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Piñeiro Fernández L, Byers KJR.P, Cai J, Sedeek KEM, Kellenberger RT, Russo A, Qi W, Aquino Fournier C, Schlüter PM. A Phylogenomic Analysis of the Floral Transcriptomes of Sexually Deceptive and Rewarding European Orchids, Ophrys and Gymnadenia. FRONTIERS IN PLANT SCIENCE 2019; 10:1553. [PMID: 31850034 PMCID: PMC6895147 DOI: 10.3389/fpls.2019.01553] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 11/07/2019] [Indexed: 05/30/2023]
Abstract
The orchids (Orchidaceae) constitute one of the largest and most diverse families of flowering plants. They have evolved a great variety of adaptations to achieve pollination by a diverse group of pollinators. Many orchids reward their pollinators, typically with nectar, but the family is also well-known for employing deceptive pollination strategies in which there is no reward for the pollinator, in the most extreme case by mimicking sexual signals of pollinators. In the European flora, two examples of these different pollination strategies are the sexually deceptive genus Ophrys and the rewarding genus Gymnadenia, which differ in their level of pollinator specialization; Ophrys is typically pollinated by pseudo-copulation of males of a single insect species, whilst Gymnadenia attracts a broad range of floral visitors. Here, we present and describe the annotated floral transcriptome of Ophrys iricolor, an Andrena-pollinated representative of the genus Ophrys that is widespread throughout the Aegean. Furthermore, we present additional floral transcriptomes of both sexually deceptive and rewarding orchids, specifically the deceptive Ophrys insectifera, Ophrys aymoninii, and an updated floral transcriptome of Ophrys sphegodes, as well as the floral transcriptomes of the rewarding orchids Gymnadenia conopsea, Gymnadenia densiflora, Gymnadenia odoratissima, and Gymnadenia rhellicani (syn. Nigritella rhellicani). Comparisons of these novel floral transcriptomes reveal few annotation differences between deceptive and rewarding orchids. Since together, these transcriptomes provide a representative sample of the genus-wide taxonomic diversity within Ophrys and Gymnadenia (Orchidoideae: Orchidinae), we employ a phylogenomic approach to address open questions of phylogenetic relationships within the genera. Specifically, this includes the controversial placement of O. insectifera within the Ophrys phylogeny and the placement of "Nigritella"-type morphologies within the phylogeny of Gymnadenia. Whereas in Gymnadenia, several conflicting topologies are supported by a similar number of gene trees, a majority of Ophrys gene topologies clearly supports a placement of O. insectifera as sister to a clade containing O. sphegodes.
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Affiliation(s)
- Laura Piñeiro Fernández
- Institute of Botany, University of Hohenheim, Stuttgart, Germany
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Kelsey J. R .P. Byers
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Jing Cai
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Khalid E. M. Sedeek
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Laboratory for Genome Engineering and Synthetic Biology, Division of Biological Sciences, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Agricultural Genetic Engineering Research Institute (AGERI), Agriculture Research Centre, Giza, Egypt
| | - Roman T. Kellenberger
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Alessia Russo
- Institute of Botany, University of Hohenheim, Stuttgart, Germany
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Weihong Qi
- Functional Genomics Centre Zurich, Zurich, Switzerland
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The discovery of 2,5-dialkylcyclohexan-1,3-diones as a new class of natural products. Proc Natl Acad Sci U S A 2009; 106:8877-82. [PMID: 19470640 DOI: 10.1073/pnas.0900646106] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Orchids employing sexual deceit attract males of their pollinator species through specific volatile signals that mimic female-released sex pheromones. One of these signals proved to be 2-ethyl-5-propylcyclohexan-1,3-dione (chiloglottone1), a new natural product that was shown to be most important in the relations between orchids of the genus Chiloglottis, native to Australia, and corresponding pollinator species. Systematic investigations on the mass spectrometric fragmentation pattern of 2,5-dialkylcyclohexan-1,3-diones identified key ions providing information about the structures of the substituents at positions 2 and 5. Results enabled us to identify 2-ethyl-5-pentylcyclohexan-1,3-dione (chiloglottone2) and 2-butyl-5-methylcyclohexan-1,3-dione (chiloglottone3) as new natural products that play a decisive role in the pollination syndrome of some Chiloglottis species. During field bioassays, pure synthetic samples of chiloglottone1-3 or mixtures thereof proved to be attractive to the corresponding orchid pollinators. Because of their likely biogenesis from ubiquitous fatty acid precursors, 2,5-dialkylcyclohexan-1,3-diones may represent a hitherto overlooked, widespread class of natural products.
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