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Zhang L, Li P, Zhang X, Li J. Two floral forms in the same species-distyly. PLANTA 2023; 258:72. [PMID: 37656285 DOI: 10.1007/s00425-023-04229-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 08/23/2023] [Indexed: 09/02/2023]
Abstract
MAIN CONCLUSION This paper reviews the progress of research on the morphology, physiology and molecular biology of distyly in plants. It will help to elucidate the mysteries of distyly in plants. Distyly is a unique representative type of heterostyly in plants, primarily characterized by the presence of long style and short style within the flowers of the same species. This interesting trait has always fascinated researchers. With the rapid development of molecular biology, the molecular mechanism for the production of dimorphic styles in plants is also gaining ground. Researchers have been studying plant dimorphic styles from various perspectives. The researchers are gradually unravelling the mechanisms by which plants produce distyly traits. This paper reviews advances in the study of plant dimorphic style characteristics, mainly in terms of the morphology, physiology and molecular biology of plants with dimorphic styles. The aim is to provide a theoretical basis for the study of the mechanism of distyly formation in plants.
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Affiliation(s)
- Lu Zhang
- College of Landscape and Tourism, Hebei Agricultural University, No. 289 Lingyusi Street, P. O. Box 28, Baoding, 071000, Hebei, China
| | - Ping Li
- College of Landscape and Tourism, Hebei Agricultural University, No. 289 Lingyusi Street, P. O. Box 28, Baoding, 071000, Hebei, China.
| | - Xiaoman Zhang
- College of Landscape and Tourism, Hebei Agricultural University, No. 289 Lingyusi Street, P. O. Box 28, Baoding, 071000, Hebei, China.
| | - Jinfeng Li
- College of Landscape and Tourism, Hebei Agricultural University, No. 289 Lingyusi Street, P. O. Box 28, Baoding, 071000, Hebei, China
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2
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Luo Z, Zhao Z, Xu Y, Shi M, Tu T, Pei N, Zhang D. Comprehensive transcriptomic profiling reveals complex molecular mechanisms in the regulation of style-length dimorphism in Guettarda speciosa (Rubiaceae), a species with "anomalous" distyly. FRONTIERS IN PLANT SCIENCE 2023; 14:1116078. [PMID: 37008460 PMCID: PMC10060554 DOI: 10.3389/fpls.2023.1116078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 02/16/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND The evolution of heterostyly, a genetically controlled floral polymorphism, has been a hotspot of research since the 19th century. In recent years, studies on the molecular mechanism of distyly (the most common form of heterostyly) revealed an evolutionary convergence in genes for brassinosteroids (BR) degradation in different angiosperm groups. This floral polymorphism often exhibits considerable variability that some taxa have significant stylar dimorphism, but anther height differs less. This phenomenon has been termed "anomalous" distyly, which is usually regarded as a transitional stage in evolution. Compared to "typical" distyly, the genetic regulation of "anomalous" distyly is almost unknown, leaving a big gap in our understanding of this special floral adaptation strategy. METHODS Here we performed the first molecular-level study focusing on this floral polymorphism in Guettarda speciosa (Rubiaceae), a tropical tree with "anomalous" distyly. Comprehensive transcriptomic profiling was conducted to examine which genes and metabolic pathways were involved in the genetic control of style dimorphism and if they exhibit similar convergence with "typical" distylous species. RESULTS "Brassinosteroid homeostasis" and "plant hormone signal transduction" was the most significantly enriched GO term and KEGG pathway in the comparisons between L- and S-morph styles, respectively. Interestingly, homologs of all the reported S-locus genes either showed very similar expressions between L- and S-morph styles or no hits were found in G. speciosa. BKI1, a negative regulator of brassinosteroid signaling directly repressing BRI1 signal transduction, was identified as a potential gene regulating style length, which significantly up-regulated in the styles of S-morph. DISCUSSION These findings supported the hypothesis that style length in G. speciosa was regulated through a BR-related signaling network in which BKI1 may be one key gene. Our data suggested, in species with "anomalous" distyly, style length was regulated by gene differential expressions, instead of the "hemizygous" S-locus genes in "typical" distylous flowers such as Primula and Gelsemium, representing an "intermediate" stage in the evolution of distyly. Genome-level analysis and functional studies in more species with "typical" and "anomalous" distyly would further decipher this "most complex marriage arrangement" in angiosperms and improve our knowledge of floral evolution.
