Lilac Aldehyde Research Articles

Nocturnal moth pollination in an alpine orchid, Platanthera tipuloides

AbstractPollination success of alpine plants is often restricted by low and unpredictable pollinator activity because of harsh and unstable weather conditions, where nocturnal pollination is rare. The alpine orchid, Platanthera tipuloides (Orchidaceae), has inconspicuous greenish yellow flowers with a sweet scent and a long spur that contains nectar. These floral traits are expected to be related to nocturnal moth pollination. To elucidate the pollination mode and reproductive characteristics of this species, we measured floral traits (spur length, nectar content in the spur, floral scent), documented flower visitors using camera traps, and quantified self‐compatibility and the degree of pollen limitation through controlled pollinations at two study plots in the Taisetsu Mountains, northern Japan. It was revealed that P. tipuloides is self‐incompatible and pollen limitation was absent at one of the study plots. The flowers emitted more volatile substances during the night, including lilac aldehyde isomers, which are known to attract moths. A nocturnal moth, Entephria amplicosta, was observed foraging nectar from the flowers, while no diurnal visitors were observed. The proboscis of E. amplicosta was shorter than the spur length, but it was long enough to access the accumulated nectar in the spurs. These results suggest that nocturnal pollination by moths is possible and can be efficient even in an alpine ecosystem with harsh environmental conditions.

Sensory Attributes and Chemical Composition: The Case of Three Monofloral Honey Types from Algeria.

There is a demand from the scientific, beekeeping and consumer sectors to characterize honey based on its botanical origin, as it provides unique and distinctive properties. Nevertheless, existing studies on the physicochemical properties and the sensorial profile of honey in relation to botanical origin remain insufficient. This study aimed to understand the relationships between sensory profile and various chemical compounds (minerals, sugars, water content and volatiles) of three monofloral honeys (Atractylis serratuloides, Retama sphaerocarpa and Eruca sativa) produced in Algeria using principal component analysis. Crystallization was detected as a distinctive attribute of Eruca and Atractylis honey. A candy aroma and odor with floral nuances, light color, crystallized state and the volatile compounds Alpha-Bisabolol and Beta-eudesmol characterized the Atractylis honey. Eruca honeys were distinguished by an animal and degraded odor, bitter taste, light color and the presence of Dimethyl trisulfide and Dimethyl tetrasulfide. Finally, a vegetal aroma, some saltiness and sourness, dark amber color, lower sugar content, higher K content and Lilac aldehyde and Lilac aldehyde D characterized Retama honeys.

Biomarker Aroma Compounds of Monofloral Honey From Kazakhstan by Gas Chromatography–Mass Spectrometry (GC–MS) and Chemometric Analysis*

The aroma compounds of honey provide useful information to determine the geographical origin. This work focuses on the study of aroma compounds of 16 honey samples using headspace (HS)-solid-phase microextraction (SPME) gas chromatography–mass spectrometry (GC-MS) to reaffirm the geographical features of 4 monofloral honey. 7 sunflower, 3 buckwheat, 2 agrimonia, and 4 tamarix monofloral honey samples were obtained from four regions of Kazakhstan. Moreover, the GC-MS data were applied to chemometric analysis for the common aroma compounds to discriminate the monofloral honeys. In total, 76 aroma compounds were detected and 72 were identified. α-Pinene, benzaldehyde, octanal, hotrienol, limonene, cosmene, nonanol, linalool oxide, dehydro-p-cymene, β-linalool, 2-nonen-1-ol, carvacrol, lilac aldehyde A, β-citral, 2-decen-1-al, and β-damascenone were identified as common aroma compounds for all honey types. According to principal component analysis (PCA), the aroma compounds of sunflower, buckwheat, agrimonia, and tamarix honey were distinguished. Dehydro-p-cymene, β-linalool, 2-nonen-1-ol, and linalool oxide were determined as dominant compounds for agrimonia honey, while nonanol, benzaldehyde, octanol, dehydro-p-cymene and β-linalool for buckwheat, β-citral, lilac aldehyde A, 2-decen-1-al, D-limonene, β-damascenone, linalool oxide for tamarix honey, and hotrienol, cosmene, α-pinene, and carvacrol for the sunflower product. PCA revealed that the dominant compounds for each honey could be used as biomarker compounds to detect the origin of the honey and possible adulteration, such as blending and inverted sugar addition.

