1
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Schiestl FP. Is experimental evolution relevant for botanical research? Am J Bot 2024; 111:e16296. [PMID: 38384109 DOI: 10.1002/ajb2.16296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/18/2024] [Accepted: 01/18/2024] [Indexed: 02/23/2024]
Affiliation(s)
- Florian P Schiestl
- Department Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, 8008, Zürich, Switzerland
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2
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Frachon L, Schiestl FP. Rapid genomic evolution in Brassica rapa with bumblebee selection in experimental evolution. BMC Ecol Evol 2024; 24:7. [PMID: 38195402 PMCID: PMC10775529 DOI: 10.1186/s12862-023-02194-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/20/2023] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND Insect pollinators shape rapid phenotypic evolution of traits related to floral attractiveness and plant reproductive success. However, the underlying genomic changes remain largely unknown despite their importance in predicting adaptive responses to natural or to artificial selection. Based on a nine-generation experimental evolution study with fast cycling Brassica rapa plants adapting to bumblebees, we investigate the genomic evolution associated with the previously observed parallel phenotypic evolution. In this current evolve and resequencing (E&R) study, we conduct a genomic scan of the allele frequency changes along the genome in bumblebee-pollinated and hand-pollinated plants and perform a genomic principal component analysis (PCA). RESULTS We highlight rapid genomic evolution associated with the observed phenotypic evolution mediated by bumblebees. Controlling for genetic drift, we observe significant changes in allelic frequencies at multiple loci. However, this pattern differs according to the replicate of bumblebee-pollinated plants, suggesting putative non-parallel genomic evolution. Finally, our study underlines an increase in genomic variance implying the putative involvement of multiple loci in short-term pollinator adaptation. CONCLUSIONS Overall, our study enhances our understanding of the complex interactions between pollinator and plants, providing a stepping stone towards unravelling the genetic basis of plant genomic adaptation to biotic factors in the environment.
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Affiliation(s)
- Léa Frachon
- Department of Systematic and Evolutionary Botany, University of Zürich, Zürich, Switzerland.
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zürich, Switzerland
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3
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Frachon L, Arrigo L, Rusman Q, Poveda L, Qi W, Scopece G, Schiestl FP. Putative Signals of Generalist Plant Species Adaptation to Local Pollinator Communities and Abiotic Factors. Mol Biol Evol 2023; 40:7043265. [PMID: 36795638 PMCID: PMC10015620 DOI: 10.1093/molbev/msad036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/31/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023] Open
Abstract
The reproductive success of flowering plants with generalized pollination systems is influenced by interactions with a diverse pollinator community and abiotic factors. However, knowledge about the adaptative potential of plants to complex ecological networks and the underlying genetic mechanisms is still limited. Based on a pool-sequencing approach of 21 natural populations of Brassica incana in Southern Italy, we combined a genome-environmental association analysis with a genome scan for signals of population genomic differentiation to discover genetic variants associated with the ecological variation. We identified genomic regions putatively involved in the adaptation of B. incana to the identity of local pollinator functional categories and pollinator community composition. Interestingly, we observed several shared candidate genes associated with long-tongue bees, soil texture, and temperature variation. We established a genomic map of potential generalist flowering plant local adaptation to complex biotic interactions, and the importance of considering multiple environmental factors to describe the adaptive landscape of plant populations.
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Affiliation(s)
| | - Luca Arrigo
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Quint Rusman
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Lucy Poveda
- Functional Genomics Center Zurich, ETH Zurich/University of Zurich, Zurich, Switzerland
| | - Weihong Qi
- Functional Genomics Center Zurich, ETH Zurich/University of Zurich, Zurich, Switzerland
- SIB Swiss Institute of Bioinformatics, 1202 Geneva, Switzerland
| | - Giovanni Scopece
- Department of Biology, University of Naples Federico II, Complesso Universitario MSA, Naples, Italy
- NBFC: National Biodiversity Future Center, Palermo 90133, Italy
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
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4
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Dorey T, Schiestl FP. Plant phenotypic plasticity changes pollinator-mediated selection. Evolution 2022; 76:2930-2944. [PMID: 36250479 DOI: 10.1111/evo.14634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 08/19/2022] [Accepted: 09/03/2022] [Indexed: 01/22/2023]
Abstract
Many organisms change their phenotype in response to the environment, a phenomenon called phenotypic plasticity. Although plasticity can dramatically change the phenotype of an organism, we hardly understand how this can affect biotic interactions and the resulting phenotypic selection. Here, we use fast cycling Brassica rapa plants in an experiment in the greenhouse to study the link between plasticity and selection. We detected strong plasticity in morphology, nectar, and floral scent in response to different soil types and aphid herbivory. We found positive selection on nectar and morphological traits in hand- and bumblebee-pollinated plants. Bumblebee-mediated selection on a principal component representing plant height, flower number, and flowering time (mPC3) differed depending on soil type and herbivory. For plants growing in richer soil, selection was stronger in the absence of herbivores, whereas for plants growing in poorer soil selection was stronger with herbivory. We showed that bumblebees visited tall plants with many flowers overproportionally in plants in poor soil with herbivory (i.e., when tall plants were rare), thus causing stronger positive selection on this trait combination. We suggest that with strong plasticity under most stressful conditions, pollinator-mediated selection may promote adaptation to local environmental factors given sufficient heritability of the traits under selection.
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Affiliation(s)
- Thomas Dorey
- Department of Systematic and Evolutionary Botany, University of Zürich, Zürich, CH-8008, Switzerland
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zürich, CH-8008, Switzerland
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5
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Huber FK, Schiestl FP. Scent releasing silicone septa: A versatile method for bioassays with volatiles. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.958982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Volatile organic compounds are of great importance for communication within biological systems. For the experimental investigation of the functions of volatiles, methods for experimental manipulation are needed. Based on scent-release methods from pheromone research, we describe a simple and cheap method for scent manipulation using silicone rubber (i.e. a silicone septum). Volatile compounds are applied to the septum by soaking the septa for 1 h in a solvent/volatile solution. After removal of the septum from the solution and a drying period of 1 h to allow for evaporation of the solvent, the silicone emits the volatiles at a continuously decreasing rate for a minimum of 24 h. In this study, we measure the variability of the emission and quantify the emission of 22 common floral scent compounds at four different time points and in four different soaking concentrations. Our results show that for the same compound and soaking concentration, variability of volatile emission was low, showing the method leads to repeatable emission rates and can be fine-tuned to the desired emission rate. We provide a calculation tool based on linear regression to allow an experimenter to calculate soaking concentration for each of the 22 compounds to achieve a desirable emission from the septa, as well as to estimate the emission rate of a volatile from the septa after a given time.
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Ghaninia M, Zhou Y, Knauer AC, Schiestl FP, Sharpee TO, Smith BH. Hyperbolic odorant mixtures as a basis for more efficient signaling between flowering plants and bees. PLoS One 2022; 17:e0270358. [PMID: 35830455 PMCID: PMC9278781 DOI: 10.1371/journal.pone.0270358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 06/08/2022] [Indexed: 11/19/2022] Open
Abstract
Animals use odors in many natural contexts, for example, for finding mates or food, or signaling danger. Most analyses of natural odors search for either the most meaningful components of a natural odor mixture, or they use linear metrics to analyze the mixture compositions. However, we have recently shown that the physical space for complex mixtures is ‘hyperbolic’, meaning that there are certain combinations of variables that have a disproportionately large impact on perception and that these variables have specific interpretations in terms of metabolic processes taking place inside the flower and fruit that produce the odors. Here we show that the statistics of odorants and odorant mixtures produced by inflorescences (Brassica rapa) are also better described with a hyperbolic rather than a linear metric, and that combinations of odorants in the hyperbolic space are better predictors of the nectar and pollen resources sought by bee pollinators than the standard Euclidian combinations. We also show that honey bee and bumble bee antennae can detect most components of the B. rapa odor space that we tested, and the strength of responses correlates with positions of odorants in the hyperbolic space. In sum, a hyperbolic representation can be used to guide investigation of how information is represented at different levels of processing in the CNS.
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Affiliation(s)
- Majid Ghaninia
- School of Life Sciences, Arizona State University, Tempe, AZ, United States of America
| | - Yuansheng Zhou
- The Salk Institute for Biological Studies, Computational Neurobiology Laboratory, La Jolla, CA, United States of America
- University of California, San Diego, La Jolla, CA, United States of America
| | - Anina C. Knauer
- Institute of Systematic and Evolutionary Botany University of Zurich, Zollikerstrasse, Zurich, Switzerland
| | - Florian P. Schiestl
- Institute of Systematic and Evolutionary Botany University of Zurich, Zollikerstrasse, Zurich, Switzerland
| | - Tatyana O. Sharpee
- The Salk Institute for Biological Studies, Computational Neurobiology Laboratory, La Jolla, CA, United States of America
- University of California, San Diego, La Jolla, CA, United States of America
- * E-mail: (TOS); , (BHS)
| | - Brian H. Smith
- School of Life Sciences, Arizona State University, Tempe, AZ, United States of America
- * E-mail: (TOS); , (BHS)
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7
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Knauer AC, Kokko H, Schiestl FP. Pollinator behaviour and resource limitation maintain honest floral signalling. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anina C. Knauer
- Department of Systematic and Evolutionary Botany University of Zurich Zürich Switzerland
| | - Hanna Kokko
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zürich Switzerland
| | - Florian P. Schiestl
- Department of Systematic and Evolutionary Botany University of Zurich Zürich Switzerland
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8
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Cozzolino S, Scopece G, Lussu M, Cortis P, Schiestl FP. Do floral and ecogeographic isolation allow the co-occurrence of two ecotypes of Anacamptis papilionacea (Orchidaceae)? Ecol Evol 2021; 11:9917-9931. [PMID: 34367549 PMCID: PMC8328454 DOI: 10.1002/ece3.7432] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/10/2021] [Accepted: 02/18/2021] [Indexed: 11/08/2022] Open
Abstract
Ecotypes are relatively frequent in flowering plants and considered central in ecological speciation as local adaptation can promote the insurgence of reproductive isolation. Without geographic isolation, gene flow usually homogenizes the allopatrically generated phenotypic and ecological divergences, unless other forms of reproductive isolation keep them separated. Here, we investigated two orchid ecotypes with marked phenotypic floral divergence that coexist in contact zones. We found that the two ecotypes show different ecological habitat preferences with one being more climatically restricted than the other. The ecotypes remain clearly morphologically differentiated both in allopatry and in sympatry and differed in diverse floral traits. Despite only slightly different flowering times, the two ecotypes achieved floral isolation thanks to different pollination strategies. We found that both ecotypes attract a wide range of insects, but the ratio of male/female attracted by the two ecotypes was significantly different, with one ecotype mainly attracts male pollinators, while the other mainly attracts female pollinators. As a potential consequence, the two ecotypes show different pollen transfer efficiency. Experimental plots with pollen staining showed a higher proportion of intra- than interecotype movements confirming floral isolation between ecotypes in sympatry while crossing experiments excluded evident postmating barriers. Even if not completely halting the interecotypes pollen flow in sympatry, such incipient switch in pollination strategy between ecotypes may represent a first step on the path toward evolution of sexual mimicry in Orchidinae.
