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1.
The Apocynaceae–Asclepiadoideae are well known for their specialized floral morphologies and pollination systems and many species have distinct floral aromas. However, our knowledge on the chemistry of floral volatiles in this plant family is relatively limited although it has been suspected that floral scent plays a key function for pollinator attraction. This is the third paper in a series of papers reporting on the floral odours of Asclepiadoideae. Floral odours of eleven species from seven genera (Cibirhiza, Fockea, Gymnema, Hoya, Marsdenia, Stephanotis and Telosma) of early diverging taxa of Apocynaceae–Asclepiadoideae, and two species of Secamone (Apocynaceae–Secamonoideae) were collected using headspace sampling and then analyzed via GC–MS. We detected 151 compounds, of which 103 were identified. The vast majority of chemicals identified are common components in flower odour bouquets of angiosperms. However, striking was the high relative amount of acetoin (97.6%) in the flower scent of Cibirhiza albersiana. This compound has rarely been reported as a flower scent component and is more commonly found in fermentation odours. Bray–Curtis similarities and Nonmetric-Multidiminsional Scaling (NMDS) analyses showed that each of the species has a distinct odour pattern. This is mostly due to only twelve compounds which singly or in different combinations dominated the scent of the species: the benzenoids benzyl acetate, benzaldehyde, methyl benzoate, and 2-phenylethyl alcohol; the monoterpenoids (E)-ocimene, (Z)-ocimene, linalool, and eucalyptol; and the aliphatic compounds acetoin, and (E,Z)-2,6-nonadienal. The floral scent compositions are discussed in relation to tribal affiliations and their potential role for pollinator attraction, and are compared with the scent data available from other Asclepiadoideae species. 相似文献
2.
Sylvie Baudino Jean-Claude Caissard Véronique Bergougnoux Frédéric Jullien Jean-Louis Magnard Gabriel Scalliet J Mark Cock Philippe Hugueney 《Plant signaling & behavior》2007,2(6):525-526
We localized the tissues and cells that contribute to scent biosynthesis in scented and non-scented Rosa × hybrida cultivars as part of a detailed cytological analysis of the rose petal. Adaxial petal epidermal cells have a typical conical, papillate shape whereas abaxial petal epidermal cells are flat. Using two different techniques, solid/liquid phase extraction and headspace collection of volatiles, we showed that, in roses, both epidermal layers are capable of producing and emitting scent volatiles, despite the different morphologies of the cells of these two tissues. Moreover, OOMT, an enzyme involved in scent molecule biosynthesis, was localized in both epidermal layers. These results are discussed in view of results found in others species such as Antirrhinum majus, where it has been shown that the adaxial epidermis is the preferential site of scent production and emission.Key Words: floral scent, petal epidermis, Rosa, terpenes, volatilesMany plant species produce volatile compounds and these molecules serve a range of purposes. For example, compounds that are emitted from leaves are generally required for the defence of the plant against insect predators. On the other hand, floral compounds attract beneficial insects, leading to pollination of the flower. In leaves, scent compounds are very often synthesised in specialized cells grouped in structures termed trichomes or secretory glands. In many flowers, it is well documented that floral fragrance is produced by the corolla,1 although other flower parts, such as the stamens in Ranunculus acris,2 sometimes play an important role in fragrance emission. In some flowers, in particular those belonging to the Orchidaceae family, scent is emitted by specialized areas of the petal, which have been termed osmophores by Vogel.3 However, in most flowers, when petals produce scent, it is thought to be emitted by all the cells of the petal in a diffusive manner.4 In many flowers, such as roses, the adaxial petal epidermal cells have a conical-papillate shape whereas the cells of the abaxial epidermis are flat (Fig. 1).5 The shape of these conical cells is controlled by a Myb-factor named MIXTA in Antirrhinum majus6 and their shape has been shown to play a role in the diffusion of light, thereby enhancing the attractiveness of the flower.7 Flowers of the mixta mutant have flat adaxial petal epidermal cells that reflect less light8 and as a consequence attract less insects.9 Along the same lines, Kolosova et al.10 demonstrated that S-adenosyl-L-methionine:benzoic acid carboxyl methyltransferase (BAMT), an enzyme involved in scent biosynthesis, was localized in the conical cells of the inner epidermal layer and to a much lesser extent, in the cells of the outer epidermis of the lobes of snapdragon petals. On the basis of these latter observations, some authors have proposed that the papillate cell shape could enhance the diffusion of scent molecules or influence its directionality