Yellow Petals Research Articles

DhMYB2 and DhbHLH1 regulates anthocyanin accumulation via activation of late biosynthesis genes in Phalaenopsis-type Dendrobium.

Phalaenopsis-type Dendrobium is a popular orchid with good ornamental and market value. Despite their popularity, molecular regulation of anthocyanin biosynthesis during flower development remains poorly understood. In this study, we systematically investigated the regulatory roles of the transcription factors DhMYB2 and DhbHLH1 in anthocyanins biosynthesis. Gene expression analyses indicated that both DhMYB2 and DhbHLH1 are specifically expressed in flowers and have similar expression patterns, showing high expression in purple floral tissues with anthocyanin accumulation. Transcriptomic analyses showed 29 differentially expressed genes corresponding to eight enzymes in anthocyanin biosynthesis pathway have similar expression patterns to DhMYB2 and DhbHLH1, with higher expression in the purple lips than the yellow petals and sepals of Dendrobium 'Suriya Gold'. Further gene expression analyses and Pearson correlation matrix analyses of Dendrobium hybrid progenies revealed expression profiles of DhMYB2 and DhbHLH1 were positively correlated with the structural genes DhF3'H1, DhF3'5'H2, DhDFR, DhANS, and DhGT4. Yeast one-hybrid and dual-luciferase reporter assays revealed DhMYB2 and DhbHLH1 can bind to promoter regions of DhF3'H1, DhF3'5'H2, DhDFR, DhANS and DhGT4, suggesting a role as transcriptional activators. These results provide new evidence of the molecular mechanisms of DhMYB2 and DhbHLH1 in anthocyanin biosynthesis in Phalaenopsis-type Dendrobium.

Transcriptomic and metabolomic profiling of flavonoid biosynthesis provides novel insights into petals coloration in Asian cotton (Gossypium arboreum L.)

BackgroundAsian cotton (Gossypium arboreum L.), as a precious germplasm resource of cotton with insect resistance and stress tolerance, possesses a broad spectrum of phenotypic variation related to pigmentation. Flower color affects insect pollination and the ornamental value of plants. Studying flower color of Asian cotton varieties improves the rate of hybridization and thus enriches the diversity of germplasm resources. Meanwhile, it also impacts the development of the horticultural industry. Unfortunately, there is a clear lack of studies concerning intricate mechanisms of cotton flower-color differentiation. Hereby, we report an integrative approach utilizing transcriptome and metabolome concerning flower color variation in three Gossypium arboreum cultivars.ResultsA total of 215 differentially accumulated metabolites (DAMs) were identified, including 83 differentially accumulated flavonoids (DAFs). Colorless kaempferol was more abundant in white flowers, while gossypetin-fer showed specificity in white flowers. Quercetin and gossypetin were the main contributors to yellow petal formation. Pelargonidin 3-O-beta-D-glucoside and cyanidin-3-O-(6''-Malonylglucoside) showed high accumulation levels in purple petals. Quercetin and gossypetin pigments also promoted purple flower coloration. Moreover, 8178 differentially expressed genes (DEGs) were identified by RNA sequencing. The correlation results between total anthocyanins and DEGs were explored, indicating that 10 key structural genes and 29 transcription factors promoted anthocyanin biosynthesis and could be candidates for anthocyanin accumulation. Ultimately, we constructed co-expression networks of key DAFs and DEGs and demonstrated the interactions between specific metabolites and transcripts in different color flowers.ConclusionThis study provides new insights into elucidating the regulatory mechanisms of cotton flower color and lays a potential foundation for generate cotton varieties with highly attractive flowers for pollinators.

Genetic and multi-omics analyses reveal BnaA07.PAP2In-184-317 as the key gene conferring anthocyanin-based color in Brassica napus flowers.