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Affiliation(s)
| | - Giovanni Scopece
- Department of BiologyUniversity Federico II of NaplesNapoliItaly
| | - Michele Lussu
- Department of Life and Environmental SciencesUniversity of CagliariCagliariItaly
- Istituto Regionale per la Floricoltura (IRF)SanremoItaly
| | - Pierluigi Cortis
- Department of Life and Environmental SciencesUniversity of CagliariCagliariItaly
| | - Florian P. Schiestl
- Department of Systematic and Evolutionary Botany and Botanical GardensUniversity of ZurichZurichSwitzerland
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Frachon L, Stirling SA, Schiestl FP, Dudareva N. Combining biotechnology and evolution for understanding the mechanisms of pollinator attraction. Curr Opin Biotechnol 2021; 70:213-219. [PMID: 34217123 DOI: 10.1016/j.copbio.2021.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 11/15/2022]
Abstract
Many flowering plants rely on pollinators for their reproductive success. Plant-pollinator interactions usually depend on a complex combination of traits based on a fine-tuned biosynthetic machinery, with many structural and regulatory genes involved. Yet, the physiological mechanisms in plants are the product of evolutionary processes. While evolution has been modifying flowers through millions of years, it is also a rapid process that can change plant traits within few generations. Here we discuss both mechanistic and evolutionary aspects of pollinator attraction. We also propose how latest advances in biotechnology and evolutionary studies, and their combination, will improve the elucidation of molecular mechanisms and evolutionary dynamics of pollinator attraction in changing environments.
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Affiliation(s)
- Léa Frachon
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| | - Shannon A Stirling
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN 47907-2063, USA
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland.
| | - Natalia Dudareva
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN 47907-2063, USA; Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA.
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10
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, CH- 8008 Zürich;,
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11
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Ramos SE, Schiestl FP. Herbivory and pollination impact on the evolution of herbivore-induced plasticity in defense and floral traits. Evol Lett 2020; 4:556-569. [PMID: 33312690 PMCID: PMC7719550 DOI: 10.1002/evl3.200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 07/22/2020] [Accepted: 10/04/2020] [Indexed: 02/04/2023] Open
Abstract
Theory predicts that herbivory should primarily determine the evolution of herbivore‐induced plasticity in plant defenses, but little is known about the influence of other interactions such as pollination. Pollinators may exert negative selection on the herbivore‐induced plasticity of chemical defenses when floral signals and rewards are indirectly affected, provoking deterrent effects on these mutualists. We investigated the influence of constant herbivory and pollination on the evolved patterns and degree of herbivore‐induced plasticity in chemical plant defenses and floral morphometry and volatiles in fast‐cycling Brassica rapa plants. To do this, we used plants from an evolution experiment that had evolved under bee/hand pollination and herbivory manipulated in a 2 × 2 factorial design during six generations, producing four selection treatments. We grew sibling plant pairs from each of the four selection treatments of the last generation and infested one group with herbivores and left the other uninfested. Herbivore‐induced plasticity was analyzed within‐ and between‐selection treatments. We found support for the hypothesis that constant herbivory favors the evolution of higher constitutive yet lower herbivore‐induced plasticity in defenses. However, this only occurred in plants that evolved under hand pollination and constant herbivory. Bee pollination had a strong influence on the evolution of herbivore‐induced plasticity of all traits studied. Plants that evolved under bee pollination, with and without constant herbivory, showed remarkably similar patterns of herbivore‐induced plasticity in their defense‐ and floral traits and had a higher number of plastic responses compared to plants with hand pollination. Such patterns support the hypothesis that bee pollination influenced the evolution of herbivore‐induced plasticity, most likely via indirect effects, such as links between defense‐ and floral traits. We conclude that interactions other than herbivory, such as pollination, may impact herbivore‐induced plasticity, through indirect effects and metabolic trade‐offs, when it contributes to trait evolution in plants.
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Affiliation(s)
- Sergio E Ramos
- Department of Systematic and Evolutionary Botany University of Zurich Zurich CH-8008 Switzerland.,Current Address: Department of Biological Sciences University of Pittsburgh, Pittsburgh, PA, USA
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany University of Zurich Zurich CH-8008 Switzerland
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12
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Zu P, Schiestl FP, Gervasi D, Li X, Runcie D, Guillaume F. Floral signals evolve in a predictable way under artificial and pollinator selection in Brassica rapa. BMC Evol Biol 2020; 20:127. [PMID: 32972368 PMCID: PMC7517814 DOI: 10.1186/s12862-020-01692-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 09/16/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Angiosperms employ an astonishing variety of visual and olfactory floral signals that are generally thought to evolve under natural selection. Those morphological and chemical traits can form highly correlated sets of traits. It is not always clear which of these are used by pollinators as primary targets of selection and which would be indirectly selected by being linked to those primary targets. Quantitative genetics tools for predicting multiple traits response to selection have been developed since long and have advanced our understanding of evolution of genetically correlated traits in various biological systems. We use these tools to predict the evolutionary trajectories of floral traits and understand the selection pressures acting on them. RESULTS We used data from an artificial selection and a pollinator (bumblebee, hoverfly) evolution experiment with fast cycling Brassica rapa plants to predict evolutionary changes of 12 floral volatiles and 4 morphological floral traits in response to selection. Using the observed selection gradients and the genetic variance-covariance matrix (G-matrix) of the traits, we showed that the observed responses of most floral traits including volatiles were predicted in the right direction in both artificial- and bumblebee-selection experiment. Genetic covariance had a mix of constraining and facilitating effects on evolutionary responses. We further revealed that G-matrices also evolved in the selection processes. CONCLUSIONS Overall, our integrative study shows that floral signals, especially volatiles, evolve under selection in a mostly predictable way, at least during short term evolution. Evolutionary constraints stemming from genetic covariance affected traits evolutionary trajectories and thus it is important to include genetic covariance for predicting the evolutionary changes of a comprehensive suite of traits. Other processes such as resource limitation and selfing also need to be considered for a better understanding of floral trait evolution.
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Affiliation(s)
- Pengjuan Zu
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
| | - Daniel Gervasi
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
| | - Xin Li
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Daniel Runcie
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Frédéric Guillaume
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
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Desurmont GA, von Arx M, Turlings TCJ, Schiestl FP. Floral Odors Can Interfere With the Foraging Behavior of Parasitoids Searching for Hosts. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00148] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Ramos SE, Schiestl FP. Rapid plant evolution driven by the interaction of pollination and herbivory. Science 2019; 364:193-196. [DOI: 10.1126/science.aav6962] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/20/2018] [Accepted: 02/28/2019] [Indexed: 11/02/2022]
Abstract
Pollination and herbivory are both key drivers of plant diversity but are traditionally studied in isolation from each other. We investigated real-time evolutionary changes in plant traits over six generations by using fast-cycling Brassica rapa plants and manipulating the presence and absence of bumble bee pollinators and leaf herbivores. We found that plants under selection by bee pollinators evolved increased floral attractiveness, but this process was compromised by the presence of herbivores. Plants under selection from both bee pollinators and herbivores evolved higher degrees of self-compatibility and autonomous selfing, as well as reduced spatial separation of sexual organs (herkogamy). Overall, the evolution of most traits was affected by the interaction of bee pollination and herbivory, emphasizing the importance of the cross-talk between both types of interactions for plant evolution.
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Junker RR, Kuppler J, Amo L, Blande JD, Borges RM, van Dam NM, Dicke M, Dötterl S, Ehlers BK, Etl F, Gershenzon J, Glinwood R, Gols R, Groot AT, Heil M, Hoffmeister M, Holopainen JK, Jarau S, John L, Kessler A, Knudsen JT, Kost C, Larue-Kontic AAC, Leonhardt SD, Lucas-Barbosa D, Majetic CJ, Menzel F, Parachnowitsch AL, Pasquet RS, Poelman EH, Raguso RA, Ruther J, Schiestl FP, Schmitt T, Tholl D, Unsicker SB, Verhulst N, Visser ME, Weldegergis BT, Köllner TG. Covariation and phenotypic integration in chemical communication displays: biosynthetic constraints and eco-evolutionary implications. New Phytol 2018; 220:739-749. [PMID: 28256726 DOI: 10.1111/nph.14505] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/29/2017] [Indexed: 05/04/2023]
Abstract
Chemical communication is ubiquitous. The identification of conserved structural elements in visual and acoustic communication is well established, but comparable information on chemical communication displays (CCDs) is lacking. We assessed the phenotypic integration of CCDs in a meta-analysis to characterize patterns of covariation in CCDs and identified functional or biosynthetically constrained modules. Poorly integrated plant CCDs (i.e. low covariation between scent compounds) support the notion that plants often utilize one or few key compounds to repel antagonists or to attract pollinators and enemies of herbivores. Animal CCDs (mostly insect pheromones) were usually more integrated than those of plants (i.e. stronger covariation), suggesting that animals communicate via fixed proportions among compounds. Both plant and animal CCDs were composed of modules, which are groups of strongly covarying compounds. Biosynthetic similarity of compounds revealed biosynthetic constraints in the covariation patterns of plant CCDs. We provide a novel perspective on chemical communication and a basis for future investigations on structural properties of CCDs. This will facilitate identifying modules and biosynthetic constraints that may affect the outcome of selection and thus provide a predictive framework for evolutionary trajectories of CCDs in plants and animals.
