Floral Scent Research Articles

Post-processing of a lavender flowers solvent extract using supercritical CO2 fractionation

BackgroundSupercritical Fluid Extraction (SFE) was performed using an unconventional material, the solid extract of lavender flowers obtained by liquid solvent extraction and subsequent solvent elimination. MethodsSystematic extraction experiments were carried out at 8 MPa and 40 °C, and the extract was fractionated in semi-continuous mode in the SFE plant. To understand mass transfer phenomena driving the process, CO2 mass flow rates ranging between 0.60 and 1.50 kg/h were used, and yield vs. time curves were obtained. Significant findingsFractionation produced a cuticular waxes selective precipitation in the first separator and the floral fragrance in the second separator. The most abundant species in the extract were τ-cadinol (13%), lavandulol (10.5%), β-caryophyllene (10%), viridiflorene (8.5%), isocaryophyllene (6%), cedrenalol (4.5%), linalool (4%) and 1,8-cineol (4%). The fragrance contained no waxes, indicating that the fractionation was successful. At higher mass flow rates (from 0.90 to 1.50 kg/h), an asymptotic extraction yield of 5.2% w/w was obtained; whereas, at lower mass flow rates, the extraction yield was lower (2.3% w/w) since the vegetable bed was not completely wetted by the extraction fluid. The overall results indicated that an external mass transfer resistance controlled the process.

Differences in Aroma Metabolite Profile, Microstructure, and Rheological Properties of Fermented Milk Using Different Cultures.

Texture and flavour are the key attributes determining sensory quality and are highly affected by starter cultures. A selection of phenotypic strains is needed to create diverse texture and flavour to meet consumers' preferences. In this study, the use of five lactic acid bacteria strains in the production of fermented milk, along with the metabolite profiles, microstructure, and rheological properties of the fermented milk samples, was investigated. Our results showed that Lactobacillus helveticus (LH) and Streptococcus thermophilus (ST) had a stronger acidification during fermentation but resulted in products with a coarser protein network compared to Lactococcus lactis (BL1) and Leuconostoc mesenteroides (CL3). Milk fermented by LH had the highest viscosity and exopolysaccharide concentration, while milk fermented by ST had the highest concentration of diacetyl. Although Leuconostoc pseudomesenteroides (CL3ST) had a minimal acidification capability, it produced high levels of ethyl-derived compounds associated with sweet, fruity, and floral fragrances. The results demonstrated that LH and ST could be used as starter cultures targeting fermented milks with different viscosities, while BL1, CL3, and CL3ST are suitable as adjunct cultures to impact different acidic sharpness and flavour notes.

Sweet as Vanilla hartii: Evidence for a nectar-rewarding pollination mechanism in Vanilla (Orchidaceae) flowers

Little is known about the pollination mechanisms of species belonging to the genus Vanilla (Orchidaceae). Both autonomous self-pollination and animal-mediated pollination mechanisms seem to exist amongst the Vanilla species, yet few studies provided real evidence on pollination events. The aim of this study was to better understand the pollination mechanism of Vanilla hartii. Four V. hartii populations were selected within our study area in southern Costa Rica to observe pollination events and identify the natural pollinators of this Neotropical Vanilla species. We tested for nectar presence, analysed nectar composition, and examined floral fragrances. Furthermore, we identified floral visitors and documented their behaviour, quantified fruit set during two years, and compared morphological traits of flowers and their visitors. Sampled flowers contained 1.85 ± 1.07 µL nectar that averaged 34.79% sugar, dominated by sucrose. We observed orchid bees belonging to the genus Euglossa entering the tube formed by the labellum to search for nectar, indicated by their extended proboscis and prolonged visits, some of which exited the labellar tube with pollen masses attached to their scutellum. Combining our behavioural and phytochemical data, we demonstrate the presence of a nectar-rewarding pollination mechanism in the genus Vanilla that shows a higher natural fruit set compared to deceptive Vanilla species. An overview of the pollination mechanisms known so far provides insights into the potential evolution of reproductive strategies within this commercially important orchid genus.

