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PubMed2001

Caterpillar-induced nocturnal plant volatiles repel conspecific females.

Plants respond to insect herbivory by synthesizing and releasing complex blends of volatile compounds, which provide important host-location cues for insects that are natural enemies of herbivores. The effects of these volatile blends on herbivore behaviour have been investigated to only a limited extent, in part because of the assumption that herbivore-induced volatile emissions occur mainly during the light phase of the photoperiod. Because many moths-whose larvae are some of the most important insect herbivores-are nocturnal, herbivore-induced plant volatiles have not hitherto been considered to be temporally available as host-location cues for ovipositing females. Here we present chemical and behavioural assays showing that tobacco plants (Nicotiana tabacum) release herbivore-induced volatiles during both night and day. Moreover, several volatile compounds are released exclusively at night and are highly repellent to female moths (Heliothis virescens). The demonstration that tobacco plants release temporally different volatile blends and that lepidopteran herbivores use induced plant signals released during the dark phase to choose sites for oviposition adds a new dimension to our understanding of the role of chemical cues in mediating tritrophic interactions.

Animals↗
PubMed1998

Identification of volatile organic compounds emitted in the field by oilseed rape (Brassica napus ssp. oleifera) over the growing season.

BACKGROUND: Oilseed rape has been associated by rural dwellers with seasonal symptoms, such as sneezing, coughing, headache and eye irritation, during its flowering season, for a number of years. This study was performed to identify the volatile chemicals emitted from oilseed rape in the field. OBJECTIVE: The objective of this study was to establish which volatile chemicals may be causative factors of oilseed rape allergy/toxicity. METHODS: The volatile organic compounds were sampled over the flowering period using a modified entrainment technique for headspace analysis under field conditions. These volatiles were then identified using thermal desorption-gas chromatography-mass spectrometry. RESULTS: The major constituents identified were the monoterpenes limonene, sabinene, beta-myrcene, and cis-3-hexen-l-ol acetate, a 'green leaf' volatile. The minor constituents included monoterpenes, sesquiterpenes, short chain aldehydes and ketones, other 'green leaf' volatiles and organic sulphides including the respiratory irritant, dimethyl disulphide. CONCLUSIONS: This report highlights the diversity of volatile chemicals emitted by oilseed rape and confirms field emissions to be broadly similar to those found previously in laboratory studies. A review is carried out on the scientific literature already published on oilseed rape flower headspace analysis.

Aldehydes↗
PubMed2003

Bacterial volatiles promote growth in Arabidopsis.

Several chemical changes in soil are associated with plant growth-promoting rhizobacteria (PGPR). Some bacterial strains directly regulate plant physiology by mimicking synthesis of plant hormones, whereas others increase mineral and nitrogen availability in the soil as a way to augment growth. Identification of bacterial chemical messengers that trigger growth promotion has been limited in part by the understanding of how plants respond to external stimuli. With an increasing appreciation of how volatile organic compounds signal plants and serve in plant defense, investigations into the role of volatile components in plant-bacterial systems now can follow. Here, we present chemical and plant-growth data showing that some PGPR release a blend of volatile components that promote growth of Arabidopsis thaliana. In particular, the volatile components 2,3-butanediol and acetoin were released exclusively from two bacterial strains that trigger the greatest level of growth promotion. Furthermore, pharmacological applications of 2,3-butanediol enhanced plant growth whereas bacterial mutants blocked in 2,3-butanediol and acetoin synthesis were devoid in this growth-promotion capacity. The demonstration that PGPR strains release different volatile blends and that plant growth is stimulated by differences in these volatile blends establishes an additional function for volatile organic compounds as signaling molecules mediating plant-microbe interactions.

Arabidopsis↗
PubMed2000

Involvement of jasmonate- and salicylate-related signaling pathways for the production of specific herbivore-induced volatiles in plants.