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Affiliation(s)
- Robert R Junker
- Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Jonas Kuppler
- Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Luisa Amo
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), NL-6700, EH Wageningen, the Netherlands
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales (CSIC), 28006, Madrid, Spain
| | - James D Blande
- Department of Environmental and Biological Sciences, University of Eastern Finland, 70211, Kuopio, Finland
| | - Renee M Borges
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India
| | - Nicole M van Dam
- German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig/Friedrich-Schiller-Universität Jena, Deutscher Platz 5e, 04103, Leipzig, Germany
| | - Marcel Dicke
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA, Wageningen, the Netherlands
| | - Stefan Dötterl
- Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Bodil K Ehlers
- Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600, Silkeborg, Denmark
| | - Florian Etl
- Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
- Department of Botany and Biodiversity Research, University of Vienna, 1030, Vienna, Austria
| | - Jonathan Gershenzon
- Department of Biochemistry, Max-Planck Institute for Chemical Ecology, 07745, Jena, Germany
| | - Robert Glinwood
- Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Box 7043, S750 07, Uppsala, Sweden
| | - Rieta Gols
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA, Wageningen, the Netherlands
| | - Astrid T Groot
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, 1090 GE, Amsterdam, the Netherlands
- Department of Entomology, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany
| | - Martin Heil
- Departamento de Ingeniería Genética, CINVESTAV - Irapuato, Irapuato, CP 36821, México
| | - Mathias Hoffmeister
- Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Jarmo K Holopainen
- Department of Environmental and Biological Sciences, University of Eastern Finland, 70211, Kuopio, Finland
| | - Stefan Jarau
- Institute for Neurobiology, Ulm University, Helmholtzstr. 10/1, 89081, Ulm, Germany
| | - Lena John
- Institute for Neurobiology, Ulm University, Helmholtzstr. 10/1, 89081, Ulm, Germany
| | - Andre Kessler
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Jette T Knudsen
- Deptartment of Biology, Lund University, SE 223 62, Lund, Sweden
- Nattaro Labs AB, Medicon Village, 223 81, Lund, Sweden
| | - Christian Kost
- Max Planck Institute for Chemical Ecology, Research Group Experimental Ecology and Evolution, 07745, Jena, Germany
- Department of Ecology, School of Biology/Chemistry, University of Osnabrück, 49074, Osnabrück, Germany
| | - Anne-Amélie C Larue-Kontic
- Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Sara Diana Leonhardt
- Department of Animal Ecology and Tropical Biology, Würzburg University, 97074, Würzburg, Germany
| | - Dani Lucas-Barbosa
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA, Wageningen, the Netherlands
| | - Cassie J Majetic
- Department of Biology, Saint Mary's College, Notre Dame, IN, 46556, USA
| | - Florian Menzel
- Institute of Zoology, University of Mainz, 55128, Mainz, Germany
| | - Amy L Parachnowitsch
- Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, 75236, Sweden
| | - Rémy S Pasquet
- Department of ECOBIO, IRD, 44 Bd de Dunkerque, 13572, Marseille Cedex 02, France
| | - Erik H Poelman
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA, Wageningen, the Netherlands
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
| | - Joachim Ruther
- Institute of Zoology, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, 8008, Zürich, Switzerland
| | - Thomas Schmitt
- Department of Animal Ecology and Tropical Biology, Würzburg University, 97074, Würzburg, Germany
| | - Dorothea Tholl
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Sybille B Unsicker
- Department of Biochemistry, Max-Planck Institute for Chemical Ecology, 07745, Jena, Germany
| | - Niels Verhulst
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA, Wageningen, the Netherlands
| | - Marcel E Visser
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), NL-6700, EH Wageningen, the Netherlands
| | - Berhane T Weldegergis
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA, Wageningen, the Netherlands
| | - Tobias G Köllner
- Department of Biochemistry, Max-Planck Institute for Chemical Ecology, 07745, Jena, Germany
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17
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Schiestl FP, Balmer A, Gervasi DD. Real‐time evolution supports a unique trajectory for generalized pollination*. Evolution 2018; 72:2653-2668. [DOI: 10.1111/evo.13611] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 08/13/2018] [Accepted: 09/05/2018] [Indexed: 01/18/2023]
Affiliation(s)
- Florian P. Schiestl
- Institute of Systematic and Evolutionary BotanyUniversity of Zürich Zollikerstrasse 107, CH‐8008 Zürich Switzerland
| | - Alice Balmer
- Institute of Systematic and Evolutionary BotanyUniversity of Zürich Zollikerstrasse 107, CH‐8008 Zürich Switzerland
| | - Daniel D. Gervasi
- Institute of Systematic and Evolutionary BotanyUniversity of Zürich Zollikerstrasse 107, CH‐8008 Zürich Switzerland
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18
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Pérez-Barrales R, Abarca CA, Santos-Gally R, Schiestl FP, Arroyo J. The function of the floral corona in the pollination of a Mediterranean style dimorphic daffodil. Plant Biol (Stuttg) 2018; 20 Suppl 1:118-127. [PMID: 29105981 DOI: 10.1111/plb.12657] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Narcissus papyraceus is a style dimorphic species with two floral forms, with anthers at similar height and stigmas above (long-styled L) and below (short-styled S) the anther level. The species is self-incompatible, but intra- and inter-morph compatible. Populations are either dimorphic (including both morphs) in the region of the Strait of Gibraltar, or L-monomorphic (with only L plants) in the inland of the Iberian Peninsula. This variation correlates with the most common floral visitors, being primarily long-tongued and short-tongued pollinators, respectively, a rare condition in Mediterranean plants. The maintenance of S-flowers relies on long-tongued insects, as only those deliver pollen to short-styled stigmas. Narcissus flowers present a long and narrow tube, at the bottom of which nectar accumulates, and a floral corona, which has been proposed as an important trait for the attraction of pollinators. Here we tested the importance of the corona on pollination of L and S flowers. We described UV reflectance patterns of the corona and tepals, and characterised VOCs in intact flowers and flowers with trimmed coronas. We also conducted a field experiment in the dimorphic and monomorphic region to estimate the importance of corona removal on seed production in stands with solitary plants and in groups to control for compatible pollen limitation. Reflectance was higher in the tepals than the corona, although both traits presented a reflectance peak around 450 nm wavelength. L- and S-flowers produced similar volatiles, regardless of the manipulation of the corona. Across dimorphic and monomorphic regions, S-flowers with the corona removed suffered a reduction in seed production of ca. 50%, while seed production remained similar in L flowers both with the corona intact and removed. Plants in solitary stands suffered a strong reduction in seed production, which was more pronounced in the monomorphic region. Our results suggest that the corona in Narcissus is more important for the pollination of S-flowers, which generally have lower seed production compared to L-flowers. Taken together, these results suggest that the floral corona indirectly plays an important role for maintenance of the polymorphism.
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Affiliation(s)
- R Pérez-Barrales
- School of Biological Sciences, University of Portsmouth, Portsmouth, UK
| | - C A Abarca
- Unidad Lerma Departamento de Ecología Evolutiva, Departamento de Ciencias Ambientales, Universidad Autónoma Metropolitana, Mexico City, México
| | - R Santos-Gally
- CONACYT-Departamento de Ecología Evolutiva, Instituto de Ecología, UNAM, Mexico City, México
| | - F P Schiestl
- Institute of Systematic Botany, University of Zurich, Zurich, Switzerland
| | - J Arroyo
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
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19
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Abstract
Receiver bias in plant–animal interactions is here defined as “selection mediated by behavioral responses of animals, where those responses have evolved in a context outside the interactions.” As a consequence, the responses are not necessarily linked to fitness gains in interacting animals. Thus, receiver bias can help explain seemingly maladaptive patterns of behavior in interacting animals and the evolution of plant traits that trigger such behavior. In this review, I discuss principles of receiver bias, show its overlap with mimicry and how it differs from mimicry, and outline examples in different plant–animal interactions. The most numerous and best documented examples of receiver bias occur within plant–pollinator interactions. I elaborate on the ability of some plants to heat up their flowers (i.e., floral thermogenesis) and argue that this trait likely evolved under receiver bias, especially in pollination systems with oviposition mimicry. Further examples include signals in insect-mediated seed dispersal and plant defense through repellence of aphids. These examples show that receiver bias is widespread in different plant–animal interactions. For a broader understanding of the role of receiver bias in those interactions, we need more data on how animals respond to plant signals, the context and evolutionary history of those behaviors, and the evolutionary patterns of plant signals.