Surface and Adhesion Properties of a Softener Containing Fragrances Microencapsulated with Poly (Methyl Methacrylate) on Cotton, Polyester, and a Mixture of Cotton and Polyester Fabrics

The distribution and adhesion of microcapsules on fabric surfaces are crucial factors for the production of long-lasting fragrance textiles. The objective of this research was to study the adhesion property of a softener containing microencapsulated fragrances on fabrics. Pink fruity fragrance (PF), and white floral fragrance (WF) were encapsulated with poly (methyl methacrylate) or PMMA, using the micro-suspension photopolymerization method, to form PF-PMMA, and WF-PMMA microcapsules, respectively. The particle sizes and zeta potential of the capsules were determined. The PF-PMMA and WF-PMMA were added to the fabric softener before being applied to three types of fabrics, cotton, TK (polyester), and TC (a mixture of cotton and TK). Surface morphologies of the fabrics treated with the softener were studied by scanning electron microscope (SEM). Interactions between the microcapsules and the fabrics were studied using a contract angle measurement device, Fourier Transform Infrared (FTIR) spectrometer, and Raman microscope. The average size of PF-PMMA was 484.8 ± 4.0 nm, smaller than that of WF-PMMA (664.6 ± 2.9 nm). Cotton was found to be hydrophilic with a rough surface due to cellulose fibers, while TK surface was smooth and hydrophobic. The different fiber structures and surface properties of the fabrics gave rise to different adhesion behavior, evidenced by the contract angle and Raman microscopic data. After 60 days of storage, the microencapsulated fragrances were found to remain on the cotton surfaces, but that on the TC and the TK surfaces disappeared. The results illustrated the interaction between the fabric surface and the microcapsules encapsulated with fragrances, which affected their adhesion. The knowledge obtained can be applied to the development of household products with long-lasting fragrances.

Effect of culture and familiarity on wine perception: a study with British and Spanish wine experts

The main objective of the present work was to evaluate the effect of culture through familiarity of wine technical experts on the perception of wine quality. A total of 32 wine experts from the United Kingdom and Spain undertook two sensory tasks with a total of 18 still white wines from these countries. The first assignment consisted in a descriptive task followed by a labelled free sorting task. The second assignment was a categorisation task in which experts had to classify the samples into groups based on five pre-established quality categories (ranging from very low to very high quality). Finally, experts evaluated their level of familiarity with the grape varieties employed. Results showed that grape variety was a key marker of the sensory profile of the evaluated wines. Wines made of the Albariño variety were described mainly as sour and as having a white fruit aroma, Verdejo wines were mainly sour and had fresh fruity aromas, the Bacchus variety was described as having floral aromas, and the Ortega wines as having oxidised, animal and defective aromas. In terms of perceived quality, leaving aside the wines of the Ortega variety, which showed an oxidation character resulting in the lowest quality scores according to both British and Spanish experts, it was observed that there is a clear effect of familiarity on the perception of quality. Spanish experts were significantly more familiar with Verdejo and Albariño varieties than with Bacchus, resulting in higher quality scores for Spanish varieties. In contrast, quality scores of the Bacchus wines and the wines produced from the two Spanish varieties were not significantly different in terms of quality according to the British experts, as were the familiarity scores reported by this group of experts. This work increases knowledge about the formation of quality perception and confirms the effect of familiarity on perceived quality among wine experts, highlighting the importance of cognitive factors in the construction of wine perception.

Integrated metabolome and transcriptome analysis provides insights on the floral scent formation in Hydrangea arborescens.