The molecular mechanisms underlying anthocyanin-based flower coloration remain unknown in Brassica napus. To identify the key genes and metabolites associated with apricot and pink flower colors, metabolome, BSA-seq, and RNA-seq analyses were conducted on apricot-, pink-, yellow-, and white-flowered F2B. napus. Yellow carotenoids and red anthocyanins were abundant in apricot petals, while colorless carotenoids and red anthocyanins accumulated in pink petals. Most carotenoid genes were not differentially regulated between apricot and yellow or between pink and white petals. Three regulator genes, BnaMYBL2, BnaA07.PAP2, and BnaTT8, and structural genes in anthocyanin biosynthesis were dramatically enhanced in apricot and pink petals in comparison with yellow and white petals. Map-based cloning revealed that BnaA07.PAP2 is responsible for anthocyanin-based flower color and encodes a nucleus-localized protein predominantly expressed in apricot and pink flowers. Two insertions in the promoter region are responsible for the transcriptional activation of BnaA07.PAP2 in flowers. Introducing the BnaA07.PAP2In-184-317 allele broadly activated the expression of anthocyanin-related genes and promoted anthocyanin accumulation in flowers, yielding color change from yellow to apricot. These findings illustrate the genetic basis of anthocyanin-based flower coloration and provide a valuable genetic resource for breeding varieties with novel flower colors in B. napus.

BnaA03.ANS Identified by Metabolomics and RNA-seq Partly Played Irreplaceable Role in Pigmentation of Red Rapeseed (Brassica napus) Petal.

Colorful flowers of rapeseed (Brassica napus L.) have been a hotspot for researchers, but the underlying mechanisms of pigment formation still need to be clarified. In this study, two stages of unopened rapeseed petals with red, white, and yellow colors were selected to identify the metabolites and genes involved in red pigment formation. Metabolomic analysis showed that flavonoids enriched the most co-differentially accumulated metabolites among all categories, and showed higher accumulation in red petal rapeseed than in white and yellow petal ones. RNA-seq analysis showed that among co-differentially expressed genes involved in red pigment formation, genes involved in anthocyanin (belonging to flavonoids) biosynthesis pathway were largely regulated by ANS, DFR, and UF3GT. The expression of those genes was higher in red petals of rapeseed than in white and yellow petals ones as well. Results of RNA interference of BnaA03.ANS in red rapeseed altered petal colors from raspberry red to beige red and zinc yellow under different interference levels, with the contents of pelargonidin, cyanidin, lutein, neoxanthin, β-carotene, and lycopene significantly decreased. However, overexpression of BnaA03.ANS in yellow rapeseed petals did not change the color of yellow petals. This study confirmed the important function of flavonoids, especially anthocyanins on red pigment formation, and for the first time, identified the irreplaceable role of BnaA03.ANS on red-flowered rapeseed.

Changes of Crocin and Other Crocetin Glycosides in Saffron Through Cooking Models, and Discovery of Rare Crocetin Glycosides in the Yellow Flowers of Freesia Hybrida.

Crocetin glycosides such as crocin are noted as functional food materials since the preventive effects of crocin have been reported against chronic disease and cancer. However, it is unclear how these apocarotenoids are structurally changed through cooking for our intake. We examined such changes in crocetin glycosides (crocin, tricrocin, and crocin-3) contained in saffron (stigmas of Crocus sativus) through cooking models. These glycosides were almost kept stable in boiling for 20 min (a boiled cooking model), while hydrolysis of the ester linkage between glucose and the crocetin aglycone occurred in a grilled cooking model (180°C, 5 min), along with a 13-cis isomerization reaction in a part of crocetin subsequently generated. We further here revealed that the yellow petals of freesia (Freesia x hybrida) with yellow flowers accumulate two unique crocetin glycosides, which were identified to be crocetin (mono)neapolitanosyl ester and crocetin dineapolitanosyl ester. A similar result as above was obtained on their changes through the cooking models. Utility applications of the freesia flowers as edible flowers are also suggested in this study. Additionally, we evaluated singlet oxygen (1O2)-quenching activities of the crocetin glycosides contained in saffron and freesia, and crocetin and 13-cis crocetin contained in the grilled saffron, indicating that they possessed moderate 1O2-quenching activities (IC50 24–64 μM).

