1
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Backes A, Turchetto C, Mäder G, Segatto ALA, Bonatto SL, Freitas LB. Shades of white: The Petunia long corolla tube clade evolutionary history. Genet Mol Biol 2024; 47:e20230279. [PMID: 38385448 PMCID: PMC10882218 DOI: 10.1590/1415-4757-gmb-2023-0279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 12/21/2023] [Indexed: 02/23/2024] Open
Abstract
Delimiting species is challenging in recently diverged species, and adaptive radiation is fundamental to understanding the evolutionary processes because it requires multiple ecological opportunities associated with adaptation to biotic and abiotic environments. The young Petunia genus (Solanaceae) is an excellent opportunity to study speciation because of its association with pollinators and unique microenvironments. This study evaluated the phylogenetic relationships among a Petunia clade species with different floral syndromes that inhabit several environments. We based our work on multiple individuals per lineage and employed nuclear and plastid phylogenetic markers and nuclear microsatellites. The phylogenetic tree revealed two main groups regarding the elevation of the distribution range, whereas microsatellites showed high polymorphism-sharing splitting lineages into three clusters. Isolation by distance, migration followed by new environment colonization, and shifts in floral syndrome were the motors for lineage differentiation, including infraspecific structuring, which suggests the need for taxonomic revision in the genus.
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Affiliation(s)
- Alice Backes
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Porto Alegre, RS, Brazil
| | - Caroline Turchetto
- Universidade Federal do Rio Grande do Sul, Departamento de Botânica, Porto Alegre, RS, Brazil
| | - Geraldo Mäder
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Porto Alegre, RS, Brazil
| | - Ana Lúcia A Segatto
- Universidade Federal de Santa Maria, Departamento de Bioquímica e Biologia Molecular, Santa Maria, RS, Brazil
| | - Sandro L Bonatto
- Pontifícia Universidade Católica do Rio Grande do Sul, A Escola de Ciências da Saúde e da Vida, Porto Alegre, RS, Brazil
| | - Loreta B Freitas
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Porto Alegre, RS, Brazil
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2
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Stone BW, Wessinger CA. Ecological Diversification in an Adaptive Radiation of Plants: The Role of De Novo Mutation and Introgression. Mol Biol Evol 2024; 41:msae007. [PMID: 38232726 PMCID: PMC10826641 DOI: 10.1093/molbev/msae007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/01/2024] [Accepted: 01/10/2024] [Indexed: 01/19/2024] Open
Abstract
Adaptive radiations are characterized by rapid ecological diversification and speciation events, leading to fuzzy species boundaries between ecologically differentiated species. Adaptive radiations are therefore key systems for understanding how species are formed and maintained, including the role of de novo mutations versus preexisting variation in ecological adaptation and the genome-wide consequences of hybridization events. For example, adaptive introgression, where beneficial alleles are transferred between lineages through hybridization, may fuel diversification in adaptive radiations and facilitate adaptation to new environments. In this study, we employed whole-genome resequencing data to investigate the evolutionary origin of hummingbird-pollinated flowers and to characterize genome-wide patterns of phylogenetic discordance and introgression in Penstemon subgenus Dasanthera, a small and diverse adaptive radiation of plants. We found that magenta hummingbird-adapted flowers have apparently evolved twice from ancestral blue-violet bee-pollinated flowers within this radiation. These shifts in flower color are accompanied by a variety of inactivating mutations to a key anthocyanin pathway enzyme, suggesting that independent de novo loss-of-function mutations underlie the parallel evolution of this trait. Although patterns of introgression and phylogenetic discordance were heterogenous across the genome, a strong effect of gene density suggests that, in general, natural selection opposes introgression and maintains genetic differentiation in gene-rich genomic regions. Our results highlight the importance of both de novo mutation and introgression as sources of evolutionary change and indicate a role for de novo mutation in driving parallel evolution in adaptive radiations.
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Affiliation(s)
- Benjamin W Stone
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208-3401, USA
| | - Carolyn A Wessinger
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208-3401, USA
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3
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Stone BW, Wessinger CA. Ecological diversification in an adaptive radiation of plants: the role of de novo mutation and introgression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.01.565185. [PMID: 37961506 PMCID: PMC10635055 DOI: 10.1101/2023.11.01.565185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Adaptive radiations are characterized by rapid ecological diversification and speciation events, leading to fuzzy species boundaries between ecologically differentiated species. Adaptive radiations are therefore key systems for understanding how species are formed and maintained, including the role of de novo mutations vs. pre-existing variation in ecological adaptation and the genome-wide consequences of hybridization events. For example, adaptive introgression, where beneficial alleles are transferred between lineages through hybridization, may fuel diversification in adaptive radiations and facilitate adaptation to new environments. In this study, we employed whole-genome resequencing data to investigate the evolutionary origin of hummingbird-pollinated flowers and to characterize genome-wide patterns of phylogenetic discordance and introgression in Penstemon subgenus Dasanthera, a small and diverse adaptive radiation of plants. We found that magenta hummingbird-adapted flowers have apparently evolved twice from ancestral blue-violet bee-pollinated flowers within this radiation. These shifts in flower color are accompanied by a variety of inactivating mutations to a key anthocyanin pathway enzyme, suggesting that independent de novo loss-of-function mutations underlie parallel evolution of this trait. Although patterns of introgression and phylogenetic discordance were heterogenous across the genome, a strong effect of gene density suggests that, in general, natural selection opposes introgression and maintains genetic differentiation in gene-rich genomic regions. Our results highlight the importance of both de novo mutation and introgression as sources of evolutionary change and indicate a role for de novo mutation in driving parallel evolution in adaptive radiations.
