Dahlia Doctor Research Library: Dahlia Flower Color Genetics and Pigment Biochemistry

A Curated Knowledge Card Collection

Copyright © 2026 by Steve K. Lloyd
All Rights Reserved

Dahlias are famous for their colors, but their color range is not random decoration. It is the visible result of pigment chemistry, gene regulation, metabolic competition, small-RNA silencing, temperature response, and the unusual genetic complexity of an octoploid crop. A red dahlia, a yellow dahlia, a white dahlia, a bicolor dahlia, and a near-black dahlia are not simply different points on a color wheel. They can reflect different biochemical pathways, different regulatory switches, and different ways the plant turns pigment production on, off, up, down, or into a different branch of the pathway.

This is one reason dahlias have mattered in flower-color research for nearly a century. Early work connected flower color to specific pigments and inheritance patterns. Modern studies have gone much deeper, identifying anthocyanins, flavones, chalcones, chalcone synthase silencing, flavone synthase suppression, bHLH transcription factors, Dicer-like RNA interference loops, and temperature-sensitive fading mechanisms. Together, these studies help explain some of the questions growers and breeders keep asking: why dahlias do not produce true blue flowers, why near-black dahlias are so rare, why some bicolors are unstable, why white can mean active genetic silencing rather than simply "no pigment," and why cool conditions can change or fade certain colors.

This Research Library collection brings together Dahlia Doctor Knowledge Cards on dahlia flower color genetics and pigment biochemistry. The selected studies include historic color-genetics work, modern pigment-pathway mapping, black dahlia research, bicolor and white-flower RNA silencing studies, yellow chalcone chemistry, and research on temperature-related color fading. Together, they show that dahlia color is not only beautiful. It is one of the most scientifically revealing traits in the genus.

Each post in this series presents a curated set of Dahlia Doctor Knowledge Cards organized around a specific research topic. A Knowledge Card summarizes one scientific or technical source using a consistent structure: study system, experimental context, experimental design, key results, mechanistic insight, practical guidance, and why the source matters to dahlia growers and researchers. These summaries represent original interpretive work. They are intended as a research guide, not a substitute for reading the original papers. Each citation title links to a Google Scholar search for that source, opening in a new tab, to help you locate the original publication independently.

Each Knowledge Card appears once in this collection, placed in the topic cluster where it contributes most directly. Some sources are relevant to more than one cluster; placement reflects primary emphasis rather than exclusive relevance.

KC-0169 and KC-0596 are included in this collection as bioRxiv preprints. They are flagged here for source-type transparency. Both are useful because they address active molecular questions in dahlia pigment biology, but readers should understand that preprints are not the same source type as peer-reviewed journal articles.

This collection does not include the Tobacco Streak Virus study on flower color change in dahlia (Deguchi et al., 2015). That paper is relevant to pigment regulation because it involves FNS II, flavone accumulation, and color change, but its primary frame is virus-mediated disruption. It is better treated as a cross-reference to the Dahlia Doctor Research Library virus collection than as a main entry here.

Publication Type
Journal Article

Full Citation
Lawrence, W. J. C., & Scott-Moncrieff, R. (1935). The genetics and chemistry of flower colour in Dahlia: A new theory of specific pigmentation. Journal of Genetics, 30(2), 155–226.

Study System
Dahlia variabilis (garden dahlia)

Experimental Context
Polyploid inheritance of flower colour was examined through controlled crosses in dahlia. The study investigated how pigment identity and flower color are determined in a genetically complex, tetrasomic system.

Experimental Design
Controlled crosses were conducted across dahlia cultivars with varying flower colors. Genetic ratio analysis was applied to identify major color-determining factors. Pigment chemistry was used to characterize the compounds associated with specific color classes.

Key Results
Four major tetrasomic color factors were identified. Flower color was found to arise from pigment combinations and their interactions, not from single-pigment determination. Co-pigmentation and dosage-dependent pigment balance were observed as important contributors to expressed color.

Mechanistic Insight
Color in dahlia results from the interaction of multiple pigment-producing genetic factors operating in a tetrasomic polyploid system. Co-pigmentation between anthocyanins and flavones and dosage-dependent variation in pigment levels together shape the color a grower sees.