Comparative Transcriptome and Pigment Analyses Reveal Changes in Gene Expression Associated with Flavonol Metabolism in Yellow Camellia

The accumulation of various pigments leads to the formation of different flower colors in plants. However, the regulation mechanism of yellow flower formation and flower color differences between Camellia nitidssima C.W.Chi (CN) and its hybrids C. ‘Zhenghuangqi’ (ZHQ), C. ‘Huangxuanlv’ (HXL), and C. ‘Xinshiji’ (XSJ), remains largely unknown. Here, we showed that the content of two flavonols, quercetin-7-O-glucoside (Qu7G) and quercetin-3-O-glucoside (Qu3G), was positively correlated with the yellow degree of petals in CN and its three hybrids. Additionally, we performed a comparative transcriptomic analysis of petals of the four yellow camellia plants, which revealed 322 common upregulated and 866 common downregulated DEGs (differentially expressed genes) in the CN vs. ZHQ, CN vs. HXL, and CN vs. XSJ comparison groups. Their regulatory pathway analysis showed that flavonol biosynthesis genes (FLSs and GTs) and transcriptional regulatory genes MYBs were all expressed higher in CN than its three hybrids, which corresponded to differences in the flavonol content among the four yellow camellias. Further, two ethylene synthesis genes (ACSs, ACO) and three ethylene signaling genes (EIN2s, EIN3, ERFs) were all upregulated in the yellow petals of CN. In conclusion, the expression of flavonol-related genes and flavonols (Qu7G and Qu3G) accumulation could play a key role in the formation of yellow flowers in camellia, and the ethylene pathway might be involved in the regulation of yellow flower formation of camellias. This work describes the possible regulatory pathway of yellow camellia, thereby laying a foundation for future verification of genes linked to flower coloring and the breeding of yellow camellia.

Transcriptome Analysis Reveals Key Genes and Pathways Associated with the Petal Color Formation in Cabbage (Brassica oleracea L. var. capitata).

Petal color is an important agronomic trait in cabbage (Brassica oleracea L. var. capitata). Although the key gene BoCCD4 has been functionally characterized, the underlying molecular regulatory mechanism of petal color formation in cabbage is still unclear. In this study, we applied the transcriptome analysis of yellow petals from the cabbage inbred line YL-1 and white petals from the Chinese kale inbred line A192-1 and the BoCCD4-overexpressing transgenic line YF-2 (YL-1 background), which revealed 1928 DEGs common to both the A192-1 vs. YL-1 and the YL-1 vs. YF-2 comparison groups. One key enzyme-encoding gene, BoAAO3, and two key TF-encoding genes, Bo2g151880 (WRKY) and Bo3g024180 (SBP), related to carotenoid biosynthesis were significantly up-regulated in both the A192-1 and YF-2 petals, which was consistent with the expression pattern of BoCCD4. We speculate that these key genes may interact with BoCCD4 to jointly regulate carotenoid biosynthesis in cabbage petals. This study provides new insights into the molecular regulatory mechanism underlying petal color formation in cabbage.

Phytochemical Compositions and Antioxidant Activities of Essential Oils Extracted from the Flowers of Paeonia delavayi Using Supercritical Carbon Dioxide Fluid.

Essential oils were extracted from dark-purple, red and yellow petals of Paeonia delavayi using Supercritical Carbon Dioxide method. The compositions of essential oils were analyzed using gas chromatography-mass spectrometry (GC-MS). Antioxidant activity assays were carried out using DPPH, ABTS- and FRAP methods. Total polyphenols and total flavonoids were measured to evaluate the in vitro antioxidant activity in addition to the volatile compounds contained in the essential oils extracted from the flower petals of P. delavayi with the three flower colors. A total of 194 compounds were detected from essential oils of P. delavayi flowers, including 83 in dark-purple petals, 90 in red petals and 80 in yellow petals. These compounds mainly include alcohols, aldehydes, ketones, alkenes, alkanes, esters and polyphenols. The results showed that the volatile compounds accumulated differentially among the essential oils from the different colors of flower petals. Principal component analysis (PCA) indicated that essential oils derived from dark-purple and red petals were more closely clustered while the yellow petal essential oil was very different with both the purple-red and red. Antioxidant assays suggested that the radical scavenging activity and the iron reduction antioxidant activity in the essential oils were highly correlated with the flower petal colors. These results suggest P. delavayi flower petals are potentially good resources for high quality essential oils and natural antioxidants.

The Carotenoid Esterification Gene BrPYP Controls Pale-Yellow Petal Color in Flowering Chinese Cabbage (Brassica rapa L. subsp. parachinensis).