and be of adaptive significance not only by enhancing light reflection but also by enhancing scent production.11,12Open in a separate windowFigure 1Hand-made cross-section of Rosa × hybrida petal; Ad, adaxial epidermis; Ab, abaxial epidermis; P, spongy parenchyma. Bar = 20 µm.To test the hypothesis that the adaxial epidermis is a privileged site for the production and emission of scent, we chose a highly scented flower, the rose. Contrary to what was expected, we found that both the adaxial and abaxial epidermal layers of the petal were sites of scent production and emission. We were able to show that NaDi reagent stained purple droplets in both epidermal layers of the rose petal, indicating that they both contain terpenes. Several different techniques, including the analysis of epidermal peels and epidermal layer-specific headspace analysis failed to detect a strong difference between the production and emission of scent in the two epidermal layers. Moreover, the detection of OOMT protein, an enzyme involved in 3,5-dimethoxytoluene production, in both the abaxial and adaxial epidermis, indicated that biosynthesis of at least some phenolic scent compounds occurs in both tissues. It will be interesting to extend this approach using in situ hybridization or immunolocalization to determine whether other pathways such as terpene metabolism are also active in the abaxial epidermis.It is striking to note that in Clarkia breweri, which has actinomorphic flowers like the rose, expression of the S-adenosyl-L-methionine:(iso) eugenol O-methyltransferase (IEMT) gene seems to occur in both epidermal layers.13 A. majus flowers have a different structure, they are highly zygomorphic with a flower shape that is adapted for bee pollination and includes specialized cell types in different parts of the flower (the lobes and the tube). To determine whether emission of scent in highly specialized flowers such as A. majus is linked to cell shape, it would be very useful to know whether mixta mutant flowers which have flat epidermal cells are impaired in their capacity to emit scent. However, the explanation may not be as simple. A recent study of the synthesis and emission of methyl benzoate showed that in Nicotiana suaveolens, as in the rose, both epidermal layers of the petal lobes are involved in scent production, whereas in Stephanotis floribunda, SAMT, another enzyme involved scent biosynthesis, is localized only in the adaxial epidermis and subepidermal regions of the flower petal lobes.14 It is intriguing to note that N. suaveolens has bullate to rugose epidermal cell layers on both sides of the petal whereas S. floribunda has tight flat to bullate epidermal cells.The reasons for the differences in the potential for scent emission of the two petal epidermal layers in the rose and other species are not known. However, our results and a survey of the literature clearly indicate that, in petals, epidermal cells may have diverse shapes and that the shape of the cells is not necessarily a reliable indicator of the secretory potential of those cells. It will be interesting to see whether common structural features and/or molecular factors are responsible for the differences between these various cell types. 相似文献
3.
C.R. Marinho C.D. Souza T.C. Barros S.P. Teixeira 《Plant biology (Stuttgart, Germany)》2014,16(1):215-226
Scent glands, or osmophores, are predominantly floral secretory structures that secrete volatile substances during anthesis, and therefore act in interactions with pollinators. The Leguminosae family, despite being the third largest angiosperm family, with a wide geographical distribution and diversity of habits, morphology and pollinators, has been ignored with respect to these glands. Thus, we localised and characterised the sites of fragrance production and release in flowers of legumes, in which scent plays an important role in pollination, and also tested whether there are relationships between the structure of the scent gland and the pollinator habit: diurnal or nocturnal. Flowers in pre‐anthesis and anthesis of 12 legume species were collected and analysed using immersion in neutral red, olfactory tests and anatomical studies (light and scanning electron microscopy). The main production site of floral scent is the perianth, especially the petals. The scent glands are distributed in a restricted way in Caesalpinia pulcherrima, Anadenanthera peregrina, Inga edulis and Parkia pendula, constituting mesophilic osmophores, and in a diffuse way in Bauhinia rufa, Hymenaea courbaril, Erythrostemon gilliesii, Poincianella pluviosa, Pterodon pubescens, Platycyamus regnellii, Mucuna urens and Tipuana tipu. The glands are comprised of cells of the epidermis and mesophyll that secrete mainly terpenes, nitrogen compounds and phenols. Relationships between the presence of osmophores and type of anthesis (diurnal and nocturnal) and the pollinator were not found. Our data on scent glands in Leguminosae are original and detail the type of diffuse release, which has been very poorly studied. 相似文献
4.
