Effect on microorganisms of volatile compounds released from germinating seeds.

Volatile compounds evolved from germinating seeds of slash pine, bean, cabbage, corn, cucumber, and pea were evaluated for their ability to support growth of microorganisms in liquid mineral salts media lacking a carbon source. Growth of eight bacteria was measured turbidimetrically and of six fungi as dry weight of mycelium. Volatiles caused increased growth of Pseudomonas fluorescens, Bacillus cereus, Erwinia carotovora, Agrobacterium tumefaciens, A. radiobacter, Rhizobium japonicum, Mucor mucedo, Fusarium oxysporum f. conglutinans, Trichoderma viride, and Penicillium vermiculatum but not of Sarcina lutea, Serratia marcescens, Chaetomium globosum, or Schizophyllum commune. Spores of Trichoderma viride showed higher germination in the presence of volatiles. Effects on growth were apparent only during the first 3 or 4 days after planting the seeds. Killed or dried seeds had no effect. The volatiles did not support microbial growth in the absence of nitrogen nor did they supply growth factors. Passing volatiles through KMnO4 or hydrazone reduced growth of the bacteria, indicating that oxidizable organic compounds, primarily aldehydes, were the active components. The volatiles were not absorbed by sterile soil, clay minerals, or water, but they were absorbed by non-steril soil and activated charcoal.     

Functional evolution of biosynthetic enzymes that produce plant volatiles*

Plants synthesize volatile compounds to attract pollinators. The volatiles emitted by flowers are often complex mixtures of organic compounds; pollinators are capable of distinctly recognizing different volatile compounds. Plants also produce volatile compounds to protect themselves against herbivores and pathogens. Some of the volatile compounds produced in floral and vegetative tissues are toxic to insects and microbes. To adapt changes in the environment, plants have evolved the ability to synthesize a unique set of volatiles. Intensive studies have identified and characterized the enzymes responsible for the formation of plant volatiles. In particular, many biosynthetic genes have been isolated and their enzymatic functions have been proposed. This review describes how plants have evolved the biosynthetic pathways leading to the formation of green leaf volatiles and phenylpropene volatiles.     

Production of volatile organic compounds by the yeast fungus Dipodascus aggregatus

Summary The yeast fungus Dipodascus aggregatus was grown aerobically in a synthetic nutrient solution and the volatile compounds produced were concentrated. Identification of the volatiles was performed by combined gas chromatographymass spectrometry or by one of these methods. The compounds identified were 11 esters, 9 alcohols, 5 acids and 3 carbonyls.The time course production of volatile neutral compounds was followed. During the phase of no apparent growth only a few substances were formed (mostly alcohols). The rapid phase of growth was characterized by an intense synthesis of many compounds in relatively high concentrations and later a sudden decrease in the number and amounts of substances. A slow successive, decline in the number and amounts of volatile components was observed during the phase of no net growth.The volatiles emitted by the fungus were concentrated, when most of the compounds were most abundant and the relative amounts of the major volatile neutral compounds were determined. The main components were ethyl acetate, ethyl propionate and ethanol.     

A non-targeted approach unravels the volatile network in peach fruit

Volatile compounds represent an important part of the plant metabolome and are of particular agronomic and biological interest due to their contribution to fruit aroma and flavor and therefore to fruit quality. By using a non-targeted approach based on HS-SPME-GC-MS, the volatile-compound complement of peach fruit was described. A total of 110 volatile compounds (including alcohols, ketones, aldehydes, esters, lactones, carboxylic acids, phenolics and terpenoids) were identified and quantified in peach fruit samples from different genetic backgrounds, locations, maturity stages and physiological responses. By using a combination of hierarchical cluster analysis and metabolomic correlation network analysis we found that previously known peach fruit volatiles are clustered according to their chemical nature or known biosynthetic pathways. Moreover, novel volatiles that had not yet been described in peach were identified and assigned to co-regulated groups. In addition, our analyses showed that most of the co-regulated groups showed good intergroup correlations that are therefore consistent with the existence of a higher level of regulation orchestrating volatile production under different conditions and/or developmental stages. In addition, this volatile network of interactions provides the ground information for future biochemical studies as well as a useful route map for breeding or biotechnological purposes.     

