Search Results (285)

Fruit color is a key quality trait in cherry tomato (Solanum lycopersicum) and an important factor influencing consumer purchasing decisions. Various pigments, including flavonoids, carotenoids, and chlorophylls, form the biochemical basis of fruit coloration, imparting vivid colors such as red, yellow, orange, and green. Flavonoids and carotenoids are also essential nutritional components in cherry tomato, directly influencing their commercial value, while chlorophylls are crucial for photosynthesis and fruit development. However, conventional tomato varieties typically contain insufficient flavonoid levels to meet human dietary requirements. In this study, we quantified flavonoids, carotenoids, and chlorophyll a and b in ten high-flavonoid cherry tomato cultivars and investigated the relationships between fruit color and pigment content. The results revealed that red and orange tomato varieties contained higher flavonoid and carotenoid levels than yellow varieties, while green tomatoes exhibited elevated chlorophyll content. Yellow varieties showed the maximum L* (lightness) value. Flavonoid and carotenoid contents were significantly positively correlated with a* (red-green axis) and a*/b* (yellow-blue axis) values but negatively correlated with hue angle, whereas chlorophyll content showed no significant correlations with color parameters. Our findings provide guidance for evaluating the nutritional value of cherry tomatoes based on pigmentation. Full article

Background: Ontogenetic flower color change is a prevalent adaptive phenomenon in plants, yet the temporal orchestration of multiple pigment pathways during rapid developmental transitions remains poorly understood. This study aims to elucidate the metabolic and transcriptional basis of the petal basal marking color transition in Weigela japonica from yellow through yellow-orange to purple-red within a 4-day blooming period. Methods: Metabolomic analysis of flavonoids, anthocyanins, and carotenoids was conducted using UPLC-MS/MS across four developmental stages (S0–S3). Differentially accumulated metabolites were screened based on VIP > 1, |Log₂FC| ≥ 1, and p < 0.05. Transcriptome sequencing was performed using the NovaSeq 6000 platform, and differentially expressed genes were identified using DESeq2. Weighted gene co-expression network analysis (WGCNA) was employed to identify hub genes associated with pigment accumulation. Key structural genes were validated by qRT-PCR. Results: Metabolomics revealed distinct stage-specific pigment accumulation: carotenoids peaked during the yellow-orange stage (S2), while anthocyanins and flavonoids surged in the final purple-red stage (S3). KEGG enrichment indicated that carotenoid metabolism operates as a discrete module, anthocyanin biosynthesis as a terminal-specific route, and flavonoid metabolism as an intermediary hub bridging the two pathways. Transcriptome analysis identified stage-specific gene expression patterns: PAL and C4H were active at S0–S1, CHS/CHI/F3H peaked at S1-S2, and DFR/ANS were maximally expressed at S2–S3. Carotenoid genes (PSY, LCY, ZDS) showed synchronous expression during the yellow-orange phase. WGCNA identified MYB44, bHLH92, and ERF3 as hub genes strongly correlated with the S3 anthocyanin surge. Conclusions: These findings suggest a sequential activation model in W. japonica, in which temporally partitioned pigment metabolism and stepwise transcriptional regulation converge to orchestrate rapid ontogenetic color change. The study provides a framework for understanding developmental color transitions in ornamental plants, though causal regulatory relationships remain to be functionally validated. Full article