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Affiliation(s)
- Florian P. Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, 8008 Zürich, Switzerland
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20
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Gervasi DDL, Selosse MA, Sauve M, Francke W, Vereecken NJ, Cozzolino S, Schiestl FP. Floral scent and species divergence in a pair of sexually deceptive orchids. Ecol Evol 2017; 7:6023-6034. [PMID: 28808562 PMCID: PMC5551101 DOI: 10.1002/ece3.3147] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/14/2017] [Accepted: 05/17/2017] [Indexed: 01/08/2023] Open
Abstract
Speciation is typically accompanied by the formation of isolation barriers between lineages. Commonly, reproductive barriers are separated into pre‐ and post‐zygotic mechanisms that can evolve with different speed. In this study, we measured the strength of different reproductive barriers in two closely related, sympatric orchids of the Ophrys insectifera group, namely Ophrys insectifera and Ophrys aymoninii to infer possible mechanisms of speciation. We quantified pre‐ and post‐pollination barriers through observation of pollen flow, by performing artificial inter‐ and intraspecific crosses and analyzing scent bouquets. Additionally, we investigated differences in mycorrhizal fungi as a potential extrinsic factor of post‐zygotic isolation. Our results show that floral isolation mediated by the attraction of different pollinators acts apparently as the sole reproductive barrier between the two orchid species, with later‐acting intrinsic barriers seemingly absent. Also, the two orchids share most of their fungal mycorrhizal partners in sympatry, suggesting little or no importance of mycorrhizal symbiosis in reproductive isolation. Key traits underlying floral isolation were two alkenes and wax ester, present predominantly in the floral scent of O. aymoninii. These compounds, when applied to flowers of O. insectifera, triggered attraction and a copulation attempt of the bee pollinator of O. aymoninii and thus led to the (partial) breakdown of floral isolation. Based on our results, we suggest that adaptation to different pollinators, mediated by floral scent, underlies species isolation in this plant group. Pollinator switches may be promoted by low pollination success of individuals in dense patches of plants, an assumption that we also confirmed in our study.
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Affiliation(s)
- Daniel D L Gervasi
- Department of Systematic and Evolutionary Botany University of Zürich Zürich Switzerland
| | - Marc-Andre Selosse
- Institut de Systématique, Évolution, Biodiversité (ISYEB)UMR 7205 CNRS MNHN UPMC EPHE Muséum national d'Histoire naturelle Sorbonne Universités Paris France.,Department of Plant Taxonomy and Nature Conservation University of Gdansk Gdańsk Poland
| | - Mathieu Sauve
- Institut de Systématique, Évolution, Biodiversité (ISYEB)UMR 7205 CNRS MNHN UPMC EPHE Muséum national d'Histoire naturelle Sorbonne Universités Paris France
| | - Wittko Francke
- Institute of Organic Chemistry University of Hamburg Hamburg Germany
| | - Nicolas J Vereecken
- Agroecology and Pollination Group Landscape Ecology and Plant Production Systems Université libre de Bruxelles (ULB) Brussels Belgium
| | | | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany University of Zürich Zürich Switzerland
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21
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Borghi M, Fernie AR, Schiestl FP, Bouwmeester HJ. The Sexual Advantage of Looking, Smelling, and Tasting Good: The Metabolic Network that Produces Signals for Pollinators. Trends Plant Sci 2017; 22:338-350. [PMID: 28111171 DOI: 10.1016/j.tplants.2016.12.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/10/2016] [Accepted: 12/21/2016] [Indexed: 05/08/2023]
Abstract
A striking feature of the angiosperms that use animals as pollen carriers to sexually reproduce is the great diversity of their flowers with regard to morphology and traits such as color, odor, and nectar. These traits are underpinned by the synthesis of secondary metabolites such as pigments and volatiles, as well as carbohydrates and amino acids, which are used by plants to lure and reward animal pollinators. We review here the knowledge of the metabolic network that supports the biosynthesis of these compounds and the behavioral responses that these molecules elicit in the animal pollinators. Such knowledge provides us with a deeper insight into the ecology and evolution of plant-pollinator interactions, and should help us to better manage these ecologically essential interactions in agricultural ecosystems.
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Affiliation(s)
- Monica Borghi
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam-Golm, Germany
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, 8008 Zürich
| | - Harro J Bouwmeester
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Present address: Plant Hormone Biology group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
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22
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Zu P, Schiestl FP. The effects of becoming taller: direct and pleiotropic effects of artificial selection on plant height in Brassica rapa. Plant J 2017; 89:1009-1019. [PMID: 27889935 DOI: 10.1111/tpj.13440] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/07/2016] [Accepted: 11/18/2016] [Indexed: 06/06/2023]
Abstract
Plant height is an important trait for plant reproductive success. Plant height is often under pollinator-mediated selection, and has been shown to be correlated with various other traits. However, few studies have examined the evolutionary trajectory of plant height under selection and the pleiotropic effects of plant height evolution. We conducted a bi-directional artificial selection experiment on plant height with fast cycling Brassica rapa plants to estimate its heritability and genetic correlations, and to reveal evolutionary responses to artificial selection on height and various correlated traits. With the divergent lines obtained through artificial selection, we subsequently conducted pollinator-choice assays and investigated resource limitation of fruit production. We found that plant height variation is strongly genetically controlled (with a realized heritability of 41-59%). Thus, plant height can evolve rapidly under phenotypic selection. In addition, we found remarkable pleiotropic effects in phenology, morphology, floral scent, color, nectar and leaf glucosinolates. Most traits were increased in tall-line plants, but flower size, UV reflection and glucosinolates were decreased, indicating potential trade-offs. Pollinators preferred plants of the tall selection lines over the short selection lines in both greenhouse experiments with bumblebees and field experiment with natural pollinators. We did not detect any differences in resource limitation between plants of the different selection lines. Overall, our study predicts that increased height should evolve under positive pollinator-mediated directional selection with potential trade-offs in floral signals and herbivore defense.
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Affiliation(s)
- Pengjuan Zu
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
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23
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Kellenberger RT, Schlüter PM, Schiestl FP. Herbivore-Induced DNA Demethylation Changes Floral Signalling and Attractiveness to Pollinators in Brassica rapa. PLoS One 2016; 11:e0166646. [PMID: 27870873 PMCID: PMC5117703 DOI: 10.1371/journal.pone.0166646] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/01/2016] [Indexed: 12/27/2022] Open
Abstract
Plants have to fine-tune their signals to optimise the trade-off between herbivore deterrence and pollinator attraction. An important mechanism in mediating plant-insect interactions is the regulation of gene expression via DNA methylation. However, the effect of herbivore-induced DNA methylation changes on pollinator-relevant plant signalling has not been systematically investigated. Here, we assessed the impact of foliar herbivory on DNA methylation and floral traits in the model crop plant Brassica rapa. Methylation-sensitive amplified fragment length polymorphism (MSAP) analysis showed that leaf damage by the caterpillar Pieris brassicae was associated with genome-wide methylation changes in both leaves and flowers of B. rapa as well as a downturn in flower number, morphology and scent. A comparison to plants with jasmonic acid-induced defence showed similar demethylation patterns in leaves, but both the floral methylome and phenotype differed significantly from P. brassicae infested plants. Standardised genome-wide demethylation with 5-azacytidine in five different B. rapa full-sib groups further resulted in a genotype-specific downturn of floral morphology and scent, which significantly reduced the attractiveness of the plants to the pollinator bee Bombus terrestris. These results suggest that DNA methylation plays an important role in adjusting plant signalling in response to changing insect communities.
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Affiliation(s)
- Roman T. Kellenberger
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Philipp M. Schlüter
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Florian P. Schiestl
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
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24
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Cai J, Zu P, Schiestl FP. The molecular bases of floral scent evolution under artificial selection: insights from a transcriptome analysis in Brassica rapa. Sci Rep 2016; 6:36966. [PMID: 27841366 PMCID: PMC5107913 DOI: 10.1038/srep36966] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/13/2016] [Indexed: 12/24/2022] Open
Abstract
In an artificial selection experiment using fast-cycling Brassica rapa plants it was recently shown that floral VOCs respond rapidly to selection for increased amounts. Here we carried out transcriptome analysis in these plants to explore the molecular bases of the augmentation in the artificially selected scent compound, phenylacetaldehyde (PAA), as well as other compounds that increased through pleiotropy. In the transcriptome data, we found up-regulation of genes likely underlying PAA synthesis, but also several genes of the shikimate pathway and the related phenylalanine metabolism. As phenylalanine is the precursor of many aromatic volatiles that showed increased emission, this result could explain some of the pleiotropic evolutionary responses. In addition, we found that ribosomal protein genes were up-regulated in “high” (high PAA amount) selection line plants, a mechanism that might further augment the effect of elevated gene expression at the proteomic level. Our study shows that selection on an individual trait can impose changes in the expression of several different genes, which could explain pleiotropic responses in the biosynthetic network of floral volatiles.
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Affiliation(s)
- Jing Cai
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Pengjuan Zu
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
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25
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Zu P, Blanckenhorn WU, Schiestl FP. Heritability of floral volatiles and pleiotropic responses to artificial selection in Brassica rapa. New Phytol 2016; 209:1208-1219. [PMID: 26391626 DOI: 10.1111/nph.13652] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 08/12/2015] [Indexed: 06/05/2023]
Abstract
The evolution of the vast diversity of floral volatiles is little understood, although they serve fundamental functions, such as pollinator attraction and herbivore deterrence. Floral volatiles are often species specific, yet highly variable and sensitive to environmental factors. To date, nothing is known about the heritability of floral volatiles, and whether individual compounds can evolve independently or solely in concert with the whole volatile bouquet. We conducted bi-directional artificial selection on four target floral volatiles to estimate heritability and correlated pleiotropic responses in the wild turnip (Brassica rapa). The realized heritability of the four target volatiles ranged from 20% to 45%. The average narrow-sense heritability of all 13 analyzed floral volatiles was 18% based on parent-offspring regressions. There were pleiotropic effects of the selected floral volatile compounds on other constituents of the floral scent bouquet, on flowering time and on some morphological traits. We found that the whole floral scent bouquet changed, even when there was selection only on single compounds, with the overall phenotypic covariance being unaffected. Our study demonstrates that floral scent can evolve rapidly under phenotypic selection, but with additional correlated responses in traits that are not direct targets of selection.
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Affiliation(s)
- Pengjuan Zu
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
| | - Wolf U Blanckenhorn
- Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Florian P Schiestl
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland
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26
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Abstract
Floral scents and nectar attract both pollinators and other animals that may reduce the plant's fitness, and therefore put flowering plants in a challenging situation.