We compared volatiles from lima bean leaves (Phaseolus lunatus) infested by either beet armyworm (Spodoptera exigua), common armyworm [Mythimna (Pseudaletia) separata], or two-spotted spider mite (Tetranychus urticae). We also analyzed volatiles from the leaves treated with jasmonic acid (JA) and/or methyl salicylate (MeSA). The volatiles induced by aqueous JA treatment were qualitatively and quantitatively similar to those induced by S. exigua or M. separata damage. Furthermore, both S. exigua and aqueous JA treatment induced the expression of the same basic PR genes. In contrast, gaseous MeSA treatment, and aqueous JA treatment followed by gaseous MeSA treatment, induced volatiles that was qualitatively and quantitatively more similar to the T. urticae-induced volatiles than those induced by aqueous JA treatment. In addition, T. urticae damage resulted in the expression of the acidic and basic PR genes that were induced by gaseous MeSA treatment and by aqueous JA treatment, respectively. Based on these data, we suggest that in lima bean leaves, the JA-related signaling pathway is involved in the production of caterpillar-induced volatiles, while both the SA-related signaling pathway and the JA-related signaling pathway are involved in the production of T. urticae-induced volatiles.

Animals↗
PubMed2004

Combined transcript and metabolite analysis reveals genes involved in spider mite induced volatile formation in cucumber plants.

Many plants have an indirect defense against herbivores by emitting volatiles that attract carnivorous enemies of the herbivores. In cucumber (Cucumis sativus) the production of carnivore attractants can be induced by herbivory or jasmonic acid spraying. From the leaves of cucumber plants with and without spider mite infestation, two subtractive cDNA libraries were made that were enriched in cDNA fragments up- or down-regulated by spider mite infestation. A total of 713 randomly selected clones from these libraries were used to make a cDNA microarray. Subsequently, cucumber plants were sprayed with jasmonic acid, mechanically damaged, infested with spider mites, or left untreated (control). Leaf samples were taken at a range of different time points, and induced volatile compounds and mRNA (from the same leaves) were collected. cDNAs prepared from the mRNA were hybridized to the clones on the microarray. The resulting gene expression profiles were analyzed in combination with volatile production data in order to gain insight in the possible involvement of the studied genes in the synthesis of those volatiles. The clones on the microarray and the induced cucumber volatiles could be grouped into a number of clusters in which specific biosynthetic genes clustered with the product of that pathway. For example, lipoxygenase cDNA clones clustered with the volatile (Z)-3-hexenyl acetate and the volatile sesquiterpene (E,E)- alpha-farnesene clustered with an up-regulated sesquiterpene synthase fragment. This fragment was used to screen a cDNA library which resulted in the cloning of the cucumber (E,E)-alpha-farnesene and (E)-beta-caryophyllene synthases. The use of combined global gene expression analysis and metabolite analysis for the discovery of genes involved in specific biosynthetic processes is discussed.

Amino Acid Sequence↗
PubMed2006

Plant volatile compounds: sensory cues for health and nutritional value?

Plants produce many volatile metabolites. A small subset of these compounds is sensed by animals and humans, and the volatile profiles are defining elements of the distinct flavors of individual foods. Flavor volatiles are derived from an array of nutrients, including amino acids, fatty acids, and carotenoids. In tomato, almost all of the important flavor-related volatiles are derived from essential nutrients. The predominance of volatiles derived from essential nutrients and health-promoting compounds suggests that these volatiles provide important information about the nutritional makeup of foods. Evidence supporting a relation between volatile perception and nutrient or health value will be reviewed.

Amino Acids, Essential↗
PubMed2000

Ferrous iron-dependent volatilization of mercury by the plasma membrane of Thiobacillus ferrooxidans.

Of 100 strains of iron-oxidizing bacteria isolated, Thiobacillus ferrooxidans SUG 2-2 was the most resistant to mercury toxicity and could grow in an Fe(2+) medium (pH 2.5) supplemented with 6 microM Hg(2+). In contrast, T. ferrooxidans AP19-3, a mercury-sensitive T. ferrooxidans strain, could not grow with 0.7 microM Hg(2+). When incubated for 3 h in a salt solution (pH 2.5) with 0.7 microM Hg(2+), resting cells of resistant and sensitive strains volatilized approximately 20 and 1.7%, respectively, of the total mercury added. The amount of mercury volatilized by resistant cells, but not by sensitive cells, increased to 62% when Fe(2+) was added. The optimum pH and temperature for mercury volatilization activity were 2.3 and 30 degrees C, respectively. Sodium cyanide, sodium molybdate, sodium tungstate, and silver nitrate strongly inhibited the Fe(2+)-dependent mercury volatilization activity of T. ferrooxidans. When incubated in a salt solution (pH 3.8) with 0.7 microM Hg(2+) and 1 mM Fe(2+), plasma membranes prepared from resistant cells volatilized 48% of the total mercury added after 5 days of incubation. However, the membrane did not have mercury reductase activity with NADPH as an electron donor. Fe(2+)-dependent mercury volatilization activity was not observed with plasma membranes pretreated with 2 mM sodium cyanide. Rusticyanin from resistant cells activated iron oxidation activity of the plasma membrane and activated the Fe(2+)-dependent mercury volatilization activity of the plasma membrane.