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Affiliation(s)
- Benjamin W. Stone
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208-3401, USA
| | - Carolyn A. Wessinger
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208-3401, USA
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4
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Binaghi M, Esfeld K, Mandel T, Freitas LB, Roesti M, Kuhlemeier C. Genetic architecture of a pollinator shift and its fate in secondary hybrid zones of two Petunia species. BMC Biol 2023; 21:58. [PMID: 36941631 PMCID: PMC10029178 DOI: 10.1186/s12915-023-01561-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 03/10/2023] [Indexed: 03/23/2023] Open
Abstract
BACKGROUND Theory suggests that the genetic architecture of traits under divergent natural selection influences how easily reproductive barriers evolve and are maintained between species. Divergently selected traits with a simple genetic architecture (few loci with major phenotypic effects) should facilitate the establishment and maintenance of reproductive isolation between species that are still connected by some gene flow. While empirical support for this idea appears to be mixed, most studies test the influence of trait architectures on reproductive isolation only indirectly. Petunia plant species are, in part, reproductively isolated by their different pollinators. To investigate the genetic causes and consequences of this ecological isolation, we deciphered the genetic architecture of three floral pollination syndrome traits in naturally occurring hybrids between the widespread Petunia axillaris and the highly endemic and endangered P. exserta. RESULTS Using population genetics, Bayesian linear mixed modelling and genome-wide association studies, we found that the three pollination syndrome traits vary in genetic architecture. Few genome regions explain a majority of the variation in flavonol content (defining UV floral colour) and strongly predict the trait value in hybrids irrespective of interspecific admixture in the rest of their genomes. In contrast, variation in pistil exsertion and anthocyanin content (defining visible floral colour) is controlled by many genome-wide loci. Opposite to flavonol content, the genome-wide proportion of admixture between the two species predicts trait values in their hybrids. Finally, the genome regions strongly associated with the traits do not show extreme divergence between individuals representing the two species, suggesting that divergent selection on these genome regions is relatively weak within their contact zones. CONCLUSIONS Among the traits analysed, those with a more complex genetic architecture are best maintained in association with the species upon their secondary contact. We propose that this maintained genotype-phenotype association is a coincidental consequence of the complex genetic architectures of these traits: some of their many underlying small-effect loci are likely to be coincidentally linked with the actual barrier loci keeping these species partially isolated upon secondary contact. Hence, the genetic architecture of a trait seems to matter for the outcome of hybridization not only then when the trait itself is under selection.
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Affiliation(s)
- Marta Binaghi
- Institute of Plant Sciences, University of Bern, 3013, Bern, Switzerland
| | - Korinna Esfeld
- Institute of Plant Sciences, University of Bern, 3013, Bern, Switzerland
| | - Therese Mandel
- Institute of Plant Sciences, University of Bern, 3013, Bern, Switzerland
| | - Loreta B Freitas
- Department of Genetics, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, RS, 91501-970, Brazil
| | - Marius Roesti
- Institute of Ecology and Evolution, University of Bern, 3012, Bern, Switzerland
| | - Cris Kuhlemeier
- Institute of Plant Sciences, University of Bern, 3013, Bern, Switzerland.
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5
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Li C, Binaghi M, Pichon V, Cannarozzi G, Brandão de Freitas L, Hanemian M, Kuhlemeier C. Tight genetic linkage of genes causing hybrid necrosis and pollinator isolation between young species. NATURE PLANTS 2023; 9:420-432. [PMID: 36805038 PMCID: PMC10027609 DOI: 10.1038/s41477-023-01354-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 01/19/2023] [Indexed: 05/18/2023]
Abstract
The mechanisms of reproductive isolation that cause phenotypic diversification and eventually speciation are a major topic of evolutionary research. Hybrid necrosis is a post-zygotic isolation mechanism in which cell death develops in the absence of pathogens. It is often due to the incompatibility between proteins from two parents. Here we describe a unique case of hybrid necrosis due to an incompatibility between loci on chromosomes 2 and 7 between two pollinator-isolated Petunia species. Typical immune responses as well as endoplasmic reticulum stress responses are induced in the necrotic line. The locus on chromosome 2 encodes ChiA1, a bifunctional GH18 chitinase/lysozyme. The enzymatic activity of ChiA1 is dispensable for the development of necrosis. We propose that the extremely high expression of ChiA1 involves a positive feedback loop between the loci on chromosomes 2 and 7. ChiA1 is tightly linked to major genes involved in the adaptation to different pollinators, a form of pre-zygotic isolation. This linkage of pre- and post-zygotic barriers strengthens reproductive isolation and probably contributes to rapid diversification and speciation.
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Affiliation(s)
- Chaobin Li
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Marta Binaghi
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Vivien Pichon
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Gina Cannarozzi
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
- Chemistry/Biology/Pharmacy Information Center, ETH Zürich, Zürich, Switzerland
| | - Loreta Brandão de Freitas
- Department of Genetics, Laboratory of Molecular Evolution, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Mathieu Hanemian
- Institute of Plant Sciences, University of Bern, Bern, Switzerland.