Flower Volatiles,Crop Varieties and Bee Responses

Pollination contributes to an estimated one third of global food production, through both the improvement of the yield and the quality of crops. Volatile compounds emitted by crop flowers mediate plant-pollinator interactions, but differences between crop varieties are still little explored. We investigated whether the visitation of crop flowers is determined by variety-specific flower volatiles using strawberry varieties (Fragaria x ananassa Duchesne) and how this affects the pollination services of the wild bee Osmia bicornis L. Flower volatile compounds of three strawberry varieties were measured via headspace collection. Gas chromatography showed that the three strawberry varieties produced the same volatile compounds but with quantitative differences of the total amount of volatiles and between distinct compounds. Electroantennographic recordings showed that inexperienced females of Osmia bicornis had higher antennal responses to all volatile compounds than to controls of air and paraffin oil, however responses differed between compounds. The variety Sonata was found to emit a total higher level of volatiles and also higher levels of most of the compounds that evoked antennal responses compared with the other varieties Honeoye and Darselect. Sonata also received more flower visits from Osmia bicornis females under field conditions, compared with Honeoye. Our results suggest that differences in the emission of flower volatile compounds among strawberry varieties mediate their attractiveness to females of Osmia bicornis. Since quality and quantity of marketable fruits depend on optimal pollination, a better understanding of the role of flower volatiles in crop production is required and should be considered more closely in crop-variety breeding.     

藏药镰形棘豆挥发性成分研究(英文)

本文通过水蒸气蒸馏、超临界CO2萃取和顶空萃取三种方法并结合GC和GC/MS技术分析藏药镰形棘豆(Oxytropis falcate Bunge)中的挥发性成分,共鉴定出58个化合物,分别占71.0%,85.6%和84.5%。烷烃类、黄酮类和醛类化合物为主要挥发性成分。3种方法得到的挥发性成分在保留时间值上具有一定的连续性,能更完全地阐述清楚藏药镰形棘豆的挥发性成分,为进一步开发利用这种药用植物提供科学依据。     

复叶槭挥发性物质的日释放节律及对光肩星天牛引起的行为反应

采用动态顶空采集吸附,热脱附及GC-MS分析的方法。对活性复叶槭（Acer negundoL.)释放的挥发性物质的组成及日释放节律进行了研究。鉴定出复叶槭挥发性物质中的32种化合物成份。包括醛类,醇类,酮类,酯类,脂肪酸类,萜烯类等。日释放节律研究表明,在7月份主要挥发性物质释放高峰集中于14时左右。而8月份则提前到10时左右。虽然在7月份和8月份采样时保持条件一致。但所释放的挥发性物质在种类及相对含量上有明显的不同,这很可能与复叶槭不同时期的生长状况及叶片的衰老有关。在田间采用诱捕器研究了光肩星天牛对上述挥发性物质的行为反应。田间试验结果表明,与其它挥发物相比,顺-3-己烯-1-醇在田间对光肩是天牛具有更强的引诱活性。由1-丁醇,1-戊醇和2-戊醇混合而成的混合物具有最强的引诱活性。     