Reflectance by yellow to red carotenoid-based plumages in birds with ultraviolet-sensitive (UVS) color vision typically shifts to redder (longer) wavelengths as carotenoid consumption (Diet_c) increases. This apparent asymmetric red-shift response implies an overall bias against conceivable shifts to bluer (shorter) wavelengths. However, recent studies among species of Piciformes–Coraciiformes (e.g., woodpeckers, barbets, toucans, bee-eaters, and allies) with violet-sensitive (VS) color vision discovered two kinds of blue shifts between the same plumage and dietary traits. Compared to UVS absolute red shifts (positive slopes at higher Diet_c), VS express absolute (negative slopes at higher Diet_c for yellow and orange plumages) or relative (zero slope for red plumages) blue shifts. These contrasting patterns for different color vision systems suggest that generalized symmetry concepts of opposite (plumage shift) patterns that maintain invariant (Diet_c, perception) processes can be abstracted from physical to biological systems, with positive versus negative responses formalized as “antisymmetries” and relative responses formalized as “broken symmetries”. A subset of VS “true woodpecker” (Picinae) species with known yellow and red plumage-carotenoid chemistries demonstrated similar blue shifts for the main reflectance bands and their independence from phylogeny, sex, and specimen collection year, thus providing key chemical details to further test generalized plumage symmetries. Juxtapositions were facilitated because both yellow and red plumages in true woodpeckers contained comparatively blue- and red-shifted carotenoid types. Despite this parallel, each plumage deployed chemical variations in radically different ways. Yellow plumage contained only chemically defined yellow carotenoids, including intrinsically more red-shifted natives (i.e., hydroxy-xanthophylls) widespread among birds through their diets, and intrinsically more blue-shifted picofulvins (i.e., 7,8-di- and tetra-hydro-carotenoids) probably characteristic of and metabolized by VS birds. Higher absolute and relative (to natives) picofulvin concentrations were significant predictors of absolute blue shifts in yellow plumage reflectance, and were significantly predicted by higher Diet_c. Transitivity implied Diet_c ⟶ native ⟶ picofulvin ⟶ reflectance, such that picofulvins caused absolute blue shifts at higher Diet_c, and natives caused absolute red shifts at lower Diet_c. Moreover, opposite trends for picofulvin and native concentrations in feathers were consistent with the proposed endogenous synthesis of picofulvins from natives. Yellow plumages comprised mainly of picofulvins at very low (from very low Diet_c from ants and termites) or high (from very high Diet_c from fruits) concentrations were especially distinctive for some of these and other interrelationships, suggesting some heterogeneity in yellow pigmentation strategies from dietary idiosyncrasies. Red plumages contained only relatively low concentrations of yellow dietary natives (hydroxy-xanthophylls), but varied widely in the concentration of metabolites of comparatively intermediate (4-oxo-keto-carotenoids) or extreme (4,4′-oxo-keto-carotenoids) redness. However, different red chemistries lacked any corresponding significant relationships with variations in reflectance or Diet_c. Variations in reflectance based on chemical compositions were more visible to humans for yellow than red plumage types, setting minimum salience levels for the more discriminating diurnal avian color visions. Therefore, VS yellow plumage chemistries that emphasize deposition of easily obtained (cheaper) dietary natives at low Diet_c, and of more deliberately synthesized (costly) picofulvin metabolites at higher Diet_c were consistent with several forms of honest signaling in UVS from resource limitations based on Diet_c, including through potential costs and benefits and their trade-offs. Conversely, the diverse chemical compositions and costs of red plumages of similar physical reflectance properties, and evidence that intrinsically orange carotenoids intermediate between red and yellow ones were actively excluded from plumage, suggested that true woodpecker reds were under selection for a convergent appearance. In light of true woodpecker biology, sensory bias, and social and aposematic mimicry are likely mechanisms promoting resemblance. These results extend to the chemical level earlier interpretations of opposite shift patterns as antisymmetries of invariant processes and relative shift patterns as broken symmetries of altered processes for VS vis-à-vis UVS carotenoid-based systems. Full article

