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‣ The discovery of 2,5-dialkylcyclohexan-1,3-diones as a new class of natural products

Franke, S.; Ibarra, F.; Schulz, C. M.; Twele, R.; Poldy, J.; Barrow, R. A.; Peakall, R.; Schiestl, F. P.; Francke, W.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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Orchids employing sexual deceit attract males of their pollinator species through specific volatile signals that mimic female-released sex pheromones. One of these signals proved to be 2-ethyl-5-propylcyclohexan-1,3-dione (chiloglottone1), a new natural product that was shown to be most important in the relations between orchids of the genus Chiloglottis, native to Australia, and corresponding pollinator species. Systematic investigations on the mass spectrometric fragmentation pattern of 2,5-dialkylcyclohexan-1,3-diones identified key ions providing information about the structures of the substituents at positions 2 and 5. Results enabled us to identify 2-ethyl-5-pentylcyclohexan-1,3-dione (chiloglottone2) and 2-butyl-5-methylcyclohexan-1,3-dione (chiloglottone3) as new natural products that play a decisive role in the pollination syndrome of some Chiloglottis species. During field bioassays, pure synthetic samples of chiloglottone1–3 or mixtures thereof proved to be attractive to the corresponding orchid pollinators. Because of their likely biogenesis from ubiquitous fatty acid precursors, 2,5-dialkylcyclohexan-1,3-diones may represent a hitherto overlooked, widespread class of natural products.

‣ The evolutionary biology of pollination: studies in a genus of australian sexually deceptive orchids

Whitehead, Michael Robert
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
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There are few other structures in nature from which evolution has generated such wide diversity as the flower or inflorescence, and this diversity is commonly attributed to the influence of their animal visitors. By outsourcing their mate choice to pollinators, plants have left themselves - and especially their flowers - subject to the selective forces imposed by the behaviour, cognition and perception of the pollinators that serve them. The orchids provide some of the most remarkable and extreme examples of adaptations to specific animal pollinators. Perhaps one of the most peculiar of these strategies is sexual deception, whereby male insects are lured to the flower by mimicry of the female sex pheromone. This seemingly unlikely strategy has evolved multiple times independently on different continents in different parts of the orchid phylogeny which raises the question of what adaptive advantages might underlie such a strategy. This multidisciplinary thesis studies gene flow and pollinator behaviour in two sympatric sexually deceptive orchids in the genus Chiloglottis. The two species attract their specific wasp pollinators through emission of distinct species - specific semiochemicals. Since floral volatiles play a pre-eminent role in pollinator attraction...

‣ How an orchid harms its pollinator.

Wong, Bob B M; Schiestl, Florian P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 07/08/2002 Português
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Certain orchids produce flowers that mimic the sex pheromones and appearance of female insects in order to attract males by sexual deception for the purpose of pollination. In a series of field experiments, we found that the sexually deceptive orchid, Chiloglottis trapeziformis, can have a negative impact on its wasp pollinator Neozeleboria cryptoides. Male and female wasps, however, were affected differently by the orchid's deceit because of their different roles in the mimicry system. Male wasps could not discriminate between the chemical cues of orchids and female wasps, a vital signal in long-range attraction. Males, however, learn to avoid areas containing orchids. This strategy has implications for females attempting to attract mates in areas occupied by orchids. Compared with circumstances when females were on their own, females in the presence of orchids elicited fewer male approaches and no copulation attempts. Females in a large orchid patch also elicited fewer male approaches than females in a small patch. The nature of the orchid's impact on its wasp pollinator indicates an arms race evolutionary scenario in this interaction between plant and pollinator.

‣ Pollinator attractiveness increases with distance from flowering orchids.

Wong, Bob B M; Salzmann, Charlotte; Schiestl, Florian P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 07/05/2004 Português
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Orchids are extraordinary among plants because many species are pollinated through sexual duplicity by producing flowers that mimic female insects to lure unsuspecting males. Previous work showed that sexual deception by the orchid Chiloglottis trapeziformis can have a negative impact on its wasp pollinator Neozeleboria cryptoides. We report that female wasps may be capable of mitigating the cost of the orchids' deception. Although male wasps quickly habituated to areas planted with unrewarding flower decoys, we found that the effectiveness of the chemical cue used by the wingless females to attract males increases with increasing distance from an orchid patch. The apparent specificity of the males' site-based avoidance strategy means that females emerging in areas occupied by flowering orchids could, potentially, leave the orchid colony by walking to increase their attractiveness.

