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The food deceptive orchid, Dactylorhiza romana (Sebastiani) Soó exhibits a colour polymorphism with yellow, red, and intermediate orange morphs. In this study we tested if floral odour differed among the three distinct colour mor...
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The food deceptive orchid, Dactylorhiza romana (Sebastiani) Soó exhibits a colour polymorphism with yellow, red, and intermediate orange morphs. In this study we tested if floral odour differed among the three distinct colour morphs. We identified 23 odour compounds in D. romana, and all of them occurred in the three colour morphs. Monoterpenes dominated the floral scent. On the basis of Euclidean distances of relative amounts of compounds, yellow morphs were closer to each other than to orange or red morphs. Differentiation of the morphs was mainly due to linalool and benzaldehyde. Linalool occurred in low relative amounts in the yellow morphs, but in high amounts in some of the red individuals, whereas benzaldehyde occurred in higher relative amounts in yellow morphs. Linalool and benzaldehyde are known to be important signal-substances in plant-insect communication, however, it remains to be shown whether insects can discriminate between flower morphs on the basis of the here shown odour differences.
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Although the effect of herbivory on plant reproduction has been investigated in some detail, little is known about how herbivores affect floral signalling. Here, we investigated the effect of foliar herbivory by the African Cotton...
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Although the effect of herbivory on plant reproduction has been investigated in some detail, little is known about how herbivores affect floral signalling. Here, we investigated the effect of foliar herbivory by the African Cotton Leafworm (Spodoptera littoralis) on floral signalling and fruit set in the White Campion (Silene latifolia). We found no effects of herbivory on floral traits involved in visual signalling (flower number, corolla diameter, calyx length, petal length) or in amount of nectar produced. However, Spodoptera-infested plants emitted higher amounts of the two floral volatiles, (Z)-3-hexenyl acetate and beta-ocimene, than control plants. Open pollinated, infested plants also were found to produce more fruits than control plants, but only with nocturnal pollinators. Experimental addition of the two induced floral volatiles to non-infested Silene flowers also led to the production of more fruits with nocturnal pollination. This suggests that higher fruit production in herbivore-infested plants was caused by increased nocturnal pollinator attraction, mediated by the induced floral emission of these two volatiles. Our results show that the effects of herbivory on plant reproductive success are not necessarily detrimental, as plants can compensate herbivory with increased investment in pollinator attraction.
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The performance of electronic nose (E-nose) for Chinese Cymbidium scent profiling has been evaluated. Changes in scent profiles of two Cymbidium ensifolium cultivars have been monitored at different flowering stages (initial flowe...
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The performance of electronic nose (E-nose) for Chinese Cymbidium scent profiling has been evaluated. Changes in scent profiles of two Cymbidium ensifolium cultivars have been monitored at different flowering stages (initial flowering, full flowering, and terminal flowering) and different times combined with two gas collecting devices. Samples were collected by static headspace (SHS) method. How E-nose can be used for pattern recognition and for studying the releasing of flower scent were proposed. Data obtained were subjected to principal component analysis (PCA) and discriminant function analysis (DFA). PCA was performed on the initially instrumental data to explore the structure of each data set and such result showed that the sensory data contained information related to the cultivar and to time spots. DFA was performed to improve the results, leading to clear separations between the sample groups. Gas collecting device did not seriously affect the result of PCA and DFA. Relative aroma intensity (RAI) was proposed as an alternative concept to compare scent intensity between samples on different time points. These results demonstrate the potential application of the E-nose to evaluate the scent profile of flower
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Floral scent of 13 night-flowering Silene species (Caryophyllaceae) was collected by head-space adsorption and analysed via gas chromatography and mass spectrometry. Benzenoids together with isoprenoids dominated the scent in all ...
