151
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Hsiao YY, Huang TH, Fu CH, Huang SC, Chen YJ, Huang YM, Chen WH, Tsai WC, Chen HH. Transcriptomic analysis of floral organs from Phalaenopsis orchid by using oligonucleotide microarray. Gene 2012; 518:91-100. [PMID: 23262337 DOI: 10.1016/j.gene.2012.11.069] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/27/2012] [Indexed: 01/09/2023]
Abstract
Orchids are one of the most species rich of all angiosperm families. Their extraordinary floral diversity, especially conspicuous labellum morphology, makes them the successful species during evolution process. Because of the fine and delicate development of the perianth, orchid provides a rich subject for studying developmental biology. However, study on molecular mechanism underling orchid floral development is still in its infancy. In this study, we developed an oligomicroarray containing 14,732 unigenes based on the information of expressed sequence tags derived from Phalaenopsis orchids. We applied the oligomicroarray to compare transcriptome among different types of floral organs including sepal, petal and labellum. We discovered that 173, 11, and 285 unigenes were highly differentially expressed in sepal, petal, and labellum, respectively. These unigenes were annotated with Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and transcription factor family. Unigenes involved in energy metabolism, lipid metabolism, and terpenoid metabolism are significantly differentially distributed between labellum and two types of tepal (sepal and petal). Labellum-dominant unigenes encoding MADS-box and sepal-dominant unigenes encoding WRKY transcription factors were also identified. Further studies are required but data suggest that it will be possible to identify genes better adapted to sepal, petal and labellum function. The developed functional genomic tool will narrow the gap between approaches based on model organisms with plenty genomic resources and species that are important for developmental and evolutionary studies.
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Affiliation(s)
- Yu-Yun Hsiao
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan.
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152
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Vereecken NJ, Wilson CA, Hötling S, Schulz S, Banketov SA, Mardulyn P. Pre-adaptations and the evolution of pollination by sexual deception: Cope's rule of specialization revisited. Proc Biol Sci 2012; 279:4786-94. [PMID: 23055065 PMCID: PMC3497092 DOI: 10.1098/rspb.2012.1804] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 09/18/2012] [Indexed: 11/12/2022] Open
Abstract
Pollination by sexual deception is arguably one of the most unusual liaisons linking plants and insects, and perhaps the most illustrative example of extreme floral specialization in angiosperms. While considerable progress has been made in understanding the floral traits involved in sexual deception, less is known about how this remarkable mimicry system might have arisen, the role of pre-adaptations in promoting its evolution and its extent as a pollination mechanism outside the few groups of plants (primarily orchids) where it has been described to date. In the Euro-Mediterranean region, pollination by sexual deception is traditionally considered to be the hallmark of the orchid genus Ophrys. Here, we introduce two new cases outside of Ophrys, in plant groups dominated by generalized, shelter-mimicking species. On the basis of phylogenetic reconstructions of ancestral pollination strategies, we provide evidence for independent and bidirectional evolutionary transitions between generalized (shelter mimicry) and specialized (sexual deception) pollination strategies in three groups of flowering plants, and suggest that pseudocopulation has evolved from pre-adaptations (floral colours, shapes and odour bouquets) that selectively attract male pollinators through shelter mimicry. These findings, along with comparative analyses of floral traits (colours and scents), shed light on particular phenotypic changes that might have fuelled the parallel evolution of these extraordinary pollination strategies. Collectively, our results provide the first substantive insights into how pollination sexual deception might have evolved in the Euro-Mediterranean region, and demonstrate that even the most extreme cases of pollinator specialization can reverse to more generalized interactions, breaking 'Cope's rule of specialization'.
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Affiliation(s)
- Nicolas J Vereecken
- Evolutionary Biology and Ecology, Free University of Brussels/Université Libre de Bruxelles, Av. F. D. Roosevelt 50 CP 160/12, 1050 Brussels, Belgium.
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153
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Vignolini S, Davey MP, Bateman RM, Rudall PJ, Moyroud E, Tratt J, Malmgren S, Steiner U, Glover BJ. The mirror crack'd: both pigment and structure contribute to the glossy blue appearance of the mirror orchid, Ophrys speculum. THE NEW PHYTOLOGIST 2012; 196:1038-1047. [PMID: 23043621 DOI: 10.1111/j.1469-8137.2012.04356.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 08/23/2012] [Indexed: 05/27/2023]
Abstract
The Mediterranean orchid genus Ophrys is remarkable for its pseudocopulatory pollination mechanism; naïve male pollinators are attracted to the flowers by olfactory, visual and tactile cues. The most striking visual cue is a highly reflective, blue speculum region at the centre of the labellum, which mimics the corresponding female insect and reaches its strongest development in the mirror orchid, O. speculum. We explored the structure and properties of the much-discussed speculum by scanning and transmission electron microscopic examination of its ultrastructure, visible and ultraviolet (UV) angle-resolved spectrophotometry of the intact tissue, and mass spectrometry of extracted pigments. The speculum contrasts with the surrounding labellar epidermis in being flat-celled with a thick, smooth cuticle. The speculum is extremely glossy, reflecting intense white light in a specular direction, but at more oblique angles it predominantly reflects blue and UV light. Pigments in the speculum, dominantly the cyanidin 3-(3''-malonylglucoside), are less diverse than in the surrounding regions of the labellar epidermis and lack quercetin copigments. Several physical and biochemical processes interact to produce the striking and much-discussed optical effects in these flowers, but the blue colour is not produced by structural means and is not iridescent.
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Affiliation(s)
- Silvia Vignolini
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
- Department of Physics, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Matthew P Davey
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Richard M Bateman
- Jodrell Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3AB, UK
| | - Paula J Rudall
- Jodrell Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3AB, UK
| | - Edwige Moyroud
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Julia Tratt
- Jodrell Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3AB, UK
| | | | - Ullrich Steiner
- Department of Physics, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Beverley J Glover
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
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154
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Rakosy D, Streinzer M, Paulus HF, Spaethe J. Floral visual signal increases reproductive success in a sexually deceptive orchid. ARTHROPOD-PLANT INTERACTIONS 2012; 6:671-681. [PMID: 23750181 PMCID: PMC3672968 DOI: 10.1007/s11829-012-9217-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Sexually deceptive orchids mimic signals emitted by female insects in order to attract mate-searching males. Specific attraction of the targeted pollinator is achieved by sex pheromone mimicry, which constitutes the major attraction channel. In close vicinity of the flower, visual signals may enhance attraction, as was shown recently in the sexually deceptive orchid Ophrys heldreichii. Here, we conducted an in situ manipulation experiment in two populations of O. heldreichii on Crete to investigate whether the presence/absence of the conspicuous pink perianth affects reproductive success in two natural orchid populations. We estimated reproductive success of three treatment groups (with intact, removed and artificial perianth) throughout the flowering period as pollinaria removal (male reproductive success) and massulae deposition (female reproductive success). Reproductive success was significantly increased by the presence of a strong visual signal-the conspicuous perianth-in one study population, however, not in the second, most likely due to the low pollinator abundance in the latter population. This study provides further evidence that the coloured perianth in O. heldreichii is adaptive and thus adds to the olfactory signal to maximise pollinator attraction and reproductive success.
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Affiliation(s)
- Demetra Rakosy
- Department of Evolutionary Biology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
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155
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Whitehead MR, Peakall R. Short-term but not long-term patch avoidance in an orchid-pollinating solitary wasp. Behav Ecol 2012. [DOI: 10.1093/beheco/ars149] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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156
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Phillips RD, Dixon KW, Peakall R. Low population genetic differentiation in the Orchidaceae: implications for the diversification of the family. Mol Ecol 2012; 21:5208-20. [PMID: 23017205 DOI: 10.1111/mec.12036] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 08/01/2012] [Accepted: 08/10/2012] [Indexed: 11/27/2022]
Affiliation(s)
| | | | - Rod Peakall
- Evolution, Ecology and Genetics; Research School of Biology, The Australian National University; Canberra; ACT; 0200; Australia
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157
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Asymmetric gene introgression in two closely related Orchis species: evidence from morphometric and genetic analyses. BMC Evol Biol 2012; 12:178. [PMID: 22967086 PMCID: PMC3523012 DOI: 10.1186/1471-2148-12-178] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 09/07/2012] [Indexed: 11/16/2022] Open
Abstract
Background In food-deceptive orchids of the genera Anacamptis, Neotinea and Orchis floral isolation has been shown to be weak, whereas late-acting reproductive barriers are mostly strong, often restricting hybridization to the F1 generation. Only in a few species hybridization extends beyond the F1 generation, giving rise to hybrid swarms. However, little is known about the abundance of later-generation hybrids and what factors drive their occurrence in hybrid populations. In this study, molecular analyses were combined with detailed morphological measurements in a hybrid population of two closely related Orchis species (Orchis militaris and O. purpurea) to investigate the hypothesis that the abundance of later-generation hybrids is driven by changes in floral characters after hybridization that exert selective pressures that in turn affect hybridization. Results Both the molecular and morphological data point to extensive genetic and morphological homogenization and asymmetric introgression. Estimating genomic clines from the multi-locus genotype data and testing for deviation from neutrality revealed that 30 out of 113 (27%) AFLP markers significantly deviated from neutral expectations. Plants with large floral displays or plant with flowers that resembled more O. purpurea had higher female fitness than plants with small floral displays or plants with flowers resembling more O. militaris, suggesting that directional selection may have contributed to the observed patterns of introgression. Conclusions These results indicate that in closely related orchid species hybridization and gene introgression may be partly driven by selection for floral traits of one of the parental types. However, because some pure individuals were still present in the studied population, the parental species appeared to be sufficiently isolated to survive the challenge of sympatry.