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Affiliation(s)
- Kelsey JRP Byers
- Institute of Systematic Botany, University of Zurich, Zurich, Switzerland
| | - Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zurich, Switzerland
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27
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Desurmont GA, Laplanche D, Schiestl FP, Turlings TCJ. Floral volatiles interfere with plant attraction of parasitoids: ontogeny-dependent infochemical dynamics in Brassica rapa. BMC Ecol 2015; 15:17. [PMID: 26031290 PMCID: PMC4467598 DOI: 10.1186/s12898-015-0047-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/13/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The role of plant ontogeny on investment in direct defense against herbivores is well accepted, but the transition from the vegetative to the reproductive stage can also affect indirect resistance traits (i.e. attraction of the natural enemies of plant attackers). Here, we conducted behavioral bioassays in olfactometers to determine whether the developmental stage (vegetative, pre-flowering, and flowering) of Brassica rapa plants affects attraction of Cotesia glomerata, a parasitoid of the herbivore Pieris brassicae, and examined the blends of volatile compounds emitted by plants at each developmental stage. RESULTS Pieris-infested plants were always more attractive to parasitoids than control plants and plants infested by a non-host herbivore, independently of plant developmental stage. On the other hand, the relative attractiveness of Pieris-infested plants was ontogeny dependent: Pieris-infested plants were more attractive at the pre-flowering stage than at the vegetative stage, and more attractive at the vegetative stage than at the flowering stage. Chemical analyses revealed that the induction of leaf volatiles after herbivory is strongly reduced in flowering plants. The addition of synthetic floral volatiles to infested vegetative plants decreased their attractiveness to parasitoids, suggesting a trade-off between signaling to pollinators and parasitoids. CONCLUSION Our results show that putative indirect resistance traits are affected by plant development, and are reduced during B. rapa reproductive stage. The effects of ontogenetic shifts in resource allocation on the behavior of members of the third trophic level may have important implications for the evolution of plant defense strategies against herbivores.
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Affiliation(s)
- Gaylord A Desurmont
- Institute of Biology, University of Neuchâtel, Rue Emile-argand 11, 2000, Neuchâtel, Switzerland.
| | - Diane Laplanche
- Institute of Biology, University of Neuchâtel, Rue Emile-argand 11, 2000, Neuchâtel, Switzerland.
| | - Florian P Schiestl
- Institute of Systematic Botany, Zollikerstrasse 107, 8008, Zurich, Switzerland.
| | - Ted C J Turlings
- Institute of Biology, University of Neuchâtel, Rue Emile-argand 11, 2000, Neuchâtel, Switzerland.
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28
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Schiestl FP. Ecology and evolution of floral volatile-mediated information transfer in plants. New Phytol 2015; 206:571-7. [PMID: 25605223 DOI: 10.1111/nph.13243] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 11/13/2014] [Indexed: 05/24/2023]
Abstract
Floral volatiles are complex, multi-functional signals that are often used by pollinators in combination with other signals, such as color. Floral visitors use floral scent to estimate the amount of reward present in flowers, to facilitate the identification of a specific host flower or as signals that chemically resemble those important for pollinator insects in other ecological contexts. There is good evidence that floral scent evolves under selection imposed by both mutualists and antagonists. Antagonists may often limit the amount of scent emitted by flowers, thus contributing to spatial population variation, and select for phenotypic plasticity after enemy attack. Floral scent is also an important component of pollinator-mediated reproductive isolation, as it often co-varies with color and morphology in sister species with different pollination systems.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, Zürich, 8008, Switzerland
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29
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Scopece G, Schiestl FP, Cozzolino S. Pollen transfer efficiency and its effect on inflorescence size in deceptive pollination strategies. Plant Biol (Stuttg) 2015; 17:545-550. [PMID: 25040501 DOI: 10.1111/plb.12224] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 05/16/2014] [Indexed: 06/03/2023]
Abstract
Pollination systems differ in pollen transfer efficiency, a variable that may influence the evolution of flower number. Here we apply a comparative approach to examine the link between pollen transfer efficiency and the evolution of inflorescence size in food and sexually deceptive orchids. We examined pollination performance in nine food-deceptive, and eight sexually deceptive orchids by recording pollen removal and deposition in the field. We calculated correlations between reproductive success and flower number (as a proxy for resources allocated during reproductive process), and directional selection differentials were estimated on flower number for four species. Results indicate that sexually deceptive species experience decreased pollen loss compared to food-deceptive species. Despite producing fewer flowers, sexually deceptive species attained levels of overall pollination success (through male and female function) similar to food-deceptive species. Furthermore, a positive correlation between flower number and pollination success was observed in food-deceptive species, but this correlation was not detected in sexually deceptive species. Directional selection differentials for flower number were significantly higher in food compared to sexually deceptive species. We suggest that pollination systems with more efficient pollen transfer and no correlation between pollination success and number of flowers produced, such as sexual deception, may allow the production of inflorescences with fewer flowers that permit the plant to allocate fewer resources to floral displays and, at the same time, limit transpiration. This strategy can be particularly important for ecological success in Mediterranean water-deprived habitats, and might explain the high frequency of sexually deceptive species in these specialised ecosystems.
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Affiliation(s)
- G Scopece
- Department of Biology, University Federico II, Complesso Universitario MSA, Naples, Italy; Institute for Plant Protection, Consiglio Nazionale delle Ricerche, Sesto Fiorentino (FI), Italy
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30
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Gross K, Schiestl FP. Are tetraploids more successful? Floral signals, reproductive success and floral isolation in mixed-ploidy populations of a terrestrial orchid. Ann Bot 2015; 115:263-73. [PMID: 25652914 PMCID: PMC4551083 DOI: 10.1093/aob/mcu244] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/07/2014] [Accepted: 10/22/2014] [Indexed: 05/11/2023]
Abstract
BACKGROUND AND AIMS Polyploidization, the doubling of chromosome sets, is common in angiosperms and has a range of evolutionary consequences. Newly formed polyploid lineages are reproductively isolated from their diploid progenitors due to triploid sterility, but also prone to extinction because compatible mating partners are rare. Models have suggested that assortative mating and increased reproductive fitness play a key role in the successful establishment and persistence of polyploids. However, little is known about these factors in natural mixed-ploidy populations. This study investigated floral traits that can affect pollinator attraction and efficiency, as well as reproductive success in diploid and tetraploid Gymnadenia conopsea (Orchidaceae) plants in two natural, mixed-ploidy populations. METHODS Ploidy levels were determined using flow cytometry, and flowering phenology and herbivory were also assessed. Reproductive success was determined by counting fruits and viable seeds of marked plants. Pollinator-mediated floral isolation was measured using experimental arrays, with pollen flow tracked by means of staining pollinia with histological dye. KEY RESULTS Tetraploids had larger floral displays and different floral scent bouquets than diploids, but cytotypes differed only slightly in floral colour. Significant floral isolation was found between the two cytotypes. Flowering phenology of the two cytotypes greatly overlapped, and herbivory did not differ between cytotypes or was lower in tetraploids. In addition, tetraploids had higher reproductive success compared with diploids. CONCLUSIONS The results suggest that floral isolation and increased reproductive success of polyploids may help to explain their successful persistence in mixed-ploidy populations. These factors might even initiate transformation of populations from pure diploid to pure tetraploid.
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Affiliation(s)
- Karin Gross
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
| | - Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
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31
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Sun M, Schlüter PM, Gross K, Schiestl FP. Floral isolation is the major reproductive barrier between a pair of rewarding orchid sister species. J Evol Biol 2015; 28:117-29. [PMID: 25382492 DOI: 10.1111/jeb.12544] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 11/04/2014] [Indexed: 11/30/2022]
Abstract
The crucial role of reproductive isolation in speciation has long been recognized; however, a limited number of studies quantify different isolation barriers and embed reproductive isolation in a phylogenetic context. In this study, we investigate reproductive isolation between the often sympatrically occurring orchid species, Gymnadenia conopsea and G. odoratissima. We examine the phylogenetic relationship between the two species and analyse floral isolation, fruit set and seed viability from interspecies crosses, as well as the ploidy level. Additionally, we quantify interspecies differences in floral signals and morphology. The results suggest that the two species have a sister-species relationship. In terms of reproductive isolation, we found complete floral isolation between the two species, but little to no post-pollination isolation; the species also mostly had the same ploidy level in the studied populations. We also show clear distinctions in floral signals, as well as in floral size and spur length. We propose that respective adaptation to short- vs. long-tongued pollinators was the driver of speciation in the here studied Gymnadenia species. Our study supports the key role of floral isolation in orchid speciation and shows that floral isolation is not restricted to highly specialized pollination systems, but can also occur between species with less specialized pollination.
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Affiliation(s)
- M Sun
- Institute of Systematic Botany, University of Zürich, Zürich, Switzerland
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32
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Knauer AC, Schiestl FP. Bees use honest floral signals as indicators of reward when visiting flowers. Ecol Lett 2014; 18:135-43. [PMID: 25491788 DOI: 10.1111/ele.12386] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/20/2014] [Indexed: 11/27/2022]
Abstract
Pollinators visit flowers for rewards and should therefore have a preference for floral signals that indicate reward status, so called 'honest signals'. We investigated honest signalling in Brassica rapa L. and its relevance for the attraction of a generalised pollinator, the bumble bee Bombus terrestris (L.). We found a positive association between reward amount (nectar sugar and pollen) and the floral scent compound phenylacetaldehyde. Bumble bees developed a preference for phenylacetaldehyde over other scent compounds after foraging on B. rapa. When foraging on artificial flowers scented with synthetic volatiles, bumble bees developed a preference for those specific compounds that honestly indicated reward status. These results show that the honesty of floral signals can play a key role in their attractiveness to pollinators. In plants, a genetic constraint, resource limitation in reward and signal production, and sanctions against cheaters may contribute to the evolution and maintenance of honest signalling.