The closing apparatus in the metathoracic scent gland system of Notonecta glauca is described, and notes on the distribution of metathoracic scent glands in the family Notonectidae are included. 相似文献
5.
Trypanosoma (Megatrypanum) freitasi, a parasite of marsupials of the genus Didelphis, has been found to undergo in the lumen of the scent (anal) glands of its vertebrate host, a cycle such as usually occurs in the intestinal tract of the insect vectors of trypanosomatids and similar to what has been reported for Trypanosoma (Schizotrypanum) cruzi. The invertebrate host of Trypanosoma freitasi is still unknown. Developmental stages of the trypanosome in its mammalian host, especially the dividing epimastigotes, multinucleate plasmodial forms and rosettes found in the lumen of the scent glands of a naturally infected Didelphis marsupialis are described and illustrated. 相似文献
6.
The effect of various social environments on sociosexual behavior was examined in six young female cotton-top tamarins (Saguinus oedipus oedipus) and in three established breeding females. Behavioral observations and hormonal samples were collected on young females while they were living with their families, when they were isolated from conspecifics, and after they were paired with an unrelated male. While living with the family, all females showed a suppression of fertility and low frequencies of sociosexual behavior. Following removal from the family, isolated females displayed an increase in rate of scent marking and an increase in hormonal levels. When young females were paired with males, they were exposed to scent secretions from their natal families, from an unfamilar family, and from a control for a total of 24 weeks. After pairing, hormonal levels increased dramatically, and ovarian cyclicity began. An increase in sociosexual behavior and elevated levels of scent marking accompanied this physiological change. Newly paired females had higher rates of affiliative behavior and scent marking than did established breeding females. However, both newly paired and established breeding males were more likely to initiate contact, grooming bouts, and social sniffing than were females. Time to first ovulation was later in females who were exposed to scent secretions from their natal families than it was in those females given a control for the first 8 weeks following pairing. No female conceived during exposure to scent secretions. However, once normal ovarian cycling had begun or a pregnancy was established, exposure to scent secretions had no effect. Thus, the social environment influences the fertility, sociosexual behavior, and pair bond formation of cotton-top tamarins. In addition, chemical stimuli found in the scent secretions produced by the natal family are most likely involved in reproductive suppression. 相似文献
7.
Floral color change in diverse plants has been thought to be a visual signal reflecting changes in floral rewards, promoting pollinator foraging efficiency as well as plant reproductive success. It remains unclear whether olfactory signals co-vary with floral color change. We investigated the production rhythms of floral scent and nectar associated with floral color change in Lonicera japonica. The flowers generally last 2–3 days. They are white on opening at night (N1) and become light yellow the following day (D1), yellow on the second night (N2), and golden on the second day of flowering (D2). Our measurements in the four stages indicated that nectar production decreased significantly from N1 and D1 to N2 and D2, tracking the floral color change. A total of 34 compounds were detected in floral scent and total scent emission was significantly higher in N2 than in the other three stages. The scent emission of three major compounds, Linalool, cis-3-Hexenyl tiglate, and Germacrene D was also significantly higher in N2, but the relative content of Linalool decreased gradually, cis-3-Hexenyl tiglate increased gradually, and the relative content of Germacrene D did not differ among the four measured stages. Greater scent emission by night than by day suggested a strong olfactory signal to attract nocturnal hawkmoths, the effective pollinators. However, floral scent rhythms in the four stages did not match the color change and nectar secretion, suggesting that floral color (visual) and scent (olfactory) in this species may play different roles in attracting or filtering various visitors. 相似文献
8.
The strong aromatic scent of the male greater wax moth, Galleria mellonella, has been isolated and identified as a combination of n-nonanal and n-undecanal with the former compound predominating. Gas-liquid chromatography, electroantennagram, and bioassay studies established that the scent is the same material that causes typical sexual behaviour in the female and is the same behaviour elicited by either male moths or by authentic standards. 相似文献
9.