Costs of induced volatile production in maize

Herbivore‐induced plant volatiles have been shown to serve as indirect defence signals that attract natural enemies of herbivores. Parasitoids and predators exploit these plant‐provided cues to locate their victims and several herbivores are repelled by the volatiles. Recently, benefits, in terms of plant fitness, from the action of the parasitoids were shown for a few systems. However, the cost of production of herbivore‐induced volatiles for the plant remains unknown. Here, we estimate the fitness cost of the production of induced volatiles in maize, Zea mays. Plants were treated with regurgitant of Spodoptera littoralis or with the elicitor volicitin and we measured dry weight of plant parts at specific times after treatments. After a two‐week treatment period, the dry‐weight of leaves of induced plants was lower than that of un‐induced plants, suggesting a metabolic cost for induced defence. However, maize plants seem to compensate for this loss during subsequent growth, since seed production at maturity was not different for unharmed plants and plants treated with caterpillar regurgitant. For volicitin treated plants a small but significant reduction in seed production was found. It is likely that the treatments also induced the production of other defence compounds, which will contribute to the cost. Yet, a comparison of six maize inbred lines with distinct differences in volatile emissions showed a strong correlation between the intensity of induced emissions and reduction in plant performance. An analysis of the terpenoids that accumulated in the leaves of the inbred lines revealed non‐volatilised compounds are constitutively present in maize and only the volatilised compounds are induced. Interestingly, the lines that released the largest amounts of induced volatiles also contained more of the non‐volatile terpenoids. Based on these results and results from a previous study on the benefits of attracting parasitoids, we conclude that costs of induced volatile production in plants are counterbalanced by the benefits as long as natural enemies of the herbivores are present in the environment.     

Identification of odoriferous compounds from adults of a swallowtail butterfly, Papilio machaon (Lepidoptera: Papilionidae)

Adults, particularly males, of a papilionid butterfly, Papilio machaon hippocrates, emit a fairly strong scent perceivable by humans. We have identified a variety of volatile compounds (hydrocarbons, alcohols, aldehydes, ketones, esters, and so on) from the wings and bodies of both sexes of the butterfly. Male wings secreted n-dodecane, linalool and geranylacetone as major components together with small amounts of camphene, limonene, p-cymene, 2-phenylethanol, n-hexanal, n-decanal, isoamyl acetate, p-allylanisole, 2-pyrrolidone and other characteristic volatiles. The overall profile of volatile compounds detected from male body was quite different from that of the wings. Male body was devoid of camphene, 2-phenylethanol, n-hexanal but instead contained limonene, acetoin, a sesquiterpene hydrocarbon (C15H24, methyl n-octanoate, (E,E)-hepta-2,4-dienal, and another isomer of heptadienal as principal components, of which the last four compounds were specific to the body. All these substances seem to concurrently characterize the male odor. The chemical patterns of compounds found from female wings and body were essentially the same in quality as those of male wings and body, respectively, although their quantities in females were generally smaller than in males. Females, however, had a larger amount of acetamide than males. The chemical compositions of volatiles from the fore and hind wings of males were not greatly different from each other, and every component was considered to be present on all parts of the wings. This suggests that the scent-producing organs or scent-emitting pores are widely distributed on the whole wings. EAG responses of both sexes to 12 selected compounds identified from the butterfly were not strong at a dose of 1 microg, while both sexes showed relatively stronger responses to n-nonanal, methyl n-octanoate, D-limonene and linalool at a higher dose (10 microg). Although sexual difference in EAG response was not prominent, females appeared a little more sensitive, and n-nonanal and acetoin evoked significantly higher responses from females at 1 microg.     

Comparative analysis of the volatile fraction of fruit juice from different Citrus species

The volatile composition of fruit from four Citrus varieties (Powell Navel orange, Clemenules mandarine, and Fortune mandarine and Chandler pummelo) covering four different species has been studied. Over one hundred compounds were profiled after HS-SPME-GC-MS analysis, including 27 esters, 23 aldehydes, 21 alcohols, 13 monoterpene hydrocarbons, 10 ketones, 5 sesquiterpene hydrocarbons, 4 monoterpene cyclic ethers, 4 furans, and 2 aromatic hydrocarbons, which were all confirmed with standards. The differences in the volatile profile among juices of these varieties were essentially quantitative and only a few compounds were found exclusively in a single variety, mainly in Chandler. The volatile profile however was able to differentiate all four varieties and revealed complex interactions between them including the participation in the same biosynthetic pathway. Some compounds (6 esters, 2 ketones, 1 furan and 2 aromatic hydrocarbons) had never been reported earlier in Citrus juices. This volatile profiling platform for Citrus juice by HS-SPME-GC-MS and the interrelationship detected among the volatiles can be used as a roadmap for future breeding or biotechnological applications.     