Practical Guidance
Breeding for specific dahlia colors requires accounting for polyploidy and the interaction of multiple pigment factors simultaneously. Simple dominant-recessive expectations from diploid genetics do not apply cleanly.

Why This Source Matters
This 1935 paper is the foundational reference for dahlia flower color genetics. It established the polyploid framework for dahlia color inheritance and proposed the pigment interaction model that shaped all subsequent dahlia color research. No serious engagement with dahlia color — historical, biochemical, or molecular — can proceed without it.

Publication Type
Experimental Research Article

Full Citation
Halbwirth, H., Muster, G., & Stich, K. (2008). Unraveling the biochemical base of dahlia flower coloration. Natural Product Communications, 3(8), 1259–1266.

Study System
Dahlia variabilis cultivars with red, orange, magenta, lilac, rose, yellow, white, and unstable white-red flower coloration

Experimental Context
A biochemical survey examined flower-color pigments and flavonoid-pathway enzyme activities across 198 dahlia cultivars. Petals from young buds were used for enzyme assays, and open flowers were used for anthocyanin content measurements.

Experimental Design
Petal enzyme preparations were assayed for chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, dihydroflavonol 4-reductase, flavone synthase II, flavonol synthase, flavonoid 3′-hydroxylase, and flavonoid 3′,5′-hydroxylase activity. Anthocyanin content was measured by absorbance at 510 nm and expressed as pelargonidin equivalents. Enzyme conversion rates were grouped into activity categories.

Key Results
Red dahlia pigments were derived from pelargonidin and cyanidin. Delphinidin derivatives were not detected in any cultivar. Flavonoid 3′,5′-hydroxylase activity was not detected in any cultivar. Yellow coloration was based on 6′-deoxychalcones rather than carotenoids. Chalcone isomerase accepted 6′-hydroxychalcones but did not convert 6′-deoxychalcones to corresponding flavanones. White cultivars were frequently characterized by absence or very low activity of dihydroflavonol 4-reductase. Many yellow cultivars lacked detectable flavanone 3-hydroxylase or dihydroflavonol 4-reductase activity.

Mechanistic Insight
Dahlia flower coloration depends on flavonoids and related compounds. Red hues are associated with anthocyanin accumulation, yellow coloration with 6′-deoxychalcone accumulation, and white coloration with absence of both anthocyanins and 6′-deoxychalcone-based pigments. The absence of detectable flavonoid 3′,5′-hydroxylase activity explains why dahlias cannot produce delphinidin and therefore cannot produce true blue flowers. The pathway simply lacks a functional enzyme at that branch point.

Practical Guidance
Biochemical differences among cultivars identify pathway bottlenecks associated with each color class. Red, yellow, orange, rose, lilac, and white each reflect a different configuration of enzyme activity. Molecular work is needed to fully clarify the underlying gene expression differences, but the enzyme survey provides a clear biochemical map.

Why This Source Matters
This is the broadest biochemical survey of dahlia flower color available. Its 198-cultivar scope makes it the definitive reference for why dahlias span the color range they do — and why true blue is outside that range. It also establishes that yellow in dahlias is chalcone-based, not carotenoid-based, which is a distinction that matters for breeding and for understanding dahlia pigment chemistry correctly.

Publication Type
Experimental Research Article

Full Citation
Ohno, S., Hosokawa, M., Hoshino, A., Kitamura, Y., Morita, Y., Park, K. I., et al., & Yazawa, S. (2011). A bHLH transcription factor, DvIVS, is involved in regulation of anthocyanin synthesis in dahlia (Dahlia variabilis). Journal of Experimental Botany, 62(14), 5105–5116.

Study System
Dahlia variabilis cultivar 'Michael J' with bright yellow ray florets and orange variegation, an orange lateral bud-mutant line, and a yellow lateral bud-mutant line; ray florets were examined across five developmental stages.

Experimental Context
Flower-color differences were examined in a dahlia system where orange ray florets accumulated anthocyanidins, flavones, and chalcones, while yellow ray florets accumulated flavones and chalcones without detected anthocyanidins. The study investigated whether anthocyanin and butein/flavone synthesis were controlled by the same or different regulatory mechanisms.

