buds. Scienmag. https://scienmag.com/hormones-energy-and-anthocyanins-how-an-oil-rich-camellia-builds-its-flower-buds/
Drew Townsend. “Hormones, Energy and Anthocyanins: How an Oil-Rich Camellia Builds Its Flower Buds.” Scienmag, 12 September 2026, https://scienmag.com/hormones-energy-and-anthocyanins-how-an-oil-rich-camellia-builds-its-flower-buds/. Accessed 12 September 2026.
Drew Townsend. “Hormones, Energy and Anthocyanins: How an Oil-Rich Camellia Builds Its Flower Buds.” Scienmag. September 12, 2026. https://scienmag.com/hormones-energy-and-anthocyanins-how-an-oil-rich-camellia-builds-its-flower-buds/
Copy citation
Download RIS
Tags: abscisic acidanthocyaninsATPauxinbiochemical pathways involved in flower bud reprogrammingbiochemical regulation of flower bud maturationCamellia drupiferaCamellia drupifera flower bud developmentenergy metabolismflower abscissionflower bud developmentgibberellinimpact of hormones on oilseed crop yieldinfluence of plant hormones on anthocyanin accumulationintegrated omics approach to floweringMetabolomicsmetabolomics and proteomics in plant biologymolecular mechanisms of flower formation in woody plantsphysiological measurements in plant developmental studiesplant hormone fluctuations in flowering plantsplant hormonesProteomicsrole of auxins and gibberellins in floral initiation