- Laboratoire des Interactions Plantes-Microbes-Environnement (LIPME), INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France.
| | - Cris Kuhlemeier
- Institute of Plant Sciences, University of Bern, Bern, Switzerland.
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6
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Guzmán S, Giudicelli GC, Turchetto C, Bombarely A, Freitas LB. Neutral and outlier single nucleotide polymorphisms disentangle the evolutionary history of a coastal Solanaceae species. Mol Ecol 2022; 31:2847-2864. [PMID: 35332594 DOI: 10.1111/mec.16441] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 03/11/2022] [Accepted: 03/16/2022] [Indexed: 11/30/2022]
Abstract
Speciation begins with the isolation of some individuals or subpopulations due to drivers promoting a diverging genetic distribution. Such isolation may occur, followed by different processes and pressures. Isolation-by-distance (IBD), isolation-by-adaptation (IBA), and isolation-by-colonization (IBC) have been recognized as the main divergence patterns. Still, it is not easy to distinguish which one is the main pattern as each one may act at different points in time or even simultaneously. Using an extensive genome coverage from a Petunia species complex with coastal and inland distribution and multiple analytical approaches on population genomics and phylogeography, we showed a complex interplay between neutral and selective forces acting on the divergence process. We found 18,887 SNPs potentially neutral and 924 potentially under selection (outlier) loci. All analyses pointed that each subspecies displays its own genetic component and evolutionary history. We suggested plausible ecologic drivers for such divergence in a southernmost South Atlantic coastal plain in Brazil and Uruguay and identified a connection between adaptation and environment heterogeneity.
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Affiliation(s)
- Sebastián Guzmán
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Giovanna C Giudicelli
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Caroline Turchetto
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Department of Botany, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Loreta B Freitas
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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7
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Sun M, Zou P, Zhang W, Zhang L, Wang W, Liu G. The complete chloroplast genome of Petunia exserta (Solanaceae: Petunioideae), an endangered ornamental species. Mitochondrial DNA B Resour 2021; 6:2619-2621. [PMID: 34409158 PMCID: PMC8366615 DOI: 10.1080/23802359.2021.1962762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Petunia exserta is an ornamental species on the brink of extinction in the wild. We report here the complete chloroplast genome of P. exserta, which is 156,598 bp in size consisting of a large single-copy region (87,095 bp), a small single-copy region (18,643 bp), and a pair of inverted repeats (25,430 bp for each). The chloroplast (used ‘cp’ hereafter) genome contains 132 genes, including 8 rRNA genes, 37 tRNA genes, and 87 protein-coding genes. Phylogenetic analysis demonstrated that P. exserta was most closely related to P. hybrida, and they together were closer to Calibrachoa hybrida than other taxa in the Solanaceae family.
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Affiliation(s)
- Miaomiao Sun
- Department of Botany, Guangzhou Institute of Forestry and Landscape Architecture, Guangzhou, China
| | - Peishan Zou
- Department of Botany, Guangzhou Institute of Forestry and Landscape Architecture, Guangzhou, China
| | - Wei Zhang
- Key Laboratory of Horticulture Science for Southern Mountains Regions, Ministry of Education, College of Horticulture and Landscape Achitecture, Southwest University, Chongqing, China
| | - Linxia Zhang
- Key Laboratory of Horticulture Science for Southern Mountains Regions, Ministry of Education, College of Horticulture and Landscape Achitecture, Southwest University, Chongqing, China
| | - Wei Wang
- Department of Botany, Guangzhou Institute of Forestry and Landscape Architecture, Guangzhou, China
| | - Guofeng Liu
- Department of Botany, Guangzhou Institute of Forestry and Landscape Architecture, Guangzhou, China
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8
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Berardi AE, Esfeld K, Jäggi L, Mandel T, Cannarozzi GM, Kuhlemeier C. Complex evolution of novel red floral color in Petunia. THE PLANT CELL 2021; 33:2273-2295. [PMID: 33871652 PMCID: PMC8364234 DOI: 10.1093/plcell/koab114] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 04/12/2021] [Indexed: 05/20/2023]
Abstract
Red flower color has arisen multiple times and is generally associated with hummingbird pollination. The majority of evolutionary transitions to red color proceeded from purple lineages and tend to be genetically simple, almost always involving a few loss-of-function mutations of major phenotypic effect. Here we report on the complex evolution of a novel red floral color in the hummingbird-pollinated Petunia exserta (Solanaceae) from a colorless ancestor. The presence of a red color is remarkable because the genus cannot synthesize red anthocyanins and P. exserta retains a nonfunctional copy of the key MYB transcription factor AN2. We show that moderate upregulation and a shift in tissue specificity of an AN2 paralog, DEEP PURPLE, restores anthocyanin biosynthesis in P. exserta. An essential shift in anthocyanin hydroxylation occurred through rebalancing the expression of three hydroxylating genes. Furthermore, the downregulation of an acyltransferase promotes reddish hues in typically purple pigments by preventing acyl group decoration of anthocyanins. This study presents a rare case of a genetically complex evolutionary transition toward the gain of a novel red color.