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158
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159
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Aceto S, Gaudio L. The MADS and the Beauty: Genes Involved in the Development of Orchid Flowers. Curr Genomics 2012; 12:342-56. [PMID: 22294877 PMCID: PMC3145264 DOI: 10.2174/138920211796429754] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 06/16/2011] [Accepted: 06/21/2011] [Indexed: 11/22/2022] Open
Abstract
Since the time of Darwin, biologists have studied the origin and evolution of the Orchidaceae, one of the largest families of flowering plants. In the last two decades, the extreme diversity and specialization of floral morphology and the uncoupled rate of morphological and molecular evolution that have been observed in some orchid species have spurred interest in the study of the genes involved in flower development in this plant family. As part of the complex network of regulatory genes driving the formation of flower organs, the MADS-box represents the most studied gene family, both from functional and evolutionary perspectives. Despite the absence of a published genome for orchids, comparative genetic analyses are clarifying the functional role and the evolutionary pattern of the MADS-box genes in orchids. Various evolutionary forces act on the MADS-box genes in orchids, such as diffuse purifying selection and the relaxation of selective constraints, which sometimes reveals a heterogeneous selective pattern of the coding and non-coding regions. The emerging theory regarding the evolution of floral diversity in orchids proposes that the diversification of the orchid perianth was a consequence of duplication events and changes in the regulatory regions of the MADS-box genes, followed by sub- and neo-functionalization. This specific developmental-genetic code is termed the "orchid code."
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Affiliation(s)
- Serena Aceto
- Department of Biological Sciences, University of Naples Federico II, Via Mezzocannone 8, 80134 Napoli, Italy
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160
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Brandenburg A, Kuhlemeier C, Bshary R. Hawkmoth pollinators decrease seed set of a low-nectar Petunia axillaris line through reduced probing time. Curr Biol 2012; 22:1635-9. [PMID: 22840518 DOI: 10.1016/j.cub.2012.06.058] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 06/04/2012] [Accepted: 06/19/2012] [Indexed: 11/15/2022]
Abstract
Although deception of floral pollinators is well known among orchids, the majority of animal-pollinated plants secure pollination by nectar rewards. The costs and benefits of nectar production remain poorly understood. Here, we developed a crossing design to introgress a low-nectar-volume locus of Petunia integrifolia into the genetic background of P. axillaris. The resulting introgression line resembled P. axillaris but produced only one-third of the nectar volume. When exposed simultaneously to low-nectar and wild-type P. axillaris plants, hawkmoth pollinators reduced their probing duration on low-nectar plants but otherwise did not show any signs of discrimination against these plants. However, reduced probing duration resulted in reduced seed production in the low-nectar plants despite their higher reproductive potential as evidenced by hand pollination. In line with this interpretation, we found a positive correlation between probing duration and seed set, and hawkmoth pollination of low-nectar plants that were manually supplemented with nectar to parental levels yielded seed sets similar to hand pollination. Thus, a simple self-serving pollinator behavior--the adjustment of probing time in response to nectar volume--may select against reducing nectar and protect many plant-pollinator mutualisms against a drift toward parasitism.
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Affiliation(s)
- Anna Brandenburg
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland.
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161
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Inda LA, Pimentel M, Chase MW. Phylogenetics of tribe Orchideae (Orchidaceae: Orchidoideae) based on combined DNA matrices: inferences regarding timing of diversification and evolution of pollination syndromes. ANNALS OF BOTANY 2012; 110:71-90. [PMID: 22539542 PMCID: PMC3380586 DOI: 10.1093/aob/mcs083] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 03/01/2012] [Indexed: 05/03/2023]
Abstract
BACKGROUND AND AIMS Tribe Orchideae (Orchidaceae: Orchidoideae) comprises around 62 mostly terrestrial genera, which are well represented in the Northern Temperate Zone and less frequently in tropical areas of both the Old and New Worlds. Phylogenetic relationships within this tribe have been studied previously using only nuclear ribosomal DNA (nuclear ribosomal internal transcribed spacer, nrITS). However, different parts of the phylogenetic tree in these analyses were weakly supported, and integrating information from different plant genomes is clearly necessary in orchids, where reticulate evolution events are putatively common. The aims of this study were to: (1) obtain a well-supported and dated phylogenetic hypothesis for tribe Orchideae, (ii) assess appropriateness of recent nomenclatural changes in this tribe in the last decade, (3) detect possible examples of reticulate evolution and (4) analyse in a temporal context evolutionary trends for subtribe Orchidinae with special emphasis on pollination systems. METHODS The analyses included 118 samples, belonging to 103 species and 25 genera, for three DNA regions (nrITS, mitochondrial cox1 intron and plastid rpl16 intron). Bayesian and maximum-parsimony methods were used to construct a well-supported and dated tree. Evolutionary trends in the subtribe were analysed using Bayesian and maximum-likelihood methods of character evolution. KEY RESULTS The dated phylogenetic tree strongly supported the recently recircumscribed generic concepts of Bateman and collaborators. Moreover, it was found that Orchidinae have diversified in the Mediterranean basin during the last 15 million years, and one potential example of reticulate evolution in the subtribe was identified. In Orchidinae, pollination systems have shifted on numerous occasions during the last 23 million years. CONCLUSIONS The results indicate that ancestral Orchidinae were hymenopteran-pollinated, food-deceptive plants and that these traits have been dominant throughout the evolutionary history of the subtribe in the Mediterranean. Evidence was also obtained that the onset of sexual deception might be linked to an increase in labellum size, and the possibility is discussed that diversification in Orchidinae developed in parallel with diversification of bees and wasps from the Miocene onwards.
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Affiliation(s)
- Luis A Inda
- Escuela Politécnica Superior de Huesca, Universidad de Zaragoza, carretera de Cuarte s/n., Huesca, Spain.
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162
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Brandenburg A, Kuhlemeier C, Bshary R. Innate Adjustment of Visitation Behavior to Rewarding and Reward-Minimized Petunia axillaris (Solanacea) Plants by Hawkmoth Manduca sexta (Sphingidae). Ethology 2012. [DOI: 10.1111/j.1439-0310.2012.02055.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Cris Kuhlemeier
- Institute of Plant Science; University of Bern; Bern; Switzerland
| | - Redouan Bshary
- Institute of Biology; University of Neuchâtel; Neuchâtel; Switzerland
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163
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Guo YY, Luo YB, Liu ZJ, Wang XQ. Evolution and biogeography of the slipper orchids: Eocene vicariance of the conduplicate genera in the Old and New World Tropics. PLoS One 2012; 7:e38788. [PMID: 22685605 PMCID: PMC3369861 DOI: 10.1371/journal.pone.0038788] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 05/10/2012] [Indexed: 11/19/2022] Open
Abstract
Intercontinental disjunctions between tropical regions, which harbor two-thirds of the flowering plants, have drawn great interest from biologists and biogeographers. Most previous studies on these distribution patterns focused on woody plants, and paid little attention to herbs. The Orchidaceae is one of the largest families of angiosperms, with a herbaceous habit and a high species diversity in the Tropics. Here we investigate the evolutionary and biogeographical history of the slipper orchids, which represents a monophyletic subfamily (Cypripedioideae) of the orchid family and comprises five genera that are disjunctly distributed in tropical to temperate regions. A relatively well-resolved and highly supported phylogeny of slipper orchids was reconstructed based on sequence analyses of six maternally inherited chloroplast and two low-copy nuclear genes (LFY and ACO). We found that the genus Cypripedium with a wide distribution in the northern temperate and subtropical zones diverged first, followed by Selenipedium endemic to South America, and finally conduplicate-leaved genera in the Tropics. Mexipedium and Phragmipedium from the neotropics are most closely related, and form a clade sister to Paphiopedilum from tropical Asia. According to molecular clock estimates, the genus Selenipedium originated in Palaeocene, while the most recent common ancestor of conduplicate-leaved slipper orchids could be dated back to the Eocene. Ancestral area reconstruction indicates that vicariance is responsible for the disjunct distribution of conduplicate slipper orchids in palaeotropical and neotropical regions. Our study sheds some light on mechanisms underlying generic and species diversification in the orchid family and tropical disjunctions of herbaceous plant groups. In addition, we suggest that the biogeographical study should sample both regional endemics and their widespread relatives.