Carotenoid esterification plays indispensable roles in preventing degradation and maintaining the stability of carotenoids. Although the carotenoid biosynthetic pathway has been well characterized, the molecular mechanisms underlying carotenoid esterification, especially in floral organs, remain poorly understood. In this study, we identified a natural mutant flowering Chinese cabbage (Caixin, Brassica rapa L. subsp. chinensis var. parachinensis) with visually distinguishable pale-yellow petals controlled by a single recessive gene. Transmission electron microscopy (TEM) demonstrated that the chromoplasts in the yellow petals were surrounded by more fully developed plastoglobules compared to the pale-yellow mutant. Carotenoid analyses further revealed that, compared to the pale-yellow petals, the yellow petals contained high levels of esterified carotenoids, including lutein caprate, violaxanthin dilaurate, violaxanthin-myristate-laurate, 5,6epoxy-luttein dilaurate, lutein dilaurate, and lutein laurate. Based on bulked segregation analysis and fine mapping, we subsequently identified the critical role of a phytyl ester synthase 2 protein (PALE YELLOW PETAL, BrPYP) in regulating carotenoid pigmentation in flowering Chinese cabbage petals. Compared to the yellow wild-type, a 1,148 bp deletion was identified in the promoter region of BrPYP in the pale-yellow mutant, resulting in down-regulated expression. Transgenic Arabidopsis plants harboring beta-glucuronidase (GUS) driven by yellow (BrPYPY::GUS) and pale-yellow type (BrPYPPY::GUS) promoters were subsequently constructed, revealing stronger expression of BrPYPY::GUS both in the leaves and petals. Furthermore, virus-induced gene silencing of BrPYP significantly altered petal color from yellow to pale yellow. These findings demonstrate the molecular mechanism of carotenoid esterification, suggesting a role of phytyl ester synthase in carotenoid biosynthesis of flowering Chinese cabbage.

Comparative analyses of American and Asian lotus genomes reveal insights into petal color, carpel thermogenesis and domestication.

SUMMARY Nelumbo lutea (American lotus), which differs from Nelumbo nucifera (Asian lotus) morphologically, is one of the two remaining species in the basal eudicot family Nelumbonaceae. Here, we assembled the 843‐Mb genome of American lotus into eight pseudochromosomes containing 31 382 protein‐coding genes. Comparative analyses revealed conserved synteny without large chromosomal rearrangements between the genomes of American and Asian lotus and identified 29 533 structural variants (SVs). Carotenoid and anthocyanin pigments determine the yellow and red petal colors of American and Asian lotus, respectively. The structural genes encoding enzymes of the carotenoid and anthocyanin biosynthesis pathways were conserved between two species but differed in expression. We detected SVs caused by repetitive sequence expansion or contraction among the anthocyanin biosynthesis regulatory MYB genes. Further transient overexpression of candidate NnMYB5 induced anthocyanin accumulation in lotus petals. Alternative oxidase (AOX), uncoupling proteins (UCPs), and sugar metabolism and transportation contributed to carpel thermogenesis. Carpels produce heat with sugars transported from leaves as the main substrates, because there was weak tonoplast sugar transporter (TST) activity, and with SWEETs were highly expressed during thermogenesis. Cell proliferation‐related activities were particularly enhanced in the warmer carpels compared with stamens during the cold night before blooming, which suggested that thermogenesis plays an important role in flower protogyny. Population genomic analyses revealed deep divergence between American and Asian lotus, and independent domestication affecting seed, rhizome, and flower traits. Our findings provide a high‐quality reference genome of American lotus for exploring the genetic divergence and variation between two species and revealed possible genomic bases for petal color, carpel thermogenesis and domestication in lotus.

Development of linkage InDel markers of the white petal gene based on whole-genome re-sequencing data in <italic>Brassica napus</italic> L.

<p id="C3">InDel is widely distributed across the genome and occurs in a high density and large numbers in a genome. To date, the researches about linkage InDel markers of the white petal gene in <italic>B. napus</italic> L are very less yet. In this study, we constructed the F₂ mapping population from the cross between DH Y05 (yellow petal) and DH W01 (white petal). Two bulks with 30 yellow petal lines and 30 white petal lines of F₂ population were constructed by mixing an equal amount of DNA. Then two bulks and parents were performed 30× whole-genome re-sequencing. Darmor-bzh as the reference genome was aligned to sequence data from the two bulks and parents. QTL-seq and PoPoolation2 workflow were applied to identify the candidate region of the white petal gene. A major candidate region was identified on chromosome C03 (52-54 Mb) of Darmor-bzh. The insertion-deletion (InDel) sites can be visualized in candidate interval by Integrative Genomics Viewer (IGV). Based on these Indel variations, we used Vector and Blast to design InDel primers. Eight InDel markers closely linked to the white petal gene were screened by Polyacrylamide gel electrophoresis (PAGE). In summary, these results provide a basis for fine mapping white petal gene and InDel molecular marker located on functional genes as well as molecular marker assisted selection breeding.