‣ Bioclimatic assessment of the geographic and climatic limits to hybridisation in a sexually deceptive orchid system

Peakall, Rodney; Jones, Lauren; Bower, Colin; Mackey, Brendan
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
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Australia is a major centre of diversity for pollination by sexual deception, a pollination syndrome unique to orchids and characterised by highly specific pollinator relationships. Chiloglottis x pescottiana is a rare natural hybrid between sexually dece

‣ Chloroplast simple sequence repeat markers for evolutionary studies in the sexually deceptive orchid genus Chiloglottis

Ebert, Daniel; Hayes, Christine; Peakall, Rodney
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
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The orchids in the genus Chiloglottis are pollinated exclusively by sexual deception. Extensive sequencing (> 19.5 kb) of noncoding chloroplast DNA revealed that simple sequence repeats (cpSSRs) were abundant, enabling a set of 41 cpSSR markers to be deve

‣ UV-B light contributes directly to the synthesis of chiloglottone floral volatiles

Amarasinghe, Ranamalie; Poldy, Jacqueline; Matsuba, Yuki; Barrow, Russell; Hemmi, Jan M.; Pichersky, Eran; Peakall, Rodney
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
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Background and Aims Australian sexually deceptive Chiloglottis orchids attract their specific male wasp pollinators by means of 2,5-dialkylcyclohexane-1,3-diones or 'chiloglottones', representing a newly discovered class of volatiles with unique structure

‣ A narrow group of monophyletic Tulasnella (Tulasnellaceae) symbiont lineages are associated with multiple species of Chiloglottis (Orchidaceae): Implications for orchid diversity

Roche, Sean A.; Carter, Richard; Peakall, Rodney; Smith, Leon; Whitehead, Michael; Linde, Celeste
Fonte: Botanical Society of America Publicador: Botanical Society of America
Tipo: Artigo de Revista Científica
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Premise of the study: The Orchidaceae is characterized by exceptional species diversity. Obligate orchid mycorrhizae are predicted to determine orchid distributions, and highly specific relationships between orchids and fungi may drive orchid diversificat

‣ Identification of the First Alkenyl Chiloglottone Congener

Poldy, Jacqueline; Peakall, Rodney; Barrow, Russell
Fonte: Wiley-VCH Verlag GMBH Publicador: Wiley-VCH Verlag GMBH
Tipo: Artigo de Revista Científica
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Orchids of the genus Chiloglottis rely on sexual deception to attract a male thynnine wasp, whereupon a courtship routine results in the deposition and transfer of pollinia and subsequent pollination of the orchid. The chemical cues responsible for this b

‣ Molecular genetic analysis and ecological evidence reveals multiple cryptic species among thynnine wasp pollinators of sexually deceptive orchids

Griffiths, Kathleen; Trueman, John; Brown, Graham; Peakall, Rodney
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
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Sexually deceptive Chiloglottis orchids lure their male thynnine wasp pollinators to the flower by emitting semiochemicals that mimic the specific sex pheromone of the wasp. Sexual deception is possible because chemical rather than visual cues play the ke

‣ The production of a key floral volatile is dependent on UV light in a sexually deceptive orchid

Falara, Vasiliki; Amarasinghe, Ranamalie; Poldy, Jacqueline; Pichersky, Eran; Barrow, Russell; Peakall, Rodney
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
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Background and AimsPlants use a diverse range of visual and olfactory cues to advertize to pollinators. Australian Chiloglottis orchids employ one to three related chemical variants, all 2,5-dialkylcyclohexane-1,3-diones or 'chiloglottones' to sexually at

‣ Pheromones and analogs from Neozeleboria wasps and the orchids that seduce them: a versatile synthesis of 2,5-dialkylated 1,3-cyclohexanediones