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Affiliation(s)
- Yan-Yan Guo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, the Chinese Academy of Sciences, Beijing, China
- Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Yi-Bo Luo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, the Chinese Academy of Sciences, Beijing, China
| | - Zhong-Jian Liu
- The Orchid Conservation and Research Center of Shenzhen, Shenzhen, China
| | - Xiao-Quan Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, the Chinese Academy of Sciences, Beijing, China
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164
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Chen YY, Lee PF, Hsiao YY, Wu WL, Pan ZJ, Lee YI, Liu KW, Chen LJ, Liu ZJ, Tsai WC. C- and D-class MADS-box genes from Phalaenopsis equestris (Orchidaceae) display functions in gynostemium and ovule development. PLANT & CELL PHYSIOLOGY 2012; 53:1053-67. [PMID: 22499266 DOI: 10.1093/pcp/pcs048] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Gynostemium and ovule development in orchid are unique developmental processes in the plant kingdom. Characterization of C- and D-class MADS-box genes could help reveal the molecular mechanisms underlying gynostemium and ovule development in orchids. In this study, we isolated and characterized a C- and a D-class gene, PeMADS1 and PeMADS7, respectively, from Phalaenopsis equestris. These two genes showed parallel spatial and temporal expression profiles, which suggests their cooperation in gynostemium and ovule development. Furthermore, only PeMADS1 was ectopically expressed in the petals of the gylp (gynostemium-like petal) mutant, whose petals were transformed into gynostemium-like structures. Protein-protein interaction analyses revealed that neither PeMADS1 and PeMADS7 could form a homodimer or a heterodimer. An E-class protein was needed to bridge the interaction between these two proteins. A complementation test revealed that PeMADS1 could rescue the phenotype of the AG mutant. Overexpression of PeMADS7 in Arabidopsis caused typical phenotypes of the D-class gene family. Together, these results indicated that both C-class PeMADS1 and D-class PeMADS7 play important roles in orchid gynostemium and ovule development.
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MESH Headings
- Amino Acid Sequence
- DNA, Plant/genetics
- DNA, Plant/metabolism
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Plant
- Genes, Plant
- Genetic Complementation Test
- MADS Domain Proteins/genetics
- MADS Domain Proteins/metabolism
- Microscopy, Electron, Scanning
- Molecular Sequence Data
- Orchidaceae/anatomy & histology
- Orchidaceae/genetics
- Orchidaceae/growth & development
- Ovule/genetics
- Ovule/growth & development
- Ovule/ultrastructure
- Phenotype
- Phylogeny
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plants, Genetically Modified/anatomy & histology
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/growth & development
- Pollination
- Protein Interaction Mapping
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Affiliation(s)
- You-Yi Chen
- Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 701, Taiwan
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165
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Kisel Y, Moreno-Letelier AC, Bogarín D, Powell MP, Chase MW, Barraclough TG. TESTING THE LINK BETWEEN POPULATION GENETIC DIFFERENTIATION AND CLADE DIVERSIFICATION IN COSTA RICAN ORCHIDS. Evolution 2012; 66:3035-52. [DOI: 10.1111/j.1558-5646.2012.01663.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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166
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Pollinator-Driven Speciation in Sexually Deceptive Orchids. INTERNATIONAL JOURNAL OF ECOLOGY 2012. [DOI: 10.1155/2012/285081] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pollinator-mediated selection has been suggested to play a major role for the origin and maintenance of the species diversity in orchids. Sexually deceptive orchids are one of the prime examples for rapid, pollinator-mediated plant radiations, with many species showing little genetic differentiation, lack of postzygotic barriers, but strong prezygotic reproductive isolation. These orchids mimic mating signals of female insects and employ male insects as pollinators. This kind of sexual mimicry leads to highly specialised pollination and provides a good system for investigating the process of pollinator-driven speciation. Here, we summarise the knowledge of key processes of speciation in this group of orchids and conduct a meta-analysis on traits that contribute to species differentiation, and thus potentially to speciation. Our study suggests that pollinator shift through changes in floral scent is predominant among closely related species in sexually deceptive orchids. Such shifts can provide a mechanism for pollinator-driven speciation in plants, if the resulting floral isolation is strong. Furthermore, changes in floral scent in these orchids are likely controlled by few genes. Together these factors suggest speciation in sexually deceptive orchids may happen rapidly and even in sympatry, which may explain the remarkable species diversity observed in this plant group.
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167
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Box MS, Dodsworth S, Rudall PJ, Bateman RM, Glover BJ. Characterization of Linaria KNOX genes suggests a role in petal-spur development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 68:703-14. [PMID: 21790812 DOI: 10.1111/j.1365-313x.2011.04721.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Spurs are tubular outgrowths of perianth organs that have evolved iteratively among angiosperms. They typically contain nectar and often strongly influence pollinator specificity, potentially mediating reproductive isolation. The identification of Antirrhinum majus mutants with ectopic petal spurs suggested that petal-spur development is dependent on the expression of KNOTTED 1-like homeobox (KNOX) genes, which are better known for their role in maintaining the shoot apical meristem. Here, we tested the role of KNOX genes in petal-spur development by isolating orthologs of the A. majus KNOX genes Hirzina (AmHirz) and Invaginata (AmIna) from Linaria vulgaris, a related species that differs from A. majus in possessing long, narrow petal spurs. We name these genes LvHirz and LvIna, respectively. Using quantitative reverse-transcription PCR, we show that LvHirz is expressed at high levels in the developing petals and demonstrate that the expression of petal-associated KNOX genes is sufficient to induce sac-like outgrowths on petals in a heterologous host. We propose a model in which KNOX gene expression during early petal-spur development promotes and maintains further morphogenetic potential of the petal, as previously described for KNOX gene function in compound leaf development. These data indicate that petal spurs could have evolved by changes in regulatory gene expression that cause rapid and potentially saltational phenotypic modifications. Given the morphological similarity of spur ontogeny in distantly related taxa, changes in KNOX gene expression patterns could be a shared feature of spur development in angiosperms.
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Affiliation(s)
- Mathew S Box
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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Angulo DF, Ruiz-Sanchez E, Sosa V. Niche conservatism in the Mesoamerican seasonal tropical dry forest orchid Barkeria (Orchidaceae). Evol Ecol 2011. [DOI: 10.1007/s10682-011-9528-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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169
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Ayasse M, Stökl J, Francke W. Chemical ecology and pollinator-driven speciation in sexually deceptive orchids. PHYTOCHEMISTRY 2011; 72:1667-1677. [PMID: 21497864 DOI: 10.1016/j.phytochem.2011.03.023] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 03/23/2011] [Accepted: 03/24/2011] [Indexed: 05/30/2023]
Abstract
Sexually deceptive orchids mimic females of their pollinator species to attract male insects for pollination. Pollination by sexual deception has independently evolved in European, Australian, South African, and South American orchid taxa. Reproductive isolation is mainly based on pre-mating isolation barriers, the specific attraction of males of a single pollinator species, mostly bees, by mimicking the female species-specific sex-pheromone. However, in rare cases post-mating barriers have been found. Sexually deceptive orchids are ideal candidates for studies of sympatric speciation, because key adaptive traits such as the pollinator-attracting scent are associated with their reproductive success and with pre-mating isolation. During the last two decades several investigations studied processes of ecological speciation in sexually deceptive orchids of Europe and Australia. Using various methods like behavioural experiments, chemical, electrophysiological, and population-genetic analyses it was shown that minor changes in floral odour bouquets might be the driving force for pollinator shifts and speciation events. New pollinators act as an isolation barrier towards other sympatrically occurring species. Hybridization occurs because of similar odour bouquets of species and the overlap of flowering periods. Hybrid speciation can also lead to the displacement of species by the hybrid population, if its reproductive success is higher than that in the parental species.
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Affiliation(s)
- Manfred Ayasse
- Institute for Experimental Ecology, University of Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, Germany.
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170
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Pan ZJ, Cheng CC, Tsai WC, Chung MC, Chen WH, Hu JM, Chen HH. The duplicated B-class MADS-box genes display dualistic characters in orchid floral organ identity and growth. PLANT & CELL PHYSIOLOGY 2011; 52:1515-31. [PMID: 21757456 DOI: 10.1093/pcp/pcr092] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Orchidaceae are an excellent model to examine perianth development because of their sophisticated floral architecture. In this study, we identified 24 APETALA3 (AP3)-like and 13 PISTILLA (PI)-like genes from 11 species of orchids and characterized them into four AP3- and two PI-duplicated homologs. The first duplication event in AP3 homologs occurring in the early evolutionary history of the Orchidaceae gave rise to AP3A and AP3B clades. Further duplication events resulted in four subclades, namely AP3A1, AP3A2, AP3B1 and AP3B2, during the evolution of Orchidaceae. The AP3 paralogous genes were expressed throughout inflorescence and floral bud development. From the in situ hybridization results, we noticed that the transition timings from ubiquitous to constrained expression in floral organs for both clades are different. The transition point of expression of the AP3A clade (clades 3 and 4) was at the late floral organ primordia stage. In contrast, that for the AP3B clade (clades 1 and 2) was not observed until the late inflorescence and floral bud stages. In addition, the AP3 orthologous genes revealed diverse expression patterns in various species of orchids, whereas the PI homologs were uniformly expressed in all floral whorls. AP3A2 orthologs play a noticeable role in lip formation because of their exclusive expression in the lip. Further evidence comes from the ectopic expression of AP3A2 detected in the lip-like petals extending from the lip in four sets of peloric mutants. Finally, a Homeotic Orchid Tepal (HOT) model is proposed, in which dualistic characters of duplicated B-class MADS-box genes are involved in orchid perianth development and growth.