Consumer Preferences of Ratibida columnifera (Nutt.) Wooton &amp; Standl. Floral Characteristics

Conjoint analysis can be used to simultaneously investigate consumer preferences on multiple attributes and levels. Our objective was to gain insight regarding consumer preferences for attributes and levels attributed to Ratibida columnifera, a wildflower of potential commercial interest. A ratings-based conjoint analysis using petal color (bicolor, marble, red, yellow), petal shape (circular, oval, notched, lobed), petal number (less than 10, more than 10), and price ($10.00, $15.00, $20.00) was conducted to elucidate part-worth utility from data from 1000 subjects recruited using Amazon Mechanical Turk (MTurk), a crowdsourcing marketplace. Subjects were then clustered according to their conjoint utility scores. In addition to the conjoint analysis, a principal component analysis was performed based on native plant knowledge of the respondent. Conjoint results revealed that petal color was the most important attribute in decision making, followed by price, petal shape, and petal number. Utility values revealed preference for bicolor petals, followed by red, yellow, and marbled color petals. Preference for price went from least expensive to most expensive. Circular petals were favored over oval, notched, and lobed. Subjects also preferred to have 10 petals or more, vs. less than 10 petals. Cluster analysis yielded three consumer segments, which differed in their utility values. These clusters differed in both demographics and R. columnifera preferences. Overall, consumers preferred R. columnifera with partial (bicolor) or complete red coloration over other options, lower prices, more petals, and entire circular or oval petals.

Quercetin-derivatives painting the yellow petals of American lotus (Nelumbo lutea) and enzymatic basis for their accumulation

American lotus (Nelumbo lutea) is one of the two species in Nelumbo and has only yellow flower. Identification of total flavonoids showed wild American lotus contained almost only flavonols with quercetin 3-O-glucuronide to be the dominant pigment. The variation tendency of the total flavonol content was coincident with yellow color variation of petals during flower development. To understand the mechanism of accumulation and constituent of pigments in petals, three pivotal genes, NlFLS1, NlFLS2 and NlFLS3, which were predicted to encode flavonol synthases were isolated and characterized by analyses of basic bioinformatics, temporal and spatial expression patterns and enzymatic activity. Their temporal expression levels showed the same variation tendency, which was also consistent with the development-dependent variation of total flavonol content. Spatial expression patterns indicated the three genes should function in petals. All the three proteins were demonstrated to be bifunctional dioxygenase, possessing both flavonol synthase activity and flavanone 3-hydroxylase activity. Besides, other flavonol biosynthesis related genes were also investigated on their expression levels to give more clues on the mechanism. Substrate preferences of the three FLSs, substrate competitions between the FLSs and other flavonol biosynthesis related enzymes, and the greatly differential expression levels between F3’H (flavonoid 3′-hydroxylase) and F3’5’H (flavonoid 3′,5′-hydroxylase) contributed to the flavonol constituent in the petals of America lotus, namely abundant quercetin-derivatives while very few kaempferol-derivatives and myricetin-derivatives.

Map-Based Cloning and Characterization of Br-dyp1, a Gene Conferring Dark Yellow Petal Color Trait in Chinese Cabbage (Brassica rapa L. ssp. pekinensis)