Shama Parveen Kamil Usmani Sucheta Khokhar Vilayanoor Venkataraman Ramamurthy Jitka Vilímová 《Zoologischer Anzeiger》2014
The metathoracic scent glands in the Heteroptera produce defence secretions which are spread outside the body through and by using the thoracic external scent efferent system. That complex system was studied in 18 species from 11 genera of four subfamilies, Elvisurinae, Eurygastrinae, Hoteinae and Scutellerinae of the family Scutelleridae (Pentatomoidea). The results have been compared with published data. The pattern of that system is more consistent at the level of genus, mostly very similar in the congeneric species, but mostly variable within higher taxonomic levels, tribes and subfamilies. Five types of the external scent efferent system are recognized within the family Scutelleridae, basic two of them in studied species: (i) peritreme well developed, covering large part of metapleuron, evaporatorium small, developed only on metapleuron, (ii) evaporatorium large, more conspicuous than moderate-sized to small peritreme, extending to mesopleuron as large structure. The results do not support a hypothesis that the system of structures associated externally with metathoracic scent glands is in correlation with type of a habitat. However, these structures are well usable as diagnostic characters for scutellerid genera (e.g. Cantao, Hyperonchus, Scutellera and Solenosthedium). 相似文献
10.
Floral evolution often involves suites of traits, including morphology, colour and scent, but these traits are seldom analysed together in comparative studies. We investigated the associations between floral traits and pollination systems in Schizochilus, a southern African orchid genus with small nectar-producing flowers that has not been studied previously with respect to pollination biology. Field observations indicated the presence of distinct pollination systems in the four species which occur in the Drakensberg, including pollination by muscid flies in Schizochilus angustifolius, tachinid flies in Schizochilus zeyheri, various small flies in Schizochilus bulbinella and bees and wasps in Schizochilus flexuosus. Pollination success and pollen transfer efficiency clearly differed among the four species but were not correlated with the quantity of nectar rewards. Multivariate analysis of floral morphology and floral scent chemistry based on GC-MS data revealed significant differences among species as well as populations within species. The floral scent of S. angustifolius was dominated by the benzenoid compounds benzaldehyde and phenylacetaldehyde. Samples of one population of S. bulbinella were relatively similar to S. angustifolius but samples of another population were very distinct due to the occurrence of the nitrogen-containing compounds 3-methyl-butyl aldoxime (syn/anti) and the higher amounts of aliphatic esters, alcohols and acids. In contrast, the floral scent of S. flexuosus and S. zeyheri was characterized by high relative amounts of methyl benzoate. We conclude that Schizochilus has distinct, specialized pollination systems associated with subtle but significant variation in floral morphology and scent chemistry. We also caution that sampling of several populations may be required to characterize floral scent composition at the species-level in plants. 相似文献
11.
Marina Ibáñez-Shimabukuro M. Florencia Rey-Burusco Alan Cooper Malcolm W. Kennedy Betina Córsico Brian O. Smith 《Biomolecular NMR assignments》2014,8(1):33-36
As-p18 is produced and secreted by larvae of the parasitic nematode Ascaris suum as they develop within their eggs. The protein is a member of the fatty acid binding protein (FABP) family found in a wide range of eukaryotes, but is distinctive in that it is secreted from the synthesizing cell and has predicted additional structural features not previously seen in other FABPs. As-p18 and similar proteins found only in nematodes have therefore been designated ‘nemFABPs’. Sequence-specific 1H, 13C and 15N resonance assignments were established for the 155 amino acid recombinant protein (18.3 kDa) in complex with oleic acid, using a series of three-dimensional triple-resonance heteronuclear NMR experiments. The secondary structure of As-p18 is predicted to be very similar to other FABPs, but the protein has extended loops that have not been observed in other FABPs whose structures have so far been solved. 相似文献
12.
Protein-mediated cholesterol trafficking is central to maintaining cholesterol homeostasis in cells. START (Steroidogenic acute regulatory protein-related lipid transfer) domains constitute a sterol and lipid binding motif and the START domain protein StARD4 typifies a small family of mammalian sterol transport proteins. StARD4 consists of a single START domain and has been reported to act as a general cholesterol transporter in cells. However, the structural basis of cholesterol uptake and transport is not well understood and no cholesterol-bound START domain structures have been reported. We have undertaken the study of cholesterol binding and transport by StARD4 using solution state NMR spectroscopy. To this end, we report nearly complete 1H, 15N, and 13C backbone resonance assignments of an inactive but well behaved mutant (L124D) of StARD4. 相似文献
13.