Experimental Design
Ray-floret pigments were extracted, hydrolyzed, and analyzed by HPLC for anthocyanidins, flavones, and chalcones. Anthocyanin pathway genes and candidate transcription-factor genes were isolated by degenerate-primer cloning, cDNA library screening, and RACE. Temporal expression was compared by semi-quantitative RT-PCR and real-time RT-PCR using ray florets at five developmental stages. Genomic and cDNA sequence analyses were used to compare expressed gene copies. The DvIVS genomic region and an inserted element were cloned and sequenced. Genomic PCR, footprint analysis, RT-PCR across DvIVS regions, and 3′ RACE were used to evaluate transposable-element insertion, excision, and transcript truncation.

Key Results
Orange ray florets contained pelargonidin, cyanidin, apigenin, luteolin, butein, and isoliquiritigenin. Yellow ray florets contained apigenin, luteolin, butein, and isoliquiritigenin, but pelargonidin and cyanidin were not detected. DvCHS1, DvF3H, DvDFR, DvANS, and DvIVS expression was lower in yellow ray florets than in orange ray florets at all developmental stages examined. DvCHS2 and DvCHI did not show the same suppression pattern. DvIVS encoded a 649 amino acid bHLH transcription factor. A 5,385 bp CACTA-superfamily transposable element, Tdv1, was located in the fourth intron of DvIVS in the yellow mutant line. DvIVS transcripts in the yellow mutant were truncated and lacked the bHLH-domain region.

Mechanistic Insight
Functional DvIVS activates DvCHS1, DvF3H, DvDFR, and DvANS, allowing anthocyanidin synthesis to proceed alongside flavone and butein synthesis in orange ray florets. In the yellow mutant, transposable-element insertion in DvIVS produces truncated transcripts that lack the bHLH domain, and transcriptional regulation of anthocyanin-pathway genes fails. DvCHS2 and DvCHI are not regulated by DvIVS in the same way, which explains why flavone and butein accumulation continues in yellow ray florets even when anthocyanin synthesis is shut down.

Practical Guidance
No cultivation or management treatment was tested in this study. The findings apply to understanding genetic and molecular regulation of ray-floret color, including the role of transposable elements in generating color mutants from variegated lines.

Why This Source Matters
This study identified the key anthocyanin regulatory switch in dahlia at the molecular level. DvIVS is the bHLH transcription factor that turns anthocyanin synthesis on. Its disruption by transposable-element insertion explains how orange flowers give rise to yellow mutants while retaining flavone and butein pigmentation. It also demonstrates that dahlia color regulation involves at least two independent CHS genes with different regulatory dependencies — a distinction that matters for understanding bicolor patterning and RNA silencing in later studies.

Publication Type
Journal Article

Full Citation
Thill, J., Miosic, S., Ahmed, R., Schlangen, K., Muster, G., Stich, K., & Halbwirth, H. (2012). 'Le Rouge et le Noir': A decline in flavone formation correlates with the rare color of black dahlia (Dahlia variabilis hort.) flowers. BMC Plant Biology, 12(1), 225.

Study System
Dahlia variabilis hort. cultivars with black, red, yellow, and white flowers

Experimental Context
Comparative biochemical and molecular analysis was conducted to determine the flavonoid pathway differences associated with black flower coloration in dahlia. Black dahlia flowers are rare and their biochemical basis was not well characterized at the time of this study.

Experimental Design
Comparative pigment, enzyme-activity, and gene-expression analyses were conducted across dahlia cultivars representing black, red, yellow, and white flower colors.

Key Results
Black cultivars showed high anthocyanin accumulation and markedly reduced flavone content compared to other color classes. Reduced flavone content in black cultivars was associated with suppressed FNS II expression.

Mechanistic Insight
Suppression of flavone synthesis in black dahlia cultivars appears to redirect flavonoid pathway flux toward anthocyanin accumulation. The black-flower phenotype is not the result of a novel dark pigment. It results from high anthocyanin concentration combined with the removal of competing flavone synthesis, which would otherwise dilute or modify the color outcome. Black dahlia coloration is a flux-redirection phenomenon, not a pigment novelty.

Practical Guidance
Black dahlia coloration should be understood as high anthocyanin accumulation combined with reduced flavone formation. No true black pigment exists in these flowers. This framing matters for breeders selecting for or maintaining dark flower colors and for anyone communicating dahlia color biochemistry to growers.