Poldy, Jacqueline; Peakall, Rodney; Barrow, Russell
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
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Chiloglottone, a wasp pheromone and attractant of sexually deceptive Chiloglottis orchids, and several structural analogs were synthesized. The synthetic approach is facile, high yielding and versatile, enabling rapid divergence to generate dialkylated an

‣ Pollinator specificity, floral odour chemistry and the phylogeny of Australian sexually deceptive Chiloglottis orchids: implications for pollinator-driven speciation

Peakall, Rodney; Ebert, Daniel; Poldy, Jacqueline; Barrow, Russell; Francke, Wittko; Bower, Colin; Schiestl, F P
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica
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•Sexually deceptive orchids are predicted to represent a special case of plant speciation where strong reproductive isolation may be achieved by differences in floral scent. •In this study of Australian sexually deceptive Chiloglottis orchids, we perf

‣ How an orchid harms its pollinator

Wong, Bob; Schiestl, Florian
Fonte: Royal Society of London Publicador: Royal Society of London
Tipo: Artigo de Revista Científica
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Certain orchids produce flowers that mimic the sex pheromones and appearance of female insects in order to attract males by sexual deception for the purpose of pollination. In a series of field experiments, we found that the sexually deceptive orchid, Chiloglottis trapeziformis, can have a negative impact on its wasp pollinator Neozeleboria cryptoides. Male and female wasps, however, were affected differently by the orchid's deceit because of their different roles in the mimicry system. Male wasps could not discriminate between the chemical cues of orchids and female wasps, a vital signal in long-range attraction. Males, however, learn to avoid areas containing orchids. This strategy has implications for females attempting to attract mates in areas occupied by orchids. Compared with circumstances when females were on their own, females in the presence of orchids elicited fewer male approaches and no copulation attempts. Females in a large orchid patch also elicited fewer male approaches than females in a small patch. The nature of the orchid's impact on its wasp pollinator indicates an arms race evolutionary scenario in this interaction between plant and pollinator.

‣ Phylogeography of pollinator-specific sexually deceptive Chiloglottis taxa (Orchidaceae): evidence for sympatric divergence?

Mant, J; Bower, Colin; Weston, Peter; Peakall, Rodney
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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Divergence in sexually deceptive orchids is thought to occur through shifts in the attraction of specific pollinators, a process that is mediated by changes in the floral odours that lure sexually excited male insects. We investigated the origin of reproductive isolation in a sexually deceptive species complex of Chiloglottis R.Br.Orchidaceae: Diurideae). Two geographically separated montane regions in eastern Australia were sampled, each containing sympatric pairs of orchid taxa presently found under the name, Chiloglottis pluricallata. Behavioural tests confirmed at least three distinct orchid taxa that specifically attract different pollinators. An artificial crossing experiment among two taxa from one region demonstrated their interfertility, and confirmed isolation to be a function of pollinator attraction. A phylogeographic analysis using amplified fragment length polymorphisms (AFLPs) indicated that samples from each geographical region are most closely related, a pattern consistent with in situ or sympatric divergence. However, an extensive population genetic study on two taxa from one region failed to entirely reject the possibility of intertaxon gene flow. Although clear genetic differentiation of the taxa is evident in two out of three sites where both grow in direct sympatry...

‣ Microsatellite markers for evolutionary studies in the sexually deceptive orchid genus Chiloglottis

Flanagan, Nicola; Ebert, Daniel; Porter, Carolyn; Rossetto, Maurizio; Peakall, Rodney
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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The orchids in the genus Chiloglottis are pollinated exclusively by sexual deception. We describe 20 variable microsatellite loci that will facilitate the study of the evolution and ecology of this specialized pollination system. Two loci were isolated from Chiloglottis trilabra, with the rest derived from Chiloglottis valida. All loci were polymorphic in C. valida (HE 0.07-0.87). Most loci amplified, and were variable within close relatives of C. valida, and a number amplified more broadly, including outside the genus.