A. Heiduk I. Brake T. Tolasch J. Frank A. Jürgens U. Meve S. Dötterl 《South African Journal of Botany》2010
Ceropegia species (Apocynaceae, Asclepiadoideae) have pitfall flowers and are pollinated by small flies through deception. It has been suggested that these flies are attracted by floral scent. However, the scent that is emitted from Ceropegia flowers has not been studied using headspace and gas chromatography mass spectrometry methods. It has also been unclear whether or not the flowers are mimics of particular models that attract flies. In the present study, we determined the composition as well as the spatial and temporal patterns of floral scent emitted by C. dolichophylla. Furthermore, we determined the pollinators in the native (China) and non-native (Germany) range of this species, and tested the capability of the floral scent to attract flies in the non-native range. Our data demonstrate that the floral scent, which is emitted from morning until evening, primarily from the tips of the corolla lobes, consists mainly of spiroacetals and aliphatic compounds. Milichiid flies were common visitors/pollinators in the native as well as non-native range, and were attracted by floral scent in bioassays performed in the non-native range. The compounds emitted by C. dolichophylla are unusual for flowers, but are well known from insect pheromones and occur in the glandular secretions of insects. The milichiid flies that visit and pollinate the flowers are kleptoparasites that feed on the prey (haemolymph or other secretions) of predatory arthropods, e.g. spiders, to which they are attracted by scent. Our data thus suggest that the floral scent of C. dolichophylla mimics the feeding sites of kleptoparasitic flies. 相似文献
14.
Cloudwater Inputs of Nitrogen to Forest Ecosystems in Southern Chile: Forms, Fluxes, and Sources 总被引:6,自引:0,他引:6
Nitrogen (N) has been considered a limiting nutrient to many aquatic and terrestrial ecosystems. However, human activity has
resulted in increased atmospheric N deposition worldwide such that N pollution is now altering ecosystem function in many
locations. Research on atmospheric deposition has focused primarily on inorganic nitrogen (DIN; NH4
+-N + NO3
−-N) via rainwater and dry deposition as the main N input to ecosystems. Recently, organic N (ON) has been shown to be an important
constituent in rainwater or dry deposition. Here we show that ON dominated (66%) total N in cloudwater from a remote site
in southern Chile. Cloudwater from more human-impacted sites in northeastern USA had lower ON concentrations and DIN was dominant.
We estimate that cloudwater delivers up to 2 kg ha−1 DIN and 9 kg ha−1 ON annually, compared to less than 1 kg ha−1 of DIN deposition via rainwater, thus it may contribute substantially to the N-economy of Chilean coastal forests. We also
suggest that the adjacent ocean, where biologic productivity is high, may be a major source of N in Chilean cloudwater. This
proposed marine-terrestrial flux via cloud deposition has not previously been identified and may be an example of the ocean
feeding the forest. We suggest that this type of cross boundary flux may be common in other upwelling zones, such as along
the west coasts of Africa, North and South America and east India, and warrants further substantiation and investigation.
Received 30 June 2000; accepted 18 October 2000 相似文献
15.
Zenghui Hu Huixiu Zhang Pingsheng Leng Jing Zhao Wenhe Wang Shudong Wang 《Acta Physiologiae Plantarum》2013,35(5):1691-1700
Floral scent is an important part of volatile compounds emitted from plants, and is influenced by many environmental factors. In this study, the floral scent emitted from Lilium ‘siberia’, a common breed of lily, was collected by dynamic headspace at different levels of light intensity (0, 100, 300, 600, 1,000, and 1,500 μmol m?2 s?1) and temperature (10, 20, 30, and 40 °C). Using the automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) technique, the components and release amounts were subsequently identified to investigate the influence of light and temperature on the emission of floral scent. The results revealed that the numbers and release amounts of floral scent components were significantly influenced by light intensity and temperature, showing the similar pattern: first increasing and then decreasing. After light intensity treatment, the maximum numbers and release amounts mainly appeared at 600 and 1,000 μmol m?2 s?1. For temperature treatment, 30 °C resulted in the highest numbers and release amounts of the floral scent components. At different levels of light intensity and temperature, terpenoid compounds showed the highest numbers and release amounts among the component categories. α-Ocimene and linalool were the two terpenoid compounds with the highest release amounts, and accounted for the highest proportion. The results obtained provide evidence that both light intensity and temperature trigger the emission of floral scent. The particular response mechanisms must be investigated in future research. 相似文献
16.
