1.Herbivore-induced volatile emissions from cotton (Gossypium hirsutum L.) seedlings.
McCall PJ1, Turlings TC, Loughrin J, Proveaux AT, Tumlinson JH. J Chem Ecol. 1994 Dec;20(12):3039-50. doi: 10.1007/BF02033709.
The effect of herbivory on the composition of the volatile blends released by cotton seedlings was investigated by collecting volatiles from undamaged, freshly damaged (0-2 hr after initiation of feeding), and old damaged (16-19 hr after initiation of feeding) plants on which corn earworm caterpillars (Helicoverpa zea Boddie) were actively feeding. A blend of 22 compounds was consistently observed to be emitted by the old damaged plants with nine occurring either only in, or in significantly greater amounts in old damaged, as compared with freshly damaged plants. These were (Z)-3-hexenyl acetate, hexyl acetate, (E)-β-ocimene, (3E)-4,8-dimethyl-1,3,7-nonatriene, (Z)-3-hexenyl butyrate, (E)-2-hexenyl butyrate, (Z)-3-hexenyl 2-methylbutyrate, (E)-2-hexenyl 2-methylbutyrate, and indole. The nature of this response is compared with other studies where herbivore-induced volatile responses are also known. The presence of large amounts of terpenes and aldehydes seen at the onset of feeding and the appearance of other compounds hours later suggest that cotton defense mechanisms may consist of a constitutive repertoire that is augmented by an induced mechanism mobilized in response to attack.
2.Identification of potent odourants in wine and brewed coffee using gas chromatography-olfactometry and comprehensive two-dimensional gas chromatography.
Chin ST1, Eyres GT, Marriott PJ. J Chromatogr A. 2011 Oct 21;1218(42):7487-98. doi: 10.1016/j.chroma.2011.06.039. Epub 2011 Jun 17.
Volatile constituents in wine and brewed coffee were analyzed using a combined system incorporating both GC-olfactometry (GC-O) and comprehensive two-dimensional GC-flame ionization detection (GC×GC-FID). A column set consisting of a 15m first dimension ((1)D; DB-FFAP (free fatty acid phase)), and a 1.0m (2)D column (DB-5 phase) was applied to achieve the GC×GC separation of the volatile extracts isolated by using solid phase extraction (SPE). While 1D GC resulted in many overlapping peaks, GC×GC allowed resolution of co-eluting compounds which coincided with the odour region located using GC-O. Character-impact odourants were tentatively identified through data correlation of GC×GC contour plots across results obtained using either time-of-flight mass spectrometry (TOFMS), or with flame photometric detection (FPD) for sulfur speciation. The odourants 2-methyl-2-butenal, 2-(methoxymethyl)-furan, dimethyl trisulfide, 2-ethyl-5-methyl-pyrazine, 2-octenal, 2-furancarboxaldehyde, 3-mercapto-3-methyl-1-butanol, 2-methoxy-3-(2-methylpropyl)-pyrazine, 2-furanmethanol and isovaleric acid were suspected to be particularly responsible for coffee aroma using this approach.
3.Female-induced increase of host-plant volatiles enhance specific attraction of aphid male Dysaphis plantaginea (Homoptera: Aphididae) to the sex pheromone.
van Tol RW1, Helsen HH, Griepink FC, de Kogel WJ. Bull Entomol Res. 2009 Dec;99(6):593-602. doi: 10.1017/S0007485309006634. Epub 2009 Feb 19.
All aphid species studied so far share the same sex pheromone components, nepetalactol and nepetalactone. Variation by different enantiomers and blends of the two components released by different aphid species are limited and can only partially explain species-specific attraction of males to females. While some host-plant odours are known to enhance specific attraction of aphid species, herbivore-induced plant volatiles that synergise attractiveness to the sex pheromone are unknown. Here, we demonstrate that for the host-alternating rosy apple aphid (Dysaphis plantaginea (Passerini)) specificity of attraction of males to females is triggered by female-induced tree odours in combination with a 1:8 ratio of (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol. Female aphid infestation induces increased release of four esters (hexyl butyrate, (E)-2-hexenyl butyrate, (Z)-3-hexenyl 3-methylbutyrate and hexyl 2-methylbutyrate) from apple leaves.
4.Aroma extract dilution analysis of cv. Meeker (Rubus idaeus L.) red raspberries from Oregon and Washington.
Klesk K1, Qian M, Martin RR. J Agric Food Chem. 2004 Aug 11;52(16):5155-61.
The aromas of cultivar Meeker red raspberry from Oregon and Washington were analyzed by aroma extract dilution analysis. Seventy-five aromas were identified [some tentatively (superscript T)] by mass spectrometry and gas chromatography-retention index; 53 were common to both, and 22 have not been previously reported in red raspberry. Twenty-one compounds had an equivalent odor impact in both: 2,5-dimethyl-4-hydroxy-3-(2H)-furanone, hexanal, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one, (E)-beta-3,7-dimethyl-1,3,6-octatrieneT, 6,6-dimethyl-2-methylenebicyclo[3.1.1]heptaneT, 1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-2-buten-1-one, ethanoic acid, (Z)-3-hexenalT, 3-methylmercaptopropionaldehyde, (Z)-3-hexenol, 2,6-dimethyl-2,7-octadien-6-ol, butanoic acid, ethyl 2-methylpropanoate, (E)-2-hexenal, hexyl formateT, 2,3-butanedione, heptanalT, thiacyclopentadieneT, cyclohexane carbaldehydeT, (E)-3,7-dimethyl-2,6-octadien-1-olT, and 4-(p-hydroxyphenyl)-2-butanone.