Azurin↗
PubMed1995

Volatile organic compounds in the breath of patients with schizophrenia.

AIMS: To analyse the breath of patients with schizophrenia for the presence of abnormal volatile organic compounds. METHODS: A case comparison study was performed in two community hospitals in Staten Island, New York. Twenty five patients with schizophrenia, 26 patients with other psychiatric disorders, and 38 normal controls were studied. Alveolar breath samples were collected from all participants, and volatile organic compounds in the breath were assayed by gas chromatography with mass spectroscopy. Differences in the distribution of volatile organic compounds between the three groups were compared by computerised pattern recognition analysis. RESULTS: Forty eight different volatile organic compounds were observed in the breath samples. Three separate pattern recognition methods indicated an increased differentiation capability between the patients with schizophrenia and the other subjects. Pattern recognition category classification models using 11 of these volatile organic compounds identified the patients with schizophrenia with a sensitivity of 80.0% and a specificity of 61.9%. Volatile organic compounds in breath were not significantly affected by drug therapy, age, sex, smoking, diet, or race. CONCLUSIONS: Microanalysis of volatile organic compounds in breath combined with pattern recognition analysis of data may provide a new approach to the diagnosis and understanding of schizophrenia. The physiological basis of these findings is still speculative.

Breath Tests↗
PubMed2001

Volatilization of mercury under acidic conditions from mercury-polluted soil by a mercury-resistant Acidithiobacillus ferrooxidans SUG 2-2.

Volatilization of mercury under acidic conditions from soil polluted with mercuric chloride (1.5 mg Hg/kg soil) was studied with resting cells of a mercury-resistant strain, Acidithiobacillus ferrooxidans SUG 2-2. When resting cells of SUG 2-2 (0.01 mg of protein) were incubated for 10 d at 30 degrees C in 20 ml of 1.6 mM sulfuric acid (pH 2.5) with ferrous sulfate (3%) and mercury-polluted soil (1 g), which contained 7.5 nmol of Hg, approximately 4.1 nmol of mercury was volatilized, indicating that 54% of the total mercury in the soil was volatilized. The amount of mercury volatilized from the soil was dependent on the concentration of Fe2+ added to the medium. When elemental sulfur, sodium tetrathionate, and pyrite were used as an electron donor for the mercury reduction, 16, 2.4 and 0.84%, respectively, of the total mercury added to the solution were volatilized. The optimum pH and temperature for mercury volatilization were 2.5 and 30 degrees C. Approximately 92% of the total mercury in a salt solution (pH 2.5) with resting cells of SUG 2-2 (0.01 mg of protein), ferrous sulfate (3%) and mercury-polluted soil (1 g) was volatilized by further addition of both resting cells and Fe2+ and by incubating for 30 d at 30 degrees C.

Hydrogen-Ion Concentration↗
PubMedDate not supplied

Management factors affecting ammonia volatilization from land-applied cattle slurry in the Mid-Atlantic USA.

