Major Volatiles Research Articles

Chemical constituents in leaves and aroma products of Nicotiana rustica L. tobacco

Nicotiana rustica L. (Aztec tobacco) is the only Nicotiana species, except common tobacco (N. tabacum L.), which is cultivated for tabacco products. The leaves of N. rustica, however, accumulate various specialized metabolites of potential interest. Therefore, the objective of this study was to evaluate certain classes of metabolites (by HPLC and GC-MS) in the leaves, the essential oil (EO), concrete and resinoid of N. rustica. Three pentacyclic triterpenes were identified in the leaves (by HPLC): betulin (252.78 µg g-1), betulinic (182.53 µg g-1) and oleanolic (69.44 µg g-1) acids. The dominant free phenolic acids in the leaves (by HPLC) were rosmarinic (4257.38 µg g-1) and chlorogenic (1714.40 µg g-1), and conjugated forms of vanillic (3445.71 µg g-1), sinapic (1963.11 µg g-1), and syringic (1784.96 µg g-1). The major flavonoids in the leaves were luteolin (960.44 µg g-1), apigenin (880.66 µg g-1) and hyperosid (780.72 µg g-1). The GS-MS profiling of the EO identified 19 components and the major ones were phytol (43.68 %), solanone (5.54 %), cis-5-butyl-4-methyldihydrofuran-2(3H)-one (5.23 %), dihydro-β-ionone (4.25 %), α-ionene (3.54 %),and β-damascenone (3.03 %). The major volatiles in the concrete were isoamyl alcohol (28.82 %), oxynicotine (9.02 %), phytol (7.80 %), 4-mеthyl-1-penthanol (6.33 %), cotinine (5.55 %) and 3-metyl-3-penthanol (4.09 %). Resinoid composition was dominant by nicotine (39.75 %), phytol (11.23 %), eicosane (4.88 %), diethyl phthalate (4.19 %), dibutyl phthalate (3.48 %) and solanone (3.27 %). Concrete and resinoid showed weak antibacterial activity . These results create grounds for considering N. rustica as a source to obtain aroma or other bioproducts.

Characterization of free and glycosidically bound volatile compounds from tamarillo (Solanum betaceum Cav.) with considerations on hydrolysis strategies and incubation time

Two different hydrolysis strategies, namely acid hydrolysis (pH 0 and 3) and enzyme hydrolysis (Rapidase AR2000, β-glucosidase, 5.6 nkat/mg), and the effect of hydrolysis time on the liberation of glycosidically bound volatiles from tamarillo (Solanum beaceum Cav.), were evaluated. Free and bound volatile profiles in tamarillo were also compared. Enzymatic hydrolysis was favoured for the liberation of aldehydes, esters, and terpenes. Harsh acidic hydrolysis (pH 0) was particularly effective at releasing C13-norisoprenoids including 3-hydroxy-β-damascone and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), but those compounds cannot contribute to the pleasant odour. Moreover, the longer the duration of enzymatic hydrolysis, the higher was the concentration of alcohols, terpenes, benzenoids, ketones, and volatile phenols. On the other hand, 33 free and 49 bound volatiles were identified in tamarillo with a complementary profile: the major free volatiles were alcohols ((Z)-3-hexenol, 1-hexanol) and esters (methyl caproate, methyl butanoate and ethyl butanoate), while bound volatile compounds showed higher concentrations of benzenoids (benzyl alcohol and phenylethyl alcohol) and terpenes, including prenol, linalool and α-terpineol. Many glycosidically bound volatiles are available as aroma reservoirs in tamarillo, and to liberate these compounds during tamarillo-based product development, attention should be given to hydrolysis strategies and incubation time.

Prickly Pear Seed Oil by Shelf-Grown Cactus Fruits: Waste or Maste?