Night and day: Contributions of diurnal and nocturnal visitors to pollen dispersal, paternity diversity, and fruit set in an early-blooming shrub, Daphne jezoensis.

Under uncertain pollinator visit conditions, plants often exhibit long flowering periods and generalized pollination systems. Flowering of the gynodioecious shrub Daphne jezoensis occurs in early spring in cool temperate forests. Pollination by nocturnal moths is expected, given the species' tubular-shaped flowers with sweet fragrance and nectar. However, the effectiveness of nocturnal moths under cool conditions is unknown. We evaluated the relative importance of diurnal and nocturnal visitors as pollinators in early spring. We investigated flowering duration, flower visitors, and floral scents in a natural population. We experimentally exposed flowers to visitors only during daytime or nighttime using bagging treatments and evaluated the contributions of diurnal and nocturnal insects to fruit set, pollen dispersal distance, and paternity diversity using 16 microsatellite markers. Female flowers lasted ~3 wk, which was ~8 d longer than the flowering period of hermaphrodites. Various insects, including Coleoptera, Diptera, Hymenoptera, and Lepidoptera, visited the flowers during both daytime and nighttime. Flowers emitted volatiles, such as lilac aldehyde isomers and β-ocimene, which are known to attract moths. Fruit-set rate in the night-open treatment was similar to or higher than that in the day-open treatment. However, pollen dispersal distance in the night-open treatment was shorter than that in the day-open treatment. Paternity diversity was similar in day-open and night-open treatments. Early-blooming plants ensure pollen receipt and dispersal by having a long flowering period and using both diurnal and nocturnal flower visitors, suggesting the importance of a generalized pollination system under uncertain pollinator visit conditions.

Comprehensive study of volatile compounds of rare Leucosceptrum canum Smith honey: Aroma profiling and characteristic compound screening via GC–MS and GC–MS/MS

Monofloral honeys are highly valued for their unique flavors and potential health benefits. In this study, the aromatic attributes of rare Leucosceptrum canum Smith honey (LCH) were characterized by GC–MS coupled with GC–MS/MS. Based on their odor contribution rates (OCRs), linalool (74.22%), 3-methyl-1-butanol (18.19%), benzeneacetaldehyde (1.31%) and lilac aldehyde B (2.78%) were largely responsible for the unique and complex flavor of LCH – flowery, spicy, sweet, fruity and fresh. Compared to other tested honeys, linalool (0.18 mg/kg), which has known antibacterial properties, was higher in LCH. However, it was not the main antibacterial compound in LCH, suggesting as of now unknown antibacterial compounds. This study provides the first aromatic profile of LCH, which will be useful for the authentication of LCH and for uncovering the mechanisms behind its perceived health benefits.

Machine Learning Algorithms Applied to Semi-Quantitative Data of the Volatilome of Citrus and Other Nectar Honeys with the Use of HS-SPME/GC-MS Analysis, Lead to a New Index of Geographical Origin Authentication.

The scope of the current study was to monitor if semi-quantitative data of volatile compounds (volatilome) of citrus honey (ch) produced in different countries could potentially lead to a new index of citrus honey authentication using specific ratios of the identified volatile compounds in combination with machine learning algorithms. In this context, the semi-quantitative data of the volatilome of 38 citrus honey samples from Egypt, Morocco, Greece, and Spain (determined by headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS)) was subjected to supervised and unsupervised chemometrics. Results showed that honey samples could be classified according to the geographical origin based on specific volatile compounds. Data were further evaluated with additional nectar honey samples introduced in the multivariate statistical analysis model and the classification results were not affected. Specific volatile compounds contributed to the discrimination of citrus honey in different amounts according to geographical origin. These were lilac aldehyde D, dill ether, 2-methylbutanal, heptane, benzaldehyde, α,4-dimethyl-3-cyclohexene-1-acetaldehyde, and herboxide (isomer II). The numerical data of these volatile compounds was summed up and divided by the total semi-quantitative volatile content (Rch, Karabagias-Nayik index) of citrus honey, according to geographical origin. Egyptian citrus honey had a value of Rch = 0.35, Moroccan citrus honey had a value of Rch = 0.29, Greek citrus honey had a value of Rch = 0.04, and Spanish citrus honey had a value of Rch = 0.27, leading to a new hypothesis and a complementary index for the control of citrus honey authentication.