On-line monitoring of important organoleptic methyl-branched aldehydes during batch fermentation of starter culture Staphylococcus xylosus reveal new insight into their production in a model fermentation

A small fermentor (55 mL) was directly interfaced to a membrane inlet mass spectrometer for continuous on-line monitoring of oxygen and volatile metabolites during batch fermentations of the starter culture Staphylococcus xylosus. Using this technique, we were able to correlate production of the very important flavor compounds 2-methylbutanal, 3-methylbutanal, and 2-methylpropanal with various growth conditions. We found that the aldehydes were present in the culture broth only as transient metabolites. They were produced in the exponential growth phase, reached a maximum concentration when the culture became anaerobic, and then they rapidly disappeared from the culture medium. This general pattern was observed for three different strains of S. xylosus and S. carnosus. Small amounts of inoculum or increased exposure to oxygen were found to favor production of the aldehydes as a result of a longer aerobic growth period. Growing S. xylosus under conditions resembling those in a fermented sausage revealed that NaCl (5%) increased aldehyde production considerably, whereas KNO(3) (0.03%) or NaNO(2) (0.03%) had little effect. A lowering of pH from 7.2 to 6.0 reduced cell density, but had a minor affect on aldehyde production.     

Induced emissions of apple fruit volatiles by the codling moth: changing patterns with different time periods after infestation and different larval instars

The changes in the emission of volatiles from mature apple fruits in response to larval feeding by the codling moth (Cydia pomonella) under laboratory conditions are reported. A time course experiment investigated the emission of volatiles throughout the period of larval development following infestation. The volatiles consisted mainly of esters, a few aldehydes, and the terpene alpha-farnesene. Infested apples emitted the same compounds as healthy apples. The quantities of volatiles released were much higher for infested as compared to healthy fruits for an initial three day period. Following this period there was a decrease in volatile emissions (days 6-9), eventually declining back to the levels emitted from healthy apples or below by 9-21 days after infestation. In a separate experiment, the volatile emissions from healthy and artificially damaged fruits were compared to those from herbivore damaged fruits for each of the five larval instars of C. pommonella. The results from the discriminant analysis indicate that the most effective induction of volatiles occurred when fruits were infested with first instar larvae. Induction by first instar larvae was generally higher than after infestation by later instars, and for most compounds it also exceeded the emission from artificially damaged fruits.     

The volatile fraction of herbal teas

The use of herbal teas, infusions or tisanes in folk medicine, medicinal phytotherapy as well as for food purposes is still very popular. In classical phytotherapy the active principles of herbal teas are often attributed to their volatile constituents. On the other hand, safety concerns could arise from volatiles as ingredients of infusions. In any case, information on the aromatic composition and volatile fraction of herbal teas is limited. There is a lack of qualitative and quantitative data on the volatile compounds in infusions as well as on the changes of volatile composition during the tea preparation process. For isolation of the volatile compounds from infusions several methods like liquid–liquid extraction, hydrodistillation or solid phase micro extraction have been used. Primarily, the composition has been determined by GC-FID or GC–MS analysis, in exceptional cases by HPLC-PDA or HPLC–MS analysis. The profile of the volatile fraction of herbal teas classified by chemical functionalities of the compounds (hydrocarbons, oxides, alcohols/ethers, aldehydes/ketones, acids/esters) differs from the profile of the corresponding genuine essential oil. Remarkable are losses of hydrocarbons in infusions. This review will cover the phytochemical research that has been carried out on the volatiles of herbal teas and will focus on results of the volatile fraction especially from rosemary (Rosmarinus officinalis), fennel (Foeniculum vulgare subsp. vulgare), lavender (Lavandula angustifolia), thyme (Thymus vulgaris) and chamomile (Matricaria recutita) infusions.     