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Affiliation(s)
- Zhao-Jun Pan
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
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171
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Urru I, Stensmyr MC, Hansson BS. Pollination by brood-site deception. PHYTOCHEMISTRY 2011; 72:1655-66. [PMID: 21419464 DOI: 10.1016/j.phytochem.2011.02.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 02/16/2011] [Accepted: 02/16/2011] [Indexed: 05/11/2023]
Abstract
Pollination is often regarded as a mutualistic relationship between flowering plants and insects. In such a relationship, both partners gain a fitness benefit as a result of their interaction. The flower gets pollinated and the insect typically gets a food-related reward. However, flower-insect communication is not always a mutualistic system, as some flowers emit deceitful signals. Insects are thus fooled by irresistible stimuli and pollination is accomplished. Such deception requires very fine tuning, as insects in their typically short life span, try to find mating/feeding breeding sites as efficiently as possible, and following deceitful signals thus is both costly and time-consuming. Deceptive flowers have thus evolved the ability to emit signals that trigger obligate innate or learned responses in the targeted insects. The behavior, and thus the signals, exploited are typically involved in reproduction, from attracting pheromones to brood/food-site cues. Chemical mimicry is one of the main modalities through which flowers trick their pollen vectors, as olfaction plays a pivotal role in insect-insect and insect-plant interactions. Here we focus on floral odors that specifically mimic an oviposition substrate, i.e., brood-site mimicry. The phenomenon is wide spread across unrelated plant lineages of Angiosperm, Splachnaceae and Phallaceae. Targeted insects are mainly beetles and flies, and flowers accordingly often emit, to the human nose, highly powerful and fetid smells that are conversely extremely attractive to the duped insects. Brood-site deceptive plants often display highly elaborate flowers and have evolved a trap-release mechanism. Chemical cues often act in unison with other sensory cues to refine the imitation.
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Affiliation(s)
- Isabella Urru
- Department of Evolutionary Neuroethology, Max-Planck-Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745 Jena, Germany.
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172
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Hsiao YY, Pan ZJ, Hsu CC, Yang YP, Hsu YC, Chuang YC, Shih HH, Chen WH, Tsai WC, Chen HH. Research on orchid biology and biotechnology. PLANT & CELL PHYSIOLOGY 2011; 52:1467-86. [PMID: 21791545 DOI: 10.1093/pcp/pcr100] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Orchidaceae constitute one of the largest families of angiosperms. They are one of the most ecological and evolutionary significant plants and have successfully colonized almost every habitat on earth. Because of the significance of plant biology, market needs and the current level of breeding technologies, basic research into orchid biology and the application of biotechnology in the orchid industry are continually endearing scientists to orchids in Taiwan. In this introductory review, we give an overview of the research activities in orchid biology and biotechnology, including the status of genomics, transformation technology, flowering regulation, molecular regulatory mechanisms of floral development, scent production and color presentation. This information will provide a broad scope for study of orchid biology and serve as a starting point for uncovering the mysteries of orchid evolution.
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Affiliation(s)
- Yu-Yun Hsiao
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
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173
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Zitari A, Scopece G, Helal AN, Widmer A, Cozzolino S. Is floral divergence sufficient to maintain species boundaries upon secondary contact in Mediterranean food-deceptive orchids? Heredity (Edinb) 2011; 108:219-28. [PMID: 21792224 DOI: 10.1038/hdy.2011.61] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Analyzing the processes that determine whether species boundaries are maintained on secondary contact may shed light on the early phase of speciation. In Anacamptis morio and Anacamptis longicornu, two Mediterranean orchid sister-species, we used molecular and morphological analyses, together with estimates of pollination success and experimental crosses, to assess whether floral isolation can shelter the species' genomes from genetic admixture on secondary contact. We found substantial genetic and morphological homogenization in sympatric populations in combination with an apparent lack of postmating isolation. We further detected asymmetric introgression in the sympatric populations and an imbalance in cytotype representation, which may be due either to a difference in flowering phenology or else be a consequence of cytonuclear incompatibilities. Estimates of genetic clines for markers across sympatric zones revealed markers that significantly deviated from neutral expectations. We observed a significant correlation between spur length and reproductive success in sympatric populations, which may suggest that directional selection is the main cause of morphological differentiation in this species pair. Our results suggest that allopatric divergence has not led to the evolution of sufficient reproductive isolation to prevent genomic admixture on secondary contact in this orchid species pair.
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Affiliation(s)
- A Zitari
- Department of Structural and Functional Biology, University Federico II of Naples, Naples, Italy
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174
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Hsiao YY, Chen YW, Huang SC, Pan ZJ, Fu CH, Chen WH, Tsai WC, Chen HH. Gene discovery using next-generation pyrosequencing to develop ESTs for Phalaenopsis orchids. BMC Genomics 2011; 12:360. [PMID: 21749684 PMCID: PMC3146457 DOI: 10.1186/1471-2164-12-360] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 07/12/2011] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Orchids are one of the most diversified angiosperms, but few genomic resources are available for these non-model plants. In addition to the ecological significance, Phalaenopsis has been considered as an economically important floriculture industry worldwide. We aimed to use massively parallel 454 pyrosequencing for a global characterization of the Phalaenopsis transcriptome. RESULTS To maximize sequence diversity, we pooled RNA from 10 samples of different tissues, various developmental stages, and biotic- or abiotic-stressed plants. We obtained 206,960 expressed sequence tags (ESTs) with an average read length of 228 bp. These reads were assembled into 8,233 contigs and 34,630 singletons. The unigenes were searched against the NCBI non-redundant (NR) protein database. Based on sequence similarity with known proteins, these analyses identified 22,234 different genes (E-value cutoff, e-7). Assembled sequences were annotated with Gene Ontology, Gene Family and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Among these annotations, over 780 unigenes encoding putative transcription factors were identified. CONCLUSION Pyrosequencing was effective in identifying a large set of unigenes from Phalaenopsis. The informative EST dataset we developed constitutes a much-needed resource for discovery of genes involved in various biological processes in Phalaenopsis and other orchid species. These transcribed sequences will narrow the gap between study of model organisms with many genomic resources and species that are important for ecological and evolutionary studies.
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Affiliation(s)
- Yu-Yun Hsiao
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
- Orchid Research Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Yun-Wen Chen
- Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Shi-Ching Huang
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Zhao-Jun Pan
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Chih-Hsiung Fu
- Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan
| | - Wen-Huei Chen
- Orchid Research Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Wen-Chieh Tsai
- Orchid Research Center, National Cheng Kung University, Tainan 701, Taiwan
- Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Hong-Hwa Chen
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
- Orchid Research Center, National Cheng Kung University, Tainan 701, Taiwan
- Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 701, Taiwan
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175
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Di Stilio VS. Empowering plant evo-devo: Virus induced gene silencing validates new and emerging model systems. Bioessays 2011; 33:711-8. [DOI: 10.1002/bies.201100040] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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176
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Yu Q, Li DX, Luo W, Guo YH. Function and evolution of sterile sex organs in cryptically dioecious Petasites tricholobus (Asteraceae). ANNALS OF BOTANY 2011; 108:65-71. [PMID: 21546429 PMCID: PMC3119616 DOI: 10.1093/aob/mcr105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Accepted: 03/18/2011] [Indexed: 05/30/2023]
Abstract
BACKGROUND AND AIMS Why are sterile anthers and carpels retained in some flowering plants, given their likely costs? To address this question, a cryptically dioecious species, Petasites tricholobus, in which male and female plants each have two floret types that appear pistillate and hermaphroditic, was studied. The aim was to understand the function of sterile hermaphroditic florets in females. In addition, the first examination of functions of sterile female structures in male plants was conducted in the hermaphroditic florets on males of this species. These female structures are exceptionally large in this species despite being sterile. METHODS Differences in floret morphology between the sex morphs were documented and the possible functions of sterile sex organs investigated using manipulative experiments. Tests were carried out to find out if sterile female structures in male florets attract pollinators and if they aid in pollen dispersal, also to find out if the presence and quantity of sterile hermaphroditic florets in females increase pollinator attraction and reproductive success. To investigate what floret types provide nectar, all types of florets were examined under a scanning electron microscope to search for nectaries. KEY RESULTS The sterile female structures in male florets did not increase pollinator visits but were essential to secondary pollen presentation, which significantly enhanced pollen dispersal. Sterile pistillate florets on male plants did not contribute to floral display and disappeared in nearly half of the male plants. The sterile hermaphroditic florets on female plants attracted pollinators by producing nectar and enhanced seed production. CONCLUSIONS The presence of female structures in male florets and hermaphroditic florets on female plants is adaptive despite being sterile, and may be evolutionarily stable. However, the pistillate florets on male plants appear non-adaptive and are presumably in decline. Differential fates of the sterile sex organs in the species are determined by both the historical constraints and the ecological functions.
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177
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Mondragón-Palomino M, Theissen G. Conserved differential expression of paralogous DEFICIENS- and GLOBOSA-like MADS-box genes in the flowers of Orchidaceae: refining the 'orchid code'. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 66:1008-19. [PMID: 21435045 DOI: 10.1111/j.1365-313x.2011.04560.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
In flowering plants, class-B floral homeotic genes encode MADS-domain transcription factors, which are key in the specification of petal and stamen identity, and have two ancient clades: DEF-like and GLO-like genes. Many species have one gene of each clade, but orchids have typically four DEF-like genes, representing ancient gene clades 1, 2, 3 and 4. We tested the 'orchid code', a combinatorial genetic model suggesting that differences between the organs of the orchid perianth (outer tepals, inner lateral tepals and labellum) are generated by the combinatorial differential expression of four DEF-like genes. Our experimental test involves highly sensitive and specific measurements, with qRT-PCR of the expression of DEF- and GLO-like genes from the distantly related Vanilla planifolia and Phragmipedium longifolium, as well as from wild-type and peloric Phalaenopsis hybrid flowers. Our findings support the first 'orchid code' hypothesis, in that absence of clade-3 and -4 gene expression distinguishes the outer tepals from the inner tepals. In contrast to the original hypothesis, however, mRNA of both clade-3 and -4 genes accumulates in wild-type inner lateral tepals and the labellum, and in labellum-like inner lateral tepals of peloric flowers, albeit in different quantities. Our data suggest a revised hypothesis where high levels of clade-1 and -2, and low levels of clade-3 and -4, gene expression specify inner lateral tepals, whereas labellum development requires low levels of clade-1 and -2 expression and high levels of clade-3 and -4 expression.