Jian Xie Zhenming Du Brian Callahan Marlene Belfort Chunyu Wang 《Biomolecular NMR assignments》2014,8(2):279-281
The Hedgehog (Hh) signaling pathway plays important roles in embryonic growth and patterning in different organisms. Abnormal activity of the Hh signaling pathway has been associated to cancers, holoprosencephaly and autism spectrum disorders. The backbone and side chain resonance assignments of a Drosophila Hh autoprocessing domain have been determined based on triple-resonance experiments with the [13C, 15N]-labeled and [2H, 13C, 15N])-labeled proteins. 相似文献
17.
Fujio Hyodo Junko Nishikawa Ayato Kohzu Noboru Fujita Izuru Saizen Jamsran Tsogtbaatar Choijilsuren Javzan Mangaa Enkhtuya Davaadorj Gantomor Narantsetsegiin Amartuvshin Reiichiro Ishii Eitaro Wada 《Limnology》2012,13(1):155-161
The stable nitrogen (N) isotope ratio (??15N) has been used to examine the anthropogenic N input (i.e., septic water, wastewater, and manure) to aquatic ecosystems, because anthropogenic N generally has a ??15N signature distinct from that found in nature. Aquatic organisms and the derived organic matter such as sediments are reported to become increasingly enriched in 15N as the human population density increases in watersheds. However, little is known about the relationship in steppe ecosystems, where the livestock population is greater than that of humans. Here, we conducted a preliminary study in the Selenga river mainstream watershed in Mongolia, which covers an area of approximately 300,000?km2. A multiple regression analysis revealed that the ??15N of the riverine sediment was significantly affected by the human population density and more significantly by livestock population density. The population density, including both humans and livestock, significantly influenced ??15N of the macrophytic Potamogeton spp. The results showed that ??15N of riverine organic matter can be an indicator of the human and livestock population density, which is likely associated with the status of N cycles in livestock-dominated watersheds. 相似文献
18.
Alpine meadows of high ecological value could be severely endangered by anthropogenic N enrichment, modifying the relationships between species and the environment. While a constraint exerted by N availability on alpine plant development has been demonstrated by some fertilization experiments, in others no effect was observed. Basically, the problem is that mineral N absorption has not been characterized in alpine plants. In growth chamber experiments, we investigated the component fluxes of 15NO3? and 15NH4+ uptake in a tussock grass (Festuca nigrescens) very common and representative of the dominant plant growth form in European alpine meadows. Rates of influx supported data already published for low elevation herbaceous species. These rates were up to ten times higher for NH4+ than for NO3? but rates of net uptake were similar for both ions demonstrating the occurrence of elevated NH4+ efflux (80% of primary influx). An increase in external N in the range of field-relevant concentrations did not substantially enhance net uptake. Thus, the alpine plant which is assumed to be adapted to relatively high soil NH4+ responded like an NH4+-sensitive species: as if it was unable to use the incoming nitrogen. It is suggested that the ability of this typical alpine grass to respond to increasing N availability due to global changes is limited. 相似文献
19.
Nicotiana glauca is a naturalised introduced species widely distributed in Australia. A survey of stands in the central zone of its recorded distribution has shown that a type of tobacco mosaic virus which characteristically induces a bright yellow mosaic symptom (TMV-Y) is commonly associated with N. glauca throughout this zone. Surveys of a natural community of N. glauca less than 5 yr old, and in an experimental block, showed that TMV-Y could spread at a rate, and in a pattern, which could not be explained by contact transmission alone, and which indicated that an airborne vector was probably involved in transmission. These results together have led to the conclusion that the common association of TMV-Y with N. glauca is due to spread of the virus by an unknown vector(s). Seed transmission of TMV-Y in N. glauca has not been detected. Molecular hybridisation analysis has shown that all but one of the TMV-Y isolates studied were related to TMV-U2, and that the isolate which was unrelated to U2, was partially related to TMV-U1, TMV-U5, and tomato mosaic virus. Selected isolates which showed a close relationship to TMV-U2, also showed a close relationship to TMV-U5, a distant relationship to TMV-U1, and tomato mosaic, and very little or no relationship with three other tobamoviruses (sunn-hemp mosaic virus, odontoglossum ringspot virus, and cucumber virus 4). These results show that the Australian TMV-Y isolates are similar to the TMV isolated from N. glauca in California. 相似文献
20.