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Affiliation(s)
- Andrea E. Berardi
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
| | - Korinna Esfeld
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
| | - Lea Jäggi
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
| | - Therese Mandel
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
| | | | - Cris Kuhlemeier
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
- Author for correspondence:
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9
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Xu YC, Guo YL. Less Is More, Natural Loss-of-Function Mutation Is a Strategy for Adaptation. PLANT COMMUNICATIONS 2020; 1:100103. [PMID: 33367264 PMCID: PMC7743898 DOI: 10.1016/j.xplc.2020.100103] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/08/2020] [Accepted: 08/12/2020] [Indexed: 05/12/2023]
Abstract
Gene gain and loss are crucial factors that shape the evolutionary success of diverse organisms. In the past two decades, more attention has been paid to the significance of gene gain through gene duplication or de novo genes. However, gene loss through natural loss-of-function (LoF) mutations, which is prevalent in the genomes of diverse organisms, has been largely ignored. With the development of sequencing techniques, many genomes have been sequenced across diverse species and can be used to study the evolutionary patterns of gene loss. In this review, we summarize recent advances in research on various aspects of LoF mutations, including their identification, evolutionary dynamics in natural populations, and functional effects. In particular, we discuss how LoF mutations can provide insights into the minimum gene set (or the essential gene set) of an organism. Furthermore, we emphasize their potential impact on adaptation. At the genome level, although most LoF mutations are neutral or deleterious, at least some of them are under positive selection and may contribute to biodiversity and adaptation. Overall, we highlight the importance of natural LoF mutations as a robust framework for understanding biological questions in general.
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Affiliation(s)
- Yong-Chao Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ya-Long Guo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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10
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Schnitzler CK, Turchetto C, Teixeira MC, Freitas LB. What could be the fate of secondary contact zones between closely related plant species? Genet Mol Biol 2020; 43:e20190271. [PMID: 32556035 PMCID: PMC7299303 DOI: 10.1590/1678-4685-gmb-2019-0271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 03/24/2020] [Indexed: 11/26/2022] Open
Abstract
Interspecific hybridization has been fundamental in plant evolution.
Nevertheless, the fate of hybrid zones throughout the generations remains poorly
addressed. We analyzed a pair of recently diverged, interfertile, and sympatric
Petunia species to ask what fate the interspecific hybrid
population has met over time. We analyzed the genetic diversity in two
generations from two contact sites and evaluated the effect of introgression. To
do this, we collected all adult plants from the contact zones, including
canonicals and intermediary colored individuals, and compared them with purebred
representatives of both species based on seven highly informative microsatellite
loci. We compared the genetic diversity observed in the contact zones with what
is seen in isolated populations of each species, considering two generations of
these annual species. Our results have confirmed the genetic differentiation
between the species and the hybrid origin of the majority of the intermediary
colored individuals. We also observed a differentiation related to genetic
variability and inbreeding levels among the populations. Over time, there were
no significant differences per site related to genetic diversity or phenotype
composition. We found two stable populations kept by high inbreeding and
backcross rates that influence the genetic diversity of their parental species
through introgression.
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Affiliation(s)
- Carolina K Schnitzler
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
| | - Caroline Turchetto
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
| | - Marcelo C Teixeira
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
| | - Loreta B Freitas
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
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11
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Abstract
Pollination is the transfer of pollen grains from the stamens to the stigma, an essential requirement of sexual reproduction in flowering plants. Cross-pollination increases genetic diversity and is favored by selection in the majority of situations. Flowering plants have evolved a wide variety of traits that influence pollination success, including those involved in optimization of self-pollination, attraction of animal pollinators, and the effective use of wind pollination. In this review we discuss our current understanding of the molecular basis of the development and production of these various traits. We conclude that recent integration of molecular developmental studies with population genetic approaches is improving our understanding of how selection acts on key floral traits in taxonomically diverse species, and that further work in nonmodel systems promises to provide exciting insights in the years to come.
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Affiliation(s)
- Róisín Fattorini
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom;
| | - Beverley J Glover
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom;
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12
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Esfeld K, Berardi AE, Moser M, Bossolini E, Freitas L, Kuhlemeier C. Pseudogenization and Resurrection of a Speciation Gene. Curr Biol 2018; 28:3776-3786.e7. [PMID: 30472000 DOI: 10.1016/j.cub.2018.10.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/05/2018] [Accepted: 10/05/2018] [Indexed: 12/13/2022]
Abstract
A persistent question in evolutionary biology is how complex phenotypes evolve and whether phenotypic transitions are reversible. Multiple losses of floral pigmentation have been documented in the angiosperms, but color re-gain has not yet been described, supporting that re-gain is unlikely. Pollinator-mediated selection in Petunia has resulted in several color shifts comprised of both losses and gains of color. The R2R3-MYB transcription factor AN2 has been identified as a major locus responsible for shifts in pollinator preference. Whereas the loss of visible color has previously been attributed to repeated pseudogenization of AN2, here, we describe the mechanism of an independent re-gain of floral color via AN2 evolution. In P. secreta, purple color is restored through the improbable resurrection of AN2 gene function from a non-functional AN2-ancestor by a single reading-frame-restoring mutation. Thus, floral color evolution in Petunia is mechanistically dependent on AN2 functionality, highlighting its role as a hotspot in color transitions and a speciation gene for the genus.
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Affiliation(s)
- Korinna Esfeld
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Andrea E Berardi
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Michel Moser
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Eligio Bossolini
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Loreta Freitas
- Department of Genetics, University Fed Rio Grande do Sul, POB 15053, Porto Alegre, 91501970 Rio Grande do Sul, Brazil
| | - Cris Kuhlemeier
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland.