The chemical composition and properties of seed oils have attracted researchers nowadays. By this meaning, the physicochemical and bioactivity profile of prickly pear seed oil (PPSO) (a product of prickly pear fruits waste) were investigated. Seeds of shelf-grown cactus fruits (Opuntia ficus indica L.) were subjected to analysis. Moisture content (gravimetric analysis), seed content (gravimetric analysis), oil yield (Soxhlet extraction/gravimetric analysis), volatile compounds (HS-SPME/GC-MS), fatty acids profile (GC-FID), in vitro antioxidant activity (DPPH assay), and total phenolic content (Folin-Cioacalteu assay) were determined. Results showed that prickly pear seeds had a moisture content of 6.0 ± 0.1 g/100 g, whereas the oil yield ranged between 5.4 ± 0.5 g/100 g. Furthermore, the PPSO had a rich aroma because of acids, alcohols, aldehydes, esters, hydrocarbons, ketones, and other compounds, with the major volatiles being 2-propenal, acetic acid, pentanal, 1-pentanol, hexanal, 2-hexenal, heptanal, 2-heptenal (Z), octanal, 2-octenal, nonanal, 2,4-decadienal (E,E), and trans-4,5-epoxy-(E)-2-decenal. Among the fatty acids, butyric, palmitic, stearic, and oleic acids were the dominant. Finally, the pure PPSO had a high in vitro antioxidant activity (84 ± 0.010%) and total phenolic content (551 ± 0.300 mg of gallic acid equivalents/L). PPSO may be then used as a beneficial by-product, in different food systems as a flavoring, antioxidant, and nutritional agent.

E -Waste: Characterization and Disposal through Solid State Route

Present work demonstrates the PCB waste characterization using solid state route. Microwave and resistive heating have been used for heating the PCB waste sample and inter-comparison studies have been carried out in order to understand the nature of volatiles and residue obtained during the two different heating processes. GC -MS was used to analyze the volatiles, collected during microwave heating and shows the presence of CO2 as major volatile. Simultaneous TG -DTA -EGA (FTIR) was used in air and inert atmospheres for online analysis of volatiles where CO2 was observed as major volatile in inert atmosphere along with moisture while CO evolution was also confirmed as major evolved gas along with CO2 and moisture in air atmosphere.

Impact of harvest date on the content of volatile components in garlic

The aim of this study was to define optimal harvesting date of garlic cv. 'Istarski crveni' by comparing the amount of volatile compounds as one of quality indicators. In total 17 volatile compounds were determined in tested garlic samples by headspace solid-phase microextraction coupled to gas chromatography with flame ionization and mass spectrometric detection (HS-SPME-GC-FID-MS) regardless of harvesting date. Major volatiles diallyl trisulfide, diallyl sulfide, methyl allyl disulfide and diallyl disulfide representing 98.5 % of all the determined compounds have shown no significant difference between harvest dates. Significantly higher content of the two minor volatiles, allyl mercaptane and thieno[2,3-b]thiophene, was found in the last and second when compared to the first harvest date. Principal components PC1 and PC2 explained 78% of the total variance and pointed to certain relations between harvest dates and volatiles. The technological maturity had probably been reached at the first harvesting date since similar amounts of volatiles were found during the observed period.

Transcriptome and methylome analysis reveals effects of ripening on and off the vine on flavor quality of tomato fruit

Abstract Current commercial harvest procedures for tomatoes usually involve harvesting the fruit at an early ripening stage with high firmness suitable for storage and transportation followed by ethylene treatment to accelerate fruit ripening. However, harvesting at an immature stage results in reduced flavor quality. Here, we provide major insights into the effect of ethylene-induced ripening of immature fruit on consumer liking, flavor-related compounds, transcriptomes and DNA methylation. Reduced flavor quality of off-vine ripened fruit treated with ethylene is associated with significantly higher content of malic acid, a lower sugar/acid ratio, as well as changes in major volatiles. Altered levels of flavor-related compounds are associated with significant changes in expression of genes encoding key biosynthetic enzymes for malic acid and specific volatiles. Transcripts involved in ethylene formation and signaling are induced by exogenous ethylene treatment. Meanwhile, significant difference in transcript levels of genes related to auxin response are observed between fruit ripened on and off the vine. Differences in transcript levels of volatile synthesis-related genes, including LOXC, BCAT1 and AADC1A, are accompanied by major changes in DNA methylation status of their transcriptional promoter regions. Our analysis provides molecular insights into tomato fruit flavor loss caused by artificial ripening using postharvest ethylene treatment.