Studies of floral scent generally assume that genetic adaptation due to pollinator-mediated natural selection explains a significant amount of phenotypic variance, ignoring the potential for phenotypic plasticity in this trait. In this paper, we assess this latter possibility, looking first at previous studies of floral scent variation in relation to abiotic environmental factors. We then present data from our own research that suggests among-population floral scent variation is determined, in part, by environmental conditions and thus displays phenotypic plasticity. Such an outcome has strong ramifications for the study of floral scent variation; we conclude by presenting some fundamental questions that should lead to greater insight into our understanding of the evolution of this trait, which is important to plant-animal interactions.Key words: abiotic factors, aromatics, floral scent, GxE interaction, phenotypic plasticity, pollination, terpenoids, volatilesFloral scent is thought to function as a major non-visual attractive cue for many pollinators in a large number of plant systems1,2 and therefore most research on this plant trait has proceeded in the context of pollination ecology. Such studies have revealed the physiological and behavioral responses of pollinators to various floral volatiles (reviewed in refs. 3 and 4), convergent evolution of odor phenotypes attractive to specific pollinator classes (reviewed in refs. 5 and 6), reproductive isolation of plant species due to differences in pollinator attraction by scent,7 and instances of deception in which flowers mimic insect pheromones to effect pollination.8 Together, this body of evidence suggests that specific floral scent profiles can have important implications for the reproductive potential of many plant species.This pollinator-centered viewpoint has carried through to research on floral scent variation, including our most recent work on the insect-pollinated species Hesperis matronalis (Brassicaceae).9 Such studies usually suggest that the floral scent variation commonly found within and among individuals, populations and species (reviewed in ref. 2) is due to genetic differentiation as a result of selection by pollinators over time (reviewed in ref. 10). But an organism''s genes are only one factor determining phenotype. Both biotic (living) and abiotic (non-living) environmental conditions can profoundly affect phenotype expression, leading to significant variation. For plants, abiotic factors such as climate and soil chemistry can have particularly strong effects on phenotypes. When these environmental conditions cause changes in phenotype, we would say that a trait displays phenotypic plasticity.11–13 A number of studies have uncovered phenotypic plasticity for many different plant traits.12 However, while phenotypic variation in floral scent has been well-documented1,2 and correlated with variation in biotic factors like pollinator behavior,14–17 these studies were decidedly focused on natural selection, rather than phenotypic plasticity, as an organizational framework.However, in examining the scientific literature on floral scent, we found four studies in which the effects of naturally variable abiotic factors on floral scent profiles were examined, three of which were performed by the same research group (18–21 (21). Moreover, these studies are decidedly not analyzed and interpreted using standard protocols for phenotypic plasticity studies.13
Open in a separate window*Plus signs indicate a numerical increase, minus signs indicate a decrease; ER = floral scent emission rate, SC = scent composition.Research we have conducted in conjunction with our recently published work on the floral scent of H. matronalis9 suggests that some of the natural variation in the odor of this species may be attributable to phenotypic plasticity. We reared potted H. matronalis rosettes from two populations (PA1 and PA2) in northwestern Pennsylvania in a common garden environment and upon flowering, collected scent from these individuals using dynamic headspace extractions (reviewed in ref. 9). We then compared floral scent composition and emission rates of potted plants with each other (between populations in a common garden), as well as with the floral scent profiles of plants reared in their source population (i.e., between individuals from the same population reared in different environments). The results were striking. Analysis of scent composition using non-metric multidimensional scaling and analysis of similarity (NMDS and ANOSIM, respectively: reviewed in ref. 9) suggested that the scent composition of plant populations reared in their native environments differ significantly from each other in terms of two major biosynthetic classes of volatiles—aromatics and terpenoids (Fig. 1, filled symbols only). This was especially true for the aromatic eugenol and derivatives of the terpenoid linalool (furanoid linalool oxides and linalool epoxide). In contrast, common-garden reared plants from different populations did not differ in floral scent composition, regardless of their original source population. Perhaps even more interestingly, while both populations showed changes due to rearing environment, the degree of change differed: in only one population (PA1) did scent composition change significantly between native and garden reared plants (Fig. 1).Open in a separate windowFigure 1NMDS (non-metric multidimensional scaling) plots of scent composition for purple morphs from two populations of Hesperis matronalis—(A) Aromatics and (B) Terpenoids. Filled