Why This Source Matters
This paper provided the first clear biochemical explanation of black dahlia coloration. Its finding that FNS II suppression drives flux toward anthocyanin accumulation — rather than any unique dark pigment — reframed how black dahlias are understood. It is the Austrian biochemistry group's contribution to the black dahlia problem and the essential companion to the molecular silencing studies that followed.

Publication Type
Journal Article

Full Citation
Deguchi, A., Tatsuzawa, F., Hosokawa, M., Doi, M., & Ohno, S. (2016). Quantitative evaluation of the contribution of four major anthocyanins to petal blackening in dahlia. The Horticulture Journal, 85(4), 340–350.

Study System
Dahlia variabilis flower petals

Experimental Context
This study examined which specific anthocyanin compounds and structural modifications are most responsible for the dark, near-black coloration in black dahlia cultivars.

Experimental Design
Purified anthocyanins were analyzed by in vitro colorimetric assay across a range of pH levels and concentrations. Anthocyanin composition in cultivars was quantified by HPLC.

Key Results
Cyanidin 3-malonylglucoside-5-glucoside (Cy 3MG5G) lowered lightness values and chromatic saturation more than pelargonidin-based forms. Cyanidin 3MG5G anthocyanins predominated in black cultivars. High overall anthocyanin concentration was required to achieve black petal coloration.

Mechanistic Insight
Anthocyanin structural modification — specifically the malonylation and glycosylation pattern of cyanidin — determines its contribution to dark petal coloration. Cy 3MG5G is the most effective of the four major dahlia anthocyanins at reducing lightness. Achieving black color requires both the right anthocyanin structure and high pigment concentration. Neither factor alone is sufficient.

Practical Guidance
Selecting for black flower color in dahlia breeding should emphasize cyanidin 3MG5G accumulation and overall high pigment levels, not simply any anthocyanin type. The structural specifics of the anthocyanin matter.

Why This Source Matters
This study moves from the question of why black dahlias suppress flavones (addressed in KC-0150 and KC-0580) to the question of which anthocyanins actually produce the color. Its quantitative colorimetric approach established that not all anthocyanins contribute equally to darkness and that the malonylated cyanidin form is the critical compound. It completes the biochemical picture of black dahlia coloration at the pigment level.

Publication Type
Journal Article

Full Citation
Deguchi, A., Ohno, S., Hosokawa, M., Tatsuzawa, F., & Doi, M. (2013). Endogenous post-transcriptional gene silencing of flavone synthase resulting in high accumulation of anthocyanins in black dahlia cultivars. Planta, 237(5), 1325–1335.

Study System
Dahlia variabilis cultivars

Experimental Context
Comparative analysis was conducted of black and purple dahlia cultivars to determine the molecular mechanism responsible for suppressed flavone synthase expression in black-flowered lines.

Experimental Design
Pigment quantification, gene expression analysis, and siRNA detection and mapping were conducted across black and purple cultivars.

Key Results
Black cultivars showed silencing of DvFNS (flavone synthase), high anthocyanidin accumulation, and high cyanidin content with low lightness values. Small interfering RNAs targeting DvFNS were detected in black cultivars.

Mechanistic Insight
Post-transcriptional gene silencing of flavone synthase redirects flavonoid pathway flux toward anthocyanidin accumulation in black dahlia cultivars. The suppression of DvFNS is endogenous and RNA-mediated — the same class of silencing mechanism that controls white and bicolor patterning operates here in a different direction, shutting down flavone synthesis rather than chalcone synthesis.

Practical Guidance
No cultivation or management treatment was tested. The study identifies the molecular mechanism underlying the biochemical findings in KC-0150 and provides the molecular evidence that PTGS, not transcriptional repression alone, drives flavone synthase suppression in black cultivars.

Why This Source Matters
This paper established the molecular mechanism behind black dahlia coloration. Where KC-0150 showed that black dahlias have reduced flavone synthesis, KC-0580 showed why: endogenous small-RNA-mediated silencing of DvFNS. It connects the black dahlia phenotype to the broader RNA silencing framework that also controls white flowers and bicolor patterning, showing that the same molecular toolkit shapes multiple color outcomes in dahlia.