Flavonoids are essential secondary metabolites that predominantly affect flower pigmentation in plants. Understanding the molecular mechanisms underlying flower color divergence is crucial for ornamental plant breeding. This study aimed to elucidate the factors responsible for the differences in color between white-petaled Cosmos bipinnatus and orange-petaled Cosmos sulphureus. We employed an integrated approach combining untargeted LC–MS/MS metabolomics and high-throughput transcriptome sequencing of fresh petals to analyze pigment composition and differential gene expression. Petal pigment extraction, total flavonoid quantification, and metabolomic profiling consistently revealed that differences in flavonoid abundance are responsible for flower color divergence between the two species. In contrast, carotenoids, previously considered potential contributors to flower coloration, were neither evident in the oil phase of the pigment extracts nor detected by metabolomic analysis. Flavonoid compounds accumulated at relatively high levels in the orange petals of C. sulphureus, reaching 11.36 times that of C. bipinnatus, contributing to its bright appearance. Transcriptomic analysis revealed differences in gene expression patterns between the two species, highlighting key candidate genes involved in the flavonoid biosynthesis pathway, such as chalcone synthase. These findings indicate that the orange coloration of C. sulphureus may be associated with CHS-regulated accumulation of naringenin chalcone and downstream compounds in the flavonoid metabolic pathway after CHS, providing valuable theoretical support for a deeper understanding of the causes underlying the differences in flower color between C. bipinnatus and the orange-petaled C. sulphureus. Full article

Natural microbial pigments offer important advantages and are widely studied for food applications. We investigated the biosynthetic pathways, characteristics, and bioactivities of the orange–red pigment produced by Bacillus velezensis YM–3, a strain isolated from the traditional Pixian Douban condiment. Whole-genome sequencing revealed complete pathways for melanin, phytoene, and heme biosynthesis. The purified extracellular pigment was characterized using ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and ultra-performance liquid chromatography–high-resolution mass spectrometry; it was preliminarily characterized as melanin-like pigment. The pigment was highly soluble in alkaline solutions, moderately soluble in water, and insoluble in common organic solvents. It exhibited strong photostability and remained stable at low temperature, precipitated under acidic conditions, and showed high stability under alkaline environments. Furthermore, the pigment demonstrated in vitro free radical scavenging activity. Hence, this study provides a scientific foundation for exploring the potential utility of B. velezensis YM–3 and its pigment metabolites as functional agents. Full article

Seasonal changes in leaf coloration are a key ecological and ornamental characteristic of Liquidambar formosana. To clarify the molecular basis of this process, we performed an integrated transcriptomic and metabolomic investigation comparing wild-type L. formosana (FX) with the autumn-red cultivar ‘Jinyu’ (JY). Leaves were sampled before and after the color transition. Analyses revealed distinct metabolic pathways driving coloration in each genotype. In JY, the red phenotype was primarily attributed to the activation of anthocyanin biosynthesis, characterized by coordinated upregulation of key structural genes (LfDFR, LfANS, LfBZ1) and significant accumulation of anthocyanins, especially pelargonidin derivatives. Conversely, FX exhibited enhanced flavonol biosynthesis and carotenoid/terpenoid metabolism, leading to greater yellow pigment accumulation and an orange-yellow hue. Weighted gene co-expression network analysis (WGCNA) identified a core module strongly correlated with anthocyanin content in JY, which was significantly enriched with transcription factors from the MYB, bHLH, and WRKY families. These results demonstrate that different L. formosana genotypes employ divergent metabolic strategies for autumn coloration, governed by specific transcriptional regulatory networks. This study provides crucial insights into pigment regulation in woody plants and offers valuable candidate genes for the molecular breeding of ornamental L. formosana cultivars. Full article