Composition of Essential Oils from Roots and Aerial Parts of Carpesium divaricatum, a Traditional Herbal Medicine and Wild Edible Plant from South-East Asia, Grown in Poland.

Carpesium divaricatum Sieb. and Zucc. has long been used both as traditional medicine and seasonal food. The most extensively studied specialized metabolites synthesized by the plant are sesquiterpene lactones of germacrane-type. Low-molecular and volatile terpenoids produced by C. divaricatum, however, have never been explored. In this work, compositions of essential oils distilled from roots and shoots of C. divaricatum plants, cultivated either in the open field or in the glasshouse have been studied by GC-MS-FID supported by NMR spectroscopy. The analyses led to the identification of 145 compounds in all, 112 of which were localized in aerial parts and 80 in roots of the plants grown in the open field. Moreover, remarkable differences in composition of oils produced by aerial and underground parts of C. divaricatum have been observed. The major volatiles found in the shoots were: α-pinene (40%), nerol (4%) and neryl-isobutyrate (3%), whereas predominant components of the root oil were 10-isobutyryloxy-8,9-epoxythymyl-isobutyrate (29%), thymyl-isobutyrate (6%) and 9-isobutyryloxythymyl-isobutyrate (6%). In the analyzed oils, seventeen thymol derivatives were identified. Among them eight compounds were specific for roots. Roots of the plants cultivated in the glasshouse were, in general, a poor source of essential oil in comparison with those of the plants grown in the open field. Chemophenetic relationships with other taxa of the Inuleae-Inulineae were also briefly discussed.

Nonideal MHD Simulation of HL Tau Disk: Formation of Rings

Abstract Recent high-resolution observations unveil ring structures in circumstellar disks. The origin of these rings has been widely investigated under various theoretical scenarios. In this work we perform global 3D nonideal MHD simulations including effects from both ohmic resistivity and ambipolar diffusion (AD) to model the HL Tau disk. The nonideal MHD diffusion profiles are calculated based on the global dust evolution calculation including sintering effects. Disk ionization structure changes dramatically across the snow line due to the change of dust size distribution close to the snow line of major volatiles. We find that accretion is mainly driven by disk wind. Gaps and rings can be quickly produced from different accretion rates across the snow line. Furthermore, AD leads to highly preferential accretion at the midplane, followed by magnetic reconnection. This results in a local zone of decretion that drains the mass in the field reconnection area, which leaves a gap and an adjacent ring just outside of it. Overall, under favorable conditions, both snow lines and nonideal MHD effects can lead to gaseous gaps and rings in protoplanetary disks.

Fast ascent rate during the 2017–2018 Plinian eruption of Ambae (Aoba) volcano: a petrological investigation