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13
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Kholina AB, Kozyrenko MM, Artyukova EV, Sandanov DV. Modern State of Populations of Endemic Oxytropis Species from Baikal Siberia and Their Phylogenetic Relationships Based on Chloroplast DNA Markers. RUSS J GENET+ 2018. [DOI: 10.1134/s1022795418070050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Ma XG, Sun WG, Sun H. Historical introgression among the species of Rodgersia (Saxifragaceae) in mountainous forests of southwest China. Mol Phylogenet Evol 2018. [PMID: 29526806 DOI: 10.1016/j.ympev.2018.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In the present study, we used genetic data and ecological niche modelling to explore possible historical introgressions among the species of Rodgersia (Saxifragaceae) in central-southwest China. Markedly differentiated chloroplast haplotypes were found in R. aesculifolia, R. sambucifolia and the Lijiang (LJ) population of R. pinnata, respectively, and differentiated chloroplast haplotypes within each of them showed the closest relationships with haplotypes from different species. ITS cloning did not reveal any shared ribotype between R. aesculifolia and the remaining species. Historical introgression between R. aesculifolia and R. sambucifolia (or R. pinnata) seems to be the most plausible explanation according to the geographical pattern and derivative status of putative introgressed chloroplast haplotypes, and also from morphological evidence. Introgressions were also found among R. sambucifolia, R. pinnata, and R. henricii from Yunnan. Frequent gene exchanges may have promoted the diversity of leaf shapes in this genus. Ecological niche modelling indicated that past secondary contact following range shifts during Pleistocene cold periods may have provided opportunities for ancient introgression between R. aesculifolia and adjacent species.
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Affiliation(s)
- Xiang-Guang Ma
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, No. 132, Lanhei Road, Kunming, Yunnan 650201, China
| | - Wen-Guang Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, No. 132, Lanhei Road, Kunming, Yunnan 650201, China
| | - Hang Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, No. 132, Lanhei Road, Kunming, Yunnan 650201, China.
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Segatto ALA, Reck-Kortmann M, Turchetto C, Freitas LB. Multiple markers, niche modelling, and bioregions analyses to evaluate the genetic diversity of a plant species complex. BMC Evol Biol 2017; 17:234. [PMID: 29187208 PMCID: PMC5707870 DOI: 10.1186/s12862-017-1084-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 11/17/2017] [Indexed: 02/01/2023] Open
Abstract
Background The classification of closely related plants is not straightforward. These morphologically similar taxa frequently maintain their inter-hybridization potential and share ancestral polymorphisms as a consequence of their recent divergence. Under the biological species concept, they may thus not be considered separate species. The Petunia integrifolia complex is especially interesting because, in addition to the features mentioned above, its taxa share a pollinator, and their geographical ranges show multiple overlaps. Here, we combined plastid genome sequences, nuclear microsatellites, AFLP markers, ecological niche modelling, and bioregions analysis to investigate the genetic variability between the different taxa of the P. integrifolia complex in a comprehensive sample covering the entire geographical range of the complex. Results Results from molecular markers did not fully align with the current taxonomic classification. Niche modelling and bioregions analyses revealed that taxa were associated with different ecological constraints, indicating that the habitat plays an important role in preserving species boundaries. For three taxa, our analyses showed a mostly conserved, non-overlapping geographical distribution over time. However, for two taxa, niche modelling found an overlapping distribution over time; these taxa were also associated with the same bioregions. Conclusions cpDNA markers were better able to discriminate between Petunia taxa than SSRs and AFLPs. Overall, our results suggest that the P. integrifolia complex represents a continuum of individuals from distant and historically isolated populations, which share some morphological traits, but are established in four different evolutionary lineages. Electronic supplementary material The online version of this article (10.1186/s12862-017-1084-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ana Lúcia A Segatto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, RS, 91501-970, Brazil
| | - Maikel Reck-Kortmann
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, RS, 91501-970, Brazil
| | - Caroline Turchetto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, RS, 91501-970, Brazil
| | - Loreta B Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, RS, 91501-970, Brazil.
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16
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Amrad A, Moser M, Mandel T, de Vries M, Schuurink RC, Freitas L, Kuhlemeier C. Gain and Loss of Floral Scent Production through Changes in Structural Genes during Pollinator-Mediated Speciation. Curr Biol 2016; 26:3303-3312. [PMID: 27916524 DOI: 10.1016/j.cub.2016.10.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 10/06/2016] [Accepted: 10/12/2016] [Indexed: 10/20/2022]
Abstract
The interactions of plants with their pollinators are thought to be a driving force in the evolution of angiosperms. Adaptation to a new pollinator involves coordinated changes in multiple floral traits controlled by multiple genes. Surprisingly, such complex genetic shifts have happened numerous times during evolution. Here we report on the genetic basis of the changes in one such trait, floral scent emission, in the genus Petunia (Solanaceae). The increase in the quantity and complexity of the volatiles during the shift from bee to hawkmoth pollination was due to de novo expression of the genes encoding benzoic acid/salicylic acid carboxyl methyltransferase (BSMT) and benzoyl-CoA:benzylalcohol/2-phenylethanol benzoyltransferase (BPBT) together with moderately increased transcript levels for most enzymes of the phenylpropanoid/benzenoid pathway. Loss of cinnamate-CoA ligase (CNL) function as well as a reduction in the expression of the MYB transcription factor ODO1 explain the loss of scent during the transition from moth to hummingbird pollination. The CNL gene in the hummingbird-adapted species is inactive due to a stop codon, but also appears to have undergone further degradation over time. Therefore, we propose that loss of scent happened relatively early in the transition toward hummingbird pollination, and probably preceded the loss of UV-absorbing flavonols. The discovery that CNL is also involved in the loss of scent during the transition from outcrossing to selfing in Capsella (Brassicaceae) (see the accompanying paper) raises interesting questions about the possible causes of deep evolutionary conservation of the targets of evolutionary change.
