Search Results (80)

Flower fragrance is a crucial ornamental and economic trait of Dendrobium chrysotoxum, and the most abundant and diverse aroma-active compounds are terpenes. Terpene synthase (TPS) is the ultimate enzyme for the biosynthesis of various types of terpenes, and TPS genes were identified as the key regulators governing the spatiotemporal release of volatile terpene compounds. Until recently, the TPS gene family in D. chrysotoxum has remained largely unexplored. Our study characterizes the TPS genes in D. chrysotoxum and identifies 37 DcTPS gene family members. It helped identify the DcTPS genes, gene characteristics, the phylogeny relationship, conserved motif location, gene exon/intron structure, cis-elements in the promoter regions, protein–protein interaction (PPI) network, tissue specific expression and verification of the expression across different flowering stages and floral organs. Three highly expressed DcTPS genes were cloned, and their functions were verified using a transient expressed in tobacco leaves. Further functional verification showed that the proteins encoded by these genes were enzymes involved in monoterpene synthesis, and they were all involved in the synthesis of linalool. This study comprehensively expatiates on the TPS gene family members in D. chrysotoxum for the first time. These data will help us gain a deeper understanding of both the molecular mechanisms and the effects of the TPS genes. Furthermore, the discovery that three TPS-b genes (DcTPS 02, 10, 32) specifically drive linalool-based scent in D. chrysotoxum, will provide new insights for expanding the TPS-b subfamily in orchids and identifying the linalool synthases contributing to orchid fragrance. Full article

Flower-scented teas become increasingly popular to new generations, due to their infused floral essences of diverse volatile compounds and additional health functions. Flower-scented teas have significantly broadened the spectrum of aroma perception, intensity, and longevity. Here, Chimonanthus praecox flowers were used to scent tea dhools to create different Chimonanthus teas with strong and characteristic aromas. The dynamic absorption of aromas by three tea dhools, and aroma compatibility in three flower-scented teas, and the aroma retention in Chimonanthus teas during storage were investigated. At least twelve aroma compounds were selectively absorbed by three tea dhools, with seven compounds, pulegone, 3-phenylpropanol, (E)-cinnamaldehyde, cinnamyl alcohol, γ-phenylpropyl acetate, (E)-isoeugenol, and (E)-cinnamyl acetate, commonly absorbed to three Chimonanthus teas. The different absorption preferences to floral volatiles and absorption capacity of three tea dhools could be related to their surface structures and trichome conditions. Linalool, phenylmethyl acetate, and methyl salicylate as significant volatile components were substantially enhanced for both Chimonanthus flowers and tea dhools, thereby augmenting the floral bouquet of Chimonanthus tea. After 56 days of storage, alcohol volatiles emerged as the predominant volatile types, although esters are the major contributors to the aroma of freshly prepared Chimonanthus teas. Full article

Spreading is the key process for ensuring green tea quality. However, the effect of blue light intensity conditions on the formation of green tea aroma and the evolution of key volatile compounds has not been assessed to date. Four tea samples treated with different light conditions (blue light intensities) were used to investigate the effect of spreading treatment on changes in the composition and content of volatile compounds. Volatile compounds in green tea samples were detected using headspace-solid phase microextraction and gas chromatography-mass spectrometry under different light conditions. Orthogonal partial least squares discriminant analysis (OPLS-DA) and relative odor activity value (rOAV) analyses were then applied to clarify the best blue light condition for forming aroma and associated compounds. The 116 volatile compounds were detected in the green tea samples, of which alcohols were the most abundant. The findings demonstrated that MBL (middle-intensity blue light; 150 μmol/(m²∙s)) treatment was the most effective condition for developing an intense and persistent fruity and floral scent compared to HBL (high-intensity blue light; 300 μmol/(m²∙s)) and LBL (low-intensity blue light; 75 μmol/(m²∙s)). This study underscores how blue light intensity conditions shape green tea aromas and offers operational insights. It also provides a theoretical basis for controlling light conditions in the process of green tea spreading Full article