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Floral scent of 13 night-flowering Silene species (Caryophyllaceae) was collected by head-space adsorption and analysed via gas chromatography and mass spectrometry. Benzenoids together with isoprenoids dominated the scent in all species. Among the benzenoids, benzaldehyde (Silene subconica 35.5%, Silene succulenta 23.1%, Silene sericea 15.6%, Silene vulgaris 12.2%, and Silene nutans 9.9%), methylbenzoate (Silene saxifraga 96.1%, S. succulenta 15.2%), benzyl acetate (Silene dichotoma 37.8%, S. nutans 30.1%, Silene italica 9.0%, and Silene latifolia 5.5%), or benzyl alcohol (Silene viscosa 36.1%) occur in the largest amounts. p-Cresol is only found in the floral scent of S. dichotoma (28.5%). Among the isoprenoids, monoterpenes occur in the largest amounts (myrcene 23% in Silene chlorantha, trans-beta-ocimene 27.2% in S. nutans and 34.9% in S. sericea, fenchyl acetate 12.7% in S. chlorantha, beta-linalool 40.5% in S. chlorantha and 14.5% in S. italica). Relatively high amounts of lilac compounds occur in S. latifolia (49.1%), Silene otites (35.7%), S. subconica (15.2%), and S. vulgaris (59.6%). Higher amounts of sesquiterpenes (isoprenoids) were only found in Silene vallesia with beta-bourbonene and gamma-muurolene.
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Orchid flowers have a unique structure that consists of three sepals and three petals, with one of the petals forming the labellum (lip) that can be differentiated into the hypochile and epichile. In orchids, the emission of flora...
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Orchid flowers have a unique structure that consists of three sepals and three petals, with one of the petals forming the labellum (lip) that can be differentiated into the hypochile and epichile. In orchids, the emission of floral scent is specific and spatially complex. Little is understood about the molecular and biochemical mechanisms of the differing scent emissions between the parts of orchid flowers. Here, we investigated this in the Cattleya hybrid KOVA, and our study showed that monoterpenes, including linalool and geraniol, are the main components responsible for the KOVA floral scent. The KOVA flower was scentless to the human nose before it reached full bloom, potentially because the 1-deoxy-d-xylulose 5-phosphate synthases (RcDXSs) and 4-hydroxy-3-methylbut-2-enyl diphosphate synthases (RcHDSs) that biosynthesize monoterpenes were highly expressed in flowers only when it reached full flowering. Additionally, the spatial expression profile of the monoterpene synthases (RcMTPSs), which were highly expressed in the basal region of the lip (hypochile), contributed to the highest monoterpene emissions from this part of the flower. This might have caused the hypochile to be more fragrant than the other parts of the flower. These findings enrich our understanding of the difference in scents between different flower parts in plants and provide information to breed novel orchid cultivars with special floral scents.
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Flowers of the alpine skypilot, Polemonium viscosum, are attacked by nectar thieving ants of Formica neorufibarbus gelida. Ants exert selection on flower scent, size and shape in skypilots by damaging the pistils. Here, I report o...
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Flowers of the alpine skypilot, Polemonium viscosum, are attacked by nectar thieving ants of Formica neorufibarbus gelida. Ants exert selection on flower scent, size and shape in skypilots by damaging the pistils. Here, I report on the frequency and nature of contact between ants and pollen-bearing anthers and determine the consequences of such contact for pollen performance and pollen donor paternity. In laboratory trials, ants entered flowers with full intact anthers and emasculated (female) flowers equivalently. Similarly, flower visitation rates of ants foraging naturally were not affected by the frequency of male phase flowers per plant. Ants actively interacted with the pollen-bearing anthers during 21% of flower visits, on average. The rate at which such interactions occurred was predicted by the proportion of flowers in the male phase, under a random foraging model. The effect of ants on pollen fertility was tested experimentally by enclosing ants in male-phase flowers on intact inflorescences. Adjacent control flowers were left un-occupied. Pollen from flowers with a history of ant occupancy had significantly lower germination on virgin recipient stigmas than pollen from unoccupied control flowers. With hand-pollination, sufficient pollen was transferred from ant-occupied flowers to saturate seed set. However, a model based on the relationship between seed set and compatible pollen delivery by natural pollinators indicated that ant damage to pollen should reduce paternity accruing per flower visit by 20-26% on average, in nature. Results support the hypothesis that in P. viscosum, selection on floral traits by nectar-thieving ants operates through male as well as female function.
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Scent production is a rare phenomenon in the genus Camellia, which is otherwise very diverse. This study provides the first report of GC-MS analyses of the volatile compounds synthesized and emitted by six Camellia species belongi...