Flower color is an important trait in Brassica species. However, genes responsible for the dark yellow flower trait in Chinese cabbage have not been reported. In this study, we identified a dark-yellow-flowered Chinese cabbage line SD369. Genetic analysis indicated that the dark yellow flower trait in SD369 was controlled by a single recessive locus, Br-dyp1 (dark yellow petal color 1 in Brassica rapa). Using bulked segregant RNA sequencing and kompetitive allele-specific PCR assays, Br-dyp1 was fine-mapped to an interval of 53.6 kb on chromosome A09. Functional annotation analysis, expression analysis, and sequence variation analysis revealed that Bra037130 (BraA09.ZEP), which encodes a zeaxanthin epoxidase, was the most likely candidate gene for Br-dyp1. Carotenoid profile analysis suggested that Bra037130 (BraA09.ZEP) might participate in the epoxidation from zeaxanthin to violaxanthin. The 679 bp insertion in dark yellow petal caused premature stop codon, thus caused the loss-of-function of the enzyme zeaxanthin epoxidase (ZEP), which disturbed the carotenoid metabolism, and caused the increased accumulation of total carotenoid, and finally converted the flower color from yellow to dark yellow. Comparative transcriptome analysis also showed that the “carotenoid biosynthesis” pathway was significantly enriched, and genes involved in carotenoid degradation and abscisic acid biosynthesis and metabolism were significantly downregulated. Furthermore, we developed and validated the functional marker Br-dyp1-InDel for Br-dyp1. Overall, these results provide insight into the molecular basis of carotenoid-based flower coloration in B. rapa and reveal valuable information for marker-assisted selection breeding in Chinese cabbage.

Pitcairniaabscondita (Pitcairnioideae, Bromeliaceae), a hidden novelty from north-western Jalisco, Mexico.

Pitcairniaabsconditasp. nov., known until now only from the Municipalities of Cabo Corrientes, Mascota, Puerto Vallarta, San Sebastián del Oeste and Talpa de Allende in the State of Jalisco, Mexico, is here described and illustrated. The new taxon was confused with P.imbricata for long time, but differs from this species by its green floral bracts with the apex divergent to spreading (vs. red and appressed) and by the appendiculate at the base chartreuse-green petals (vs. not appendiculate yellow petals). Images and a distribution map of the taxa are presented.

Comparative analysis of the orange versus yellow petal of rapeseed (Brassica napus) using UPLC‐HESI‐MS/MS and transcriptome analysis

AbstractThe petal colour of rapeseed plants is usually yellow but can range from milky white to orange or pink, making petal colour a popular target in rapeseed breeding programmes. In this study, metabolites and RNA were extracted from the yellow (Bn‐Y) and orange (Bn‐O) petal colour lines in rapeseed. Chromatography analysis, RNA‐Seq and quantitative RT‐PCR analysis were conducted. A total of 89 differential metabolites including 64 down‐regulated and 25 up‐regulated metabolites were identified in the petals of orange versus yellow rapeseed by UHPLC‐ESI‐MS/MS. A total of 168 differentially expressed genes (DEGs) were detected in the petals of Bn‐O versus Bn‐Y plants. KEGG functional annotation and quantitative RT‐PCR analysis showed that BnaC08g39510D and BnaA09g10680D expression was significantly higher in orange petals than in yellow and that BnaC09g07880D and BnaC09g08690D were strongly expressed in yellow petals but were not expressed in orange petals. These results will be useful for further understanding the molecular mechanisms underlying petal colour and provide the theoretical and practical basis for breeding varieties with colourful petals.

The esterification of xanthophylls in Solanum lycopersicum (tomato) chromoplasts; the role of a non-specific acyltransferase

The esterification of carotenoids has been associated with high-level accumulation, greater stability and potentially improved dietary bioavailability. Engineering the formation of ketocarotenoids into tomato fruit has resulted in the esterification of these non-endogenous metabolites. A genotype of tomato was created that contains; (i) the mutant pale yellow petal (pyp)1-1 allele, which is responsible for the absence of carotenoid esters in tomato flowers and (ii) the heterologous enzymes for ketocarotenoid formation. Analysis of the resulting progeny showed altered quantitative and qualitative differences in esterified carotenoids. For example, in ripe fruit tissues, in the presence of the pyp mutant allele, non-endogenous ketocarotenoid esters were absent while their free forms accumulated. These data demonstrate the involvement of the PYP gene product in the esterification of diverse xanthophylls.

Distinguishing between isomeric neoxanthin and violaxanthin esters in yellow flower petals using liquid chromatography/photodiode array atmospheric pressure chemical ionization mass spectrometry and tandem mass spectrometry.