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Affiliation(s)
- Zhonglai Luo
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, China
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Zhongtao Zhao
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Yuanqing Xu
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Miaomiao Shi
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Tieyao Tu
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Nancai Pei
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou, China
| | - Dianxiang Zhang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
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3
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Henning PM, Roalson EH, Mir W, McCubbin AG, Shore JS. Annotation of the Turnera subulata (Passifloraceae) Draft Genome Reveals the S-Locus Evolved after the Divergence of Turneroideae from Passifloroideae in a Stepwise Manner. PLANTS (BASEL, SWITZERLAND) 2023; 12:286. [PMID: 36679000 PMCID: PMC9862265 DOI: 10.3390/plants12020286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/27/2022] [Accepted: 01/03/2023] [Indexed: 06/17/2023]
Abstract
A majority of Turnera species (Passifloraceae) exhibit distyly, a reproductive system involving both self-incompatibility and reciprocal herkogamy. This system differs from self-incompatibility in Passiflora species. The genetic basis of distyly in Turnera is a supergene, restricted to the S-morph, and containing three S-genes. How supergenes and distyly evolved in Turnera, and the other Angiosperm families exhibiting distyly remain largely unknown. Unraveling the evolutionary origins in Turnera requires the generation of genomic resources and extensive phylogenetic analyses. Here, we present the annotated draft genome of the S-morph of distylous Turnera subulata. Our annotation allowed for phylogenetic analyses of the three S-genes' families across 56 plant species ranging from non-seed plants to eudicots. In addition to the phylogenetic analysis, we identified the three S-genes' closest paralogs in two species of Passiflora. Our analyses suggest that the S-locus evolved after the divergence of Passiflora and Turnera. Finally, to provide insights into the neofunctionalization of the S-genes, we compared expression patterns of the S-genes with close paralogs in Arabidopsis and Populus trichocarpa. The annotation of the T. subulata genome will provide a useful resource for future comparative work. Additionally, this work has provided insights into the convergent nature of distyly and the origin of supergenes.
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Affiliation(s)
- Paige M. Henning
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
- Center for Genomic Science Innovation, University of Wisconsin Madison, 425 Henry Mall, Madison, WI 53706-1577, USA
| | - Eric H. Roalson
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Wali Mir
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Andrew G. McCubbin
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Joel S. Shore
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
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4
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Henning PM, Shore JS, McCubbin AG. The S-Gene YUC6 Pleiotropically Determines Male Mating Type and Pollen Size in Heterostylous Turnera (Passifloraceae): A Novel Neofunctionalization of the YUCCA Gene Family. PLANTS (BASEL, SWITZERLAND) 2022; 11:2640. [PMID: 36235506 PMCID: PMC9572539 DOI: 10.3390/plants11192640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/27/2022] [Accepted: 10/05/2022] [Indexed: 06/16/2023]
Abstract
In heterostylous, self-incompatible Turnera species, a member of the YUCCA gene family, YUC6, resides at the S-locus and has been hypothesized to determine the male mating type. YUCCA gene family members synthesize the auxin, indole-3-acetic acid, via a two-step process involving the TAA gene family. Consequently, it has been speculated that differences in auxin concentration in developing anthers are the biochemical basis underlying the male mating type. Here, we provide empirical evidence that supports this hypothesis. Using a transgenic knockdown approach, we show that YUC6 acts pleiotropically to control both the male physiological mating type and pollen size, but not the filament length dimorphism associated with heterostyly in Turnera. Using qPCR to assess YUC6 expression in different transgenic lines, we demonstrate that the level of YUC6 knockdown correlates with the degree of change observed in the male mating type. Further assessment of YUC6 expression through anther development, in the knockdown lines, suggests that the male mating type is irreversibly determined during a specific developmental window prior to microsporogenesis, which is consistent with the genetically sporophytic nature of this self-incompatibility system. These results represent the first gene controlling male mating type to be characterized in any species with heterostyly.