Hydrangea (Hydrangea arborescens var. "Annabelle") flowers are composed of sweet aroma sepals rather than true petals and can change color. Floral volatiles plays important roles in plants, such as attracting pollinators, defending against herbivores, and signaling. However, the biosynthesis and regulatory mechanisms underlying fragrance formation in H. arborescens during flower development remain unknown. In this study, a combination of metabolite profiling and RNA sequencing (RNA-seq) was employed to identify genes associated with floral scent biosynthesis mechanisms in "Annabelle" flowers at three developmental stages (F1, F2, and F3). The floral volatile data revealed that the "Annabelle" volatile profile includes a total of 33 volatile organic compounds (VOCs), and VOCs were abundant during the F2 stage of flower development, followed by the F1 and F3 stages, respectively. Terpenoids and benzenoids/phenylpropanoids were abundant during the F2 and F1 stages, with the latter being the most abundant, whereas fatty acid derivatives and other compounds were found in large amounts during the F3 stage. According to ultra-performance liquid chromatography-tandem mass spectrometer analysis, benzene and substituted derivatives, carboxylic acids and derivatives, and fatty acyls play a significant role in the floral metabolite profile. The transcriptome data revealed a total of 17,461 differentially expressed genes (DEGs), with 7585, 12,795, and 9044 DEGs discovered between the F2 and F1, F3 and F1, and F2 and F3 stages, respectively. Several terpenoids and benzenoids/phenylpropanoids biosynthesis-related DEGs were identified, and GRAS/bHLH/MYB/AP2/WRKY were more abundant among transcription factors. Finally, DEGs interlinked with VOCs compounds were determined using Cytoscape and k-means analysis. Our results pave the way for the discovery of new genes, critical data for future genetic studies, and a platform for the metabolic engineering of genes involved in the production of Hydrangea's signature floral fragrance.

Chronic larval exposure to thiacloprid impairs honeybee antennal selectivity, learning and memory performances.

The use of agricultural neonicotinoid insecticides has sub-lethal chronic effects on bees that are more prevalent than acute toxicity. Among these insecticides, thiacloprid, a commonly used compound with low toxicity, has attracted significant attention due to its potential impact on the olfactory and learning abilities of honeybees. The effect of sub-lethal larval exposure to thiacloprid on the antennal activity of adult honeybees (Apis mellifera L.) is not yet fully understood. To address this knowledge gap, laboratory-based experiments were conducted in which honeybee larvae were administered thiacloprid (0.5mg/L and 1.0mg/L). Using electroantennography (EAG), the impacts of thiacloprid exposure on the antennal selectivity to common floral volatiles were evaluated. Additionally, the effects of sub-lethal exposure on odor-related learning and memory were also assessed. The results of this study reveal, for the first time, that sub-lethal larval exposure to thiacloprid decreased honeybee antenna EAG responses to floral scents, leading to increased olfactory selectivity in the high-dose (1.0mg/L) group compared to the control group (0mg/L vs. 1.0mg/L: p = 0.042). The results also suggest that thiacloprid negatively affected odor-associated paired learning acquisition, as well as medium-term (1h) (0mg/L vs. 1.0mg/L: p = 0.019) and long-term memory (24h) (0mg/L vs. 1.0mg/L: p = 0.037) in adult honeybees. EAG amplitudes were dramatically reduced following R-linalool paired olfactory training (0mg/L vs. 1.0mg/L: p = 0.001; 0mg/L vs. 0.5mg/L: p = 0.027), while antennal activities only differed significantly in the control between paired and unpaired groups. Our results indicated that exposure to sub-lethal concentrations of thiacloprid may affect olfactory perception and learning and memory behaviors in honeybees. These findings have important implications for the safe use of agrochemicals in the environment.

Biochemistry and Genetics of Floral Scent - A Historical Perspective.

Floral scent plays a crucial role in the reproduction process of many plants. Humans have been fascinated by floral scents throughout history, and have transported and traded floral scent products, for which they have found multiple uses as food additives, hygiene and perfume products, and medicines. Yet the scientific study of how plants synthesize floral scent compounds began later than studies on most other major plant metabolites, and the first report of the characterization of an enzyme responsible for the synthesis of a floral scent compound - linalool in Clarkia breweri, a California annual - appeared in 1994. In the almost 30 years since, enzymes and genes involved in the synthesis of hundreds of scent compounds from multiple plant species have been described. This review recapitulates this history and describes the major findings relating to the various aspects of floral scent biosynthesis and emission, including genes and enzymes and their evolution, storage and emission of scent volatiles, and the regulation of the biochemical processes.

Labellum Features and Chemical Composition of Floral Scent in Bulbophyllum carunculatum Garay, Hamer & Siegrist (Section Lepidorhiza Schltr., Bulbophyllinae Schltr., Orchidaceae Juss.)