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Affiliation(s)
- Avichai Amrad
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Michel Moser
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Therese Mandel
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
| | - Michel de Vries
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands
| | - Robert C Schuurink
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands
| | - Loreta Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Avenida Bento Goncalves, 9500 Porto Alegre, Brazil
| | - Cris Kuhlemeier
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland.
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Segatto ALA, Thompson CE, Freitas LB. Contribution of WUSCHEL-related homeobox (WOX) genes to identify the phylogenetic relationships among Petunia species. Genet Mol Biol 2016; 39:658-664. [PMID: 27768156 PMCID: PMC5127159 DOI: 10.1590/1678-4685-gmb-2016-0073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 07/31/2016] [Indexed: 12/14/2022] Open
Abstract
Developmental genes are believed to contribute to major changes during plant
evolution, from infrageneric to higher levels. Due to their putative high sequence
conservation, developmental genes are rarely used as molecular markers, and few
studies including these sequences at low taxonomic levels exist.
WUSCHEL-related homeobox genes (WOX) are
transcription factors exclusively present in plants and are involved in developmental
processes. In this study, we characterized the infrageneric genetic variation of
Petunia WOX genes. We obtained phylogenetic relationships
consistent with other phylogenies based on nuclear markers, but with higher
statistical support, resolution in terminals, and compatibility with flower
morphological changes.
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Affiliation(s)
- Ana Lúcia Anversa Segatto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Claudia Elizabeth Thompson
- Center for Biotechnology, Department of Molecular Biology and Biotechnology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Loreta Brandão Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
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18
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Turchetto C, Segatto ALA, Mäder G, Rodrigues DM, Bonatto SL, Freitas LB. High levels of genetic diversity and population structure in an endemic and rare species: implications for conservation. AOB PLANTS 2016; 8:plw002. [PMID: 26768602 PMCID: PMC4768524 DOI: 10.1093/aobpla/plw002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 01/05/2016] [Indexed: 05/23/2023]
Abstract
The analysis of genetic structure and variability of isolated species is of critical importance in evaluating whether stochastic or human-caused factors are affecting rare species. Low genetic diversity compromises the ability of populations to evolve and reduces their chances of survival under environmental changes. Petunia secreta, a rare and endemic species, is an annual and heliophilous herb that is bee-pollinated and easily recognizable by its purple and salverform corolla. It was described as a new species of the Petunia genus in 2005. Few individuals of P. secreta have been observed in nature and little is known about this species. All the natural populations of P. secreta that were found were studied using 15 microsatellite loci, two intergenic plastid sequences and morphological traits. Statistical analysis was performed to describe the genetic diversity of this rare species and the results compared with those of more widespread and frequent Petunia species from the same geographic area to understand whether factors associated with population size could affect rare species of this genus. The results showed that despite its rarity, P. secreta presented high genetic diversity that was equivalent to or even higher than that of widespread Petunia species. It was shown that this species is divided into two evolutionary lineages, and the genetic differentiation indices between them and other congeneric species presented different patterns. The major risk to P. secreta maintenance is its rarity, suggesting the necessity of a preservation programme and more biological and evolutionary studies that handle the two evolutionary lineages independently.
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Affiliation(s)
- Caroline Turchetto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, 91501-970 Rio Grande do Sul, Brazil
| | - Ana Lúcia A Segatto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, 91501-970 Rio Grande do Sul, Brazil
| | - Geraldo Mäder
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, 91501-970 Rio Grande do Sul, Brazil
| | - Daniele M Rodrigues
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, 91501-970 Rio Grande do Sul, Brazil
| | - Sandro L Bonatto
- Laboratory of Genomics and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, 90619-900 Rio Grande do Sul, Brazil
| | - Loreta B Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, 91501-970 Rio Grande do Sul, Brazil
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MYB-FL controls gain and loss of floral UV absorbance, a key trait affecting pollinator preference and reproductive isolation. Nat Genet 2015; 48:159-66. [PMID: 26656847 DOI: 10.1038/ng.3462] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/12/2015] [Indexed: 01/26/2023]
Abstract
Adaptations to new pollinators involve multiple floral traits, each requiring coordinated changes in multiple genes. Despite this genetic complexity, shifts in pollination syndromes have happened frequently during angiosperm evolution. Here we study the genetic basis of floral UV absorbance, a key trait for attracting nocturnal pollinators. In Petunia, mutations in a single gene, MYB-FL, explain two transitions in UV absorbance. A gain of UV absorbance in the transition from bee to moth pollination was determined by a cis-regulatory mutation, whereas a frameshift mutation caused subsequent loss of UV absorbance during the transition from moth to hummingbird pollination. The functional differences in MYB-FL provide insight into the process of speciation and clarify phylogenetic relationships between nascent species.