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Affiliation(s)
- A C Knauer
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
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33
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Sedeek KEM, Scopece G, Staedler YM, Schönenberger J, Cozzolino S, Schiestl FP, Schlüter PM. Genic rather than genome‐wide differences between sexually deceptive
O
phrys
orchids with different pollinators. Mol Ecol 2014; 23:6192-205. [DOI: 10.1111/mec.12992] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/25/2014] [Accepted: 10/29/2014] [Indexed: 01/12/2023]
Affiliation(s)
- Khalid E. M. Sedeek
- Institute of Systematic Botany University of Zurich Zollikerstr. 107 CH‐8008 Zurich Switzerland
| | - Giovanni Scopece
- Department of Biology University of Naples Federico II Complesso Universitario MSA Via Cinthia I‐80126 Naples Italy
| | - Yannick M. Staedler
- Department of Botany and Biodiversity Research University of Vienna Rennweg 14 A‐1030 Vienna Austria
| | - Jürg Schönenberger
- Department of Botany and Biodiversity Research University of Vienna Rennweg 14 A‐1030 Vienna Austria
| | - Salvatore Cozzolino
- Department of Biology University of Naples Federico II Complesso Universitario MSA Via Cinthia I‐80126 Naples Italy
| | - Florian P. Schiestl
- Institute of Systematic Botany University of Zurich Zollikerstr. 107 CH‐8008 Zurich Switzerland
| | - Philipp M. Schlüter
- Institute of Systematic Botany University of Zurich Zollikerstr. 107 CH‐8008 Zurich Switzerland
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Desurmont GA, Harvey J, van Dam NM, Cristescu SM, Schiestl FP, Cozzolino S, Anderson P, Larsson MC, Kindlmann P, Danner H, Turlings TCJ. Alien interference: disruption of infochemical networks by invasive insect herbivores. Plant Cell Environ 2014; 37:1854-65. [PMID: 24689553 DOI: 10.1111/pce.12333] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 05/09/2023]
Abstract
Insect herbivores trigger various biochemical changes in plants, and as a consequence, affect other organisms that are associated with these plants. Such plant-mediated indirect effects often involve herbivore-induced plant volatiles (HIPVs) that can be used as cues for foraging herbivores and their natural enemies, and are also known to affect pollinator attraction. In tightly co-evolved systems, the different trophic levels are expected to display adaptive response to changes in HIPVs caused by native herbivores. But what if a new herbivore invades such a system? Current literature suggests that exotic herbivores have the potential to affect HIPV production, and that plant responses to novel herbivores are likely to depend on phylogenetic relatedness between the invader and the native species. Here we review the different ways exotic herbivores can disrupt chemically mediated interactions between plants and the key users of HIPVs: herbivores, pollinators, and members of the third (i.e. predators and parasitoids) and fourth (i.e. hyperparasitoids) trophic levels. Current theory on insect invasions needs to consider that disruptive effects of invaders on infochemical networks can have a short-term impact on the population dynamics of native insects and plants, as well as exerting potentially negative consequences for the functioning of native ecosystems.
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Affiliation(s)
- Gaylord A Desurmont
- Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
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35
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Schiestl FP, Kirk H, Bigler L, Cozzolino S, Desurmont GA. Herbivory and floral signaling: phenotypic plasticity and tradeoffs between reproduction and indirect defense. New Phytol 2014; 203:257-266. [PMID: 24684288 DOI: 10.1111/nph.12783] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 02/24/2014] [Indexed: 06/03/2023]
Abstract
Plant defense against herbivores may compromise attraction of mutualists, yet information remains limited about the mechanisms underlying such signaling tradeoffs. Here, we investigated the effects of foliar herbivory by two herbivore species on defense compounds, floral signaling, pollinator and parasitoid attraction, and seed production. Herbivory generally reduced the quantity of many floral volatile organic compounds VOCs) in Brassica rapa. By contrast, floral color, flower diameter, and plant height remained unaffected. The decreased amounts of floral volatiles led to reduced attractiveness of flowers to pollinators, but increased the attractiveness of herbivore-infested plants to parasitoids. Plants infested with the native butterfly Pieris brassicae produced more flowers during early flowering, effectively compensating for the lower olfactory attractiveness. Herbivory by the invasive Spodoptera littoralis increased the amounts of glucobrassicanapin, and led to delayed flowering. These plants tended to attract fewer pollinators and to produce fewer seeds. Our study indicates a tradeoff between pollinator attraction and indirect defense (parasitoid attraction), which can be mitigated by reduced floral VOC emission and production of more early flowers. We suggest that this compensatory mechanism is specific to plant-herbivore associations with a coevolutionary history.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, 8008, Zürich, Switzerland
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Page P, Favre A, Schiestl FP, Karrenberg S. Do flower color and floral scent of silene species affect host preference of Hadena bicruris, a seed-eating pollinator, under field conditions? PLoS One 2014; 9:e98755. [PMID: 24905986 PMCID: PMC4048206 DOI: 10.1371/journal.pone.0098755] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 05/06/2014] [Indexed: 01/19/2023] Open
Abstract
Specialization in plant–insect interactions is an important driver of evolutionary divergence; yet, plant traits mediating such interactions are poorly understood. In this study, we investigated how flower color and floral scent are related to seed predation by a seed-eating pollinator. We used field-transplanted recombinant F2 hybrids between Silene latifolia and S. dioica that are the preferred and alternative hosts of the moth Hadena bicruris and crosses within these species for comparison. We scored seed predation and flower color and analyzed floral scent. Pinker S. dioica-like flowers and emission of α-pinene decreased the odds of seed predation while emission of benzyl acetate and 6-methyl-5-hepten-2-one increased the odds of seed predation. Emission of these compounds did not differ significantly between the two Silene species. Our results suggest that flower color plays an important role in the specific interaction of H. bicruris with its preferred host S. latifolia. The compounds α-pinene, benzyl acetate and 6-methyl-5-hepten-2-one could represent non-specific deterrents and attractants to ovipositing moths. Alternatively, emission of these compounds could be related to herbivory or pathogen attack and act as a signal for host quality. This would weaken the predictability of the plant's costs and benefits of the interaction and act to maintain an imperfect degree of specialization.
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Affiliation(s)
- Paul Page
- ETH Zurich, Institute of Integrative Biology (IBZ), Zurich, Switzerland
| | - Adrien Favre
- ETH Zurich, Institute of Integrative Biology (IBZ), Zurich, Switzerland
- Department of Molecular Evolution and Systematics of Plants, Institute of Biology, University of Leipzig, Leipzig, Germany
| | - Florian P. Schiestl
- ETH Zurich, Institute of Integrative Biology (IBZ), Zurich, Switzerland
- Institute of Systematic Botany, University of Zurich, Zurich, Switzerland
| | - Sophie Karrenberg
- ETH Zurich, Institute of Integrative Biology (IBZ), Zurich, Switzerland
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- * E-mail:
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37
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Schiestl FP. Correlation analyses between volatiles and glucosinolates show no evidence for chemical defense signaling in Brassica rapa. Front Ecol Evol 2014. [DOI: 10.3389/fevo.2014.00010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Sun M, Gross K, Schiestl FP. Floral adaptation to local pollinator guilds in a terrestrial orchid. Ann Bot 2014; 113:289-300. [PMID: 24107683 PMCID: PMC3890390 DOI: 10.1093/aob/mct219] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 07/29/2013] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS Studies of local floral adaptation in response to geographically divergent pollinators are essential for understanding floral evolution. This study investigated local pollinator adaptation and variation in floral traits in the rewarding orchid Gymnadenia odoratissima, which spans a large altitudinal gradient and thus may depend on different pollinator guilds along this gradient. METHODS Pollinator communities were assessed and reciprocal transfer experiments were performed between lowland and mountain populations. Differences in floral traits were characterized by measuring floral morphology traits, scent composition, colour and nectar sugar content in lowland and mountain populations. KEY RESULTS The composition of pollinator communities differed considerably between lowland and mountain populations; flies were only found as pollinators in mountain populations. The reciprocal transfer experiments showed that when lowland plants were transferred to mountain habitats, their reproductive success did not change significantly. However, when mountain plants were moved to the lowlands, their reproductive success decreased significantly. Transfers between populations of the same altitude did not lead to significant changes in reproductive success, disproving the potential for population-specific adaptations. Flower size of lowland plants was greater than for mountain flowers. Lowland plants also had significantly higher relative amounts of aromatic floral volatiles, while the mountain plants had higher relative amounts of other floral volatiles. The floral colour of mountain flowers was significantly lighter compared with the lowland flowers. CONCLUSIONS Local pollinator adaptation through pollinator attraction was shown in the mountain populations, possibly due to adaptation to pollinating flies. The mountain plants were also observed to receive pollination from a greater diversity of pollinators than the lowland plants. The different floral phenotypes of the altitudinal regions are likely to be the consequence of adaptations to local pollinator guilds.
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Abstract
Flowers exist in exceedingly complex fitness landscapes, in which subtle variation in each trait can affect the pollinators, herbivores and pleiotropically linked traits in other plant tissues. A whole-genome approach to flower evolution will help our understanding of plant-pollinator interactions.
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Affiliation(s)
- Elizabeth L Clare
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Andrew R Leitch
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Lars Chittka
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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40
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Sedeek KEM, Qi W, Schauer MA, Gupta AK, Poveda L, Xu S, Liu ZJ, Grossniklaus U, Schiestl FP, Schlüter PM. Transcriptome and proteome data reveal candidate genes for pollinator attraction in sexually deceptive orchids. PLoS One 2013; 8:e64621. [PMID: 23734209 PMCID: PMC3667177 DOI: 10.1371/journal.pone.0064621] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 04/17/2013] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Sexually deceptive orchids of the genus Ophrys mimic the mating signals of their pollinator females to attract males as pollinators. This mode of pollination is highly specific and leads to strong reproductive isolation between species. This study aims to identify candidate genes responsible for pollinator attraction and reproductive isolation between three closely related species, O. exaltata, O. sphegodes and O. garganica. Floral traits such as odour, colour and morphology are necessary for successful pollinator attraction. In particular, different odour hydrocarbon profiles have been linked to differences in specific pollinator attraction among these species. Therefore, the identification of genes involved in these traits is important for understanding the molecular basis of pollinator attraction by sexually deceptive orchids. RESULTS We have created floral reference transcriptomes and proteomes for these three Ophrys species using a combination of next-generation sequencing (454 and Solexa), Sanger sequencing, and shotgun proteomics (tandem mass spectrometry). In total, 121 917 unique transcripts and 3531 proteins were identified. This represents the first orchid proteome and transcriptome from the orchid subfamily Orchidoideae. Proteome data revealed proteins corresponding to 2644 transcripts and 887 proteins not observed in the transcriptome. Candidate genes for hydrocarbon and anthocyanin biosynthesis were represented by 156 and 61 unique transcripts in 20 and 7 genes classes, respectively. Moreover, transcription factors putatively involved in the regulation of flower odour, colour and morphology were annotated, including Myb, MADS and TCP factors. CONCLUSION Our comprehensive data set generated by combining transcriptome and proteome technologies allowed identification of candidate genes for pollinator attraction and reproductive isolation among sexually deceptive orchids. This includes genes for hydrocarbon and anthocyanin biosynthesis and regulation, and the development of floral morphology. These data will serve as an invaluable resource for research in orchid floral biology, enabling studies into the molecular mechanisms of pollinator attraction and speciation.