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178
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De Hert K, Jacquemyn H, Van Glabeke S, Roldán-Ruiz I, Vandepitte K, Leus L, Honnay O. Patterns of hybridization between diploid and derived allotetraploid species of Dactylorhiza (Orchidaceae) co-occurring in Belgium. AMERICAN JOURNAL OF BOTANY 2011; 98:946-955. [PMID: 21653507 DOI: 10.3732/ajb.1000367] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
PREMISE OF THE STUDY Although the potential for gene flow between species with large differences in chromosome numbers has long been recognized, only few studies have thoroughly investigated in situ hybridization across taxa with different ploidy levels. We combined morphological, cytological, and genetic marker data with pollination experiments to investigate the degree, direction, and spatial pattern of hybridization between the diploid Dactylorhiza incarnata and its tetraploid derivative, D. praetermissa. METHODS To identify hybrids, 169 individuals were genotyped using AFLPs and morphologically characterized. Individuals were clustered on the basis of their AFLP profile using the program Structure. To reduce the dimensionality of the plant-trait matrix, PCA was applied. The origin of suspected hybrid individuals was verified using flow cytometry. An AMOVA and spatial autocorrelation analysis were used to indirectly infer the extent of gene flow. KEY RESULTS Only five individuals were regarded as putative hybrids on the basis of the AFLP data; all had been assigned to the D. praetermissa morphotype. Only one had deviating DNA content and was presumably a triploid. High Φ(ST) values between different subpopulations and significant spatial genetic structure were observed, suggesting localized gene flow. CONCLUSIONS Using combined data to study hybridization between D. incarnata and D. praetermissa, very few unequivocal hybrids were observed. We propose several non-mutually exclusive explanations. Localized pollen flow, in combination with different microhabitat preferences, is probably one of the reasons for the low frequency of hybrids. Also, the triploid first-generation hybrids may experience difficulties in successful establishment, as a result of genic incompatibilities.
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Affiliation(s)
- Koen De Hert
- Biology Department, Laboratory of Plant Ecology, University of Leuven, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium.
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179
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Abstract
The extraordinary taxonomic and morphological diversity of orchids is accompanied by a remarkable range of pollinators and pollination systems. Sexually deceptive orchids are adapted to attract specific male insects that are fooled into attempting to mate with orchid flowers and inadvertently acting as pollinators. This review summarises current knowledge, explores new hypotheses in the literature, and introduces some new approaches to understanding sexual deception from the perspective of the duped pollinator. Four main topics are addressed: (1) global patterns in sexual deception, (2) pollinator identities, mating systems and behaviours, (3) pollinator perception of orchid deceptive signals, and (4) the evolutionary implications of pollinator responses to orchid deception, including potential costs imposed on pollinators by orchids. A global list of known and putative sexually deceptive orchids and their pollinators is provided and methods for incorporating pollinator perspectives into sexual deception research are provided and reviewed. At present, almost all known sexually deceptive orchid taxa are from Australia or Europe. A few sexually deceptive species and genera are reported for New Zealand and South Africa. In Central and Southern America, Asia, and the Pacific many more species are likely to be identified in the future. Despite the great diversity of sexually deceptive orchid genera in Australia, pollination rates reported in the literature are similar between Australian and European species. The typical pollinator of a sexually deceptive orchid is a male insect of a species that is polygynous, monandrous, haplodiploid, and solitary rather than social. Insect behaviours involved in the pollination of sexually deceptive orchids include pre-copulatory gripping of flowers, brief entrapment, mating, and very rarely, ejaculation. Pollinator behaviour varies within and among pollinator species. Deception involving orchid mimicry of insect scent signals is becoming well understood for some species, but visual and tactile signals such as colour, shape, and texture remain neglected. Experimental manipulations that test for function, multi-signal interactions, and pollinator perception of these signals are required. Furthermore, other forms of deception such as exploitation of pollinator sensory biases or mating preferences merit more comprehensive investigation. Application of molecular techniques adapted from model plants and animals is likely to deliver new insights into orchid signalling, and pollinator perception and behaviour. There is little current evidence that sexual deception drives any species-level selection on pollinators. Pollinators do learn to avoid deceptive orchids and their locations, but this is not necessarily a response specific to orchids. Even in systems where evidence suggests that orchids do interfere with pollinator mating opportunities, considerable further research is required to determine whether this is sufficient to impose selection on pollinators or generate antagonistic coevolution or an arms race between orchids and their pollinators. Botanists, taxonomists and chemical ecologists have made remarkable progress in the study of deceptive orchid pollination. Further complementary investigations from entomology and behavioural ecology perspectives should prove fascinating and engender a more complete understanding of the evolution and maintenance of such enigmatic plant-animal interactions.
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Affiliation(s)
- A C Gaskett
- Department of Biological Sciences, Macquarie University, NSW, Australia.
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180
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van der Niet T, Hansen DM, Johnson SD. Carrion mimicry in a South African orchid: flowers attract a narrow subset of the fly assemblage on animal carcasses. ANNALS OF BOTANY 2011; 107:981-92. [PMID: 21402538 PMCID: PMC3080630 DOI: 10.1093/aob/mcr048] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 12/13/2010] [Accepted: 02/03/2011] [Indexed: 05/11/2023]
Abstract
BACKGROUND AND AIMS Although pollination of plants that attract flies by resembling their carrion brood and food sites has been reported in several angiosperm families, there has been very little work done on the level of specificity in carrion mimicry systems and the importance of plant cues in mediating such specialization. Specificity may be expected, as carrion-frequenting flies often exploit different niches, which has been interpreted as avoidance of interspecific competition. Interactions between the orchid Satyrium pumilum and a local assemblage of carrion flies were investigated, and the functional significance of floral traits, especially scent, tested. Pollination success and the incidence of pollinator-mediated self-pollination were measured and these were compared with values for orchids with sexual- and food-deceptive pollination systems. METHODS AND KEY RESULTS Observations of insect visitation to animal carcasses and to flowers showed that the local assemblage of carrion flies was dominated by blow flies (Calliphoridae), house flies (Muscidae) and flesh flies (Sarcophagidae), but flowers of the orchid were pollinated exclusively by flesh flies, with a strong bias towards females that sometimes deposited live larvae on flowers. A trend towards similar partitioning of fly taxa was found in an experiment that tested the effect of large versus small carrion quantities on fly attraction. GC-MS analysis showed that floral scent is dominated by oligosulfides, 2-heptanone, p-cresol and indole, compounds that also dominate carrion scent. Flesh flies did not distinguish between floral and carrion scent in a choice experiment using olfactory cues only, which also showed that scent alone is responsible for fly attraction. Pollination success was relatively high (31·5 % of flowers), but tracking of stained pollinia also revealed that a relatively high percentage (46 %) of pollen deposited on stigmas originates from the same plant. CONCLUSIONS Satyrium pumilum selectively attracts flesh flies, probably because its relatively weak scent resembles that of the small carrion on which these flies predominate. In this way, the plants exploit a specific subset of the insect assemblage associated with carrion. Pollination rates and levels of self-pollination were high compared with those in other deceptive orchids and it is therefore unlikely that this mimicry system evolved to promote outcrossing.
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Affiliation(s)
- Timotheüs van der Niet
- School of Biological and Conservation Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, South Africa.
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181
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Flowers of Cypripedium fargesii (Orchidaceae) fool flat-footed flies (Platypezidae) by faking fungus-infected foliage. Proc Natl Acad Sci U S A 2011; 108:7478-80. [PMID: 21502502 DOI: 10.1073/pnas.1103384108] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Charles Darwin was fascinated by the orchid-pollinator interactions, but he did not realize that many orchid species are pollinated by deceit. Cypripedium, a model lineage of nonrewarding orchid flowers, is pollinated primarily by bees. Here we present both an example of floral mimesis of fungus-infected foliage in orchids and an example of flat-footed flies (Agathomyia sp.; Platypezidae) as pollen vectors for angiosperms. Cypripedium fargesii is a nectarless, terrestrial, endangered orchid from southwestern China that requires cross-pollination to produce the maximum number of viable embryos. All insects caught entering or leaving the labellum sac were Agathomyia sp. carrying conidia of Cladosporium sp. on their mouthparts and legs, suggesting mycophagy. Blackish hairy spots on the upper surface of foliage may imitate black mold spots, serving as short-term visual lures. Some odor molecules also associated with Cladosporium cultures were isolated in the floral scent. Mimesis of fungus-infected foliage probably represents an overlooked but important option in angiosperm diversification, because there are three to five more Cypripedium spp. in southwestern China with the same mode of floral presentation and black-spotted hairy leaves.