In September 2017, after more than a hundred years of quiescence, Ambae (Aoba), Vanuatu’s largest volcano, entered a new phase of eruptive activity, triggering the evacuation of the island’s 11,000 inhabitants resulting in the largest volcanic disaster in the country’s history. Three subsequent eruptive phases in November 2017, March 2018, and July 2018 expelled some of the largest tropospheric and stratospheric SO2 clouds observed in the last decade. Here, we investigate the mechanisms and dynamics of this eruption. We use major elements, trace elements, and volatiles in olivine and clinopyroxene hosted melt inclusions, embayments, crystals, and matrix glasses together with clinopyroxene geobarometry and olivine, plagioclase, and clinopyroxene geothermometry to reconstruct the physical and chemical evolution of the magma, as it ascends to the surface. Volatile elements in melt inclusions and geobarometry data suggest that the magma originated from depth of ~ 14 km before residing at shallow (~ 0.5 to 3 km) levels. Magma ascent to the surface was likely facilitated by shallow phreatic eruptions that opened a pathway for magma to ascend. Succeeding eruptive phases are characterised by increasingly primitive compositions with evidence of small amounts of mixing having taken place. Mg–Fe exchange diffusion modelling yields olivine residence times in the magma chamber ranging from a few days to a year prior to eruption. Diffusion modelling of volatiles along embayments (melt channels) from the first two phases of activity and microlite number density suggests rapid magma ascent in the range of 15–270 km/h, 4–75 m/s (decompression rates of 0.1 to ~ 2 MPa/s) corresponding to a short travel time between the top of the shallow reservoir and the surface of less than 2 min.

Effect of pretreatment and low‐temperature low humidity drying on quality characteristics of coriander foliage

AbstractPretreatment followed by low‐temperature low humidity drying was explored for efficient dehydration of coriander foliage to retain its quality characteristics. Newton, Page, Handerson & Pabis, Logarithmic & Midilli and Kucuk models were used to study the drying kinetics. Hygienic shelf‐stable green dried coriander foliage (HSSGDCF) obtained was evaluated for their flavour, physico‐chemical, microbial and sensory qualities during storage at ambient (65% RH, 27 ± 1°C) and accelerated (92% RH, 37 ± 1°C) conditions for 90 days. Logarithmic model with higher (R2 = 0.9997) and lower root mean square error value (0.0050) showed the best‐fitted model. Major volatiles identified in HSSGDCF were decanal (5.103%), 2‐decenal (10.021%), dodecanal (7.314%), 2‐dodecenal (7.684%), tetradecanal (8.509%), 13‐tetradecenal (19.393%) and decanoic acid decyl ester (6.051%). Degradation of chlorophyll, carotenoid and colour values were higher at 37 ± 1°C during storage. HSSGDCF was found to be microbiologically safe and sensorily acceptable at the end of 90 days at 27 ± 1°C.

On the Origin(s) and Evolution of Earth's Carbon

The isotopic “flavor” of Earth's major volatiles, including carbon, can be compared to the known reservoirs of volatiles in the solar system and so determine the source of Earth's carbon. This requires knowing Earth's bulk carbon isotope value, which is not straightforward to determine. During Earth's differentiation, carbon was partitioned into the core, mantle, crust, and atmosphere. Therefore, although carbon is omnipresent within the Earth system, scientists have yet to determine its distribution and relative abundances. This article addresses what we know of the processes involved in the formation of Earth's carbon reservoirs, and, by deduction, what we know about the possible origins of Earth's carbon.

Probing CO and N2 Snow Surfaces in Protoplanetary Disks with N2H+ Emission

Abstract Snowlines of major volatiles regulate the gas and solid C/N/O ratios in the planet-forming midplanes of protoplanetary disks. Snow surfaces are the 2D extensions of snowlines in the outer disk regions, where radiative heating results in an increasing temperature with disk height. CO and N2 are two of the most abundant carriers of C, N, and O. N2H+ can be used to probe the snow surfaces of both molecules, because it is destroyed by CO and formed from N2. Here we present Atacama Large Millimeter/submillimeter Array (ALMA) observations of N2H+ at ∼0.″2–0.″4 resolution in the disks around LkCa 15, GM Aur, DM Tau, V4046 Sgr, AS 209, and IM Lup. We find two distinctive emission morphologies: N2H+ is either present in a bright, narrow ring surrounded by extended tenuous emission, or in a broad ring. These emission patterns can be explained by two different kinds of vertical temperature structures. Bright, narrow N2H+ rings are expected in disks with a thick Vertically Isothermal Region above the Midplane (VIRaM) layer (LkCa 15, GM Aur, DM Tau) where the N2H+ emission peaks between the CO and N2 snowlines. Broad N2H+ rings come from disks with a thin VIRaM layer (V4046 Sgr, AS 209, IM Lup). We use a simple model to extract the first sets of CO and N2 snowline pairs and corresponding freeze-out temperatures toward the disks with a thick VIRaM layer. The results reveal a range of N2 and CO snowline radii toward stars of similar spectral type, demonstrating the need for empirically determined snowlines in disks.