An Investigation into Corsican Honey: Chemical Composition and Biological Activities

The present work studied five corsican honey varieties (spring maquis, autumn maquis, spring honey, summer maquis, and blended honey) and the correlation of their chemical composition, antioxidant activity, and ability to inhibit enzymes (acetylcholinesterase [AChE] and tyrosinase), which are associated with several diseases, such as Alzheimer’s disease. Analysis using headspace-solid phase microextraction (HS-SPME)/Gas chromatography (GC)/GC-Mass spectrometry (MS) indicated that the samples presented different chemical profiles. The main components of spring maquis honey are 4-propylanisol (14.7%) and p-anisaldehyde (11.7%). For autumn maquis honey, they are isophorone (34.8%) and 3,4,5-trimethylphenol (27.1%), and for spring honey, they are phenylacetaldehyde (15.8%) and (2R, 2’S, 5’S)-lilac aldehyde (10.1%). For blended honey, they are 3-furaldehyde (13.9%) and 4-propylanisol (10.8%), and for summer maquis honey, they are phenylacetaldehyde (33.6%) and benzaldehyde (9.1%). All the types of honey studied showed antioxidant activity in the three tests studied. The most potent honey in the DPPH test (IC50 = 73.69 µg/mL), the reducing iron test (IC50 = 45.12 µg/mL), and the β-carotene test (IC50 = 53.80 µg/mL) was autumn scrub honey. All the types of honey studied have inhibitory capacities on acetylcholinesterase and tyrosinase. Our study found that corsican honey is a rich source of organic compounds that could positively impact health.

Sexual Differences in Eurya loquaiana Dunn Floral Scent and How Pollinators Respond.

Eurya plants are usually dioecious or subdioecious with small fragrant flowers. Here, we investigate the floral scent components of the subdioecious species Eurya loquaiana Dunn and how floral scent affects pollinators. Headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) was used to compare the floral scents of male, female, and hermaphrodite flowers. We also test whether differences in floral scent affect the foraging behaviors of pollinators and describe the flower morphological traits of the three sexes. Twenty-eight floral scent compounds were tentatively identified, and four monoterpenoids were tentatively identified as the most abundant compounds: linalool oxide (pyranoid), linalool, lilac aldehyde, and linalool oxide (furanoid). There were floral scent differences among the sex types, and male flowers were more attractive to pollinators in the wild, even when visual factors were excluded, indicating that pollinators likely distinguish sexual differences by floral scent. In the competition for pollinators, the advantage that male flowers have over female and hermaphrodite flowers can likely be accounted for the differences in floral scent and display size.

Detection of spoilage-causing yeasts and bacteria in tchapalo, the Ivorian traditional sorghum beer.

In this study, we aimed to analyse the spoilage potential of the isolated yeast, LAB and AAB species. Thus, 11 strains were inoculated at 0·3% (v/v) into a sterile filtered tchapalo and stored for 3 days at ambient temperature (27-30°C). All the tested strains grew well or remained stable except for Limosilactobacillus fermentum and Pediococcus acidilactici, which decreased throughout the storage time. A significant decrease of total soluble solids was observed only for Saccharomyces cerevisiae (from 7·8 to 5·8 °Brix) and Meyerozyma guilliermondii (from 7·8 to 5·5 °Brix). The tchapalo samples inoculated with the LAB strains Weissella paramesenteroides, P. acidilactici, L. fermentum and the yeast strain Candida tropicalis were judged similar to the control by the panellists. However, the strains of Lacticaseibacillus paracasei and Latilactobacillus curvatus (LAB), S. cerevisiae, M. guilliermondii and Kluyveromyces marxianus (yeasts) and Acetobacter pasteurianus and A. cerevisiae (AAB) induced the spoilage of the tchapalo appearance, smell and/or taste. In the spoiled tchapalo quantitative and qualitative modification of some volatile compounds (VOCs), such as lilac aldehyde, ethyl acetate, ethyl hexanoate, ethyl octanoate and phenethyl acetate, were observed. These results provide information about the microorganisms that need to be removed to extend the shelf life of tchapalo.

Mineral Content and Volatile Profiling of Prunus avium L. (Sweet Cherry) By-Products from Fundão Region (Portugal).