Volatiles from four Astragalus species: phenological changes and their chemotaxonomical application

This paper shows the changes of the volatile compounds from four Astragalus species at three phenological stages: leaf development, flowering and fructification, which might be connected with the plant defense. After GC/MS analyses of Astragalus glycyphyllos L., A. hamosus L., A. cicer L. and A. spruneri Boiss., different groups of volatile compounds were found: hydrocarbons, alcohols, aldehydes and ketones, esters, terpenes, chlorinated compounds, etc. Identified volatiles were used for a cluster analysis in order to make chemotaxonomic conclusions for these evolutionary different species.     

Host plant volatiles induce oriented flight behaviour in male European grapevine moths, Lobesia botrana

The European grapevine moth Lobesia botrana relies on a female produced sex pheromone for long-distance mate finding. Grapevine moth males compete heavily during limited time windows for females. The aim of this study was to investigate the perception of host plant volatiles by grapevine moth males and whether such compounds elicit upwind oriented flights. We compared five host plant headspace extracts by means of gas chromatography linked electroantennogram (EAG) recording. We identified 12 common host plant volatiles (aliphatic esters, aldehydes, and alcohols, aromatic compounds and terpenes) that elicit EAG responses from grapevine moth males and that occur in at least three of the host plant volatile headspace extracts tested. Subsequently the behavioural response of grapevine moth males to four these compounds presented singly and in mixtures (1-hexanol, 1-octen-3-ol, (Z)-3-hexenyl acetate and (E)-β-caryophyllene) was recorded in a wind tunnel. Grapevine moth males engaged in upwind flights to all of four compounds when released singly at 10,000 pg/min and to all, except 1-octen-3-ol, when released at 100 pg/min. A blend of the four host plant volatiles released at 10,000 pg/min and mixed at a ratio based on the analysis of Vitis vinifera cv. Solaris volatile emissions attracted significantly more males than any single compound. Grapevine moth males perceive and respond to host plant volatiles at biologically relevant levels indicating that host plant volatiles figure as olfactory cues and that L. botrana males can discern places where the likelihood of encountering females is higher.     

Volatile compounds from the symbiotic system Azolla filiculoides‐Anabaena azollae bacteria

Abstract

Azolla filiculoides is an aquatic pteridophyte that may be used as animal food, biofertilizer and phytoremediation. Its volatile composition was never studied although several phytochemical analyses were performed. The volatile composition of A. filiculoides grown outdoors in a pond at the Botanical Garden of Lisbon University (BGLU) or in culture conditions as well as the effect of different harvesting times and the storage type were evaluated. The volatiles isolated by hydrodistillation and distillation‐extraction were analysed by gas chromatography and gas chromatography‐mass spectrometry. The oil of all the A. filiculoides samples studied affords a yellowish colour and an unpleasant odour in a yield of 0.01% (v/fw). Alcohols, aldehydes, alkanes and ketones dominated the culture samples, while aldehydes, alcohols, terpenoids and alkanes represented the main volatiles of the BGLU samples. Some quantitative differences were detected in seasonal and type of storage (fresh, dry or frozen at ?20°C) studies of A. filiculoides from the BGLU. The BGLU and culture volatiles showed qualitative differences: 2‐ethyl‐1‐hexanol was only identified in the fern culture, whereas acetophenone, pentylfuran, acetylpyridine and 2‐octanone were only detected in BGLU samples. The dendrogram showed two distinct clusters (culture and BGLU samples). The possible biological origin and bioactivity of some of the volatile compounds is discussed.