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Affiliation(s)
- Paige M. Henning
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Joel S. Shore
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada
| | - Andrew G. McCubbin
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
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Genomic analyses of the Linum distyly supergene reveal convergent evolution at the molecular level. Curr Biol 2022; 32:4360-4371.e6. [PMID: 36087578 DOI: 10.1016/j.cub.2022.08.042] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/11/2022] [Accepted: 08/15/2022] [Indexed: 11/23/2022]
Abstract
Supergenes govern multi-trait-balanced polymorphisms in a wide range of systems; however, our understanding of their origins and evolution remains incomplete. The reciprocal placement of stigmas and anthers in pin and thrum floral morphs of distylous species constitutes an iconic example of a balanced polymorphism governed by a supergene, the distyly S-locus. Recent studies have shown that the Primula and Turnera distyly supergenes are both hemizygous in thrums, but it remains unknown whether hemizygosity is pervasive among distyly S-loci. As hemizygosity has major consequences for supergene evolution and loss, clarifying whether this genetic architecture is shared among distylous species is critical. Here, we have characterized the genetic architecture and evolution of the distyly supergene in Linum by generating a chromosome-level genome assembly of Linum tenue, followed by the identification of the S-locus using population genomic data. We show that hemizygosity and thrum-specific expression of S-linked genes, including a pistil-expressed candidate gene for style length, are major features of the Linum S-locus. Structural variation is likely instrumental for recombination suppression, and although the non-recombining dominant haplotype has accumulated transposable elements, S-linked genes are not under relaxed purifying selection. Our findings reveal remarkable convergence in the genetic architecture and evolution of independently derived distyly supergenes, provide a counterexample to classic inversion-based supergenes, and shed new light on the origin and maintenance of an iconic floral polymorphism.
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6
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You W, Chen X, Zeng L, Ma Z, Liu Z. Characterization of PISTILLATA-like Genes and Their Promoters from the Distyly Fagopyrum esculentum. PLANTS (BASEL, SWITZERLAND) 2022; 11:1047. [PMID: 35448776 PMCID: PMC9032694 DOI: 10.3390/plants11081047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/05/2022] [Accepted: 04/10/2022] [Indexed: 06/14/2023]
Abstract
Arabidopsis PISTILLATA (PI) encodes B-class MADS-box transcription factor (TF), and works together with APETALA3 (AP3) to specify petal and stamen identity. However, a small-scale gene duplication event of PI ortholog was observed in common buckwheat and resulted in FaesPI_1 and FaesPI_2. FaesPI_1 and FaesPI_2 were expressed only in the stamen of dimorphic flower (thrum and pin) of Fagopyrum esculentum. Moreover, intense beta-glucuronidase (GUS) staining was found in the entire stamen (filament and anther) in pFaesPI_1::GUS transgenic Arabidopsis, while GUS was expressed only in the filament of pFaesPI_2::GUS transgenic Arabidopsis. In addition, phenotype complementation analysis suggested that pFaesPI_1::FaesPI_1/pFaesPI_2::FaesPI_2 transgenic pi-1 Arabidopsis showed similar a flower structure with stamen-like organs or filament-like organs in the third whorl. This suggested that FaesPI_2 only specified filament development, but FaesPI_1 specified stamen development. Meanwhile, FaesPI_1 and FaesPI_2 were shown to function redundantly in regulating filament development, and both genes work together to require a proper stamen identity. The data also provide a clue to understanding the roles of PI-like genes involved in floral organ development during the early evolution of core eudicots and also suggested that FaesPI_1 and FaesPI_2 hold the potential application in bioengineering to develop a common buckwheat male sterile line.
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Potente G, Léveillé-Bourret É, Yousefi N, Choudhury RR, Keller B, Diop SI, Duijsings D, Pirovano W, Lenhard M, Szövényi P, Conti E. Comparative genomics elucidates the origin of a supergene controlling floral heteromorphism. Mol Biol Evol 2022; 39:6526404. [PMID: 35143659 PMCID: PMC8859637 DOI: 10.1093/molbev/msac035] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Supergenes are nonrecombining genomic regions ensuring the coinheritance of multiple, coadapted genes. Despite the importance of supergenes in adaptation, little is known on how they originate. A classic example of supergene is the S locus controlling heterostyly, a floral heteromorphism occurring in 28 angiosperm families. In Primula, heterostyly is characterized by the cooccurrence of two complementary, self-incompatible floral morphs and is controlled by five genes clustered in the hemizygous, ca. 300-kb S locus. Here, we present the first chromosome-scale genome assembly of any heterostylous species, that of Primula veris (cowslip). By leveraging the high contiguity of the P. veris assembly and comparative genomic analyses, we demonstrated that the S-locus evolved via multiple, asynchronous gene duplications and independent gene translocations. Furthermore, we discovered a new whole-genome duplication in Ericales that is specific to the Primula lineage. We also propose a mechanism for the origin of S-locus hemizygosity via nonhomologous recombination involving the newly discovered two pairs of CFB genes flanking the S locus. Finally, we detected only weak signatures of degeneration in the S locus, as predicted for hemizygous supergenes. The present study provides a useful resource for future research addressing key questions on the evolution of supergenes in general and the S locus in particular: How do supergenes arise? What is the role of genome architecture in the evolution of complex adaptations? Is the molecular architecture of heterostyly supergenes across angiosperms similar to that of Primula?