Large amounts of Prunus avium L. by-products result from sweet cherry production and processing. This work aimed to evaluate the mineral content and volatile profiling of the cherry stems, leaves, and flowers of the Saco cultivar collected from the Fundão region (Portugal). A total of 18 minerals were determined by ICP-MS, namely 8 essential and 10 non-essential elements. Phosphorus (P) was the most abundant mineral, while lithium (Li) was detected in trace amounts. Three different preparations were used in this work to determine volatiles: hydroethanolic extracts, crude extracts, and aqueous infusions. A total of 117 volatile compounds were identified using HS-SPME/GC-MS, distributed among different chemical classes: 31 aldehydes, 14 alcohols, 16 ketones, 30 esters, 4 acids, 4 monoterpenes, 3 norisoprenoids, 4 hydrocarbons, 7 heterocyclics, 1 lactone, 1 phenol, and 2 phenylpropenes. Benzaldehyde, 4-methyl-benzaldehyde, hexanal, lilac aldehyde, and 6-methyl-5-hepten-2-one were the major volatile compounds. Differences in the types of volatiles and their respective amounts in the different extracts were found. This is the first study that describes the mineral and volatile composition of Portuguese sweet cherry by-products, demonstrating that they could have great potential as nutraceutical ingredients and natural flavoring agents to be used in the pharmaceutical, cosmetic, and food industries.

Comprehensive Evaluation of the Volatomic Fingerprint of Saffron from Campania towards Its Authenticity and Quality.

The volatile profiles of eight saffron samples (seven cultivated and one spontaneous) grown in different geographical districts within the Campania region (southern Italy) were compared. Using headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME/GC-MS), overall, 80 volatiles were identified in the eight landraces. Among them, safranal and its isomers and other related compounds such as isophorones, which are not only key odorants but also pharmacologically active metabolites, have been detected in all the investigated samples. Principal Component Analysis performed on the volatiles’ compounds revealed that the spontaneous sample turned out to be an outlier. In particular, the volatile organic compounds (VOCs) profile of the spontaneous saffron presented four lilac aldehydes and four lilac alcohol isomers, which, to the authors’ knowledge, have never been identified in the volatile signature of this spice. The multivariate statistical analysis allowed the discrimination of the seven cultivate saffron ecotypes in four well-separated clusters according to variety. Moreover, 20 VOCs, able to differentiate the clusters in terms of single volatile metabolite, were discovered. Altogether, these results could contribute to identifying possible volatile signature metabolites (biomarkers) or patterns that discriminate saffron samples grown in Campania region on a molecular basis, encouraging future biodiversity programs to preserve saffron landraces revealing valuable genetic resources.

Retama sphaerocarpa, Atractylis serratuloides and Eruca sativa honeys from Algeria: Pollen dominance and volatile profiling (HS-SPME/GC–MS)

The volatile fraction of three monofloral honey types produced in arid and semiarid areas of Algeria was studied to establish a link between their chemical composition and their botanical origin. Palynological analysis was performed to confirm the main botanical origin. Volatile extraction using HS-SPME coupled to GC–MS revealed exclusive components for each type: 1,6,10-dodecatrien-3-ol,3,7,11-trimethyl-, (E); 1,6-octadien-3-ol,3,7- dimethyl; phenol, 2-methoxy and 2-naphtalene methanol, decahydro-α,α,4a- trimethyl-8-methylene-, [2R-(2α,4aα,8a,8aβ)] for Atractylis honey, lilac aldehyde and lilac aldehyde D for Retama honey, and dimethyl trisulfide for Eruca. The PCA analysis made it possible to correlate some volatile compounds with the most important pollen types, and to evaluate the authenticity related to the geographical and botanical origin of the honey.

Volatile profile of Spanish raw citrus honey: The best strategy for its correct labeling

The objective of this study was to evaluate the presence of specific volatile compounds (analyzed by SPME-GC-MS) in citrus honey, comparing thyme, and sunflower, and to correlate their abundance with the level of methyl-anthranilate (accepted as a true marker in citrus honey), for which a minimum content is mandatory in commercial transactions. Methyl-anthranilate is well correlated with certain volatile compounds such as 1-p-menthene-9-al (0.903), limonene (0.885), dill-ether (0.842), and ethyl linalool (0.832), and slightly lower with the four lilac aldehydes (0.717–0.764). However, the latter, together with methyl-anthranilate, are of special interest because these were found in all citrus honey samples. Consequently, the information provided by these five compounds could facilitate the unmistakable classification of this honey. Thanks to these positive results and even though that this method is not commonly practiced to objectively differentiate between monofloral honey it can be considered an interesting analytical tool in the future. Practical applications Proper classification of citrus honey before entering as a raw material in the honey-packaging process would ensure its correct labeling. This would benefit the consumer and the beekeepers. The results of this study intend to shed some light to help the industry achieve correct cataloging of citrus honey by proposing an alternative technique based on the characterization of its volatile fraction.