symbols represent scent from home environment in situ plants, which are significantly different from one another as determined by analysis of similarity (ANOSIM: aromatics—p = 0.03, R = 0.22; terpenoids—p = 0.01, R = 0.25). Open symbols represent scent from plants reared in a common environment. Population PA1 is represented by triangles and population PA2 is represented by squares. Arrows indicate the direction of shift from home environment to common garden floral scent composition; black arrows represent a significant difference between groups determined by ANOSIM (Aromatics—p = 0.01, R = 0.30; Terpenoids—p = 0.06; R = 0.20) and gray arrows represent a non-significant difference.Floral scent emission rate also showed environmentally induced differences. While wild plants from our two populations differed significantly in the amount of scent emitted in situ, with PA1 emitting more total scent, total aromatics and total terpenoids,9 we found that rearing plants from these sites in a common garden environment either significantly reverses the direction of differences in emission rates seen between natural populations, with PA2 now emitting more aromatic scent (Analysis of Variance: F = 4.09; p = 0.05; Fig. 2A), or homogenizes the quantity of scent emitted (i.e., no significant differences in emission rates between populations; Fig. 2B and C).Open in a separate windowFigure 2Box plots of scent emission rates for purple Hesperis matronalis plants grown in common garden environments in terms of (A) Aromatics, (B) Terpenoids and (C) Total Scent. The edges of each box represent the range of data between the 25th percentile and the 75th percentile, while the horizontal bar indicates the median for each population. The error bars on each box extend to the 5th and 95th percentile of the data range respectively. To the right of each box plot, the mean is presented as a horizontal line, with standard error bars. Mean values not sharing letters are significantly different as determined by analysis of variance (ANOVA).Together, these results suggest that rearing environment can have a profound effect on floral scent composition and emission rate, such that plants from the same maternal environment can have radically different floral scent phenotypes in response to differential growing conditions. If our work effectively incorporates a random genetic sample from each population into each growing environment, then at least some of the phenotypic variation we describe here could be interpreted as phenotypic plasticity. This experiment does not allow us to pinpoint the exact environmental conditions associated with phenotypic differences in floral scent (although variation in nutrient or water availability between wild and common-garden settings is likely), nor does it completely conform to the traditional “reactionnorm” studies associated with plasticity research which would allow detection of genetic variation in scent plastiticy.12,13 However, our results suggest that floral scent of plants grown in wild populations may be plastic, which provides some additional insight into our recently published work uncovering significant among-population variation in floral scent.9 For researchers that study phenotypic plasticity, such an outcome is probably not a surprise, nor is our finding that populations respond differently to environmental conditions (i.e., potential GxE interaction, reflecting genetic variability in plasticity).However, if floral scent can be plastic, this raises a number of biologically relevant questions that should be addressed in floral scent research, including: (1) Is there truly a canonical floral scent blend that can be attributed to a given plant species, as is normally supposed by those studying floral scent from an evolutionary perspective? (2) Which environmental conditions exert the strongest influence on floral scent profiles in a species? (3) How do such conditions interact with genetic variation in the factors responsible for scent biosynthesis and emission? (4) Are floral scent profiles plastic within a single flowering period; if so, what impact does this have on pollinator behavior and therefore plant fitness? (5) At what scale do biotic agents such as pollinators and herbivores respond to quantitative and qualitative variation in floral scent? Studies that address these questions should lead us to a more mature understanding of the causes and consequences of natural variation in floral scent. 相似文献
Table 1
A survey of previous studies examining changes in floral scent phenotype due to abiotic factorsStudy | Species | Environmental characteristic | Plant material | Study location | Change in volatile emissions? | Direction of change |
Loper and Berdel 1978 | Medicago sativa L. | Irrigation | Clones | Experimental farm | No | n/a |
Cutting | Clones | Experimental farm | No | n/a | ||
Hansted et al. 1994 | Ribes nigrum | Temperature | Two varieties | Growth chamber | Yes | + temperature, + ER* |
Jakobsen and Olsen 1994 | Trifolium repens L. | Temperature | Cultivar | Growth chamber | Yes | + temperature, + ER |
Irradiance | Cultivar | Growth chamber | Yes | + irradiance, + ER | ||
Air Humidity | Cultivar | Growth chamber | Yes | + humidity, − ER | ||
Nielsen et al. 1995 | Hesperis matronalis L. | Temperature | Wild seeds | Growth chamber | Yes | + temperature, |
+ monoterpene ER | ||||||
This study, 2009 | Hesperis matronalis | Growing | Wild plants | Wild vs. | Yes | Wild—different ER, |
Environment | Common Garden | SC between populations; | ||||
Garden—similar ER, | ||||||
SC between populations |