Grafting is a widely used technique to improve stress tolerance in horticultural plants. However, little is known about how grafting affects citrus growth under low-nitrogen (N) stress. To investigate the responses of different grafting combinations to low N availability, we examined root morphology, photosynthesis, chlorophyll fluorescence and semi-quantitative mineral profiles in grafted and ungrafted citrus plants subjected to two N levels (10 and 0.15 mM NO₃⁻ -N) under potted conditions. Analyses were performed on roots and leaves of six plant combinations: ungrafted Trifoliate orange (Poncitrus trifoliata L. Raf., Pt) and red tangerine (Citrus reticulata Blanco, Cr); self-grafted combinations (Pt/Pt and Cr/Cr); and reciprocal heterografts (Pt/Cr and Cr/Pt). Under low-N stress, plant height decreased by 12.3–36.8%, stem diameter by 2.9–31.8%, leaf area by 18.2–26.3%, and SPAD by 11.6–24.5% across the six combinations, with the Cr/Cr combination showing the largest reductions in all parameters. The highest net photosynthetic rate (P_n), intercellular CO₂ concentration (C_i), stomatal conductance (Gs), electron transport rate (ETR), maximum quantum efficiency of PSII (Fv/Fm) and effective quantum efficiency of PSII (Fv’/Fm’) were observed in the Pt and Pt/Pt plants. Low-N stress reduced chloroplastid pigment contents and limited photosynthetic rates. Under 10 mM N treatment, the Fv/Fm values of Pt, Cr, Pt/Pt, and Cr/Pt were approximately 0.82, whereas those of Pt/Cr and Cr/Cr were below 0.82, suggesting lower maximal PSII efficiency in combinations with Cr rootstock. Regarding mineral elements, under low-N stress, the relative levels of P, K, Ca, Mg, and Fe in leaf and root sap increased, while those of N, Cu, Zn, B, and Mn decreased. Overall, combinations with Pt rootstock (Pt/Pt and Cr/Pt) showed better growth and photosynthetic performance, and more stable mineral profiles under low-N stress than combinations with Cr rootstock (Cr/Cr and Pt/Cr). These findings provide a physiological basis for understanding rootstock-specific responses to low-N stress under controlled conditions. Full article

The color origin of precious coral, a highly valued biogenic polycrystalline gemstone, has long remained elusive. In this study, an integrated approach employing spectrophotometry, Raman, FTIR, and UV-Vis spectroscopy, coupled with Spearman correlation analysis, was utilized to investigate a color-graded series of precious coral samples ranging from white to red. The results demonstrate that the calcareous composition of the samples tested in our study consists exclusively of calcite. The actual chromophores are identified as a blend of multiple distinct polyene species, characterized by Raman shifts at 1126 and 1515 cm⁻¹, with density functional theory (DFT) calculations determining the number of conjugated (C=C) bonds in the polyene chain to be 10–11. Inherently exhibiting a red-orange hue, the progressive accumulation of these polyenes drives a systematic color transition from orange to red. Both absorption bands at 314 nm and 532 nm in the UV-Vis spectra are attributed to the polyene pigment molecules. Specifically, the broad 532 nm band is dominated by π-π* electronic transitions, while the 314 nm band likely arises from terminal benzene rings and their derivatives. As the pigment concentration increases, this band exhibits pronounced broadening and an increase in absorbance, accompanied by a redshift in the maximum absorption peak. This spectral evolution leads to an intensified absorption in the yellow-orange region, elucidating the intrinsic mechanism underlying the color transition of precious coral from orange to red with increasing pigment content. This work lays a solid foundation for the non-destructive identification of precious corals and future research on their color genesis. Full article

This study investigated bract color phenotypes and pigment composition in Bougainvillea × buttiana ‘Mrs. Butt’ and six bud-sport varieties at the full-bloom stage. Bract color was evaluated using the Royal Horticultural Society Colour Chart and CIELAB parameters, whereas pigment classes and contents were determined using qualitative color reactions, UV–Vis spectroscopy, and spectrophotometric assays. Data were analyzed using one-way ANOVA, Duncan’s multiple range test, Pearson correlation analysis, cluster analysis, and pigment ratio analysis. The seven varieties were classified into red/pink and orange/yellow groups, which differed significantly in L*, a*, b*, C*, and H°. Betalains and flavonoids appeared to be the predominant pigment classes, whereas chlorophylls and carotenoids were present at relatively low levels; no characteristic anthocyanin absorption peak was detected under the present UV–Vis conditions. The betaxanthin/betacyanin ratio was positively correlated with L* and b* and negatively correlated with a*, suggesting that this ratio is associated with variation from red-dominant to yellow-dominant bract coloration. These findings suggest that bract color variation in this bud-sport lineage is associated with the combined effects of betalains and flavonoids, and that the betaxanthin/betacyanin ratio could serve as a practical indicator for color classification and low-cost assisted selection in Bougainvillea. Full article