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Affiliation(s)
- Giacomo Potente
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.,BaseClear BV, Leiden, The Netherlands.,Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Étienne Léveillé-Bourret
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.,Institut de Recherche en Biologie Végétale and Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
| | - Narjes Yousefi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Rimjhim Roy Choudhury
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Barbara Keller
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Seydina Issa Diop
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.,BaseClear BV, Leiden, The Netherlands.,Zurich-Basel Plant Science Center, Zurich, Switzerland
| | | | | | - Michael Lenhard
- Institute for Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Péter Szövényi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.,Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Elena Conti
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.,Zurich-Basel Plant Science Center, Zurich, Switzerland
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Huu CN, Plaschil S, Himmelbach A, Kappel C, Lenhard M. Female self-incompatibility type in heterostylous Primula is determined by the brassinosteroid-inactivating cytochrome P450 CYP734A50. Curr Biol 2021; 32:671-676.e5. [PMID: 34906354 DOI: 10.1016/j.cub.2021.11.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 10/15/2021] [Accepted: 11/17/2021] [Indexed: 10/19/2022]
Abstract
Most flowering plants are hermaphrodites, with flowers having both male and female reproductive organs. One widespread adaptation to limit self-fertilization is self-incompatibility (SI), where self-pollen fails to fertilize ovules.1,2 In homomorphic SI, many morphologically indistinguishable mating types are found, although in heteromorphic SI, the two or three mating types are associated with different floral morphologies.3-6 In heterostylous Primula, a hemizygous supergene determines a short-styled S-morph and a long-styled L-morph, corresponding to two different mating types, and full seed set only results from intermorph crosses.7-9 Style length is controlled by the brassinosteroid (BR)-inactivating cytochrome P450 CYP734A50,10 yet it remains unclear what defines the male and female incompatibility types. Here, we show that CYP734A50 also determines the female incompatibility type. Inactivating CYP734A50 converts short S-morph styles into long styles with the same incompatibility behavior as L-morph styles, and this effect can be mimicked by exogenous BR treatment. In vitro responses of S- and L-morph pollen grains and pollen tubes to increasing BR levels could only partly explain their different in vivo behavior, suggesting both direct and indirect effects of the different BR levels in S- versus L-morph stigmas and styles in controlling pollen performance. This BR-mediated SI provides a novel mechanism for preventing self-fertilization. The joint control of morphology and SI by CYP734A50 has important implications for the evolutionary buildup of the heterostylous syndrome and provides a straightforward explanation for why essentially all of the derived self-compatible homostylous Primula species are long homostyles.11.
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Affiliation(s)
- Cuong Nguyen Huu
- University of Potsdam, Institute for Biochemistry and Biology, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany
| | - Sylvia Plaschil
- Julius Kühn-Institut (JKI) - Federal Research Centre for Cultivated Plants, Institute for Breeding Research on Horticultural Crops, Erwin-Baur-Str. 27, 06484 Quedlinburg, Germany
| | - Axel Himmelbach
- Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, Corrensstrasse 3, 06466 Stadt Seeland, Germany
| | - Christian Kappel
- University of Potsdam, Institute for Biochemistry and Biology, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany
| | - Michael Lenhard
- University of Potsdam, Institute for Biochemistry and Biology, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany.
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9
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Pistil Mating Type and Morphology Are Mediated by the Brassinosteroid Inactivating Activity of the S-Locus Gene BAHD in Heterostylous Turnera Species. Int J Mol Sci 2021; 22:ijms221910603. [PMID: 34638969 PMCID: PMC8509066 DOI: 10.3390/ijms221910603] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 09/23/2021] [Accepted: 09/28/2021] [Indexed: 01/05/2023] Open
Abstract
Heterostyly is a breeding system that promotes outbreeding through a combination of morphological and physiological floral traits. In Turnera these traits are governed by a single, hemizygous S-locus containing just three genes. We report that the S-locus gene, BAHD, is mutated and encodes a severely truncated protein in a self-compatible long homostyle species. Further, a self-compatible long homostyle mutant possesses a T. krapovickasii BAHD allele with a point mutation in a highly conserved domain of BAHD acyl transferases. Wild type and mutant TkBAHD alleles were expressed in Arabidopsis to assay for brassinosteroid (BR) inactivating activity. The wild type but not mutant allele caused dwarfism, consistent with the wild type possessing, but the mutant allele having lost, BR inactivating activity. To investigate whether BRs act directly in self-incompatibility, BRs were added to in vitro pollen cultures of the two mating types. A small morph specific stimulatory effect on pollen tube growth was found with 5 µM brassinolide, but no genotype specific inhibition was observed. These results suggest that BAHD acts pleiotropically to mediate pistil length and physiological mating type through BR inactivation, and that in regard to self-incompatibility, BR acts by differentially regulating gene expression in pistils, rather than directly on pollen.