Ammonia (NH3) volatilization commonly causes a substantial loss of crop-available N from surface-applied cattle slurry. Field studies were conducted with small wind tunnels to assess the effect of management factors on NH3 volatilization. Two studies compared NH3 volatilization from grass sward and bare soil. The average total NH3 loss was 1.5 times greater from slurry applied to grass sward. Two studies examined the effect of slurry dry matter (DM) content on NH3 loss under hot, summer conditions in Maryland, USA. Slurry DM contents were between 54 and 134 g kg(-1). Dry matter content did not affect total NH3 loss, but did influence the time course of NH3 loss. Higher DM content slurries had relatively higher rates of NH3 volatilization during the first 12 to 24 h, but lower rates thereafter. Under the hot conditions, the higher DM content slurries appeared to dry and crust more rapidly causing smaller rates of NH3 volatilization after 12 to 24 h, which offset the earlier positive effects of DM content on NH3 volatilization. Three studies compared immediate incorporation with different tillage implements. Total NH3 loss from unincorporated slurry was 45% of applied slurry NH4+-N, while losses following immediate incorporation with a moldboard plow, tandem-disk harrow, or chisel plow were, respectively, 0 to 3, 2 to 8, and 8 to 12%. These ground cover and DM content data can be used to improve predictions of NH3 loss under specific farming conditions. The immediate incorporation data demonstrate management practices that can reduce NH3 volatilization, which can improve slurry N utilization in crop-forage production.

Ammonia↗
PubMedDate not supplied

Estimating turf pesticide volatilization from simple evapotranspiration models.

A previously developed model by Haith et al. (2002) related pesticide volatilization from turf to evapotranspiration (ET) by scaling factors determined from vapor pressures and heats of vaporization. Although the model provided volatilization estimates that compared well with field measurements, it relied on the Penman ET equation, requiring hourly temperature, wind speed, and solar radiation data, none of which are routinely available at field sites. The current study determined that the volatilization model works equally well with a simpler ET equation requiring only daily temperatures. Three daily temperature-based ET models were evaluated as vehicles for estimating pesticide volatilization from turf: Hamon, Hargreaves-Samani, and a modified Priestley-Taylor. When compared with field volatilization measurements for eight pesticides, volatilization estimates produced from the Hargreaves-Samani model most closely approximated both the field observations and the previous estimates based on the more data-intensive Penman model. Mean estimated volatilization exceeded mean observations by 15% and the coefficient of variation (R2) between estimates and observations was 0.65. The comparable values based on Penman ET were 17% and 0.63, respectively.

Models, Theoretical↗
PubMed2006

Effect of scraping frequency in a freestall barn on volatile nitrogen loss from dairy manure.

The objective of this investigation was to evaluate the effect of scraping frequency (2x vs. 6x daily) on N volatilization from manure on the floor of a dairy free-stall barn. Three trials (crossover design) were conducted in the summers of 2001 and 2002, and in the winter of 2003. Nitrogen volatilization was estimated from the change in the N:P ratio in excreta at the time of excretion to the time when manure was scraped from the barn. Total N loss was considered a maximum estimate of NH3-N loss, because small amounts of nonammonia N may be volatilized. Nitrogen was determined after manure subsamples were lyophilized; P content was measured by direct current emission spectroscopy of ashed subsamples of manure. Lactating dairy cows were fed high-protein (18.5 to 19.3% crude protein), alfalfa-based diets. Average milk yield was 31.9 (SD = 7.4) kg/d. Scraping frequency had no effect on N loss in summer 2001. An average of 41% of excreted N, or 238 +/- 19.0 g of N/d per cow, was volatilized. For the trial in summer 2002, nitrogen volatilization was reduced from 50% of the excreted N with 2x to 46.7% with 6x, equivalent to 265 and 248 g of N lost/d per cow, respectively. Scraping had no effect on N volatilization during the winter trial. An average of 17.7% of excreted N was volatilized during the winter, equivalent to 109 +/- 11.0 g of N lost/d per cow. Scraping frequency of manure had little or no effect on N loss from manure in a freestall barn. Nitrogen loss during the winter was less than half of the loss during the summer.

Air Pollutants↗
PubMed1983

Net volatile fatty acid absorption in nonlactating holstein cows.