The vast majority of fly-pollinated Bulbophyllum species use a combination of visual and olfactory clues to mimic food sources and brood/oviposition sites of pollinators. The aims of the present work were to characterize the floral secretory tissue and the floral scent and compare them with those previously described in B. echinolabium. Based on the histochemical results, the labellar secretion in B. carunculatum is the protein-rich mucilage. The adaxial epidermal cells of the labellum showed typical features of secretory activity. Plastids contained plastoglobuli, which are thought to be the places for scent production in osmophores. Juxtaposed with FeCl3 staining, the presence of dihydroxyphenolic globules in the cytoplasm of the epidermis and sub-epidermis was confirmed. Phenolic derivatives were also described with GC/MS analysis of the floral scent. The number of aromatic compounds and hydrocarbons was indicated in the floral scent of B. carunculatum. Moreover, pregnane-3,20-dione, occurring in the highest percentage in the floral fragrance of B. carunculatum, is a biologically active, 5-alpha-reduced metabolite of plasma progesterone. Progesterone is a mammalian gonadal hormone, but, like other steroid hormones, has been found in plants as intermediates in different biosynthetic pathways. The research on biosynthesis and functions of progesterone and its derivatives in flowers is still lacking.

Novel hybrids with floral scent between Lagerstroemia caudata and three L. indica cultivars

L. caudata, native to China, is valued for its floral fragrance while flower size and color still negatively affects their economic value. In this study, three L. indica cultivars ‘Bai Yun Ying Xia’, ‘Qiao Jia Ren’ and ‘Fen Hu Die’ with diverse flower traits were chosen to make cross with L. caudata. Finally, a total of 2832 crosses were obtained, including interspecific, backcross and self-pollination combinations between L. caudata and L. indica. Nearly 260 hybrid seedlings were survived. Hybridity was confirmed by both morphological comparison and simple sequence repeat markers (SSR) technique. All obtained interspecific seedlings were generally intermediate in morphological traits of their parents, but variable in leaf blade length, leaf blade width, leaf blade length/width ratio, flower diameter, flower claw length, petal length, flower color and floral fragrance. Our results suggested that it is possible to optimize floral fragrance of Lagerstroemia cultivars by using L. caudata and the hybrids obtained in this study. These findings could be served as the basis for the development of superior plants with unique combinations of ornamental traits.

The LibHLH22 and LibHLH63 from Lilium ‘Siberia’ Can Positively Regulate Volatile Terpenoid Biosynthesis

Basic helix-loop-helix (bHLH) transcription factors (TFs) play irreplaceable roles in plant growth and development, especially in plant secondary metabolism. However, the functions of most bHLH TFs in Lilium ‘Siberia’ are still unknown, especially their roles in regulating floral fragrance. In this study, two bHLH TFs in lily, i.e., LibHLH22 and LibHLH63, were identified and functionally characterized. A bioinformatics analysis revealed that LibHLH22 and LibHLH63 were unstable proteins. Subcellular localization demonstrated that LibHLH22 and LibHLH63 proteins were in the cell nucleus. Quantitative real-time PCR showed that the highest expression level of LibHLH22 was at the initial flowering stage and in the stigma, and the highest expression level of LibHLH63 was at the budding stage and in the filaments. The results of transient overexpression and virus-induced gene silencing (VIGS) of LibHLH22 and LibHLH63 in lily petals showed that these two transcription factors significantly promoted the expression of LiDXR and LiTPS2, and thus, markedly enhanced the release of floral fragrance. Our results indicated that LibHLH22 and LibHLH63 could effectively regulate the fragrance of Lilium ‘Siberia’, laying the foundation for fragrance breeding and improving the terpenoid transcriptional regulatory pathway.

Cloning and Functional Characterization of 2-C-methyl-D-erythritol-4-phosphate cytidylyltransferase (LiMCT) Gene in Oriental Lily (Lilium 'Sorbonne').