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10
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Gutiérrez-Valencia J, Hughes PW, Berdan EL, Slotte T. The Genomic Architecture and Evolutionary Fates of Supergenes. Genome Biol Evol 2021; 13:6178796. [PMID: 33739390 PMCID: PMC8160319 DOI: 10.1093/gbe/evab057] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2021] [Indexed: 12/25/2022] Open
Abstract
Supergenes are genomic regions containing sets of tightly linked loci that control multi-trait phenotypic polymorphisms under balancing selection. Recent advances in genomics have uncovered significant variation in both the genomic architecture as well as the mode of origin of supergenes across diverse organismal systems. Although the role of genomic architecture for the origin of supergenes has been much discussed, differences in the genomic architecture also subsequently affect the evolutionary trajectory of supergenes and the rate of degeneration of supergene haplotypes. In this review, we synthesize recent genomic work and historical models of supergene evolution, highlighting how the genomic architecture of supergenes affects their evolutionary fate. We discuss how recent findings on classic supergenes involved in governing ant colony social form, mimicry in butterflies, and heterostyly in flowering plants relate to theoretical expectations. Furthermore, we use forward simulations to demonstrate that differences in genomic architecture affect the degeneration of supergenes. Finally, we discuss implications of the evolution of supergene haplotypes for the long-term fate of balanced polymorphisms governed by supergenes.
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Affiliation(s)
- Juanita Gutiérrez-Valencia
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - P William Hughes
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - Emma L Berdan
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
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11
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Keller B, Ganz R, Mora-Carrera E, Nowak MD, Theodoridis S, Koutroumpa K, Conti E. Asymmetries of reproductive isolation are reflected in directionalities of hybridization: integrative evidence on the complexity of species boundaries. THE NEW PHYTOLOGIST 2021; 229:1795-1809. [PMID: 32761901 DOI: 10.1111/nph.16849] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 07/23/2020] [Indexed: 05/26/2023]
Abstract
The complex nature of species boundaries has been a central topic in evolutionary biology ever since Darwin. Despite numerous separate studies on reproductive isolation and hybridization, their relationship remains underinvestigated. Are the strengths and asymmetries of reproductive barriers reflected in the extent and directionalities of interspecific genetic exchange? We combined field, experimental, and molecular data to quantify strengths and asymmetries of sympatric reproductive barriers and hybridization between florally heteromorphic primroses. We also assessed whether generalist pollinators discriminate between different floral cues and contribute to reproductive isolation, a long-debated topic. Sympatric reproductive isolation is high but incomplete, and most phenotypic intermediates are genetic F1 hybrids, whereas backcrosses are rare, revealing low interspecific gene flow. Species integrity rests on multiple barriers, but ethological isolation is among the strongest, demonstrating that even generalist pollinators crucially contribute to the maintenance of species boundaries. Furthermore, reproductive barriers are weaker for Primula veris and short-styled plants, results corroborated by molecular data. Thus, in florally heteromorphic systems, both species- and morph-dependent asymmetries affect permeability of species boundaries. Our study illustrates how the interactions between complex floral syndromes and pollinators shape species boundaries in unique, previously undescribed ways.