Fruit coloration is a key determinant of tomato quality, yet how light and temperature interact to regulate pigmentation during ripening remains unclear. Using a semi-in-fruit experimental system, we demonstrate that while high light accelerates chlorophyll degradation and lycopene accumulation at 25 °C, supra-optimal temperature (40 °C) completely abolishes lycopene biosynthesis irrespective of light conditions, primarily through transcriptional suppression of SlPSY1 and SlGGPS2. Elevated postharvest temperatures (≥30 °C) not only change the carotenoid composition but also reduce the antioxidant capacity and vitamin C content in fruit. Temperature-switch experiments revealed a critical developmental window, days 2–4 after ethylene treatment, during which temperature exerts dominant control over carotenoid metabolism. Exposure to high temperature within this window irreversibly shifts pigment accumulation from lycopene to yellow/orange carotenoids. These findings identify a temporally precise regulatory nexus integrating environmental signals with the ripening program, offering a framework for targeted temperature management to optimize tomato color and nutritional quality. Full article

Replacing artificial dyes with natural pigments in foods, especially carotenoids, has proven to be technologically feasible. This study developed a high-performance pitanga carotenoid extraction process using ionic liquids (ILs) and a factorial design to identify a potential substitute for artificial azo dyes, specifically Allura Red AC and Sunset Yellow FCF. 1-Hexyl-3-methyl-imidazolium chloride [C6mim]Cl was the most efficient IL. The optimized process conditions included a solid–liquid ratio R(S/L) of 1:10 m/m, an IL to ethanol co-solvent ratio R(IL/E) of 1:1 m/m, ultrasound power of 350 W, and six extraction cycles of 7 min each. These conditions yielded a total carotenoid content of 100.40 ± 3.71 μg/g (dry matter), demonstrating effective pigment recovery and a concentration suitable for practical use as a natural colorant alternative to synthetic azo dyes. The reuse of ILs and carotenoid purification were achieved through solid-phase extraction (SPE) using XAD-7HXP adsorbent, resulting in recovery rates of 89.2–76.2% for [C6mim]Cl and 108.9–23.2% for carotenoids. The major carotenoids identified were all-trans-β-cryptoxanthin, all-trans-rubixanthin, and all-trans-lycopene, whose combined presence contributed to a yellowish-orange hue similar to that of Sunset Yellow FCF, as confirmed by CIELAB parameters. Additionally, the [C6mim]Cl carotenoid extract exhibited high antioxidant activity, with an antioxidant capacity of 23.54 µmol of α-tocopherol equivalent. Full article

Epoxy resins are widely used in coatings and adhesives due to their strong adhesion and processability. In this study, epoxy-based coatings were prepared with two synthesized pigments: cobalt blue and chrome orange. The coatings were applied to aluminum, phosphor bronze, and brass substrates to evaluate mechanical and adhesive performance. Microhardness was analyzed using the Chen–Gao model to exclude substrate effects, while adhesion was assessed via parameter b. Pigment morphology strongly influenced the properties: Pb-orange exhibited hollow micro-tube structures, while Co-blue showed an irregular morphology. Results revealed that epoxy coatings on brass with Pb-orange pigment reached a hardness of 242.6 MPa, compared to 187.2 MPa for Co-blue, representing a 22.8% increase. Adhesion was superior in epoxy/Pb-orange, with values 1.3 times higher than epoxy/Co-blue and 1.8 times higher than neat epoxy on brass. However, pigments have no influence on the intrinsic hardness of the epoxy coating. The orange pigment in the epoxy impairs wetting resistance, while the blue pigmented epoxy coating becomes hydrophobic. In this way, in addition to colorizing epoxy coatings, multifunctional coatings with adjustable adhesion, free surface energy, and hardness are also obtained. These findings highlight the potential of pigment-modified coatings for tailored industrial applications, offering improved properties depending on pigment selection. Full article