Synthesis and Olfactory Properties of Seco-Analogues of Lilac Aldehydes.

Lilac aldehydes are considered as principal olfactory molecules of lilac flowers. We have designed, prepared, and evaluated a set of racemic seco-analogues of such natural products. The synthesis employs commercially available α-chloroketones as substrates that are transformed in four steps to target compounds. Their qualitative olfactory analysis revealed that the opening of the tetrahydrofuran ring leads to a vanishing of original flowery scent with the emergence of spicy aroma accompanied by green notes, and/or fruity aspects of novel seco-analogues. These results suggest the important osmophoric role of THF moiety for the generation of the typical flowery aroma associated with lilac aldehydes.

Screening of the Honey Aroma as a Potential Essence for the Aromachology

The aim of the study was to determine the aroma profiles of four kinds of Slovak honey (sunflower, honeydew, acacia, and linden) by a qualitative and quantitative screening of their volatile compounds and by gas chromatography for the potential use in the aromachology and the business sphere. The results showed that several unique volatiles were identified in one kind of honey, while they were not identified in the remaining ones. The acacia honey had the unique volatile linalool oxide (1.13–3.9%); linden honey had the unique volatiles nerol oxide (0.6–1.6%), ethyl esters (0.41–8.78%), lilac aldehyde D (6.6%), and acetophenone (0.37%). The honeydew honey had the unique volatiles santene (0.28%) and cyclofenchene (0.59–1.39%), whereas 2-bornene (0.43–0.81%) was typical for sunflower honey. While linden honey was characterized by fruity ethyl esters, honeydew honey had more monoterpenoid compounds. In the principal component analysis model, the four kinds of honey could not be differentiated by aroma volatiles. However, it was possible to classify the linden and sunflower honey using the LDA. In conclusion, the current study provided experimental evidence that the marker compounds from different kinds of honey might be promising candidates for production of inhaling aromas.

Chemical components of male and female flowers of Schisandra chinensis

Schisandra chinensis (Turcz.) Baill. is one of the important traditional medicinal plants in East Asia. It is a dioecious plant with aromatic flowers. The female and male flowers of S. chinensis possess slightly different fragrance characteristics. The overall scent of S. chinensis flowers is quite similar to that of Syringa dilatata (Korean lilac) flowers. Hence, this study aimed to understand the aromatic profile of the hexane extract from female and male flowers of S. chinensis and to compare their profile with the hexane extract of Korean lilac flowers. The chemical composition of hexane extract was determined by gas chromatography and mass spectrometry (GC-MS) analysis. In total, 67 different components were detected in the hexane extract of female (48) and male flowers (51) of S. chinensis; 32 of which were common to both female and male flowers. In regards to gender difference, 16 components were found only in female flowers, and 19 components were found only in male flowers. The results revealed that the most abundant components in the hexane extract of both female and male flowers were lilac alcohol C (9.53 and 7.00%), lilac alcohol A (6.55 and 5.71%), n-hexadecanoic acid (6.21 and 6.96%), linoleic acid (5.14 and 7.61%), β-elemene (5.12 and 1.99), and lilac aldehyde D (4.13 and 4.97%). The data suggest that the major compounds in the hexane extract of S. chinensis flowers were generally similar, but they varied quantitatively according to gender. The presence of 10 components in both S. chinensis and Korean lilac flowers may be responsible for their similar fragrance characteristics. It could be concluded that the different fragrance characteristics of these flowers may be due to the presence of several gender-specific aromatic compounds in minor percentages.

The olfactory basis of orchid pollination by mosquitoes.

Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid's scent and the balance of excitation and inhibition in the mosquito's antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species-not visited by mosquitoes-emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethyl-meta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors.