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Affiliation(s)
- Barbara Keller
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, 8008, Switzerland
| | - Rita Ganz
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, 8008, Switzerland
| | - Emiliano Mora-Carrera
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, 8008, Switzerland
| | - Michael D Nowak
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, 8008, Switzerland
| | - Spyros Theodoridis
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, 8008, Switzerland
| | - Konstantina Koutroumpa
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, 8008, Switzerland
| | - Elena Conti
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, 8008, Switzerland
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12
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Matzke CM, Shore JS, Neff MM, McCubbin AG. The Turnera Style S-Locus Gene TsBAHD Possesses Brassinosteroid-Inactivating Activity When Expressed in Arabidopsis thaliana. PLANTS 2020; 9:plants9111566. [PMID: 33202834 PMCID: PMC7697239 DOI: 10.3390/plants9111566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/06/2020] [Accepted: 11/11/2020] [Indexed: 11/29/2022]
Abstract
Heterostyly distinct hermaphroditic floral morphs enforce outbreeding. Morphs differ structurally, promote cross-pollination, and physiologically block self-fertilization. In Turnera the self-incompatibility (S)-locus controlling heterostyly possesses three genes specific to short-styled morph genomes. Only one gene, TsBAHD, is expressed in pistils and this has been hypothesized to possess brassinosteroid (BR)-inactivating activity. We tested this hypothesis using heterologous expression in Arabidopsis thaliana as a bioassay, thereby assessing growth phenotype, and the impacts on the expression of endogenous genes involved in BR homeostasis and seedling photomorphogenesis. Transgenic A. thaliana expressing TsBAHD displayed phenotypes typical of BR-deficient mutants, with phenotype severity dependent on TsBAHD expression level. BAS1, which encodes an enzyme involved in BR inactivation, was downregulated in TsBAHD-expressing lines. CPD and DWF, which encode enzymes involved in BR biosynthesis, were upregulated. Hypocotyl growth of TsBAHD dwarfs responded to application of brassinolide in light and dark in a manner typical of plants over-expressing genes encoding BR-inactivating activity. These results provide empirical support for the hypothesis that TsBAHD possesses BR-inactivating activity. Further this suggests that style length in Turnera is controlled by the same mechanism (BR inactivation) as that reported for Primula, but using a different class of enzyme. This reveals interesting convergent evolution in a biochemical mechanism to regulate floral form in heterostyly.
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Affiliation(s)
- Courtney M. Matzke
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA;
| | - Joel S. Shore
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J1P3, Canada;
| | - Michael M. Neff
- Department of Crops and Soils, Washington State University, PO Box 644236, Pullman, WA 99164, USA;
| | - Andrew G. McCubbin
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA;
- Correspondence:
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13
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Supergene evolution via stepwise duplications and neofunctionalization of a floral-organ identity gene. Proc Natl Acad Sci U S A 2020; 117:23148-23157. [PMID: 32868445 DOI: 10.1073/pnas.2006296117] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Heterostyly represents a fascinating adaptation to promote outbreeding in plants that evolved multiple times independently. While l-morph individuals form flowers with long styles, short anthers, and small pollen grains, S-morph individuals have flowers with short styles, long anthers, and large pollen grains. The difference between the morphs is controlled by an S-locus "supergene" consisting of several distinct genes that determine different traits of the syndrome and are held together, because recombination between them is suppressed. In Primula, the S locus is a roughly 300-kb hemizygous region containing five predicted genes. However, with one exception, their roles remain unclear, as does the evolutionary buildup of the S locus. Here we demonstrate that the MADS-box GLOBOSA2 (GLO2) gene at the S locus determines anther position. In Primula forbesii S-morph plants, GLO2 promotes growth by cell expansion in the fused tube of petals and stamen filaments beneath the anther insertion point; by contrast, neither pollen size nor male incompatibility is affected by GLO2 activity. The paralogue GLO1, from which GLO2 arose by duplication, has maintained the ancestral B-class function in specifying petal and stamen identity, indicating that GLO2 underwent neofunctionalization, likely at the level of the encoded protein. Genetic mapping and phylogenetic analysis indicate that the duplications giving rise to the style-length-determining gene CYP734A50 and to GLO2 occurred sequentially, with the CYP734A50 duplication likely the first. Together these results provide the most detailed insight into the assembly of a plant supergene yet and have important implications for the evolution of heterostyly.
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14
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Henning PM, Shore JS, McCubbin AG. Transcriptome and Network Analyses of Heterostyly in Turnera subulata Provide Mechanistic Insights: Are S-Loci a Red-Light for Pistil Elongation? PLANTS 2020; 9:plants9060713. [PMID: 32503265 PMCID: PMC7356734 DOI: 10.3390/plants9060713] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/21/2020] [Accepted: 05/29/2020] [Indexed: 12/19/2022]
Abstract
Heterostyly employs distinct hermaphroditic floral morphs to enforce outbreeding. Morphs differ structurally in stigma/anther positioning, promoting cross-pollination, and physiologically blocking self-fertilization. Heterostyly is controlled by a self-incompatibility (S)-locus of a small number of linked S-genes specific to short-styled morph genomes. Turnera possesses three S-genes, namely TsBAHD (controlling pistil characters), TsYUC6, and TsSPH1 (controlling stamen characters). Here, we compare pistil and stamen transcriptomes of floral morphs of T. subulata to investigate hypothesized S-gene function(s) and whether hormonal differences might contribute to physiological incompatibility. We then use network analyses to identify genetic networks underpinning heterostyly. We found a depletion of brassinosteroid-regulated genes in short styled (S)-morph pistils, consistent with hypothesized brassinosteroid-inactivating activity of TsBAHD. In S-morph anthers, auxin-regulated genes were enriched, consistent with hypothesized auxin biosynthesis activity of TsYUC6. Evidence was found for auxin elevation and brassinosteroid reduction in both pistils and stamens of S- relative to long styled (L)-morph flowers, consistent with reciprocal hormonal differences contributing to physiological incompatibility. Additional hormone pathways were also affected, however, suggesting S-gene activities intersect with a signaling hub. Interestingly, distinct S-genes controlling pistil length, from three species with independently evolved heterostyly, potentially intersect with phytochrome interacting factor (PIF) network hubs which mediate red/far-red light signaling. We propose that modification of the activities of PIF hubs by the S-locus could be a common theme in the evolution of heterostyly.