Drying methods play a crucial role in the formation of green tea aromas. This study investigated the aroma characteristics and volatile component profiles of large-leaf green tea under hot-air drying, pan-fired drying, and sun drying. The results revealed significant differences in the sensory aroma characteristics and volatile components of the large-leaf green tea among the three drying methods. The pan-fire-dried green tea (PDGT) exhibited a distinct roasted aroma, while the hot-air-dried green tea (HDGT) and sun-dried green tea (SDGT) displayed a faint scent and lasting aroma characteristics, with the SDGT additionally featuring a noticeable sun-dried odor. A total of 48 differential volatile components were identified, among which β-Ionone, (E)-β-Ionone, 2,2,6-Trimethylcyclohexanone, Dihydroactinidiolide, BenzeneacetAldehyde, 2-Pentylfuran, 1,1,6-Trimethyl-1,2-dihydronaphthalene, δ-Cadinene, β-Myrcene, Geranylacetone, o-Cymene, 6-Methyl-5-hepten-2-one, (E)-β-Ocimene, and BenzAldehyde were identified as the primary contributors to the aroma differences among the three large-leaf green teas. Additionally, 43 differential volatile compounds were found to be significantly correlated with at least one of the aroma types (floral, sweet, green, faint scent, nutty, or roasted). The findings of this study provide a theoretical foundation for understanding the formation of aroma qualities in large-leaf green tea and offer valuable insights for improving its aromatic characteristics. Full article

Understanding the complexity of flower scent—a crucial attractant for pollinators and a key factor in ensuring plant reproduction—is an essential ecological task for highly endangered orchids. To address this issue, we studied the flower volatiles profile of Neottia ovata, a nectar-rewarding orchid known for its generalist pollination strategy. We then compared the chemical composition of N. ovata floral scent with scent data of other orchid species to place our findings in the context of general volatile attractants emitted by nectar-rewarding or food-deceptive species. Our results contribute to understanding the complexity of the N. ovata floral scent profile and provide valuable methodological insights. The scented bouquet of N. ovata comprises 100 compounds with a relatively consistent composition across the analyzed samples. It is rich in terpenes, including linalool and trans-/cis-sabinene hydrate, compounds commonly associated with generalized rewarding or food-deceptive pollination systems. Other terpenes identified include α- and β-pinene, limonene, and β-phellandrene, whose presence underscores the generalized nature of the floral scent. Interestingly, in the studied N. ovata populations, the dominance among terpenes is shifting markedly towards γ-terpinene, α-terpinene, and terpinene-4-ol, commonly found in essential oils and the floral scents of some supergeneralist-pollination plants. Aromatic compounds were less represented in the N. ovata scent profile and those of other orchids studied, though benzyl alcohol and benzaldehyde were noticeably more abundant. Aliphatic compounds composed the least prevalent fraction, showing a marked decreasing trend among nectar-rewarding species with generalized or specialized pollination systems. It is worth emphasizing that the applied methodology revealed an extensive group of low-frequency compounds in the N. ovata floral scent. This finding raises new ecological questions about the intraspecific diversity of floral scent profiles and sheds new light on the factors determining effective reproduction in this species of orchid. Full article

LBD transcription factors are critical regulators of plant growth and development. Recent studies highlighted their significant role in the transcriptional regulation of plant growth and metabolism. Thus, identifying the CeLBD gene in Cymbidium ensifolium, a species abundant in floral scent metabolites, could provide deeper insights into its functional significance. A total of 34 LBD genes were identified in C. ensifolium. These CeLBDs fell into two major groups: Class I and Class II. The Class I group contained 30 genes, while the Class II group included only 4 genes. Among the 30 Class I genes, several genes in the Ie branch exhibited structural variations or partial deletions (CeLBD20 and CeLBD21) in the coiled-coil motif (LX₆LX₃LX₆L). These changes may contribute to the difficulty in root hair formation in C. ensifolium. The variations may prevent normal transcription, leading to low or absent expression, which may explain the fleshy and corona-like root system of C. ensifolium without prominent lateral roots. The expansion for CeLBDs was largely due to special WGD events in orchids during evolution, or by segmental duplication and tandem duplication. CeLBDs in different branches exhibit similar functions and expression characteristics. Promoter analysis enriched environmental response elements, such as AP2/ERF, potentially mediating the specific expression of CeLBDs under different stresses. CeLBDs were predicted to interact with multiple transcription factors or ribosomal proteins, forming complex regulatory networks. CeLBD20 was localized in the cytoplasm, it may act as a signaling factor to activate other transcription factors. CeLBD6 in Class II was significantly up-regulated under cold, drought, and ABA treatments, suggesting its role in environmental responses. Furthermore, metabolic correlation analysis revealed that its expression was associated with the release of major aromatic compounds, such as MeJA. These findings offer valuable insights for further functional studies of CeLBD genes in C. ensifolium. Full article