Abbreviations: FID, flame ionization detector; i.d., internal diameter; v/fw, volume by fresh weight; GC, gas chromatography; GC‐MS, gas chromatography‐mass spectrometry; u, unified atomic mass unit     

Dynamic changes in volatile emissions of breeding burying beetles

Burying beetles reproduce on small vertebrate carcasses by exhibiting elaborate biparental brood care. Partner recognition in breeding Nicrophorus species (Coleoptera: Silphidae) relies substantially on information encoded in cuticular hydrocarbon profiles. Until recently, it was unknown whether breeding burying beetles also produce volatile low molecular weight substances and, if so, which functions can be attributed to such volatiles. The present study reports a survey of the volatiles released by males and females of Nicrophorus vespilloides Herbst in nonbreeding status and at different stages of breeding. Headspace analyses are performed by using solid phase micro‐extraction fibres and gas chromatography–mass spectrometry. The volatiles released by nonbreeding males and females include phenolic compounds, alcohols, aldehydes and ketones and are quite similar in both sexes. With the onset of breeding, the volatile profiles of males and females become distinct, with a number of female‐specific compounds occurring. An analysis of the anal secretions reveals the presence of some of the compounds previously detected in the headspace analysis. The specific chemical properties suggest that some of the volatiles may function against competitors and parasites, such as bacteria, fungi, nematodes and arthropods at the carcass breeding resource. By contrast, the emission of 4‐methyl branched esters by the females closely parallels the emission of the terpenoid methyl geranate and they may function together as a complex signal by the females. Signalling traits associated with biparental care and specific constraints associated with the ephemeral nature of the breeding resource may explain the occurrence of both groups of compounds in the volatile profiles.     

A combination of physiological and chemometrics analyses reveals the main associations between quality and ripening traits and volatiles in two loquat cultivars

A combined analysis of physiological traits, volatile composition and sensory evaluation of aromatic quality was conducted on the ‘Algerie’ and ‘Golden Nuggett’ cultivars at six maturity stages, covering colour breaking to complete ripening. The main difference between cultivars during ripening was aromatic character; organoleptic differences between cultivars were assessed by a taste panel and could be explained by the volatile profile at harvest, and more specifically by those volatiles showing a rapid increase as fruits fully ripened. Among the 121 volatile compounds identified in loquat fruits, 2-methyl butanoic acid was the only cultivar-specific VOC, detected only in ‘Algerie’, while the levels of other common VOCs also contributed to differentiation between cultivars. A correlation analysis ran between volatile compounds levels and loquat aroma and flavour intensity revealed that 1,2-dimethoxy-4-(2-methoxyethenyl)benzene, elemicin, (Z)-2-hexen-1-ol, methyl 2-methylbutanoate, methyl 3,4,5-trimethoxybenzoate, cis-geranylacetone, (E)-methyl cinnamate, (E)-2-decenal, cis-edulan and 1-hydroxycyclohexyl phenyl ketone were volatiles which could importantly contribute to loquat’s aromatic character, some of which are reported here for the first time as key volatiles in aromatic quality. The correlations among the physiological parameters, the volatile compounds and physiological traits, and the parallelisms between precursors and volatile product, are discussed as they offer clues about loquat quality-associated metabolic changes during ripening.     

In search of the chemical basis for MHC odourtypes

Mice can discriminate between chemosignals of individuals based solely on genetic differences confined to the major histocompatibility complex (MHC). Two different sets of compounds have been suggested: volatile compounds and non-volatile peptides. Here, we focus on volatiles and review a number of publications that have identified MHC-regulated compounds in inbred laboratory mice. Surprisingly, there is little agreement among different studies as to the identity of these compounds. One recent approach to specifying MHC-regulated compounds is to study volatile urinary profiles in mouse strains with varying MHC types, genetic backgrounds and different diets. An unexpected finding from these studies is that the concentrations of numerous compounds are influenced by interactions among these variables. As a result, only a few compounds can be identified that are consistently regulated by MHC variation alone. Nevertheless, since trained animals are readily able to discriminate the MHC differences, it is apparent that chemical studies are somehow missing important information underlying mouse recognition of MHC odourtypes. To make progress in this area, we propose a focus on the search for behaviourally relevant odourants rather than a random search for volatiles that are regulated by MHC variation. Furthermore, there is a need to consider a ‘combinatorial odour recognition’ code whereby patterns of volatile metabolites (the basis for odours) specify MHC odourtypes.