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20
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Turchetto C, Segatto ALA, Beduschi J, Bonatto SL, Freitas LB. Genetic differentiation and hybrid identification using microsatellite markers in closely related wild species. AOB PLANTS 2015; 7:plv084. [PMID: 26187606 PMCID: PMC4565426 DOI: 10.1093/aobpla/plv084] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/06/2015] [Indexed: 05/08/2023]
Abstract
Identifying the genetic basis of speciation is critical for understanding the evolutionary history of closely related wild species. Recently diverged species facilitate the study of speciation because many genetic and morphological characteristics are still shared by the organisms under study. The Petunia genus grows in South American grasslands and comprises both recently diverged wild species and commercial species. In this work, we analysed two closely related species: Petunia exserta, which has a narrow endemic range and grows exclusively in rocky shelters, and Petunia axillaris, which is widely distributed and comprises three allopatric subspecies. Petunia axillaris ssp. axillaris and P. exserta occur in sympatry, and putative hybrids between them have been identified. Here, we analysed 14 expressed sequence tag-simple sequence repeats (EST-SSRs) in 126 wild individuals and 13 putative morphological hybrids with the goals of identifying differentially encoded alleles to characterize their natural genetic diversity, establishing a genetic profile for each taxon and to verify the presence of hybridization signal. Overall, 143 alleles were identified and all taxa contained private alleles. Four major groups were identified in clustering analyses, which indicated that there are genetic distinctions among the groups. The markers evaluated here will be useful in evolutionary studies involving these species and may help categorize individuals by species, thus enabling the identification of hybrids between both their putative taxa. The individuals with intermediate morphology presented private alleles of their both putative parental species, although they showed a level of genetic mixing that was comparable with some of the individuals with typical P. exserta morphology. The EST-SSR markers scattered throughout the Petunia genome are very efficient tools for characterizing the genetic diversity in wild taxa of this genus and aid in identifying interspecific hybrids based on the presence of private alleles. These properties indicate that these markers will be helpful tools in evolutionary studies.
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Affiliation(s)
- Caroline Turchetto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil
| | - Ana Lúcia A Segatto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil
| | - Júlia Beduschi
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil
| | - Sandro L Bonatto
- Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil
| | - Loreta B Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil
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21
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Ramos-Fregonezi AMC, Fregonezi JN, Cybis GB, Fagundes NJR, Bonatto SL, Freitas LB. Were sea level changes during the Pleistocene in the South Atlantic Coastal Plain a driver of speciation in Petunia (Solanaceae)? BMC Evol Biol 2015; 15:92. [PMID: 25989835 PMCID: PMC4438590 DOI: 10.1186/s12862-015-0363-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 04/27/2015] [Indexed: 11/26/2022] Open
Abstract
Background Quaternary climatic changes led to variations in sea level and these variations played a significant role in the generation of marine terrace deposits in the South Atlantic Coastal Plain. The main consequence of the increase in sea level was local extinction or population displacement, such that coastal species would be found around the new coastline. Our main goal was to investigate the effects of sea level changes on the geographical structure and variability of genetic lineages from a Petunia species endemic to the South Atlantic Coastal Plain. We employed a phylogeographic approach based on plastid sequences obtained from individuals collected from the complete geographic distribution of Petunia integrifolia ssp. depauperata and its sister group. We used population genetics tests to evaluate the degree of genetic variation and structure among and within populations, and we used haplotype network analysis and Bayesian phylogenetic methods to estimate divergence times and population growth. Results We observed three major genetic lineages whose geographical distribution may be related to different transgression/regression events that occurred in this region during the Pleistocene. The divergence time between the monophyletic group P. integrifolia ssp. depauperata and its sister group (P. integrifolia ssp. integrifolia) was compatible with geological estimates of the availability of the coastal plain. Similarly, the origin of each genetic lineage is congruent with geological estimates of habitat availability. Conclusions Diversification of P. integrifolia ssp. depauperata possibly occurred as a consequence of the marine transgression/regression cycles during the Pleistocene. In periods of high sea level, plants were most likely restricted to a refuge area corresponding to fossil dunes and granitic hills, from which they colonized the coast once the sea level came down. The modern pattern of lineage geographical distribution and population variation was established by a range expansion with serial founder effects conditioned on soil availability. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0363-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aline M C Ramos-Fregonezi
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, Brazil.
| | - Jeferson N Fregonezi
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, Brazil.
| | - Gabriela B Cybis
- Department of Statistics, Universidade Federal do Rio Grande do Sul, P.O. Box 15080, Porto Alegre, Brazil.
| | - Nelson J R Fagundes
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, Brazil.
| | - Sandro L Bonatto
- Genomic and Molecular Biology Laboratory, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610 001, Porto Alegre, RS, Brazil.
| | - Loreta B Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, P.O. Box 15053, Porto Alegre, Brazil.