2-C-methyl-D-erythritol-phosphate cytidylyltransferase (MCT) is a key enzyme in the MEP pathway of monoterpene synthesis, catalyzing the generation of 4- (5'-pyrophosphate cytidine)-2-C-methyl-D-erythritol from 2-C-methyl-D-erythritol-4-phosphate. We used homologous cloning strategy to clone gene, LiMCT, in the MEP pathway that may be involved in the regulation of floral fragrance synthesis in the Lilium oriental hybrid 'Sorbonne.' The full-length ORF sequence was 837bp, encoding 278 amino acids. Bioinformatics analysis showed that the relative molecular weight of LiMCT protein is 68.56 kD and the isoelectric point (pI) is 5.12. The expression pattern of LiMCT gene was found to be consistent with the accumulation sites and emission patterns of floral fragrance monoterpenes in transcriptome data (unpublished). Subcellular localization indicated that the LiMCT protein is located in chloroplasts, which is consistent with the location of MEP pathway genes functioning in plastids to produce isoprene precursors. Overexpression of LiMCT in Arabidopsis thaliana affected the expression levels of MEP and MVA pathway genes, suggesting that overexpression of the LiMCT in A. thaliana affected the metabolic flow of C5 precursors of two different terpene synthesis pathways. The expression of the monoterpene synthase AtTPS14 was elevated nearly fourfold in transgenic A. thaliana compared with the control, and the levels of carotenoids and chlorophylls, the end products of the MEP pathway, were significantly increased in the leaves at full bloom, indicating that LiMCT plays an important role in regulating monoterpene synthesis and in the synthesis of other isoprene-like precursors in transgenic A. thaliana flowers. However, the specific mechanism of LiMCT in promoting the accumulation of isoprene products of the MEP pathway and the biosynthesis of floral monoterpene volatile components needs further investigation.

Analysis of Floral Scent and Volatile Profiles of Different Aster Species by E-nose and HS-SPME-GC-MS.

Plants from the Aster species are known to be a rich source of bioactive chemical compositions and are popularly known for their medicinal properties. To investigate the relationship between the nine species of Aster, the floral fragrance and volatile profile patterns were characterized using E-nose and HS-SPME-GC-MS. Initial optimization for fragrance analysis was performed with Aster yomena using E-nose by evaluating the scent patterns in different flowering stages. Aster yomena exhibited varied scent patterns in each flowering stage, with the highest relative aroma intensity (RAI) in the full flowering stage. PCA analysis to compare and analyze the scent characteristics of nine Aster species, showed a species-specific classification. HS-SPME-GC-MS analysis of flowers from nine Aster species revealed 52 volatile compounds including β-myrcene, α-phellandrene, D-limonene, trans-β-ocimene, caryophyllene, and β-cadinene. The terpenoid compounds accounted for the largest proportion. Among the nine Aster species flowers, Aster koraiensis had sesquiterpenes as the major component, and the remaining eight varieties had monoterpenes in abundance. These results could distinguish the species according to the scent patterns and volatile components of the nine Aster species. Additionally, flower extracts from the Aster species' plants exhibited radical scavenging antioxidant activity. Among them, it was confirmed that Aster pseudoglehnii, Aster maackii, and Aster arenarius had high antioxidant activity. In conclusion, the results of this study provide fundamental data of the volatile compound properties and antioxidant activity of Aster species, offering basic information of valuable natural sources that can be utilized in the pharmaceutical, perfume, and cosmetic industries.

Analysis of Aroma Volatiles from Michelia crassipes Flower and Its Changes in Different Flower Organs during Flowering

Michelia crassipes is a great ornamental plant, the flowers of which have high economic value. In this study, we employed headspace solid-phase microextraction (HS–SPME) combined with gas chromatography high-resolution mass spectrometry (GC–HRMS) for the first time to identify the volatile compounds emitted from different organs of M. crassipes flowers at different flowering stages. M. crassipes flower odor comprises 69 volatile compounds that are dominated by terpenes constituting 84% of collected volatiles. It was found that α-guaiene, β-caryophyllene and germacrene B had the highest relative amounts, while ethyl 3-methyl valerate, methyl benzoate and β-damascone had the highest odor activity values (OAVs). This contributed to the complex fruity, woody and floral aromas of M. crassipes. Total odor emission increased along the flower blooming, which was most abundant in the pistil followed by tepals and stamens. Paraffin sections of M. crassipes flower organs showed the highest density of oil secretory cells in the pistil at the full flowering stage, which was positively correlated with total odor release. The scent of the pistil and tepals was characterized by terpenes, whereas stamens was characterized by benzenoids. We suggest that the benzenoids in stamens might contribute to pollinator attraction in M. crassipes.