RationaleLiquid chromatography/photodiode array atmospheric pressure chemical ionization mass spectrometry (LC/PDA‐APCI‐MS) is used for the analysis of various carotenoid pigments in plants. Among them, it is difficult to distinguish between the isomeric violaxanthin/neoxanthin esters.MethodsThe yellow pigments of tomato petals were extracted with acetone, and the extracts were kept at −30°C to allow the contaminating triacylglycerols to settle out physically. The supernatants were analyzed using LC/PDA‐APCI‐MS with a high‐resolution orbitrap mass spectrometer for their exact masses. The expected carotenoid esters were calculated with the combination of carotenoids and fatty acids, and they were matched with the experimental exact masses. The fatty acid structures in the carotenoid esters were also identified using collision‐induced dissociation (CID) tandem mass spectrometry (MS/MS). The isomeric violaxanthin/neoxanthin esters were distinguished using CID MS/MS from their in‐source dehydrated product ions as pseudoprecursor ions.ResultsThe in‐source dehydrated ions [M − H2O + H]+ of neoxanthin diesters predominated over their protonated molecules [M + H]+ in LC/MS. By contrast, the protonated molecules of violaxanthin diesters predominated. The 92 u loss product ions [M − H2O − C7H8 + H]+ were observed from the dehydrated violaxanthin diesters, but they were not generated from the dehydrated neoxanthin diesters in the CID MS/MS of their dehydrated pseudoprecursor ion [M − H2O + H]+.ConclusionsThe allene allyl carbocation in neoxanthin diesters was generated from dehydration after preferential protonation at the hydroxy group. The epoxide group of violaxanthin diesters opens easily after protonation; however, the dehydration did not proceed at this stage. The 92 u loss of C7H8 was explained by an intramolecular [2 + 2] cycloaddition, which proceeded preferentially in dehydrated violaxanthin diesters because the carbocations in the dehydrated species were conjugated to the polyene and those double bonds were depolarized during CID MS/MS. Therefore, the isomeric neoxanthin/violaxanthin diesters were distinguished using LC/PDA‐APCI‐MS and MS/MS. This method was a practical and useful method of profiling the carotenoid esters of the yellow petals.

Morphology and distribution of species of the family Cucurbitaceae in Akwa Ibom State, Nigeria

A study of the family Cucurbitaceae in Akwa Ibom State, Nigeria, was carried out in 15 Local Government Areas in different ecological zones across the State, where collections were made between May 2017 and June 2018. A total of eleven species in nine genera were collected: Citrullus lanatus, Citrullus mucosospermus, Cucumis sativus, Cucurbita maxima, Lagenaria siceraria, Lagenaria sphaerica, Luffa aegyptiaca, Momordica charantia, Siraitia africana, Telfairia occidentalis, and Trichosanthes cucumerina. Variation in morphology were seen in the investigated species in the stem shape that were cylindrical or angular, the compound or simple types of leaves, the indumentum of the leaf, the acute or acuminate leaf apices, the yellow or white petals, the cylindrical, spherical or irregular fruit shape, the lanceolate or irregular seed shape, and the pubescent or smooth seed. Cultivated cucurbits collected were 65% of the species investigated, while 35% occurred in the wild. A survey of the Cucurbitaceae collections in the Forest Herbarium Ibadan showed only four species recorded for Akwa Ibom State, of which only Luffa aegyptica was identified and collected in the course of this work. More cultivation should be encouraged, as this will serve as a conservation measure for cucurbits in the State.

Application of new natural dyes extracted from Nasturtium flowers (Tropaeolum majus) as photosensitizer in dye-sensitized solar cells

This work reported the natural dyes extracted from yellow and orange Nasturtium (Tropaeolum majus) flower petals and then used them as sensitizer in dye-sensitized solar cells (DSSCs) for the first time. The functional groups present in the dyes were identified by FTIR spectroscopy which revealed the characteristic peaks of pigments anthocyanins and carotenoids. The UV–Visible analysis of dye extracts showed absorption in the visible region and the dye loaded TiO2 exhibited broad absorption. The density functional theory (DFT) calculation was performed on Lutein, Cyanidin-3-sophoroside, Delphinidine-3-dihexoside and Pelargonidin-3-sophoroside to find out the HOMO and LUMO levels of each. The DSSCs were constructed using these natural extracts as sensitizer dye and photovoltaic performance such as conversion efficiency (η), short-circuit current density (Jsc), open-circuit voltage (Voc) and fill factor (FF) were investigated. The electrochemical impedance spectroscopy (EIS) studies were performed to analyze the charge transfer characteristics. The light-to-electricity conversion efficiency of 0.28% is achieved with Voc of 0.556 V, Jsc of 0.72 mA/cm2 and FF of 0.70 for natural sensitizer extracted from orange petals of Nasturtium flowers.