Publication Type
Journal Article

Full Citation
Ohno, S., Hori, W., Hosokawa, M., Tatsuzawa, F., & Doi, M. (2018). Post-transcriptional silencing of chalcone synthase is involved in phenotypic lability in petals and leaves of bicolor dahlia (Dahlia variabilis) 'Yuino'. Planta, 247(2), 413–428.

Study System
Dahlia variabilis

Experimental Context
Field and greenhouse-grown bicolor and single-color dahlias were compared, including petal and leaf tissue, to investigate the molecular basis of unstable bicolor patterning in cultivar 'Yuino.'

Experimental Design
Pigment analysis, gene expression assays, small RNA mapping, protein detection, and genomic analyses were conducted across petal regions with and without pigmentation, and in corresponding leaf tissue.

Key Results
Post-transcriptional gene silencing of DvCHS2 correlates with white petal tips and flavonoid-poor leaves. Suppression of DvCHS2 by small RNA silencing reduces chalcone synthase activity in white-tipped regions. Restoring DvCHS2 activity restores red coloration in those regions.

Mechanistic Insight
DvCHS2-specific RNA silencing, driven by a duplicated genomic region, enables reversible flavonoid suppression in specific petal zones. The same silencing mechanism that creates white petal tips also affects leaf flavonoid content, linking the vegetative state of the plant to its floral phenotype. Bicolor instability in 'Yuino' reflects variation in the strength and consistency of this silencing across tissues and developmental conditions.

Practical Guidance
The instability of bicolor expression in some dahlia cultivars is not a defect or disease symptom. It reflects the variable penetrance of an RNA silencing mechanism. Understanding this helps growers recognize why bicolor patterns can shift across the season and why identical plants from the same source may express color differently.

Why This Source Matters
This study demonstrated that bicolor patterning in dahlia involves active post-transcriptional silencing of a specific chalcone synthase gene, not simply absence of pigment. It linked petal phenotype to leaf phenotype, showed the molecular basis for pattern lability, and established that DvCHS2 — rather than DvCHS1 — is the primary silencing target in this cultivar. It is a key reference for understanding why dahlia bicolors behave as they do.

Publication Type
Journal Article

Full Citation
Ohno, S., Hosokawa, M., Kojima, M., Kitamura, Y., Hoshino, A., Tatsuzawa, F., Doi, M., & Yazawa, S. (2011). Simultaneous post-transcriptional gene silencing of two different chalcone synthase genes resulting in pure white flowers in the octoploid dahlia. Planta, 234(5), 945–958.

Study System
Dahlia variabilis (octoploid garden dahlia)

Experimental Context
Flower color variation and flavonoid biosynthesis were examined in a polyploid dahlia system to determine why some cultivars produce pure white flowers despite carrying functional chalcone synthase alleles.

Experimental Design
Comparative pigment analysis, gene expression assays, siRNA detection, and small RNA sequencing were conducted across white and colored cultivars.

Key Results
Both DvCHS1 and DvCHS2 are simultaneously silenced in pure white petal areas, eliminating flavonoid pigment production entirely. Small interfering RNAs targeting both CHS genes were detected. Silencing was post-transcriptional and siRNA-mediated.

Mechanistic Insight
Pure white color in octoploid dahlia requires the suppression of all functional CHS activity across a highly redundant polyploid genome. Because dahlia is octoploid and carries multiple CHS gene copies, a single silencing event is not sufficient. The plant must silence both major CHS genes simultaneously via siRNA-mediated PTGS to eliminate all flavonoid pigment. White in dahlia is not absence of pigment-producing capacity. It is active and comprehensive silencing of that capacity.

Practical Guidance
Pure white dahlia flowers are the result of extensive RNA silencing across redundant gene copies, not a simple loss-of-function mutation. This helps explain why white color in dahlia can be unstable and why white-flowered plants may occasionally revert to color if silencing is disrupted.

Why This Source Matters
This paper established that pure white dahlia flowers require simultaneous silencing of two different CHS genes across an octoploid genome — a more demanding silencing requirement than in simpler plant systems. It demonstrated the interaction between polyploidy and RNA silencing in dahlia color control and showed that white is mechanistically distinct from bicolor white-tipping, which involves only one CHS gene. It is essential reading for understanding both the molecular basis of dahlia white flowers and the broader challenge of gene regulation in polyploid crops.