A decisive strategy for monofloral honey authentication using analysis of volatile compounds and pattern recognition techniques

In an effort to determine some undisputed markers of botanical origin, the volatile profile of Hellenic monofloral honeys was investigated using gas chromatography coupled to mass spectrometry (GC–MS) in combination with headspace solid phase microextraction (HS-SPME). Different varieties of honey (citrus, fir, pine, and thyme) were analyzed and semi-quantitative data of volatile compounds originating from 82 samples were subjected to multivariate analysis of variance (MANOVA).Results showed that by using only 9 volatiles [dill ether (0.012 mg kg−1), alpha-4-dimethyl-3-cyclohexene-1-acetaldehyde (0.030 mg kg−1), acetic acid ethyl ester (0.030–0.173 mg kg−1), octanoic acid ethyl ester (0.004–0.547 mg kg−1), methylanthranilate (0.030 mg kg−1), 2,2,4,6,6-pentamethyl-heptane (0.005–0.057 mg kg−1), phenylacetaldehyde (0.014–1.248 mg kg−1), cis-linalool oxide (0.007–0.010 mg kg−1), lilac aldehyde (isomer III) (0.032–0.437 mg kg−1)] honeys could be classified correctly according to botanical origin. The correct prediction rates were 93.9%, 96.8%, and 89.5%, based on the cross-validation method and using stepwise linear discriminant analysis, training and holdout partitions (k-nearest neighbors analysis), respectively. The efficiency of the discrimination model was confirmed further by application to mixed floral honeys and the use of the aforementioned consecutive pattern recognition techniques. The use of specific volatile compounds in combination with statistical tools may constitute a fast, decisive and accurate strategy for monofloral honey authentication.

Fragrance components of Platanthera bifolia subsp. osca and Platanthera chlorantha collected in several sites in Italy

Platanthera bifolia subsp. osca sample collected at Grisolia showed as main components linalool (17.8%), benzyl benzoate (55.8%), and benzyl 2-hydroxybenzoate (6.7%). Four samples of P. bifolia subsp. osca were collected at Pignola: the main components of the aroma are lilac derivatives (49.02–79.00%), mainly lilac alcohols B (7.41–13.52%), C (10.10–18.45%), and D (7.50–34.28%). Three samples were analyzed from the site of Marsico Nuovo. The main components of the scent found in this site were linalool (1.54–10.00%), lilac aldehydes (3.98–11.15%), and mainly lilac alcohols (50.68–61.51%). The main components of the sample collected at Palena were methyl benzoate (9.04%) and benzyl benzoate (74.72%). The analysis of the composition of the aroma of a Platanthera chlorantha plant has been performed. The main components were lilac derivatives. The reported behavior could be explained admitting an adaptive modification of the scent considering the nature of possible pollinating agents due to different habitats.

Scents in orchards: floral volatiles of four stone fruit crops and their attractiveness to pollinators

Stone fruit crops grow in various regions around the world and are highly valued for their nutritional content, delicious taste, and economic importance, with an annual worldwide production of up to 42 million tonnes. In spite of their importance as a food resource, little is known about the chemistry of the floral volatiles of these crops, especially in relation to plant–pollinator interactions. In this study, the floral volatiles from four major stone fruit crops (apricot, Prunus armeniaca L.; plum, Prunus domestica L.; cherry, Prunus avium L.; and peach, Prunus persica L.) were collected and analysed by coupled gas chromatography/mass spectrometry (GC/MS). This was followed by several field trials, where selected floral volatiles were tested for attractiveness to flower visitors and pollinators. Twenty-six floral volatile compounds were identified in the headspace of the four Prunus spp. Benzaldehyde was present in the headspace of all four species. The norisoprenoid 4-oxoisophorone and lilac aldehyde were the main compounds in the headspace of P. armeniaca, P. domestica, and P. avium. The floral headspace of P. persica was distinct from the other three Prunus species, with 3,5-dimethoxytoluene being the most prominent compound (> 95%). In the field trapping trials, 4-oxoisophorone was attractive to various flower visitor species in a number of habitats when tested alone or in combination with benzaldehyde. Similarly, 3,5-dimethoxytoluene attracted several flower visitor species when tested alone or in combination with benzaldehyde. Our finding suggests that chemical cues are an important signal in plant–pollinator interactions in the four stone fruit species. This work provides the first detailed analysis of the floral volatiles of these important crops, especially in the context of plant–pollinator interactions. The floral compounds identified in this study could be used to enhance pollination of these important crops, either by direct application in the field (i.e. slow-release device) to enhance pollinator foraging or by training pollinators on such signature compounds to enhance flower visitation.