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Affiliation(s)
- Paige M. Henning
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA;
| | - Joel S. Shore
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J1P3, Canada;
| | - Andrew G. McCubbin
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA;
- Correspondence:
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15
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Shore JS, Hamam HJ, Chafe PDJ, Labonne JDJ, Henning PM, McCubbin AG. The long and short of the S-locus in Turnera (Passifloraceae). THE NEW PHYTOLOGIST 2019; 224:1316-1329. [PMID: 31144315 DOI: 10.1111/nph.15970] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 05/23/2019] [Indexed: 06/09/2023]
Abstract
Distyly is an intriguing floral adaptation that increases pollen transfer precision and restricts inbreeding. It has been a model system in evolutionary biology since Darwin. Although the S-locus determines the long- and short-styled morphs, the genes were unknown in Turnera. We have now identified these genes. We used deletion mapping to identify, and then sequence, BAC clones and genome scaffolds to construct S/s haplotypes. We investigated candidate gene expression, hemizygosity, and used mutants, to explore gene function. The s-haplotype possessed 21 genes collinear with a region of chromosome 7 of grape. The S-haplotype possessed three additional genes and two inversions. TsSPH1 was expressed in filaments and anthers, TsYUC6 in anthers and TsBAHD in pistils. Long-homostyle mutants did not possess TsBAHD and a short-homostyle mutant did not express TsSPH1. Three hemizygous genes appear to determine S-morph characteristics in T. subulata. Hemizygosity is common to all distylous species investigated, yet the genes differ. The pistil candidate gene, TsBAHD, differs from that of Primula, but both may inactivate brassinosteroids causing short styles. TsYUC6 is involved in auxin synthesis and likely determines pollen characteristics. TsSPH1 is likely involved in filament elongation. We propose an incompatibility mechanism involving TsYUC6 and TsBAHD.
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Affiliation(s)
- Joel S Shore
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Hasan J Hamam
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Paul D J Chafe
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Jonathan D J Labonne
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Paige M Henning
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164-4236, USA
| | - Andrew G McCubbin
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164-4236, USA
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16
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Barrett SCH. 'A most complex marriage arrangement': recent advances on heterostyly and unresolved questions. THE NEW PHYTOLOGIST 2019; 224:1051-1067. [PMID: 31631362 DOI: 10.1111/nph.16026] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 05/23/2019] [Indexed: 05/09/2023]
Abstract
Heterostylous genetic polymorphisms provide paradigmatic systems for investigating adaptation and natural selection. Populations are usually comprised of two (distyly) or three (tristyly) mating types, maintained by negative frequency-dependent selection resulting from disassortative mating. Theory predicts this mating system should result in equal style-morph ratios (isoplethy) at equilibrium. Here, I review recent advances on heterostyly, focusing on examples challenging stereotypical depictions of the polymorphism and unresolved questions. Comparative analyses indicate multiple origins of heterostyly, often within lineages. Ecological studies demonstrate that structural components of heterostyly are adaptations improving the proficiency of animal-mediated cross-pollination and reducing pollen wastage. Both neutral and selective processes cause deviations from isoplethy in heterostylous populations, and, under some ecological and demographic conditions, cause breakdown of the polymorphism, resulting in either the evolution of autogamy and mixed mating, or transitions to alternative outcrossing systems, including dioecy. Earlier ideas on the genetic architecture of the S-locus supergene governing distyly have recently been overturned by discovery that the dominant S-haplotype is a hemizygous region absent from the s-haplotype. Ecological, phylogenetic and molecular genetic data have validated some features of theoretical models on the selection of the polymorphism. Although heterostyly is the best-understood floral polymorphism in angiosperms, many unanswered questions remain.