Publication Type
Preprint (bioRxiv)

Full Citation
Kuriyama, K., Ohno, S., Yamazaki, N., Tabara, M., Koiwa, H., Moriyama, H., & Fukuhara, T. (2023). Bidirectional feedforward regulatory loop of Dicer-like 4 and flavonoids causes floral bicolor patterning in petunia and dahlia. bioRxiv. Posted October 17, 2023.

Study System
Petunia hybrida and Dahlia variabilis

Experimental Context
Analysis of floral pigmentation patterning via RNA interference in bicolor cultivars of both petunia and dahlia. The study sought to determine how stable bicolor spatial patterns — clear boundaries between pigmented and unpigmented petal zones — are established and maintained.

Experimental Design
Comparative biochemical, molecular, and cellular assays were conducted on pigmented and unpigmented petal regions, including analysis of DCL4 activity, flavonoid aglycone levels, and RNAi pathway components.

Key Results
DCL4 activity is spatially inhibited by flavonoid aglycones in pigmented petal regions, maintaining anthocyanin synthesis in those zones. In unpigmented regions, DCL4-mediated RNAi is active and suppresses pigmentation. A reciprocal feedforward loop between DCL4 activity and flavonoid biosynthesis stabilizes the bicolor boundary.

Mechanistic Insight
Bicolor patterning in petunia and dahlia is not determined solely by static genetic information. It is dynamically maintained by a bidirectional feedforward loop: flavonoids inhibit DCL4, preventing RNAi suppression of pigmentation in colored zones, while DCL4 suppresses flavonoid biosynthesis in unpigmented zones, reinforcing the pattern boundary. The two zones stabilize each other through this reciprocal interaction.

Practical Guidance
No cultivation or management treatment was tested. The findings help explain why bicolor patterns in dahlia can be spatially stable across a petal even though the underlying regulatory mechanism is dynamic and RNA-mediated.

Why This Source Matters
This study identified the dynamic regulatory mechanism that creates and maintains stable bicolor patterning in dahlia. It extends the picture established by KC-0248 and KC-0443 — both of which showed that silencing controls pigment zones — by revealing how pattern boundaries are actively stabilized through a DCL4/flavonoid feedback loop. It is the most recent and mechanistically sophisticated study in this cluster and demonstrates that dahlia bicolor patterning is an active spatial regulation problem, not a fixed genetic outcome.

Publication Type
Preprint (bioRxiv)

Full Citation
Ohno, S., Yamada, H., Maruyama, K., Deguchi, A., Kato, Y., Yokota, M., & Doi, M. (2022). Identification of a novel chalcone reductase gene for isoliquiritigenin biosynthesis in dahlia (Dahlia variabilis). bioRxiv.

Study System
Dahlia variabilis; Nicotiana tabacum; Nicotiana benthamiana

Experimental Context
RNA-seq, gene expression analysis, phylogenetics, and heterologous expression were used to identify a chalcone reductase gene involved in yellow pigment biosynthesis in dahlia. The classical Y factor governing yellow coloration in dahlia genetics had not been characterized at the molecular level.

Experimental Design
DvCHR expression was correlated with butein accumulation across dahlia lines. Co-expression of DvCHR with pathway cofactors in tobacco systems induced isoliquiritigenin accumulation, confirming enzymatic function.

Key Results
DvCHR expression correlated with butein accumulation in dahlia. Heterologous expression confirmed that DvCHR encodes a functional chalcone reductase capable of producing isoliquiritigenin. DvCHR is phylogenetically independent from other known chalcone reductases.

Mechanistic Insight
DvCHR represents an evolutionarily independent chalcone reductase that enables 6′-deoxychalcone biosynthesis in dahlia. It provides the enzymatic basis for the classical Y factor in dahlia color genetics, explaining at the molecular level how yellow and orange dahlias produce their characteristic chalcone pigments.

Practical Guidance
No cultivation or management treatment was tested. The findings support understanding of genetic control of yellow pigmentation and provide a molecular anchor for the Y factor in dahlia breeding discussions.

Why This Source Matters
This study gave the classical Y factor a molecular identity. The Y factor — responsible for yellow and butein-based orange pigmentation in dahlia — had been a genetically defined entity for decades without a known gene. DvCHR fills that gap. It also demonstrates that dahlia yellow pigmentation has an evolutionary origin independent from chalcone reductase genes in other plant lineages, which adds phylogenetic interest to the biochemical finding.