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Affiliation(s)
- Khalid E M Sedeek
- Institute of Systematic Botany & Zürich-Basel Plant Science Centre, University of Zurich, Zürich, Switzerland
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41
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Schiestl FP, Johnson SD. Pollinator-mediated evolution of floral signals. Trends Ecol Evol 2013; 28:307-15. [PMID: 23480953 DOI: 10.1016/j.tree.2013.01.019] [Citation(s) in RCA: 290] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/30/2013] [Accepted: 01/30/2013] [Indexed: 12/27/2022]
Abstract
Because most plants rely on animals for pollination, insights from animal sensory ecology and behavior are essential for understanding the evolution of flowers. In this review, we compare and contrast three main types of pollinator responses to floral signals--receiver bias, 'adaptive' innate preferences, and associative learning--and discuss how they can shape selection on floral signals. We show that pollinator-mediated selection on floral signals can be strong and that the molecular bases of floral signal variation are often surprisingly simple. These new empirical and conceptual insights into pollinator-mediated evolution provide a framework for understanding patterns of both convergent (pollination syndromes) and advergent (floral mimicry) floral signal evolution.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
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42
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Trávníček P, Jersáková J, Kubátová B, Krejčíková J, Bateman RM, Lučanová M, Krajníková E, Těšitelová T, Štípková Z, Amardeilh JP, Brzosko E, Jermakowicz E, Cabanne O, Durka W, Efimov P, Hedrén M, Hermosilla CE, Kreutz K, Kull T, Tali K, Marchand O, Rey M, Schiestl FP, Čurn V, Suda J. Minority cytotypes in European populations of the Gymnadenia conopsea complex (Orchidaceae) greatly increase intraspecific and intrapopulation diversity. Ann Bot 2012; 110:977-86. [PMID: 23002267 PMCID: PMC3448425 DOI: 10.1093/aob/mcs171] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 06/11/2012] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Patterns of ploidy variation among and within populations can provide valuable insights into the evolutionary mechanisms shaping the dynamics of plant systems showing ploidy diversity. Whereas data on majority ploidies are, by definition, often sufficiently extensive, much less is known about the incidence and evolutionary role of minority cytotypes. METHODS Ploidy and proportions of endoreplicated genome were determined using DAPI (4',6-diamidino-2-phenylindole) flow cytometry in 6150 Gymnadenia plants (fragrant orchids) collected from 141 populations in 17 European countries. All widely recognized European species, and several taxa of less certain taxonomic status were sampled within Gymnadenia conopsea sensu lato. KEY RESULTS Most Gymnadenia populations were taxonomically and/or ploidy heterogeneous. Two majority (2x and 4x) and three minority (3x, 5x and 6x) cytotypes were identified. Evolution largely proceeded at the diploid level, whereas tetraploids were much more geographically and taxonomically restricted. Although minority ploidies constituted <2 % of the individuals sampled, they were found in 35 % of populations across the entire area investigated. The amount of nuclear DNA, together with the level of progressively partial endoreplication, separated all Gymnadenia species currently widely recognized in Europe. CONCLUSIONS Despite their low frequency, minority cytotypes substantially increase intraspecific and intrapopulation ploidy diversity estimates for fragrant orchids. The cytogenetic structure of Gymnadenia populations is remarkably dynamic and shaped by multiple evolutionary mechanisms, including both the ongoing production of unreduced gametes and heteroploid hybridization. Overall, it is likely that the level of ploidy heterogeneity experienced by most plant species/populations is currently underestimated; intensive sampling is necessary to obtain a holistic picture.
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Affiliation(s)
- Pavel Trávníček
- Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic and Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
| | - Jana Jersáková
- Faculty of Science, University of South Bohemia in České Budějovice, CZ-370 05 České Budějovice, Czech Republic
| | - Barbora Kubátová
- Biotechnological Centre, Faculty of Agriculture, University of South Bohemia in České Budějovice, CZ-370 05 České Budějovice, Czech Republic
| | - Jana Krejčíková
- Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic and Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
| | | | - Magdalena Lučanová
- Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic and Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
| | - Eva Krajníková
- Biotechnological Centre, Faculty of Agriculture, University of South Bohemia in České Budějovice, CZ-370 05 České Budějovice, Czech Republic
| | - Tamara Těšitelová
- Faculty of Science, University of South Bohemia in České Budějovice, CZ-370 05 České Budějovice, Czech Republic
| | - Zuzana Štípková
- Faculty of Science, University of South Bohemia in České Budějovice, CZ-370 05 České Budějovice, Czech Republic
| | | | - Emilia Brzosko
- Institute of Biology, University of Bialystok, Świerkowa 20B, PL-15-950 Bialystok, Poland
| | - Edyta Jermakowicz
- Institute of Biology, University of Bialystok, Świerkowa 20B, PL-15-950 Bialystok, Poland
| | | | - Walter Durka
- Helmholtz Centre for Environmental Research–UFZ, Department of Community Ecology, Theodor-Lieser-Str. 4, D-06120 Halle, Germany
| | - Peter Efimov
- Herbarium, Komarov Botanical Institute of Russian Academy of Sciences, Prof. Popov str. 2, 197376 Saint-Petersburg, Russia
| | - Mikael Hedrén
- Department of Biology, University of Lund, Solvegatan 37, SE-22362 Lund, Sweden
| | | | - Karel Kreutz
- Oude Landgraaf 35a, NL-6373 Landgraaf, The Netherlands
| | - Tiiu Kull
- Department of Botany, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 5, EE-51014 Tartu, Estonia
| | - Kadri Tali
- Department of Botany, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 5, EE-51014 Tartu, Estonia
| | | | - Manel Rey
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Florian P. Schiestl
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Vladislav Čurn
- Biotechnological Centre, Faculty of Agriculture, University of South Bohemia in České Budějovice, CZ-370 05 České Budějovice, Czech Republic
| | - Jan Suda
- Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic and Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
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Gupta AK, Akhtar TA, Widmer A, Pichersky E, Schiestl FP. Identification of white campion (Silene latifolia) guaiacol O-methyltransferase involved in the biosynthesis of veratrole, a key volatile for pollinator attraction. BMC Plant Biol 2012; 12:158. [PMID: 22937972 PMCID: PMC3492160 DOI: 10.1186/1471-2229-12-158] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 08/27/2012] [Indexed: 05/10/2023]
Abstract
BACKGROUND Silene latifolia and its pollinator, the noctuid moth Hadena bicruris, represent an open nursery pollination system wherein floral volatiles, especially veratrole (1, 2-dimethoxybenzene), lilac aldehydes, and phenylacetaldehyde are of key importance for floral signaling. Despite the important role of floral scent in ensuring reproductive success in S. latifolia, the molecular basis of scent biosynthesis in this species has not yet been investigated. RESULTS We isolated two full-length cDNAs from S. latifolia that show similarity to rose orcinol O-methyltransferase. Biochemical analysis showed that both S. latifolia guaiacol O-methyltransferase1 (SlGOMT1) &S. latifolia guaiacol O-methyltransferase2 (SlGOMT2) encode proteins that catalyze the methylation of guaiacol to form veratrole. A large Km value difference between SlGOMT1 (~10 μM) and SlGOMT2 (~501 μM) resulted that SlGOMT1 is 31-fold more catalytically efficient than SlGOMT2. qRT-PCR expression analysis showed that the SlGOMT genes are specifically expressed in flowers and male S. latifolia flowers had 3- to 4-folds higher level of GOMT gene transcripts than female flower tissues. Two related cDNAs, S. dioica O-methyltransferase1 (SdOMT1) and S. dioica O-methyltransferase2 (SdOMT2), were also obtained from the sister species Silene dioica, but the proteins they encode did not methylate guaiacol, consistent with the lack of veratrole emission in the flowers of this species. Our evolutionary analysis uncovered that SlGOMT1 and SlGOMT2 genes evolved under positive selection, whereas SdOMT1 and SdOMT2 genes show no evidence for selection. CONCLUSIONS Altogether, we report the identification and functional characterization of the gene, SlGOMT1 that efficiently catalyzes veratrole formation, whereas another copy of this gene with only one amino acid difference, SlGOMT2 was found to be less efficient for veratrole synthesis in S. latifolia.