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Scent production is a rare phenomenon in the genus Camellia, which is otherwise very diverse. This study provides the first report of GC-MS analyses of the volatile compounds synthesized and emitted by six Camellia species belonging to three subgenera. Solvent extracts mainly contained derivatives of the terpenoid, phenylpropanoid and fatty acid metabolisms. Members of subgenus Metacamellia mainly accumulated 2-phenylethanol, while C. japonica of subgenus Camellia mainly synthesized monoterpenes and C. yuhsienensis of subgenus Paracamellia displayed a balanced mix of constituents. Headspace analysis of emitted volatiles confirmed the volatile composition and the rosy note of the scent of all species (due to 2-phenylethanol, (±) linalool and some of their derivatives). Analysis of dissected tissues revealed that stamens accumulated 3-50 times more volatiles than petals and that carpels and sepals were the weakest producers of volatiles. These latter organs were the main source of heptanol. Phenylpropanoid and terpenoid derivatives accumulated differentially in both petals and stamens. Tissue distribution differed among Camellia species.
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Although the physiological states of intact and cut flowers are expected to be significantly different, the floral scent emissions of these two conditions has yet to be compared. We compared the scent emissions from intact and cut...
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Although the physiological states of intact and cut flowers are expected to be significantly different, the floral scent emissions of these two conditions has yet to be compared. We compared the scent emissions from intact and cut flowers using carnation (Dianthus caryophyllus L.) cultivars with two different scent-types-a fruity scent based on benzenoid methyl benzoate and a spicy scent based on eugenol. Methyl benzoate or eugenol, which were the principal scent components, always had the highest percentage (> 30 %) in both intact and cut flowers from flower opening to wilting. The total emissions from intact flowers remained at a similar level for approximately 6 days after flower opening, and then gradually decreased with flower senescence. The total emissions from cut flowers were highest on the day of flower opening and then decreased more rapidly than emissions from intact flowers. Furthermore, the duration of noticeable scent of cut flowers was estimated to be shorter than that of intact flowers. The expression of various scent emission-related genes encoding floral volatile benzenoid/phenylpropanoid biosynthesis enzymes, adenosine triphosphate-binding cassette transporters, and MYB transcription factors increased with flower opening and were accompanied by scent emissions. However, the expressions of most of these genes were not affected by cutting, suggesting that the decrease in scent emissions from cut flowers is unlikely due to changes in gene expression. Recently, we reported that cutting accelerates the decrease in sugar content and increases ethylene production in carnation petals, resulting in hastened flower senescence. Therefore, the rapid decrease in scent emissions from cut flowers may be due to a decrease in sugars, which are substrates for the scent components.
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The diversity of angiosperm flowers is astounding. The conventional explanation for this diversity is that it represents the great variety of ways in which flowers have adapted to attract an even greater diversity of animal pollin...
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The diversity of angiosperm flowers is astounding. The conventional explanation for this diversity is that it represents the great variety of ways in which flowers have adapted to attract an even greater diversity of animal pollinators. Many animal behaviourists are therefore interested in how changes in floral morphology affect pollinator behaviour. The establishment of well-characterised model plant species has greatly furthered our understanding of how floral morphology is generated and varied. Many of these model species are pollinated by animals and attract their pollinators through the production of colour, shape, scent, size and rewards. An understanding of the developmental plasticity of floral morphology, and the constraints upon it, should inform research into animal responses to flowers. The use of genetically characterised model species, and the isogenic and near-isogenic lines available in them, will allow dissection of the different components of floral attraction and reward in natural systems.
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Scales for a sensory evaluation of fresh flower scents were evaluated in this study on the assumption that the evaluators are not specialists. Sixteen 7-point bipolar scales, established in previous study (Takeuchi et al, 1995), w...
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Scales for a sensory evaluation of fresh flower scents were evaluated in this study on the assumption that the evaluators are not specialists. Sixteen 7-point bipolar scales, established in previous study (Takeuchi et al, 1995), were used. Evaluators assessed 30 different types of flowers that encompassed different cultivars and genera. Uniformity of evaluation was tested by split-half coefficients, whereas reproducibility was assessed by correlation coefficients. Both were shown to be statistically sufficient. Moreover, there was an improvement in reliability when the two scales, "Light-Heavy" and "Cloying-Plain", were removed from the evaluation procedure.
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