Publication Type
Journal Article

Full Citation
Ohno, S., Yokota, M., Yamada, H., Tatsuzawa, F., & Doi, M. (2021). Identification of chalcones and their contribution to yellow coloration in dahlia (Dahlia variabilis) ray florets. The Horticulture Journal, 90(4), 450–459.

Study System
Dahlia variabilis ray florets

Experimental Context
Analysis of the biochemical basis of yellow flower coloration in dahlia, using cultivars that span the yellow-to-orange range of chalcone-based pigmentation.

Experimental Design
Flavonoids were identified and characterized by HPLC and NMR. Colorimetry was used to measure flower color objectively. Correlation analysis was conducted between specific chalcone compound levels and measured color values.

Key Results
Yellow coloration in dahlia ray florets correlates strongly with accumulation of specific chalcone derivatives. The relationship between chalcone compound identity, concentration, and measured color was quantified.

Mechanistic Insight
Chalcone biosynthesis and chemical modification determine the intensity and hue of yellow coloration in dahlia. Different chalcone compounds contribute differently to yellow expression, and higher accumulation of specific derivatives drives more saturated yellow coloration.

Practical Guidance
Breeding for enhanced yellow coloration in dahlia can be approached by selecting for increased accumulation of the chalcone compounds most strongly correlated with yellow intensity. The study provides a biochemical basis for that selection strategy.

Why This Source Matters
This study established the specific chalcone compounds responsible for yellow color in dahlia ray florets and quantified their contribution to measured color. It complements KC-0169, which identified the gene producing the key chalcone precursor, by characterizing the downstream compounds and their color effects. Together, KC-0169 and KC-0188 provide a complete picture of yellow dahlia pigmentation from gene to visible color.

Publication Type
Doctoral Thesis

Full Citation
Muthamia, E. K. (2024a). Selection of non-fading lines for high quality cut-flower production in Dahlia variabilis 'Nessho' by elucidating mechanisms of low temperature induced flower color fading. Doctoral thesis, Okayama University.

Study System
Dahlia variabilis 'Nessho'

Experimental Context
Seasonal low-temperature field and greenhouse conditions were used to investigate color fading in a dahlia cut-flower cultivar. Controlled acclimation and inductive temperature and daylength treatments were applied to characterize the fading response and identify lines resistant to it.

Experimental Design
Plants were classified by color fading index. CIE Lab* color measurements were taken. Quantitative RT-PCR was used to analyze flavonoid gene expression. Small RNA sequencing was conducted. HPLC was used to quantify pigment composition.

Key Results
Color fading increased below 10°C. Elevated DvFNS expression was detected in faded tissues. Significant differences in DvFNS expression and flavone content were found between high- and low-sensitivity lines. Small-RNA-mediated silencing was associated with red flower maintenance in resistant lines.

Mechanistic Insight
Low-temperature conditions induce DvFNS expression, which shifts flavonoid pathway flux toward flavone production through substrate competition with anthocyanin synthesis. Reduced anthocyanin accumulation produces visible color fading. In resistant lines, post-transcriptional silencing suppresses DvFNS and maintains anthocyanin levels even at low temperatures. The same flavonoid pathway branching point that governs black dahlia coloration — competition between anthocyanin and flavone synthesis — is also the site of temperature-regulated fading.

Practical Guidance
DvFNS expression and flavone content in young leaves can serve as early selection markers for non-fading lines in dahlia cut-flower breeding. The study provides a practical molecular tool for identifying cold-stable color lines before field performance can be evaluated.

Why This Source Matters
This study connected temperature-mediated fading to the same flavonoid pathway branching point identified in the black dahlia research. It showed that DvFNS regulation is not only a genetic phenomenon in cultivar color determination but also an environmental response mechanism. For growers, it explains why some dahlia cultivars shift or fade in color during cool seasons and why that response varies across plants. For breeders, it provides selection markers. It also broadens the practical scope of this collection from color genetics to color stability under real growing conditions.

The Knowledge Card summaries in this collection were written by the author based on direct reading of the cited sources. AI tools assisted with retrieval, formatting, and assembly of this collection from the Dahlia Doctor research archive. All curatorial decisions — source selection, topic organization, and editorial framing — were made by the author.