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22
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Hermann K, Klahre U, Venail J, Brandenburg A, Kuhlemeier C. The genetics of reproductive organ morphology in two Petunia species with contrasting pollination syndromes. PLANTA 2015; 241:1241-1254. [PMID: 25656052 DOI: 10.1007/s00425-015-2251-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/19/2015] [Indexed: 05/29/2023]
Abstract
Switches between pollination syndromes have happened frequently during angiosperm evolution. Using QTL mapping and reciprocal introgressions, we show that changes in reproductive organ morphology have a simple genetic basis. In animal-pollinated plants, flowers have evolved to optimize pollination efficiency by different pollinator guilds and hence reproductive success. The two Petunia species, P. axillaris and P. exserta, display pollination syndromes adapted to moth or hummingbird pollination. For the floral traits color and scent, genetic loci of large phenotypic effect have been well documented. However, such large-effect loci may be typical for shifts in simple biochemical traits, whereas the evolution of morphological traits may involve multiple mutations of small phenotypic effect. Here, we performed a quantitative trait locus (QTL) analysis of floral morphology, followed by an in-depth study of pistil and stamen morphology and the introgression of individual QTL into reciprocal parental backgrounds. Two QTLs, on chromosomes II and V, are sufficient to explain the interspecific difference in pistil and stamen length. Since most of the difference in organ length is caused by differences in cell number, genes underlying these QTLs are likely to be involved in cell cycle regulation. Interestingly, conservation of the locus on chromosome II in a different P. axillaris subspecies suggests that the evolution of organ elongation was initiated on chromosome II in adaptation to different pollinators. We recently showed that QTLs for pistil and stamen length on chromosome II are tightly linked to QTLs for petal color and volatile emission. Linkage of multiple traits will enable major phenotypic change within a few generations in hybridizing populations. Thus, the genomic architecture of pollination syndromes in Petunia allows for rapid responses to changing pollinator availability.
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Affiliation(s)
- Katrin Hermann
- Institute of Plant Sciences, Altenbergrain 21, 3013, Bern, Switzerland
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Turchetto C, Lima JS, Rodrigues DM, Bonatto SL, Freitas LB. Pollen dispersal and breeding structure in a hawkmoth-pollinated Pampa grasslands species Petunia axillaris (Solanaceae). ANNALS OF BOTANY 2015; 115:939-48. [PMID: 25808656 PMCID: PMC4407064 DOI: 10.1093/aob/mcv025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 02/03/2015] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS The evolution of selfing is one of the most common transitions in flowering plants, and this change in mating pattern has important systematic and ecological consequences because it often initiates reproductive isolation and speciation. Petunia axillaris (Solanaceae) includes three allopatric subspecies widely distributed in temperate South America that present different degrees of self-compatibity and incompatibility. One of these subspecies is co-distributed with P. exserta in a restricted area and presents a complex, not well-understood mating system. Artificial crossing experiments suggest a complex system of mating in this sympatric area. The main aims of this study were to estimate the pollen dispersal distance and to evaluate the breeding structure of P. axillaris subsp. axillaris, a hawkmoth-pollinated taxon from this sympatric zone. METHODS Pollen dispersal distance was compared with nearest-neighbours distance, and the differentiation in the pollen pool among mother plants was estimated. In addition, the correlation between genetic differentiation and spatial distance among plants was tested. All adult individuals (252) within a space of 2800 m(2) and 15 open-pollinated progeny (285 seedlings) were analysed. Genetic analyses were based on 12 polymorphic microsatellite loci. KEY RESULTS A high proportion of self-pollination was found, indicating a mixed-mating system. The maximum pollen dispersal distance was 1013 m, but most pollination events (96 %) occurred at a distance of 0 m, predominantly in an inbreeding system. Both parents among sampled individuals could be identifed in 60-85 % of the progeny. CONCLUSIONS The results show that most pollen dispersal in the hawkmoth-pollinated P. axillaris subsp. axillaris occurs within populations and there is a high proportion of inbreeding. This mating system appears to favour species integrity in a secondary contact zone with the congener species P. exserta.
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Affiliation(s)
- Caroline Turchetto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil
| | - Jacqueline S Lima
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil
| | - Daniele M Rodrigues
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil
| | - Sandro L Bonatto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil
| | - Loreta B Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil
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Reck-Kortmann M, Silva-Arias GA, Segatto ALA, Mäder G, Bonatto SL, de Freitas LB. Multilocus phylogeny reconstruction: new insights into the evolutionary history of the genus Petunia. Mol Phylogenet Evol 2014; 81:19-28. [PMID: 25196589 DOI: 10.1016/j.ympev.2014.08.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 08/18/2014] [Accepted: 08/22/2014] [Indexed: 12/25/2022]
Abstract
The phylogeny of Petunia species has been difficult to resolve, primarily due to the recent diversification of the genus. Several studies have included molecular data in phylogenetic reconstructions of this genus, but all of them have failed to include all taxa and/or analyzed few genetic markers. In the present study, we employed the most inclusive genetic and taxonomic datasets for the genus, aiming to reconstruct the evolutionary history of Petunia based on molecular phylogeny, biogeographic distribution, and character evolution. We included all 20 Petunia morphological species or subspecies in these analyses. Based on nine nuclear and five plastid DNA markers, our phylogenetic analysis reinforces the monophyly of the genus Petunia and supports the hypothesis that the basal divergence is more related to the differentiation of corolla tube length, whereas the geographic distribution of species is more related to divergences within these main clades. Ancestral area reconstructions suggest the Pampas region as the area of origin and earliest divergence in Petunia. The state reconstructions suggest that the ancestor of Petunia might have had a short corolla tube and a bee pollination floral syndrome.
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Affiliation(s)
- Maikel Reck-Kortmann
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91501-970, Brazil
| | - Gustavo Adolfo Silva-Arias
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91501-970, Brazil
| | - Ana Lúcia Anversa Segatto
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91501-970, Brazil
| | - Geraldo Mäder
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91501-970, Brazil
| | - Sandro Luis Bonatto
- Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS 90610-001, Brazil
| | - Loreta Brandão de Freitas
- Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91501-970, Brazil.
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