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182
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Jacquemyn H, Brys R, Cammue BPA, Honnay O, Lievens B. Mycorrhizal associations and reproductive isolation in three closely related Orchis species. ANNALS OF BOTANY 2011; 107:347-56. [PMID: 21186239 PMCID: PMC3043927 DOI: 10.1093/aob/mcq248] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
BACKGROUND AND AIMS The maintenance of species boundaries in sympatric populations of closely related species requires some kind of reproductive isolation that limits gene flow among species and/or prevents the production of viable progeny. Because in orchids mycorrhizal fungi are needed for seed germination and subsequent seedling establishment, orchid-mycorrhizal associations may be involved in acting as a post-mating barrier. METHODS We investigated the strength of post-mating barriers up to the seed germination stage acting between three closely related Orchis species (Orchis anthropophora, O. militaris and O. purpurea) and studied the role of mycorrhizal fungi in hybridization by burying seed packets of pure and hybrid seeds. After retrieval and assessment of seed germination, the fungi associating with protocorms originating from hybrid and pure seeds were determined and compared with those associating with adult individuals using DNA array technology. RESULTS Whereas pre-zygotic post-mating barriers were rather weak in most crosses, post-zygotic post-mating barriers were stronger, particularly when O. purpurea was crossed with O. anthropophora. Germination trials in the field showed that seed germination percentages of hybrid seeds were in most cases lower than those originating from pure crosses. In all species pair combinations, total post-mating reproductive isolation was asymmetric. Protocorms associated with a smaller range of fungal symbionts than adult plants, but there was considerable overlap in mycorrhizal associations between protocorms and their respective parents. CONCLUSIONS Our results suggest that mycorrhizal associations contribute little to reproductive isolation. Pre-mating barriers are probably the main factors determining hybridization rates between the investigated species.
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Affiliation(s)
- Hans Jacquemyn
- Laboratory of Plant Ecology, Department of Biology, KU Leuven, Leuven, Belgium.
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183
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Fu CH, Chen YW, Hsiao YY, Pan ZJ, Liu ZJ, Huang YM, Tsai WC, Chen HH. OrchidBase: a collection of sequences of the transcriptome derived from orchids. PLANT & CELL PHYSIOLOGY 2011; 52:238-43. [PMID: 21245031 DOI: 10.1093/pcp/pcq201] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Orchids are one of the most ecological and evolutionarily significant plants, and the Orchidaceae is one of the most abundant families of the angiosperms. Genetic databases will be useful not only for gene discovery but also for future genomic annotation. For this purpose, OrchidBase was established from 37,979,342 sequence reads collected from 11 in-house Phalaenopsis orchid cDNA libraries. Among them, 41,310 expressed sequence tags (ESTs) were obtained by using Sanger sequencing, whereas 37,908,032 reads were obtained by using next-generation sequencing (NGS) including both Roche 454 and Solexa Illumina sequencers. These reads were assembled into 8,501 contigs and 76,116 singletons, resulting in 84,617 non-redundant transcribed sequences with an average length of 459 bp. The analysis pipeline of the database is an automated system written in Perl and C#, and consists of the following components: automatic pre-processing of EST reads, assembly of raw sequences, annotation of the assembled sequences and storage of the analyzed information in SQL databases. A web application was implemented with HTML and a Microsoft .NET Framework C# program for browsing and querying the database, creating dynamic web pages on the client side, analyzing gene ontology (GO) and mapping annotated enzymes to KEGG pathways. The online resources for putative annotation can be searched either by text or by using BLAST, and the results can be explored on the website and downloaded. Consequently, the establishment of OrchidBase will provide researchers with a high-quality genetic resource for data mining and facilitate efficient experimental studies on orchid biology and biotechnology. The OrchidBase database is freely available at http://lab.fhes.tn.edu.tw/est.
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Affiliation(s)
- Chih-Hsiung Fu
- Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan
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184
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Ellis AG, Johnson SD. Floral mimicry enhances pollen export: the evolution of pollination by sexual deceit outside of the orchidaceae. Am Nat 2011; 176:E143-51. [PMID: 20843263 DOI: 10.1086/656487] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Although the majority of flowering plants achieve pollination by exploiting the food‐seeking behavior of animals, some use alternative ploys that exploit their mate‐seeking behavior. Sexual deception is currently known only from the Orchidaceae and almost always involves pollination by male hymenoptera. An outstanding problem has been to identify the selective factors in plants that favor exploitation of mating versus feeding behaviors in pollinators. Here we show that the insectlike petal ornaments on inflorescences of the daisy Gorteria diffusa elicit copulation attempts from male bombyliid flies and that the intensity of the mating response varies across geographical floral morphotypes, suggesting a continuum in reliance on feeding through mating responses for pollination. Using pollen analogues applied to a morphotype with prominent insectlike petal ornaments, we demonstrate that mate‐seeking male flies are several‐fold more active and export significantly more pollen than females. These results suggest that selection for traits that exploit insect mating behavior can occur through the male component of plant fitness and conclusively demonstrates pollination by sexual deception in Gorteria, making this the first confirmed report of sexual deception outside of the Orchidaceae.
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Affiliation(s)
- Allan G Ellis
- School of Biological and Conservation Sciences, University of KwaZulu‐Natal, Scottsville, Pietermaritzburg 3209, South Africa.
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185
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Hsu CC, Chung YL, Chen TC, Lee YL, Kuo YT, Tsai WC, Hsiao YY, Chen YW, Wu WL, Chen HH. An overview of the Phalaenopsis orchid genome through BAC end sequence analysis. BMC PLANT BIOLOGY 2011; 11:3. [PMID: 21208460 PMCID: PMC3027094 DOI: 10.1186/1471-2229-11-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 01/06/2011] [Indexed: 05/03/2023]
Abstract
BACKGROUND Phalaenopsis orchids are popular floral crops, and development of new cultivars is economically important to floricultural industries worldwide. Analysis of orchid genes could facilitate orchid improvement. Bacterial artificial chromosome (BAC) end sequences (BESs) can provide the first glimpses into the sequence composition of a novel genome and can yield molecular markers for use in genetic mapping and breeding. RESULTS We used two BAC libraries (constructed using the BamHI and HindIII restriction enzymes) of Phalaenopsis equestris to generate pair-end sequences from 2,920 BAC clones (71.4% and 28.6% from the BamHI and HindIII libraries, respectively), at a success rate of 95.7%. A total of 5,535 BESs were generated, representing 4.5 Mb, or about 0.3% of the Phalaenopsis genome. The trimmed sequences ranged from 123 to 1,397 base pairs (bp) in size, with an average edited read length of 821 bp. When these BESs were subjected to sequence homology searches, it was found that 641 (11.6%) were predicted to represent protein-encoding regions, whereas 1,272 (23.0%) contained repetitive DNA. Most of the repetitive DNA sequences were gypsy- and copia-like retrotransposons (41.9% and 12.8%, respectively), whereas only 10.8% were DNA transposons. Further, 950 potential simple sequence repeats (SSRs) were discovered. Dinucleotides were the most abundant repeat motifs; AT/TA dimer repeats were the most frequent SSRs, representing 253 (26.6%) of all identified SSRs. Microsynteny analysis revealed that more BESs mapped to the whole-genome sequences of poplar than to those of grape or Arabidopsis, and even fewer mapped to the rice genome. This work will facilitate analysis of the Phalaenopsis genome, and will help clarify similarities and differences in genome composition between orchids and other plant species. CONCLUSION Using BES analysis, we obtained an overview of the Phalaenopsis genome in terms of gene abundance, the presence of repetitive DNA and SSR markers, and the extent of microsynteny with other plant species. This work provides a basis for future physical mapping of the Phalaenopsis genome and advances our knowledge thereof.
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Affiliation(s)
- Chia-Chi Hsu
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Yu-Lin Chung
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Tien-Chih Chen
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Yu-Ling Lee
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Yi-Tzu Kuo
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Wen-Chieh Tsai
- Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 701, Taiwan
- Orchid Research Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Yu-Yun Hsiao
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Yun-Wen Chen
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Wen-Luan Wu
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
- Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 701, Taiwan
- Orchid Research Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Hong-Hwa Chen
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
- Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 701, Taiwan
- Orchid Research Center, National Cheng Kung University, Tainan 701, Taiwan
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186
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Sun HQ, Huang BQ, Yu XH, Kou Y, An DJ, Luo YB, Ge S. Reproductive isolation and pollination success of rewarding Galearis diantha and non-rewarding Ponerorchis chusua (Orchidaceae). ANNALS OF BOTANY 2011; 107:39-47. [PMID: 20961923 PMCID: PMC3002470 DOI: 10.1093/aob/mcq210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2010] [Revised: 07/02/2010] [Accepted: 09/24/2010] [Indexed: 05/30/2023]
Abstract
BACKGROUND AND AIMS Increasing evidence challenges the conventional perception that orchids are the most distinct example of floral diversification due to floral or prezygotic isolation. Regarding the relationship between co-flowering plants, rewarding and non-rewarding orchids in particular, few studies have investigated whether non-rewarding plants affect the pollination success of rewarding plants. Here, floral isolation and mutual effects between the rewarding orchid Galearis diantha and the non-rewarding orchid Ponerorchis chusua were investigated. METHODS Flowering phenological traits were monitored by noting the opening and wilting dates of the chosen individual plants. The pollinator pool and pollinator behaviour were assessed from field observations. Key morphological traits of the flowers and pollinators were measured directly in the field. Pollinator limitation and interspecific compatibility were evaluated by hand-pollination experiments. Fruit set was surveyed in monospecific and heterospecific plots. KEY RESULTS The species had overlapping peak flowering periods. Pollinators of both species displayed a certain degree of constancy in visiting each species, but they also visited other flowers before landing on the focal orchids. A substantial difference in spur size between the species resulted in the deposition of pollen on different regions of the body of the shared pollinator. Hand-pollination experiments revealed that fruit set was strongly pollinator-limited in both species. No significant difference in fruit set was found between monospecific plots and heterospecific plots. CONCLUSIONS A combination of mechanical isolation and incomplete ethological isolation eliminates the possibility of pollen transfer between the species. These results do not support either the facilitation or competition hypothesis regarding the effect of nearby rewarding flowers on non-rewarding plants. The absence of a significant effect of non-rewarding P. chusua on rewarding G. diantha can be ascribed to low levels of overlap between the pollinator pools of two species.