Effects of processing procedures on the formation of aroma intensity and odor characteristic of Benshan tea (Oolong tea, Camellia sentences)

Benshan tea is a kind of oolong tea, and Benshan (Camellia sinensis) tea tree originates from Anxi County of Fujian Province in China, which is a national tea tree breed. Tea processing is the key to the formation of its odor characteristics. It is extremely important to step by step analyze effects of tea processing on aroma intensity and the formation of odor characteristics for optimizing tea processing process and improving tea quality. The results of this study showed that processing resulted in a significant increase in the content of volatile compounds in tea leaves, i.e., from 25.213 μg/kg to 111.223 μg/kg, in which the volatile compounds were mainly terpenoids. Secondly, the analysis found that 20 kinds of key compounds constituted to odor characteristics of Benshan tea leaves, among which geraniol, trans-β-ionone, gerol, citronellol, benzeneacetaldehyde, and trans-nerolidol were the most key six. Floral and fruity aromas, especially floral aroma, mainly formed odor characteristics of Benshan tea after processing, while floral aroma mainly came from the contribution of geraniol, which was the foremost compound in the formation of floral aroma of Benshan tea.

Investigation of Geraniol Biotransformation by Commercial Saccharomyces Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS)

Hop-derived volatile organic compounds (VOCs) and their transformation products significantly impact beer flavour and aroma. Geraniol, a key monoterpene alcohol in hops, has been reported to undergo yeast-modulated biotransformation into various terpenoids during fermentation, which impacts the citrus and floral aromas of the finished beer. This study monitored the evolution of geraniol and its transformation products throughout fermentation to provide insight into differences as a function of yeast species and strain. The headspace concentration of VOCs produced during fermentation in model wort was measured using Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS). In the absence of yeast, only geraniol was detected, and no terpenoid compounds were detected in geraniol-free ferments. During fermentation, the depletion of geraniol was closely followed by the detection of citronellol, citronellyl acetate and geranyl acetate. The concentration of the products and formation behaviour was yeast strain dependent. SPME-GC/MS provided confidence in compound identification. PTR-ToF-MS allowed online monitoring of these transformation products, showing when formation differed between Saccharomyces cerevisiae and Saccharomyces pastorianus yeasts. A better understanding of the ability of different yeast to biotransform hop terpenes will help brewers predict, control, and optimize the aroma of the finished beer.

Characterization of aroma differences on three drying treatments in Rucheng Baimao (Camellia pubescens) white tea

Rucheng Baimao (Camellia pubescens) is an excellent raw material for manufacturing white tea. Drying is the last step in white tea processing and is essential for white tea's aroma. In this study, aroma sensory evaluation combined with volatile compound analysis reveals the characteristic aroma differences of Rucheng Baimao white tea with oven drying (OD), air drying (AD), and sun drying (SD) treatments. Sensory results showed that OD samples had a stronger floral and grassy aroma, AD samples exhibited a more pronounced fresh and pekoe aroma, and SD samples exhibited a unique sunshine odor. Thirty compounds were screened as differential aroma-active compounds of the aroma difference of Rucheng Baimao white tea with three drying treatments using multivariate statistical analysis and relative odor activity value (ROAV ≥1) analysis. The weighted correlation network analysis of the differential compounds revealed the potential association between volatiles and aroma. The results showed that 17 compounds (such as hexanal and p-cymene) were significantly positively correlated with the grassy aroma and 21 compounds (such as linalool and benzeneacetaldehyde) were significantly positively correlated with the floral aroma. Most of these compounds were abundant in OD samples, contributed to its aroma characteristics.