On the account of the Moon’s gravitational field in LEND measurements

Space nuclear planetology experiments play significant role in the studies of planetary surface composition and volatiles distribution. To determine concentration of major rockforming elements and volatiles, one needs to perform model-dependent deconvolution and interpretation of experimental data. This model should completely simulate all environments and experimental conditions influencing neutron production and transport an also including finite lifetime of neutron. The existing Monte Carlo codes are extremely useful for complicated geometry simulations where time-dependent and wide-energy-range solutions are required. However, they usually do not include or include in very simplified way the gravitational field description appropriate for the simulation of neutron propagation on planetary scales. We have proposed an approach useful for surface-to-orbit transport simulations where neutron lifetime and planetary gravitational field are taken into account. The discussion how gravity force and finite neutron lifetime may influence the spectral and angular neutron distributions at different spacecraft altitudes is presented. The obtained results are implemented to the detection of hydrogen-bearing compounds in the lunar regolith. As a good example we used experimental data from LEND/LRO to evaluate how insertion of neutron finite lifetime and lunar gravitational field in numerical model of experiment may influence on the interpretation of measurements made by different LEND neutron detectors.

DIFFERENCES IN FRAGRANCE CHEMISTRY BETWEEN FLOWER PARTS OF ROSA RUGOSA THUNB. (ROSACEAE)

ABSTRACT Fragrances (volatiles) from whole flowers, petals, sepals plus gynoecium, anthers, and pollen were collected from Rosa rugosa Thunb. by headspace adsorption methods and analyzed by gas chromatography/mass spectrometry. Each flower part showed a distinctive volatile profile. Petal volatiles, dominated by terpenoid and benzenoid alcohols, contributed most to the whole-flower fragrance. Sepal odors contained mainly sesquiterpenes, together with several compounds found in the petals. The major volatiles in the androecium were more diverse and overall different from the perianth. Empty anthers shared a high proportion of their volatile profile with pollen. Pollen odor appeared to be self-contained, showing only minor adsorption of volatiles from sepals and petals. Compounds typical of the androecium were present as significant, albeit quantitatively small, components of the whole-flower fragrance, where they may well function as signals to pollen-seeking insects.

The Changes of the Volatile Compounds Derived from Lipid Oxidation of Boneless Dry‐Cured Hams During Processing

The generation of aroma during processing of boneless dry‐cured hams is investigated by evaluating neutral and acid lipases, phospholipase, lipoxygenase (LOX), thiobarbituric acid reactive substances (TBARS) values, fatty acid composition, and volatile substances derived from lipid oxidation (VCDFLO). It is found that moisture content, acid lipase, and phospholipase decreases in the whole processing, but sodium chloride content and TBARS increase. Neutral lipase, LOX, and total fatty acids increase from raw ham to the end of resting and decrease subsequently. 15 VCDFLO containing six ketones, three aldehydes, three hydrocarbons, one alcohol, one carboxylic acid, and one furan are identified. The total peak area of VCDFLO increases during the entire processing and indicates 39.76–40.75% of total volatile compounds. Hexanal, 1‐octen‐3‐ol, octanal, and nonanal are the major characteristic volatiles of boneless dry‐cured hams. Therefore, VCDFLO formation is associated with lipid‐related enzymes and helpful for the aroma.Practical Applications: The pork that has high intramuscular fat content is usually selected to produce boneless dry‐cured hams, because intramuscular phospholipids, and triglycerides are important precursors to produce aroma compounds. Exploring the formation mechanism of flavor associated with lipid oxidation will be beneficial for improving the quality of hams. Therefore, this study demonstrates the relationship between lipolysis‐oxidation and the generation of flavor compounds during the processing of boneless dry‐cured hams.This study demonstrates that thiobarbituric acid reactive substances (TBARS) values can reveal the changed trend of volatile compounds derived from lipid oxidation (VCDFLO) very well, and that lipid‐related enzymes plays an important role in the development of VCDFLO.