Lilies (Lilium spp.) are renowned for their diverse and captivating floral scents, which are highly valued both commercially and ornamentally. This review provides a comprehensive overview of recent advancements in the identification, biosynthesis, and regulation of fragrance components in lily flowers. Various volatile organic compounds (VOCs) that contribute to the unique scents of different lily species and cultivars, including terpenoids, benzenoids/phenylpropanoids, and fatty acid derivatives, are discussed. The release patterns of these compounds from different floral tissues and at different developmental stages are examined, highlighting the significant role of tepals. Detection methods such as gas chromatography–mass spectrometry (GC-MS) and sensory analysis are evaluated for their effectiveness in fragrance research. Additionally, the biosynthetic pathways of key fragrance compounds are explored, focusing on the terpenoid and benzenoid/phenylpropanoid pathways and the regulatory mechanisms involving transcription factors and environmental factors. This review also addresses the influence of genetic and environmental factors on fragrance production and proposes future research directions to enhance the aromatic qualities of lilies through selective genetic and breeding approaches. Emphasis is placed on the potential applications of these findings in the floral industry to improve the commercial value and consumer appeal of lily flowers. Full article

Improving floral scent quality is an important goal in Malus breeding. However, the inheritance regularity for volatile components of Malus remains unclear. In this study, the floral scent compounds and scent characteristics of five Malus taxa with clearly defined parent–progeny relationships were analyzed by sensory evaluation, an electronic nose, and gas chromatography–mass spectrometry. A total of 51 volatile compounds were identified in five taxa. M. ioensis showed the highest sensory intensity with the maximum total content of compounds (8247.59 ng·g⁻¹ FW·h⁻¹). Compared to its progenies and ‘Lemoinei’, terpenoid compounds in M. ioensis accounted for the largest proportion (40.46%). Most compounds in the progenies were inherited from their maternal parent (60.61–75.00%), and most of them were significantly downregulated by hybridization. However, the content of several compounds in the progenies appeared transgressive, even unique. Progenies and their maternal parents exhibited similar sensory characteristics: earthy/woody, sweet, and rose. The content of characteristic compounds (geranylacetone, 6-methyl-5-hepten-2-one, 2-phenylethanol, α-ionone, β-ionone, decanal, and so on), total content, and the response of sensor W3S positively correlated with scent intensity. The response of sensor W1W correlated significantly and positively with the compound number and the total content. Our findings provided a reference for tracking maternal parents for cultivars and enabled rapid selection of fragrant flower cultivars by electronic nose. Full article

The calamondin (Citrus × microcarpa) is highly valued for its ornamental appeal and rich aromatic compounds, making it suitable for therapeutic gardens and widely applicable in the cosmetics, food, pharmaceutical, and perfume industries. Despite its importance, there is a lack of research on its floral volatiles. This study utilized headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC–MS) to detect the volatile organic compounds (VOCs) of calamondin at different floral developmental stages: bud (BS), half-open (HS), full bloom (FS), and senescence (SS). Multivariate statistical analysis was employed to elucidate the aromatic characteristics. The results identified 67 VOCs across the four stages, including forty-eight terpenoids, six esters, five aromatics, four aldehydes, one olefin, one alcohol, and two others. Thirty-three VOCs were common across all stages, while BS, HS, FS, and SS had three, three, four, and nine unique VOCs, respectively. The total VOC content increased initially and then decreased as the flowers developed, with terpenoids being the predominant compounds, accounting for over 90% of the total emissions at all stages. Principal component analysis and hierarchical cluster analysis confirmed significant differences in VOC profiles at different stages. Partial least squares discriminant analysis identified five VOCs with variable importance in projection (VIP) values greater than one, including limonene, linalool, β-pinene, germacrene D, and β-ocimene, indicating their varying emission levels across stages. These findings enhance our understanding of the VOC characteristics of calamondin flowers and provide a scientific basis for further ornamental and industrial applications. Full article