Net absorption of volatile fatty acids was measured in four nonlactating Holstein cows fed orchardgrass-clover silage ad libitum and 50 g trace mineralized salt daily. Cows ranged in age from 2 to 4 yr and in body weight from 326 to 525 kg. Portal blood flow and volatile fatty acid concentrations of portal and arterial plasma were determined at 30-min (three cows) or 90-min (one cow) intervals for about 12 h. Mean portal blood flow was 836 liters/h. Mean volatile fatty acid concentrations of portal plasma and differences of portal-arterial concentrations were (mM): acetate 2.00, .67; propionate .264, .228; isobutyrate .022, .017; n-butyrate .057, .038; 2-methylbutyrate .017, .014; 3-methylbutyrate .007, .005; and n-valerate .012, .008. Mean net volatile fatty acid absorption was 682 mmol/h. Acetate and propionate accounted for 91% of net volatile fatty acid absorption on a molar basis and 85% on an energy basis. Net energy absorbed as volatile fatty acid was 5.43 Mcal/cow per day, which was about 35% of calculated metabolizable energy intake. Portal blood flow was maximal 1.5 h postfeeding, and net volatile fatty acid absorption was maximal 2.5 h postfeeding.

Animals↗
PubMedDate not supplied

Quantitation of volatile oils in ground cumin by supercritical fluid extraction and gas chromatography with flame ionization detection.

Ground cumin is used as a flavoring agent in a number of ethnic cuisines. The chemical entities, which primarily establish its characteristically pungent flavor, are found in the volatile oil of cumin. Fixed oils and carbohydrates tend to round out the harshness of the volatile oil components. However, the quantity of volatile oil is commonly the measure of the quality of this spice. For several decades, the spice industry has used a classical distillation procedure for the determination of volatile oil in cumin and other spices. However, the method is cumbersome and requires nearly 8 h to complete. Supercritical fluid extraction with capillary gas chromatography-flame ionization detection is utilized in the formulation of a rapid, accurate, and specific method for the determination of volatile oil in ground cumin. Samples are extracted in a static-dynamic mode with CO2 at 550 bar and 100 degrees C. Toluene is used as a static modifier addition. The extracted volatile oil, collected in toluene, is analyzed directly using tetradecane as the internal standard. Integration is performed as grouped peaks to include all chemical entities found in cumin volatile oil recovered from the official distillation procedure. Results from this procedure compare favorably with those obtained by the official procedure (coefficient of correlation = 0.995, 24 samples).

Chromatography, Gas↗
PubMed2003

A new tool for laboratory studies on volatilization: extension of applicability of the photovolatility chamber.

Volatilization from soil and plant surfaces after application is an important source of pesticide residues to the atmosphere. The laboratory photovolatility chamber allows the simultaneous measurement of volatilization and photodegradation of 14C-labeled pesticides under controlled climatic conditions. Both continuous air sampling, which quantifies volatile organic compounds and 14CO2 separately, and the detection of surface-located residues allow for a mass balance of radioactivity. The setup of the photovolatility chamber was optimized, and additional sensors were installed to characterize the influence of soil moisture, soil temperature, and evaporation on volatilization. The modified flow profile in the glass dome of the chamber arising from the use of a high-performance metal bellows pump was measured. Diminished air velocity near the soil surface and a wind velocity of 0.2 m/s in 3 cm height allowed the requirements of the German guideline on assessing pesticide volatilization for registration purposes to be fulfilled. Determination of soil moisture profiles of the upper soil layer illustrated that defined water content in the soil up to a depth of 4 cm could be achieved by water saturation of air. Cumulative volatilization of [phenyl-UL-14C]parathion-methyl ranged from 2.4% under dry conditions to 32.9% under moist conditions and revealed the clear dependence of volatilization on the water content in the top layer.

Air↗
PubMed2003

[Two chemotypes of Pogostemon cablin and influence of region of cultivation and harvesting time on volatile oil composition].