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Affiliation(s)
- Hai-Qin Sun
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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Stökl J, Brodmann J, Dafni A, Ayasse M, Hansson BS. Smells like aphids: orchid flowers mimic aphid alarm pheromones to attract hoverflies for pollination. Proc Biol Sci 2010; 278:1216-22. [PMID: 20943694 DOI: 10.1098/rspb.2010.1770] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Most insects are dependent on chemical communication for activities such as mate finding or host location. Several plants, and especially orchids, mimic insect semiochemicals to attract insects for unrewarded pollination. Here, we present a new case of pheromone mimicry found in the terrestrial orchid Epipactis veratrifolia. Flowers are visited and pollinated by several species of aphidophagous hoverflies, the females of which also often lay eggs in the flowers. The oviposition behaviour of these hoverflies is mainly guided by aphid-derived kairomones. We show that the flowers produce α- and β-pinene, β-myrcene and β-phellandrene, and that these compounds attract and induce oviposition behaviour in female hoverflies. This floral odour profile is remarkably similar to the alarm pheromone released by several aphid species, such as Megoura viciae. We therefore suggest that E. veratrifolia mimics aphid alarm pheromones to attract hoverflies for pollination; this is the first time, to our knowledge, that such a case of mimicry has been demonstrated.
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Affiliation(s)
- Johannes Stökl
- Department of Evolutionary Neuroethology, Max-Planck-Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745 Jena, Germany.
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189
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Sletvold N, Grindeland JM, Agren J. Pollinator-mediated selection on floral display, spur length and flowering phenology in the deceptive orchid Dactylorhiza lapponica. THE NEW PHYTOLOGIST 2010; 188:385-392. [PMID: 20497348 DOI: 10.1111/j.1469-8137.2010.03296.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
• Nonrewarding animal-pollinated plants commonly experience severe pollen limitation, which should result in strong selection on traits affecting the success of pollination. However, the importance of pollinators as selective agents on floral traits in deceptive species has not been quantified experimentally. • Here, we quantified pollinator-mediated selection (Δβ(poll)) on floral morphology and start of flowering in the deceptive orchid Dactylorhiza lapponica by subtracting estimates of selection gradients for plants receiving supplemental hand-pollination from estimates obtained for open-pollinated control plants. • There was directional selection for taller plants with more flowers and longer spurs, but no statistically significant selection on corolla size or flowering start. Pollinator-mediated selection accounted for all observed selection on spur length (Δβ(poll) = 0.32), 76% of the selection on plant height (Δβ(poll) = 0.19) and 42% of the selection on number of flowers (Δβ(poll = 0.30). Sixteen per cent of developing fruits were consumed by insect herbivores, but fruit herbivory had only minor effects on the strength of pollinator-mediated selection. • Our results demonstrate that pollinators mediate selection on floral traits likely to affect both pollinator attraction and pollination efficiency, and are consistent with the hypothesis that deceptive species experience strong selection for increased display and mechanical fit between flower and pollinator.
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Affiliation(s)
- Nina Sletvold
- NTNU, Museum of Natural History and Archaeology, Trondheim, Norway.
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190
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Peakall R, Ebert D, Poldy J, Barrow RA, Francke W, Bower CC, Schiestl FP. Pollinator specificity, floral odour chemistry and the phylogeny of Australian sexually deceptive Chiloglottis orchids: implications for pollinator-driven speciation. THE NEW PHYTOLOGIST 2010; 188:437-450. [PMID: 20561345 DOI: 10.1111/j.1469-8137.2010.03308.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
• 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 performed choice experiments to test for wasp pollinator specificity in the field; identified the compounds involved in pollinator attraction by gas chromatography with electroantennographic detection (GC-EAD), gas chromatography with mass selective detection (GC-MS), chemical synthesis and behavioural bioassays; and mapped our chemical findings on to a phylogeny of the orchids. • Field experiments confirmed pollination is a highly specific interaction, but also revealed a pool of nonpollinating 'minor responder' wasps. Six novel compounds, all 2,5-dialkylcyclohexan-1,3-diones, called 'chiloglottones', were discovered to be involved in pollinator attraction. Bioassays confirmed that pollinator specificity has a strong chemical basis, with specificity among sympatric orchids maintained by either different single compounds or a variation in a blend of two compounds. The phylogenetic overlay confirmed that speciation is always associated with pollinator switching and usually underpinned by chemical change. • If the chemical differences that control reproductive isolation in Chiloglottis have a strong genetic basis, and given the confirmed pool of potential pollinators, we conclude that pollinator-driven speciation appears highly plausible in this system.
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Affiliation(s)
- Rod Peakall
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT, Australia.
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191
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PINHEIRO FÁBIO, De BARROS FÁBIO, PALMA-SILVA CLARISSE, MEYER DIOGO, FAY MICHAELF, SUZUKI ROGÉRIOM, LEXER CHRISTIAN, COZZOLINO SALVATORE. Hybridization and introgression across different ploidy levels in the Neotropical orchids Epidendrum fulgens and E. puniceoluteum (Orchidaceae). Mol Ecol 2010; 19:3981-94. [DOI: 10.1111/j.1365-294x.2010.04780.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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192
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Haider N, Nabulsi I, Kamary Y. Identification of Orchidaceae species of Northern West of Syria based on chloroplast DNA. RUSS J GENET+ 2010. [DOI: 10.1134/s1022795410080065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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193
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Schatz B, Geoffroy A, Dainat B, Bessière JM, Buatois B, Hossaert-McKey M, Selosse MA. A case study of modified interactions with symbionts in a hybrid mediterranean orchid. AMERICAN JOURNAL OF BOTANY 2010; 97:1278-88. [PMID: 21616880 DOI: 10.3732/ajb.0900303] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
PREMISE OF THE STUDY Most studies on orchid hybrids examine separately the effects of hybridization on interactions with pollinators or with mycorrhizal fungi. Here, we simultaneously investigated both interactions in the mediterranean food-deceptive Orchis simia, O. anthropophora, and their hybrid (O. ×bergonii) and tested a possible breakdown of coevolution using a multidisciplinary approach. • METHODS We compared leaf growth, seed viability, emitted scent, and mycorrhizal fungi (species and rate of infection) among these three taxa. • KEY RESULTS We show that leaf surface is greater in adult hybrids than in the parental species, suggesting a heterosis effect for vegetative growth. We demonstrate that flowers of the two parental species emit well-differentiated bouquets of volatile organic compounds, while hybrids emit larger quantities, accumulating most compounds of the two parental species. However, hybrids fail to attract pollinators and have a 10 times lower fruit set. We determined that closely related Tulasnellales are mycorrhizal in the three taxa, suggesting that the mycorrhizal partner does not impair hybrid survival. We propose an interpretative model for O. ×bergonii compared with its parents. • CONCLUSIONS In hybrids, carbon resources normally devoted to reproduction may be reallocated to the mycorrhizal symbiosis as a result of the disruption of the pollination interaction in hybrids. Higher mycorrhizal infection may in turn enhance vegetative growth and scent emission. Such interplay between the two obligate biotic interactions yields new insights into hybridization among orchids.
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Affiliation(s)
- Bertrand Schatz
- Equipe Interactions Biotiques, Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR CNRS 5175, 1919 route de Mende, F-34293 Montpellier Cedex 5, France
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194
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Roche SA, Carter RJ, Peakall R, Smith LM, Whitehead MR, Linde CC. A narrow group of monophyletic Tulasnella (Tulasnellaceae) symbiont lineages are associated with multiple species of Chiloglottis (Orchidaceae): Implications for orchid diversity. AMERICAN JOURNAL OF BOTANY 2010; 97:1313-27. [PMID: 21616884 DOI: 10.3732/ajb.1000049] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
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 diversification. In this study, mycorrhizal diversity was examined in the terrestrial, photosynthetic orchid genus Chiloglottis to test the hypothesis of mycorrhizal-mediated diversification in the genus Chiloglottis. This orchid genus secures pollination by sexual deception, an obligate and highly specific pollination strategy. Here we asked whether the obligate orchid-fungal interactions are also specific. • METHODS Two sequenced loci, the internal transcribed spacer region (ITS) and mitochondrial large subunit (mtLSU), were used to identify fungal isolates and assess fungal species diversity. Symbiotic germination of two species Chiloglottis aff. jeanesii and C. valida were used to assess germination potential of isolates and confirm mycorrhizal association. • KEY RESULTS Phylogenetic analyses revealed that six representative Chiloglottis species spanning a broad survey of the genus were all associated with a narrow group of monophyletic Tulasnella fungal lineages. • CONCLUSIONS The Chiloglottis-Tulasnella interaction appears to be the first known case of such a narrow symbiont association across a broadly surveyed orchid genus. It appears that the specific pollination system of Chiloglottis, rather than specific orchid-fungal interactions has been the key driving force in the diversification of the genus. These findings also indicate that plant groups with highly specific mycorrhizal partners can have a widespread distribution.