Melatonin influence on in vitro callus induction and phenolic compound production in sweet basil (Ocimum basilicum L.)

The aim of the present study was to evaluate melatonin effects on the callus induction and phenolic compound production of Ocimum basilicum L. (sweet basil). Calluses, derived from leaf explants, were grown on Murashige and Skoog (MS) medium supplemented with 0, 100, or 200 μM melatonin, and subsequently extracted for determination of their phenolic contents. Melatonin decreased the callus induction in both concentrations. Based on the phytochemical analysis, the highest total phenolic acid contents (784.6 μg g−1 and 335.2 μg g−1, respectively) were recorded in calluses grown in 100 and 200 μM melatonin-supplemented medium, compared with the calluses induced with MS alone (192.0 μg g−1). Among the five phenolic acids confirmed in the callus samples, rosmarinic acid was the major constituent. The amount of rosmarinic acid increased significantly in callus grown on 100 μM melatonin medium by nearly 5-fold (754.2 μg g−1), compared with the control group callus. Major volatiles in basil calluses were represented by 3-methylbutanal, benzaldehyde, 1,8-cineole, 2-nonenal, eugenol, and methyl eugenol, and these were in the ranges of 4 to 14%, 24 to 50%, 2 to 3%, 0 to 0.55%, and 2 to 17% (in relative percentages), respectively. The qualitative and quantitative analyses of these substances found in calluses formed on melatonin-supplemented or melatonin-free medium were evaluated separately.

The impacts of brewing in glass tumblers and thermos vacuum mugs on the aromas of green tea (Camellia sinensis).

This study investigated the effect of brewing apparatus on the aromatic feature of tea infusion. Huangshan Maofeng tea infusion was brewed under glass tumblers (GT) or thermos vacuum mugs (TVM) for up to 180min. Tea infusion sensory attributes were evaluated using quantitative descriptive analysis and the composition of volatiles were analyzed using headspace solid phase microextraction coupled with gas chromatography-mass spectrometry. Results showed that GT tea infusion at each brewing duration possessed stronger 'Pure', 'Fresh' and 'Grassy' attributes than TVM tea infusion, whereas TVM tea infusion showed a higher intensity on 'Steamed' aroma. A total of 74 volatiles were detected in tea infusion, and aldehydes and alcohols appeared to be the major volatiles. Total aldehydes concentration percentage decreased in tea infusion with brewing process, whereas an increase on total alcohol percentage was found. Principal component analysis indicated that brewing duration and apparatus played vital roles in altering the volatile composition in tea infusion, whereas orthogonal partial least squares discriminant analysis (OPLS-DA) revealed that GT tea infusion samples were separated from TVM tea infusion samples. OPLS-DA also screened 20 volatiles that significantly contributed to the differentiation of GT and TVM tea infusion.

Allelopathic effects of volatile organic compounds released from Pinus halepensis needles and roots.