Lathyrus odoratus L., commonly known as sweet pea, is a plant with a distinctive aroma that can develop in various habitats. An analysis of the aromatic profile of the species was conducted using the HS-SPME (solid-phase microextraction headspace) technique. This study aimed to explore the composition of and variation in the floral scent emissions of L. odorathus. The floral scents from fresh flowers were collected over different months and analyzed using gas chromatography coupled with mass spectrometry on apolar and polar stationary phase columns. In the apolar column, the majority compounds included linalool (19.27–5.79%), α-trans-bergamotene (29.4–14.21%), and phenyl ethyl alcohol (30.01–1.56%), while on the polar column, the predominant compounds included myrcene (13.25%), (E,E)-α-farnesene (26.33–8.16%), α-trans-bergamotene (42.09–24.82%), and others. This investigation was complemented by enantioselective analysis using a chiral phase based in cyclodextrins, which revealed the presence of (1R)-(+)-α-pinene, (S)-(−)-limonene, (R)-(+)-germacrene D, and (R)-(E)-nerolidol as enantiomerically pure components and linalool as a racemic mixture. Notably, the principal component analysis (PCA) and heatmap revealed variations among the chemical compounds collected at different harvest times. This demonstrates that temporal factors indeed impact chemical compound production. Furthermore, research on the aromatic properties of flowers provides a theoretical basis for studying and improving the components of their scent. Full article

Tea standard samples are the benchmark for tea product quality control. Understanding the inherent differences in Chinese national standards for Lapsang Souchong black tea of different grades is crucial for the scientific development of tea standardization work. In this study, Lapsang Souchong black tea of different grades that meet Chinese national standards was selected as the research object. The aroma characteristics were comprehensively analyzed through sensory evaluation, electronic nose, and HS-SPME-GC-MS (headspace solid-phase microextraction gas chromatography–mass spectrometry). The findings indicate that the higher-grade Lapsang Souchong has a higher evaluation score. The results of electronic nose analysis indicate that the volatiles with differences in tea of different grades were mainly terpenoids and nitrogen oxides. The results of HS-SPME-GC-MS analysis show that the odor characteristics of the super-grade samples are mainly floral and fruity, and these substances mainly include D-Limonene, 3,7-dimethyl-1,6-octadien-3-ol and 3-Hydroxymandelic acid, and ethyl ester. The primary aroma characteristics of the first-grade samples are floral, sweet, woody, and green, with key contributing compounds including 2-Furanmethanol, 1-Octen-3-ol, and 5-ethenyltetrahydro-α,α,5-trimethyl-cis-, 4,5-di-epi-aristolochene. The main aroma characteristics of the second-grade samples are green, herbal scent, and fruity, and the main substances include 3,7-dimethyl-1,6-octadien-3-ol, 2,3-dimethylthiophene, Dihydroactinidiolide, and Naphthalene-1-methyl-7-(1-methylethyl)-. It is worth noting that the second-grade samples contain a large amount of phenolic substances, which are related to the smoking process during processing. This study lays a solid foundation for the preparation of tea standard samples and the construction of the tea standard system. Full article

The level of consumption of summer tea is a problem in the development of China’s tea industry. Current strategies to enhance the quality of summer and autumn teas primarily target the cultivation environment, with less emphasis on processing improvements. This study aimed to optimize the fermentation parameters to impact the quality of summer and autumn teas. We screened four strains of lactic acid bacteria (LAB) suitable for tea fermentation and determined their optimal mix. This optimized blend was applied to ferment summer and autumn teas. Through single-factor experiments, we evaluated the impact of various processing parameters, including the fixation method, rolling degree, inoculation amount, glucose concentration, fermentation temperature, and fermentation duration, on LAB growth and tea quality. The optimal processing conditions were established as microwave fixation, heavy rolling, an inoculation rate of 1.8% LAB, glucose addition at 8.8%, and fermentation at 36.5 °C for five days. Analysis revealed that the fermentation process significantly reduced the levels of polyphenols and ester-type catechins, which are associated with astringency and bitterness while enhancing the content of gamma-aminobutyric acid (GABA). Specifically, after five days, polyphenol content decreased by 26.89%, and GABA levels increased from 0.051 mg/g to 0.126 mg/g. The predominant aroma compounds in the fermented tea were alcohols with floral and fruity scents, constituting 54.63% of the total aroma profile. This research presents a methodical approach to reduce the astringency and bitterness of summer and autumn teas while concurrently increasing GABA levels. Full article