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Affiliation(s)
- Sean A Roche
- Evolution, Ecology and Genetics, Research School of Biology, 116 Daley Road, The Australian National University, Canberra, ACT 0200, Australia
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195
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Scopece G, Cozzolino S, Johnson SD, Schiestl FP. Pollination efficiency and the evolution of specialized deceptive pollination systems. Am Nat 2010; 175:98-105. [PMID: 19909087 DOI: 10.1086/648555] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The ultimate causes of evolution of highly specialized pollination systems are little understood. We investigated the relationship between specialization and pollination efficiency, defined as the proportion of pollinated flowers relative to those that experienced pollen removal, using orchids with different pollination strategies as a model system. Rewarding orchids showed the highest pollination efficiency. Sexually deceptive orchids had comparably high pollination efficiency, but food-deceptive orchids had significantly lower efficiency. Values for pollinator sharing (a measure of the degree of generalization in pollination systems) showed the reverse pattern, in that groups with high pollination efficiency had low values of pollinator sharing. Low pollinator sharing may thus be the basis for efficient pollination. Population genetic data indicated that both food- and sexually deceptive species have higher degrees of among-population gene flow than do rewarding orchids. Thus, the shift from food to sexual deception may be driven by selection for more efficient pollination, without compromising the high levels of gene flow that are characteristic of deceptive species.
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Affiliation(s)
- Giovanni Scopece
- Department of Structural and Functional Biology, University of Naples Federico II, complesso Universitario MSA, I-80126 Naples, Italy
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196
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Kay KM, Sargent RD. The Role of Animal Pollination in Plant Speciation: Integrating Ecology, Geography, and Genetics. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2009. [DOI: 10.1146/annurev.ecolsys.110308.120310] [Citation(s) in RCA: 223] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kathleen M. Kay
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California 95064;
| | - Risa D. Sargent
- Department of Biology, University of Ottawa, Ontario, K1N6N5, Canada;
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Vereecken NJ, Schiestl FP. On the roles of colour and scent in a specialized floral mimicry system. ANNALS OF BOTANY 2009; 104:1077-84. [PMID: 19692390 PMCID: PMC2766200 DOI: 10.1093/aob/mcp208] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Sexually deceptive orchids achieve cross-pollination by mimicking the mating signals of female insects, generally hymenopterans. This pollination mechanism is often highly specific as it is based primarily on the mimicry of mating signals, especially the female sex pheromones of the targeted pollinator. Like many deceptive orchids, the Mediterranean species Ophrys arachnitiformis shows high levels of floral trait variation, especially in the colour of the perianth, which is either green or white/pinkinsh within populations. The adaptive significance of perianth colour polymorphism and its influence on pollinator visitation rates in sexually deceptive orchids remain obscure. METHODS The relative importance of floral scent versus perianth colour in pollinator attraction in this orchid pollinator mimicry system was evaluated by performing floral scent analyses by gas chromatography-mass spectrometry (GC-MS) and behavioural bioassays with the pollinators under natural conditions were performed. KEY RESULTS The relative and absolute amounts of behaviourally active compounds are identical in the two colour morphs of O. arachnitiformis. Neither presence/absence nor the colour of the perianth (green versus white) influence attractiveness of the flowers to Colletes cunicularius males, the main pollinator of O. arachnitiformis. CONCLUSION Chemical signals alone can mediate the interactions in highly specialized mimicry systems. Floral colour polymorphism in O. arachnitiformis is not subjected to selection imposed by C. cunicularius males, and an interplay between different non-adaptive processes may be responsible for the maintenance of floral colour polymorphism both within and among populations.
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Affiliation(s)
- Nicolas J Vereecken
- Evolutionary Biology & Ecology, Free University of Brussels/Université Libre de Bruxelles, Av. F.D. Roosevelt 50 CP 160/12, B-1050 Brussels, Belgium.
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198
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Modification of bumblebee behavior by floral color change and implications for pollen transfer in Weigela middendorffiana. Evol Ecol 2009. [DOI: 10.1007/s10682-009-9324-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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199
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Bateman RM, James KE, Luo YB, Lauri RK, Fulcher T, Cribb PJ, Chase MW. Molecular phylogenetics and morphological reappraisal of the Platanthera clade (Orchidaceae: Orchidinae) prompts expansion of the generic limits of Galearis and Platanthera. ANNALS OF BOTANY 2009; 104:431-45. [PMID: 19383726 PMCID: PMC2720662 DOI: 10.1093/aob/mcp089] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
BACKGROUND AND AIMS The Platanthera clade dominates the North American orchid flora and is well represented in eastern Asia. It has also generated some classic studies of speciation in Platanthera sections Platanthera and Limnorchis. However, it has proved rich in taxonomic controversy and near-monotypic genera. The clade is reviewed via a new molecular phylogenetic analysis and those results are combined with brief reconsideration of morphology in the group, aiming to rationalize the species into a smaller number of larger monophyletic genera and sections. METHODS Nuclear ribosomal internal transcribed spacer (ITS) sequences were obtained from 86 accessions of 35 named taxa, supplemented from GenBank with five accessions encompassing a further two named taxa. KEY RESULTS Using Pseudorchis as outgroup, and scoring indels, the data matrix generated 30 most-parsimonious trees that differed in the placement of two major groups plus two closely related species. Several other internal nodes also attracted only indifferent statistical support. Nonetheless, by combining implicit assessment of morphological divergence with explicit assessment of molecular divergence (when available), nine former genera can be rationalized into four revised genera by sinking the monotypic Amerorchis, together with Aceratorchis and Chondradenia (neither yet sequenced), into Galearis, and by amalgamating Piperia, Diphylax and the monotypic Tsaiorchis into the former Platanthera section Platanthera. After further species sampling, this section will require sub-division into at least three sections. The present nomenclatural adjustments prompt five new combinations. CONCLUSIONS Resolution of major groups should facilitate future species-level research on the Platanthera clade. Recent evidence suggests that ITS sequence divergence characterizes most species other than the P. bifolia group. The floral differences that distinguished Piperia, Diphylax and Tsaiorchis from Platanthera, and Aceratorchis and Chondradenia from Galearis, reflect various forms of heterochrony (notably paedomorphosis); this affected both the perianth and the gynostemium, and may have proved adaptive in montane habitats. Floral reduction was combined with lateral expansion of the root tubers in Piperia and Diphylax (including Tsaiorchis), whereas root tubers were minimized in the putative (but currently poorly supported) Neolindleya-Galearis clade. Allopolyploidy and/or autogamy strongly influenced speciation in Platanthera section Limnorchis and perhaps also Neolindleya. Reproductive biology remains an important driver of evolution in the clade, though plant-pollinator specificity and distinctness of the species boundaries have often been exaggerated.
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200
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Hopper SD. Taxonomic turmoil down-under: recent developments in Australian orchid systematics. ANNALS OF BOTANY 2009; 104:447-55. [PMID: 19398445 PMCID: PMC2720664 DOI: 10.1093/aob/mcp090] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
BACKGROUND The issue of determining the most appropriate rank for each accepted taxon fuels ongoing controversy throughout systematics. The particularly marked escalation of such issues in modern Australian orchid systematics merits examination, not only because of wider implications in taxonomy but also because of direct effects on studies of comparative biology and conservation management. SCOPE This paper briefly reviews the causes of recent taxonomic turmoil for Australian orchids and outlines new research opportunities and conservation implications arising from an improved understanding of their molecular phylogenetics. CONCLUSIONS DNA sequencing and intensified field work have contributed towards a much improved understanding of Australian orchid systematics. Great progress has been made in discerning monophyletic groups or clades. Fresh interpretations of morphological evolution have been made possible by comparisons with the results of DNA analyses. Significant conceptual shifts from polymorphic species concepts to biological and phylogenetic concepts have also elevated the discovery and description of new species. Consequently, over the past decade, the number of Australian orchid species recognized by taxonomists has risen from approx. 900 to 1200. Similarly, the number of genera recognized by some taxonomists has increased from 110 to 192, resulting in 45% of Australian species/subspecies being assigned a new generic epithet since 2000. At higher taxonomic levels, much of the recent controversy in Australian orchid systematics reflects a divergence in views about where to split and assign formal names within unequivocally monophyletic groups. Differences regarding typification in the case of Caladenia have added additional confusion and complexity. However, new insights into and research opportunities concerning speciation processes in orchids have arisen from the wealth of new data and discrimination of species. Robustly supported molecular analyses of most clades enable comparative biological studies of Australian orchids to be conducted as never before. Outstanding subjects exist for exploring pollination by sexual deception and understanding the intricacies of mycorrhizal relationships and orchid conservation biology.
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