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Affiliation(s)
- Alok K Gupta
- Institute of Systematic Botany, University of Zurich, Zurich, CH-8008, Switzerland
- ETH Zurich, Institute of Integrative Biology, Plant Ecological Genetics, Zurich, CH-8092, Switzerland
| | - Tariq A Akhtar
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Alex Widmer
- ETH Zurich, Institute of Integrative Biology, Plant Ecological Genetics, Zurich, CH-8092, Switzerland
| | - Eran Pichersky
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zurich, CH-8008, Switzerland
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Xu S, Schlüter PM, Grossniklaus U, Schiestl FP. The genetic basis of pollinator adaptation in a sexually deceptive orchid. PLoS Genet 2012; 8:e1002889. [PMID: 22916031 PMCID: PMC3420943 DOI: 10.1371/journal.pgen.1002889] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 06/25/2012] [Indexed: 11/26/2022] Open
Abstract
In plants, pollinator adaptation is considered to be a major driving force for floral diversification and speciation. However, the genetic basis of pollinator adaptation is poorly understood. The orchid genus Ophrys mimics its pollinators' mating signals and is pollinated by male insects during mating attempts. In many species of this genus, chemical mimicry of the pollinators' pheromones, especially of alkenes with different double-bond positions, plays a key role for specific pollinator attraction. Thus, different alkenes produced in different species are probably a consequence of pollinator adaptation. In this study, we identify genes that are likely involved in alkene biosynthesis, encoding stearoyl-acyl carrier protein (ACP) desaturases (SAD), in three closely related Ophrys species, O. garganica, O. sphegodes, and O. exaltata. Combining floral odor and gene expression analyses, two SAD homologs (SAD1/2) showed significant association with the production of (Z)-9- and (Z)-12-alkenes that were abundant in O. garganica and O. sphegodes, supporting previous biochemical data. In contrast, two other newly identified homologs (SAD5/6) were significantly associated with (Z)-7-alkenes that were highly abundant only in O. exaltata. Both molecular evolutionary analyses and pollinator preference tests suggest that the alkenes associated with SAD1/2 and SAD5/6 are under pollinator-mediated divergent selection among species. The expression patterns of these genes in F1 hybrids indicate that species-specific expression differences in SAD1/2 are likely due to cis-regulation, while changes in SAD5/6 are likely due to trans-regulation. Taken together, we report a genetic mechanism for pollinator-mediated divergent selection that drives adaptive changes in floral alkene biosynthesis involved in reproductive isolation among Ophrys species. In plants, the extraordinary floral diversity has been suggested to be a consequence of divergent adaptation. However, the genetic basis of this process is poorly understood. In this study, we take advantage of the high specificity of plant-pollinator interactions in the sexually deceptive orchid genus Ophrys. We leverage the available, ample evidence showing that floral odors, especially alkenes, are the key factor for specific pollinator attraction in certain species of these orchids. Further, we investigate the genetic basis of pollinator adaptation. By applying an inter-disciplinary approach, including chemical ecology, gene expression analysis, population genetics, and pollinator-behavioral tests, we show that genetic changes in different copies of a biosynthetic gene are associated with the production of different floral scents and with pollinator adaptation in these orchid species. Moreover, we found that both cis- and trans-regulatory factors are likely involved in controlling gene expression of these biosynthetic gene copies. These findings support the hypothesis that adaptation is mediated by very few genetic changes with large phenotypic effects, rather than requiring a large number of co-adapted genes.
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Affiliation(s)
- Shuqing Xu
- Institute of Systematic Botany and Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
- Institute of Integrative Biology and Zürich-Basel Plant Science Center, ETH Zürich, Zürich, Switzerland
- * E-mail: (SX); (PMS)
| | - Philipp M. Schlüter
- Institute of Systematic Botany and Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
- * E-mail: (SX); (PMS)
| | - Ueli Grossniklaus
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
| | - Florian P. Schiestl
- Institute of Systematic Botany and Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
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Abstract
Coevolution is thought to be a major factor in shaping plant-pollinator interactions. Alternatively, plants may have evolved traits that fitted pre-existing preferences or morphologies in the pollinators. Here, we test these two scenarios in the plant family of Araceae and scarab beetles (Coleoptera, Scarabaeidae) as pollinators. We focused on floral volatile organic compounds (VOCs) and production/detection of VOCs by scarab beetles. We found phylogenetic structure in the production/detection of methoxylated aromatics in scarabs, but not plants. Within the plants, most of the compounds showed a well-supported pattern of correlated evolution with scarab-beetle pollination. In contrast, the scarabs showed no correlation between VOC production/detection and visitation to Araceae flowers, with the exception of the VOC skatole. Moreover, many VOCs were found in nonpollinating beetle groups (e.g., Melolonthinae) that are ancestors of pollinating scarabs. Importantly, none of the tested VOCs were found to have originated in pollinating taxa. Our analysis indicates a Jurassic origin of VOC production/detection in scarabs, but a Cretaceous/Paleocene origin of floral VOCs in plants. Therefore, we argue against coevolution, instead supporting the scenario of sequential evolution of floral VOCs in Araceae driven by pre-existing bias of pollinators.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, University of Zürich, 8008 Zürich, Switzerland.
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Staub PO, Schiestl FP, Leonti M, Weckerle CS. Chemical analysis of incense smokes used in Shaxi, Southwest China: a novel methodological approach in ethnobotany. J Ethnopharmacol 2011; 138:212-218. [PMID: 21939750 DOI: 10.1016/j.jep.2011.08.078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/24/2011] [Accepted: 08/27/2011] [Indexed: 05/31/2023]
Abstract
AIM OF THE STUDY Characterization and comparative analysis of the main VOCs (volatile organic compounds) present in the smoke of 11 experimentally combusted plant species used as incense in Shaxi, Southwest China. Substances which may be responsible for the pleasant smell of the smokes as well as substances with a potential pharmacological activity are discussed. MATERIALS AND METHODS We adopt the dynamic headspace sorption method for the collection of smoke samples as a novel methodological approach in ethnobotany. The VOCs were identified using gas chromatography-mass spectrometry (GC-MS). Principal component analysis and canonical discriminant analysis were performed using PASW statistics (Version 18.0.2). RESULTS Among the identified compounds were 10 monoterpenoids, 7 sesquiterpenoids, 6 linear hydrocarbons, 6 methoxy phenolics, 2 benzenoids, 2 polycyclic aromatic hydrocarbons, and 2 fatty acids. Based on their volatile profiles, the species are well clustered intraspecifically and separated interspecifically. The most abundant among the compounds potentially responsible for the pleasant smells of the smokes are methyl salicylate (12.28±3.90%) for Gaultheria fragrantissima leaves, δ-cadinene (15.58±2.29%) for Juniperus squamata wood, and α-Pinene for Cupressus funebris branches (9.16±7.73%) and Pistacia weinmanniifolia branches (19.52±8.66%). A couple of substances found are known for pharmacological activity, such as methylsalycilate, beta-caryophyllene and cedrol. CONCLUSIONS The species used by the local people in Shaxi for incense differ clearly with respect to the chemical compounds of their smoke. Further, incense contains substances, which are of pharmacological interest and might support medicinal uses of smoke. Cedrol with its pleasant smell and sedative properties may be an important factor why specific plants are chosen as incense. Our findings support the idea that the effects of the use of incense as well as medicinal smoke depend on both, the cultural as well as the pharmacological context.
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Affiliation(s)
- Peter O Staub
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland
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Blom D, Fabbri C, Connor EC, Schiestl FP, Klauser DR, Boller T, Eberl L, Weisskopf L. Production of plant growth modulating volatiles is widespread among rhizosphere bacteria and strongly depends on culture conditions. Environ Microbiol 2011; 13:3047-58. [PMID: 21933319 DOI: 10.1111/j.1462-2920.2011.02582.x] [Citation(s) in RCA: 204] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Recent studies have suggested that bacterial volatiles play an important role in bacterial-plant interactions. However, few reports of bacterial species that produce plant growth modulating volatiles have been published, raising the question whether this is just an anecdotal phenomenon. To address this question, we performed a large screen of strains originating from the soil for volatile-mediated effects on Arabidopsis thaliana. All of the 42 strains tested showed significant volatile-mediated plant growth modulation, with effects ranging from plant death to a sixfold increase in plant biomass. The effects of bacterial volatiles were highly dependent on the cultivation medium and the inoculum quantity. GC-MS analysis of the tested strains revealed over 130 bacterial volatile compounds. Indole, 1-hexanol and pentadecane were selected for further studies because they appeared to promote plant growth. None of these compounds triggered a typical defence response, using production of ethylene and of reactive oxygen species (ROS) as read-outs. However, when plants were challenged with the flg-22 epitope of bacterial flagellin, a prototypical elicitor of defence responses, additional exposure to the volatiles reduced the flg-22-induced production of ethylene and ROS in a dose-dependent manner, suggesting that bacterial volatiles may act as effectors to inhibit the plant's defence response.
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Affiliation(s)
- D Blom
- Department of Microbiology, Institute of Plant Biology, University of Zurich, Zurich, Switzerland
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Weckerle CS, Staub PO, Schiestl FP. Continuum Between Ritual and Medicinal Use of Plants: Smoke Analysis of Ritual Plants from Southwest China. Chimia (Aarau) 2011. [DOI: 10.2533/chimia.2011.438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Xu S, Schlüter PM, Scopece G, Breitkopf H, Gross K, Cozzolino S, Schiestl FP. Floral isolation is the main reproductive barrier among closely related sexually deceptive orchids. Evolution 2011; 65:2606-20. [PMID: 21884059 DOI: 10.1111/j.1558-5646.2011.01323.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Floral isolation is an important component of pollinator-driven speciation. However, up to now, only a few studies have quantified its strength and relative contribution to total reproductive isolation. In this study, we quantified floral isolation among three closely related, sympatric orchid species of the genus Ophrys by directly tracking pollen flow. Ophrys orchids mimic their pollinators' mating signals, and are pollinated by male insects during mating attempts. This pollination system, called sexual deception, is usually highly specific. However, whether pollinator specialization also conveys floral isolation is currently under debate. In this study, we found strong floral isolation: among 46 tracked pollen transfers in two flowering seasons, all occurred within species. Accounting for observation error rate, we estimated a floral isolation index ≥0.98 among each pair of species. Hand pollination experiments suggested that postpollination barriers were effectively absent among our study species. Genetic analysis based on AFLP markers showed a clear species clustering and very few F(1) hybrids in natural populations, providing independent evidence that strong floral isolation prevents significant interspecies gene flow. Our results provide the first direct evidence that floral isolation acts as the main reproductive barrier among closely related plant species with specialized pollination.
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Affiliation(s)
- Shuqing Xu
- Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
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