Scenting is an important process for the formation of aroma quality in floral Longjing tea. There are differences in the aroma quality of osmanthus Longjing teas processed by different scenting processes. The efficient isolated scenting method was employed to process a new product of osmanthus Longjing tea in this study, and this was compared with the traditional scenting method. The volatile compounds of osmanthus Longjing tea were analyzed by a GC-MS instrument. In addition, the effects of scenting time and osmanthus consumption on the aroma quality of Longjing tea were studied. The results indicated that there were 67 kinds of volatile compounds in the osmanthus Longjing tea produced by the isolated scenting process (O-ISP), osmanthus Longjing tea produced by the traditional scenting process (O-TSP), and raw Longjing tea embryo (R), including alcohols, ketones, esters, aldehydes, olefins, acids, furans, and other aroma compounds. The proportions of alcohol compounds, ester compounds, aldehyde compounds, and ketone compounds in O-ISP were higher than in O-TSP and R. When the osmanthus consumption was increased, the relative contents of volatile aroma compounds gradually increased, which included the contents of trans-3,7-linalool oxide II, dehydrolinalool, linalool oxide III (furan type), linalool oxide IV (furan type), 2,6-Dimethyl cyclohexanol, isophytol, geraniol, 1-octene-3-alcohol, cis-2-pentenol, trans-3-hexenol, β-violet alcohol, 1-pentanol, benzyl alcohol, trans-p-2-menthene-1-alcohol, nerol, hexanol, terpineol, 6-epoxy-β-ionone, 4,2-butanone, 2,3-octanedione, methyl stearate, cis-3-hexenyl wasobutyrate, and dihydroanemone lactone. When the scenting time was increased, the relative contents of aroma compounds gradually increased, which included the contents of 2-phenylethanol, trans-3,7-linalool oxide I, trans-3,7-linalool oxide II, dehydrolinalool, isophytol, geraniol, trans-3-hexenol, β-ionol, benzyl alcohol, trans-p-2-menthene-1-ol, nerol, hexanol, terpineol, dihydroβ-ionone, α-ionone, and β-ionone,6,10. The isolated scenting process could achieve better aroma quality in terms of the floral fragrance, refreshing fragrance, and tender fragrance than the traditional scenting process. The isolated scenting process was suitable for processing osmanthus Longjing tea with high aroma quality. This study was hoped to provide a theoretical base for the formation mechanism and control of quality of osmanthus Longjing tea. Full article

This study delves into the chemical and genetic determinants of petal color and fragrance in Rosa canina L., a wild rose species prized for its pharmacological and cosmetic uses. Comparative analysis of white and dark pink R. canina flowers revealed that the former harbors significantly higher levels of total phenolics (TPC) and flavonoids (TFC), while the latter is distinguished by elevated total anthocyanins (TAC). Essential oils in the petals were predominantly composed of aliphatic hydrocarbons, with phenolic content chiefly constituted by flavonols and anthocyanins. Notably, gene expression analysis showed an upregulation in most genes associated with petal color and scent biosynthesis in white buds compared to dark pink open flowers. However, anthocyanin synthase (ANS) and its regulatory gene RhMYB1 exhibited comparable expression levels across both flower hues. LC-MS profiling identified Rutin, kaempferol, quercetin, and their derivatives as key flavonoid constituents, alongside cyanidin and delphinidin as the primary anthocyanin compounds. The findings suggest a potential feedback inhibition of anthocyanin biosynthesis in white flowers. These insights pave the way for the targeted enhancement of R. canina floral traits through metabolic and genetic engineering strategies. Full article

Pollination by sexual deception specifically attracts male insects, through the floral scent and particular morphological features of the flower that serve as visual and tactile stimuli. The unique bond between the Ophrys speculum orchid and the male Dasyscolia ciliata wasp primarily stems from a few distinctive semiochemicals that mimic the female wasp’s sex pheromone, although the floral scent comprises a variety of compounds. An osmophore producing highly volatile compounds has been documented in four close relatives of O. speculum and is now being also investigated in this species. Given the existing debates regarding the structure of the labellum and stigmatic cavity in O. speculum, this study details their micromorphology. Additionally, comparisons of O. speculum flowers and female D. ciliata wasps under stereomicroscopy and scanning electron microscopy are conducted to seek new evidence of visual and tactile mimicry. The findings confirm that (i) an osmophore is present at the apical margin of the labellum in O. speculum flowers; (ii) the labellum features a distinct basal field homologous to those found in other Ophrys species; and (iii) the basal labellum region closely mimics the female wasp’s thorax and wings. The implications of these novel floral features are discussed within an evolutionary context. Full article