‣ Opportunistic pollinator shifts among sexually deceptive orchids indicated by a phylogeny of pollinating and non-pollinating thynnine wasps (Tiphiidae)

Mant, J; Brown, Graham; Weston, Peter
Fonte: Linnean Society of London Publicador: Linnean Society of London
Tipo: Artigo de Revista Científica
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The thynnine wasp genus Neozeleboria Rohwer is the main pollinating group of the sexually deceptive Australian orchid genus, Chiloglottis R.Br. In a highly specialized interaction, Chiloglottis species attract males from a single or very few Neozeleboria

‣ A phylogenetic study of pollinator conservatism among sexually deceptive orchids

Mant, J; Schiestl, Florian; Peakall, Rodney; Weston, Peter
Fonte: Society for the Study of Evolution Publicador: Society for the Study of Evolution
Tipo: Artigo de Revista Científica
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Orchids of the genus Chiloglottis are pollinated through the sexual deception of male wasps mainly from the genus Neozeleboria (Tiphiidae: Thynninae). The orchids mimic both the appearance and sex pheromones of wingless female thynnines but provide no reward to the deceived males. Despite the asymmetry of this interaction, strong pollinator specificity is typical. Such plant-pollinator interactions would seem to be relatively flexible in the plant's adaptive response to variation in the local pollinator resource. However, we present DNA sequence data on both orchids and wasps that demonstrate a pattern of pollinator conservatism operating at a range of taxonomic levels. Sequence data from the wasps indicate 15 of 16 Chiloglottis pollinators are closely related members of one clade of Thynninae. A pattern of congruence between orchid and wasp phylogenies is also demonstrated below the generic level, such that related orchids tend to use related thynnine wasps as specific pollinators. Comparative physiological data on the wasp responses to the floral scents of two Chiloglottis species and one outgroup, Arthrochilus, indicate similar attractive volatile chemicals are used by related orchid taxa. By extension, we infer a similarity of sex pheromone signals among related thynnines. Thus...

‣ Specific pollinator attraction and the diversification of sexually deceptive Chiloglottis (Orchidaceae)

Mant, J; Peakall, Rodney; Weston, Peter
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
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Evidence indicates that sexually deceptive Chiloglottis R.Br. (Orchidaceae) taxa specifically attract their thynnine wasp (Tiphiidae) pollinators through the floral odour mimicry of female wasp sex pheromones. We use amplified fragment length polymorphisms (AFLPs) to reconstruct the species-level phylogeny of Chiloglottis, make a preliminary evaluation of genetic distinc-tions between species, and compare the historical association among orchids and their pollinators using wasp sequence data from a previous study. AFLPs show large differences between three subgeneric clades relative to that found among species within each clade. Interspecific genetic barriers are indicated by AFLP discontinuities among species unlike in previously reported DNA sequence data. However, such barriers are demonstrated clearly in only one of the two pairs of sympatric species sampled more intensively. We interpret these patterns as indicating either (i) a rapid and recent radiation of species within each clade following histories of stasis or extinction, or (ii) alternating cycles of divergence and gene flow acting to homogenize genetic differences among species within each of the three clades.

‣ Two orchids attract different pollinators with the same floral odour compound: ecological and evolutionary implications

Schiestl, Florian; Peakall, Rodney
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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1. The sexually deceptive orchids Chiloglottis trapeziformis Fitzg. and Chiloglottis valida D.L. Jones are pollinated by the thynnine wasps Neozeleboria cryptoides (Smith) and Neozeleboria monticola Turner, respectively, during attempted mating with the flower labellum. The orchids and their pollinators occur mostly in allopatry; however on the overlapping edges of their ranges they can attract each other's pollinator, leading to rare hybrids. 2. Using gas chromatographic analyses with electroantennographic detection (GC-EAD) we demonstrate that 2-ethyl-5-propyl-1,3-cyclohexandione ('Chiloglottone'), the previously known sex pheromone of N. cryptoides and pollinator-attractant of C. trapeziformis, is also used by C. valida to attract its pollinator N. monticola. 3. In behavioural field experiments, equal numbers of males of both species responded to, and attempted copulation with, a dummy scented with synthetic Chiloglottone. In dualchoice experiments where dummies were presented at different heights, N. cryptoides males preferentially attempted copulation with dummies a few centimetres above the ground, while N. monticola males significantly more often landed on the soil and attempted copulation with dummies on the soil. 4. These behavioural differences corresponded with differences in floral height in the orchids...