The Mediterranean region is recognized as a global biodiversity hotspot. However, over the last decades, the cessation of traditional farming in the north part of the Mediterranean basin has given way to strong afforestation leading to occurrence of abandoned agricultural lands colonized by pioneer expansionist species like Pinus halepensis. This pine species is known to synthesize a wide range of secondary metabolites, and previous studies have demonstrated strong allelopathic potentialities of its needle and root leachates. Pinus halepensis is also recognized to release significant amounts of volatile organic compounds (VOC) with potential allelopathic effects that have never been investigated. In this context, the objectives of the present study were to improve our knowledge about the VOC released from P. halepensis needles and roots, determine if these VOC affect the seed germination and root growth of two herbaceous target species (Lactuca sativa and Linum strictum), and evaluate if soil microorganisms modulate the potential allelopathic effects of these VOC. Thirty terpenes were detected from both, needle and root emissions with β‐caryophyllene as the major volatile. Numerous terpenes, such as β‐caryophyllene, δ‐terpinene, or α‐pinene, showed higher headspace concentrations according to the gradient green needles < senescent needles < needle litter. Seed germination and root growth of the two target species were mainly reduced in presence of P. halepensis VOC. In strong contrast with the trend reported with needle leachates in literature, we observed an increasing inhibitory effect of P. halepensis VOC with the progress of needle physiological stages (i.e., green needle < senescent needle < needle litter). Surprisingly, several inhibitory effects observed on filter paper were also found or even amplified when natural soil was used as a substrate, highlighting that soil microorganisms do not necessarily limit the negative effects of VOC released by P. halepensis on herbaceous target species.

Attraction of the Invasive Hornet, Vespa velutina nigrithorax, by using Bacillus sp. BV&amp;#8208;1 Cultures

BACKGROUND: The invasive hornet Vespa velutina nigrithorax has becomes a public concern in rural and urban South Korea. The technologies are necessary to develop a way to counter V. velutina. In an effort to develop a way to counter V. velutina, we found that a bacillus strain, named Bacillus sp. BV-1, produces volatile compounds that attract V. velutina. METHODS AND RESULTS: Field trials of V. velutina attraction were performed using plates and traps containing BV-1 cultures grown on sugar medium. When the sugar medium and sugar-grown BV-1 cultures in the plates were placed close together, V. velutina visited preferably the plates with the BV-1 cultures. Significantly more V. velutina were caught in the traps containing BV-1 cultures than in those containing only sugar medium. Headspace solid-phase microextraction coupled with GC/MS analysis of BV-1 cultures detected 2-methyl-1-propanol, 3-methyl-1-butanol, 3-methylbutanoic acid, ethyl hexanoate, 2-pheylethanol, ethyl octanoate, and ethyl decanoate as the major volatiles. CONCLUSION: BV-1 cultures were suggested as potential agents for managing V. velutina as they produce volatile compounds that attract the hornet.

Seed Elaiosome Mediates Dispersal by Ants and Impacts Germination in Ricinus communis

Myrmecochory is ant-mediated secondary dispersal of seeds that depends on the presence of a lipid-rich seed appendage known as ‘elaiosome’. Attractive cues of elaiosome that drive such an interaction and benefits to the plant are not clearly understood. Here, using Ricinus communis, we establish reward compositions and determine the benefits of myrmecochory to the plant. We also compare elaiosome compositions across ecotypes. Our results show that the elaiosome is essential for seed displacement and olfactory cues are important attractive cues. Nonanal and 2-decenal were found to be the major attractive volatiles in the castor elaiosome. Different ant species showed different behavior towards elaiosome-bearing seeds. Among them, Pheidole grayi was efficient in dispersal but did not disperse all seed ecotypes tested. Major differences in fatty acid levels were observed between ecotypes. To determine the benefits of myrmecochory, germination rates before and after removal of elaiosome were studied. Seed germination improved upon elaiosome removal and aqueous elaiosome extract inhibited germination indicating water-soluble inhibitory factors. Further, ant nest sites were richer in nitrogen than control sites, revealing a clear benefit of seed displacement. In summary, we demonstrate the ecological significance of the seed elaiosomes in the absence of nutritive rewards for seed dispersers.