The chromosome-scale genome assembly of Jasminum sambac var. unifoliatum provides insights into the formation of floral fragrance

Jasmine [Jasminum sambac (L.) Ait.], a tropical and subtropical plant emits a sweet, heady fragrance during flower opening. However, the molecular mechanisms underlying this phenomenon remain largely unknown. In the present study, integrated Illumina sequencing, Pacbio sequencing, and high-throughput chromatin conformation capture (Hi-C) scaffolding was used to generate a 495.60 Mb genome assembly of J. sambac var. unifoliatum cultivar ‘Fuzhou Single-petal’ (JSU-FSP), with contig N50 of 16.88 Mb; 96.23% of the assembly was assigned to 13 pseudochromosomes. The genome harbors 30 989 protein-coding genes, and 49.47% of the assembled sequences are repetitive sequences. The analysis of duplication modes showed that 51% of genes were duplicated through dispersed duplication, and expanded gene families are mainly involved in photosynthesis, which may be responsible for the light-loving characteristic specific to jasmine. Transcriptome analysis revealed that at least 35 structural genes involved in the biosynthesis of volatile terpenes (VTs), volatile phenylpropanoid/benzenoids (VPBs), fatty acid-derived volatiles (FADVs), and indole were highly expressed in the flower-opening stage, both preharvest and postharvest, and are proposed to be important in endowing flower aroma. Additionally, at least 28 heat shock protein (HSP) and 11 β-glucosidase (BGLU) genes may be involved in the formation of floral fragrance. These findings provide insights into the formation of the floral fragrance of jasmine and will promote germplasm utilization for breeding improved jasmine varieties.

The multifaceted roles of R2R3 transcription factor HlMYB7 in the regulation of flavonoid and bitter acids biosynthesis, development and biotic stress tolerance in hop (Humulus lupulus L.)

Hop (Humulus lupulus) biosynthesizes the highly economically valuable secondary metabolites, which include flavonoids, bitter acids, polyphenols and essential oils. These compounds have important pharmacological properties and are widely implicated in the brewing industry owing to bittering flavor, floral aroma and preservative activity. Our previous studies documented that ternary MYB-bHLH-WD40 (MBW) and binary WRKY1-WD40 (WW) protein complexes transcriptionally regulate the accumulation of bitter acid (BA) and prenylflavonoids (PF). In the present study, we investigated the regulatory functions of the R2R3-MYB repressor HlMYB7 transcription factor, which contains a conserved N-terminal domain along with the repressive motif EAR, in regulating the PF- and BA-biosynthetic pathway and their accumulation in hop. Constitutive expression of HlMYB7 resulted in transcriptional repression of structural genes involved in the terminal steps of biosynthesis of PF and BA, as well as stunted growth, delayed flowering, and reduced tolerance to viroid infection in hop. Furthermore, yeast two-hybrid and transient reporter assays revealed that HlMYB7 targets both PF and BA pathway genes and suppresses MBW and WW protein complexes. Heterologous expression of HlMYB7 leads to down-regulation of structural genes of flavonoid pathway in Arabidopsis thaliana, including a decrease in anthocyanin content in Nicotiana tabacum. The combined results from functional and transcriptomic analyses highlight the important role of HlMYB7 in fine-tuning and balancing the accumulation of secondary metabolites at the transcriptional level, thus offer a plausible target for metabolic engineering in hop.

Cover Picture and Issue Information

Functional EcologyVolume 37, Issue 3 p. 473-475 COVER PICTURE AND ISSUE INFORMATIONFree Access Cover Picture and Issue Information First published: 02 March 2023 https://doi.org/10.1111/1365-2435.14073AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Flowering plants need pollinators to transfer pollen, such as those pictured on this Tamarix chinensis (Credit: Le Jiao). The movement behavior and strategy of pollinators significantly affects pollination success and the subsequent seed set, especially for plant populations that are faced with habitat loss. Jiao et al. 2022 (DOI: 10.1111/1365-2435.14252) simulated two key stages of pollinator movement during the pollination process: a foraging response stage towards plant patches mediated by floral scents, and an individual dispersal stage between plant patches mediated by a densitydependent dispersal strategy. Plant reproduction was negatively affected by habitat loss, as the emission amount of floral scents and the foraging success rate of pollinators decreased in the context of habitat loss. However, the pollinator movement strategy (i.e. density-dependent dispersal strategy) can help mitigate adverse impacts by promoting visitation to suboptimal plant patches, thereby improving the persistence of the plant population in fragmented landscapes. Altogether, this simulation result points to the positive role of pollinator movement strategy in alleviating the negative effects of habitat loss on plant reproduction. Volume37, Issue3March 2023Pages 473-475 RelatedInformation