The co-culture between Trametes sp. D and Aspergillus niger L14 resulted in a distinct orange-brown antagonistic band at their interface. Direct hyphal contact was associated with markedly enhanced production of numerous secondary metabolites (SMs), some of which were absent or decreased in monocultures. T. sp. D induced indolic compounds and cyclic dipeptides, such as Indole-3-acetamide and Cyclo-(Pro-Phe), whereas A. niger L14 overproduced polyketide-derived pigments and organic acids, such as Fonsecin and Kojic acid. These SMs did not inhibit their producer but suppressed the opponent’s growth, indicating reciprocal chemical antagonism. Transcriptomic analysis revealed upregulation of stress-related and metabolic genes, consistent with each fungus activating defense pathways. Biochemical assays showed that the confrontation zone had the highest oxidative stress markers, cell wall-degrading enzyme activity, and acidification (notably by A. niger L14), reflecting intense interfungal antagonism. The stress-response mitogen-activated protein kinase (MAPK) pathway was also activated in both fungi. Our findings supported a mechanistic model of fungal competition involving direct contact, chemical exchange, enzymatic attack, and stress signaling, highlighting that physical interactions likely contributed to triggering cryptic secondary metabolism and robust defense responses. Full article

Citrus bud mutants provide valuable genetic resources for breeding early-ripening cultivars with improved fruit quality. However, the physiological mechanisms underlying early ripening traits remain poorly understood. To elucidate the physiological basis for the early-ripening phenotype of the bud mutant ‘Longhuihong’ navel orange, fruit development was systematically monitored from 60 to 240 days after full bloom over two consecutive growing seasons, with the maternal cultivar ‘Newhall’ serving as a control. The results demonstrate that the precocity of ‘Longhuihong’ arises from the coordinated optimization of multiple fruit quality traits in this cultivar. The mutant exhibited enhanced fruit growth potential, with an average increase of 12.07–15.92% in single fruit weight. Peel coloration was significantly accelerated, as reflected by the faster coloring rate. Internal quality development followed a distinct pattern, characterized by high sugar accumulation, rapid acid degradation, and elevated vitamin C content. Notably, citric acid metabolism in ‘Longhuihong’ displayed a unique biphasic profile: substantial accumulation in the early stage, followed by rapid degradation in the later stage, which advanced the peak of the TSS/TA ratio by approximately 15 days. Principal component analysis further confirmed that the early ripening trait represents a systemic and integrated advancement in fruit size, sugar–acid balance, and peel pigmentation. Collectively, these findings provide a comprehensive understanding of the physiological mechanisms underlying precocity in ‘Longhuihong’ and offer key indices for breeding high-quality, early-ripening citrus cultivars. Full article

Canities results from a progressive decline in melanocyte activity and melanin synthesis and is commonly associated with aesthetic concerns that motivate the use of cosmetic products for hair color correction. Shampoo, due to its frequent use, represents a suitable vehicle for the gradual deposition of pigments on the hair fiber. This study aimed to design and develop a shampoo containing dark synthetic semi-permanent dyes for the gradual coverage of gray hair. Four shampoo formulations were developed and evaluated through in vitro tests using bleached hair tresses to assess color deposition and performance. The selected formulation was subsequently subjected to accelerated stability studies and color sustainability evaluation. The results showed that the formulation maintained organoleptic, physicochemical, microbiological, and functional stability. Color sustainability assays indicated that the gray–black coloration persisted on hair tresses containing approximately 90% canities after eight washing cycles. The formulation incorporating the semi-permanent dyes Basic Blue 124, Basic Yellow 87, Basic Orange 31, and Basic Red 51 achieved a gradual gray–black tonal effect. In conclusion, the developed shampoo demonstrated stability and effectiveness for the gradual cosmetic coverage of gray hair. Full article