AIM: To analyze and compare the constituents of the volatile oil of Pogostemon cablin collected from different regions of cultivation and harvesting times in order to evaluate the quality of Shipai Huoxiang and to expound the chemical intension of Pogostemon cablin. METHODS: The combination of GC and MS. RESULTS: The volatile oil compositions of Herba Pogostemonis collected from various of cultivation regions and harvesting times are obviously different. Based on the chemical differences of the volatile oil compositions, Pogostemon cablin is divided into two chemotypes, Pogostone-type and Patchouliol-type. The former was cultivated in Guangzhou and Gaoyao regions, locally named as "Shipai Huoxiang"; the latter was locally named as "Hainan Huoxiang", cultivated in Wuchuan, Suixi and Leizhou regions of Guangdong Province and Wanning region of Hainan Province. The Pogostone-type contains rich oxygenated components, especially pogostone in the volatile oil compositions and poor non-oxygenated composition with patchouliol. The above chemical data may be used as evaluation standard for the authentic Shipai Huoxiang. The Patchouliol-type contains similar quantities of oxygenated and non-oxygenated composition, especially rich patchouliol with poor pogostone in oxygenated compositions, rich delta-guaiene and alpha-guaiene in non-oxygenation compositions. The contents of volatile oil and their constituents were varied due to different harvesting time. The yields of pogostone and volatile oil of Shipai Huoxiang was higher in July. The quality of the samples collected in this month was better. CONCLUSION: According to the volatile oil compositions, there are two chemotypes (Pogostone-type and Patchouliol-type) in Pogostemon cablin plant. These two chemotypes correspond to the genotypes of plastid matK gene and nuclear 18s rRNA gene by cluster analysis.

Ecosystem↗
PubMed1997

[Identification of volatile compounds of hawthorn by gas chromatography/mass spectrometry (GC/MS)].

The volatile compounds of three cultivars of hawthorn were studied. Changko (Crataegus pinnatifida Bge.) hawthorn fruit was harvested after ripening from Hubei Province and those of Heihong and Dajinxing were from Shandong Province. The volatile compounds of each hawthorn cultivars were obtained by SDE (simultaneous distillation-extraction) equipment, by using CH2Cl2 as extracting solvent. The volatile extract was concentrated at 40-50 degrees C under vacuum to 0. 05mL or so and was ready for GC and GC/MS analysis. A DB-Wax fused silica capillary column (50m x 0.32mm i.d.; 1microm thickness) and a flame ionization detector (FID) was employed in GC analysis. The temperature program included of a 5 min isothermal period at 40 degrees C, temperature increases of 2 degrees C/min from 40 degrees C to 240 degrees C, and a 60 min isothermal period at 240 degrees C. Mass spectra were obtained by electron impact at 70eV and a source temperature of 250 degrees C. Thirty-two volatile compounds of the hawthorn fruit were identified, which comprised 61%-68% of the volatile fraction. The ten major components were cis-3-hexenol, cis-3-hexenyl acetate, alpha-terpineol, furfural, hexanol, hexyl acetate, nonanal, citral, 3-penten-2-one and trans-2-decenal. The molecular weight range of the major volatile fraction covers from C3 to C10. Both qualitative and quantitative differences in the volatile constituents among the three cultivars were not remarkable.

Crataegus↗
PubMed2005

Chemical composition and insecticidal activity of the volatile oils of leaves and flowers of Lantana camara L. cultivated in Egypt.

GC and GC/MS analysis of the hydrodistilled volatile oils of the leaves and flowers of Lantana camara L. cv. flava (Verbenaceae) cultivated in Egypt revealed both qualitative and quantitative variations. Experimentally, twenty-nine and twenty-two components were identified in the volatile oils of leaves and flowers representing 91.91% and 95.24% of the total composition of both oils respectively. The major constituents of the leaves volatile oil were caryophyllene (9.76%), cineol <1.8-> (9.37%) and pinene (8.15%). The flowers volatile oils were caryophyllene (18.20%), humulene (12.22 %) and bicyclegermacrene (10.33%). Comparing the chemical composition of the volatile oils of the leaves and flowers of L. canara cv., flava from different origins, seasons and even experimental conditions revealed that there are significant qualitative and quantitative variations. The larvicidal effect of the volatile oils of L. camara cv., flava leaves and flowers of was tested against the maturation of Musca domestica L. larvae in the laboratory at concentrations (0.0125%, 0.025%. 0.05%, 0.1% and 0.2%). They showed mortality rate ranged from 80%- 100%. On the other hand, 10-20% of the developed pupae emerged to adults. Adults' fecundity was in larvae given a concentration of 0.0125%. In conclusion, the volatile oils of the leaves and flowers of L. camara cv., flava can be safely recommended in controlling M. domestica 3rd stage larvae.

Animals↗