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Affiliation(s)
- Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
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Hu D, Li W, Gao S, Lei T, Hu J, Shen P, Li Y, Li J. Untargeted metabolomic profiling reveals that different responses to self and cross pollination in each flower morph of the heteromorphic plant Plumbago auriculata. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2019; 144:413-426. [PMID: 31634809 DOI: 10.1016/j.plaphy.2019.10.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 10/08/2019] [Accepted: 10/08/2019] [Indexed: 06/10/2023]
Abstract
Heteromorphic self-incompatibility (HetSI), which is regulated by sporophytes, occurs in some species as a strategy to promote cross-pollination. This research aimed to reveal metabolic changes occurring in HetSI. We used fluorescence microscopy as a tool to compare growth behavior in self-incompatible (SI) and self-compatible (SC) pollination in both pin and thrum flowers of Plumbago auriculata and to identify the ideal timepoint for sample collection for subsequent experiments. We also employed scanning electron microscopy (SEM) to evaluate intermorph structural differences in the pollen grains and stigmas in relation to HetSI. Importantly, UPLC-MS/MS was applied in this study to identify metabolites, compare metabolic differences between pin and thrum styles and monitor metabolic changes in SC and SI pollinations in the two types of flowers. The metabolites mainly included amino acids/peptides, flavonoids, glycosides/sugars, phenols, other organic acids, fatty acids (derivatives)/lipids, amines, aldehydes, alkaloids, alcohols and other compounds. Surprisingly, energy-related nutrients such as amino acids/peptides and tricarboxylic acid cycle-related metabolites were found at higher levels in SI pollinations than in SC pollinations. This result indicates that physiological changes in pollen-stigma interactions differ in pin and thrum styles and SC and SI pollinations and that energy deficiency is not one of the reasons for HetSI.
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Affiliation(s)
- Di Hu
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
| | - Wenji Li
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
| | - Suping Gao
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
| | - Ting Lei
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
| | - Ju Hu
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
| | - Ping Shen
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
| | - Yurong Li
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
| | - Jiani Li
- Landscape Research Institute, Sichuan Agricultural University, Huimin Road 211, Wenjiang District, Chengdu, 611130, China.
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18
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Zhong L, Barrett SCH, Wang XJ, Wu ZK, Sun HY, Li DZ, Wang H, Zhou W. Phylogenomic analysis reveals multiple evolutionary origins of selfing from outcrossing in a lineage of heterostylous plants. THE NEW PHYTOLOGIST 2019; 224:1290-1303. [PMID: 31077611 DOI: 10.1111/nph.15905] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 05/01/2019] [Indexed: 06/09/2023]
Abstract
Evolutionary transitions from outcrossing to selfing often occur in heterostylous plants. Selfing homostyles originate within distylous populations and frequently evolve to become reproductively isolated species. We investigated this process in 10 species of Primula section Obconicolisteri using phylogenomic approaches and inferred how often homostyly originated from distyly and its consequences for population genetic diversity and floral trait evolution. We estimated phylogenetic relationships and reconstructed character evolution using the whole plastome comprised of 76 protein-coding genes. To investigate mating patterns and genetic diversity we screened 15 microsatellite loci in 40 populations. We compared floral traits among distylous and homostylous populations to determine how phenotypically differentiated homostyles were from their distylous ancestors. Section Obconicolisteri was monophyletic and we estimated multiple independent transitions from distyly to homostyly. High selfing rates characterised homostylous populations and this was associated with reduced genetic diversity. Flower size and pollen production were reduced in homostylous populations, but pollen size was significantly larger in some homostyles than in distylous morphs. Repeated transitions to selfing in section Obconicolisteri are likely to have been fostered by the complex montane environments that species occupy. Unsatisfactory pollinator service is likely to have promoted reproductive assurance in homostyles leading to subsequent population divergence through isolation.
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Affiliation(s)
- Li Zhong
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, China
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
| | - Xin-Jia Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, China
| | - Zhi-Kun Wu
- Department of Pharmacy, Guiyang University of Traditional Chinese Medicine, Guiyang, Guizhou, 550002, China
| | - Hua-Ying Sun
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
| | - De-Zhu Li
- Plant Germplasm and Genomics Centre, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
| | - Hong Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
| | - Wei Zhou
- Plant Germplasm and Genomics Centre, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
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Global transcriptome and gene co-expression network analyses on the development of distyly in Primula oreodoxa. Heredity (Edinb) 2019; 123:784-794. [PMID: 31308492 DOI: 10.1038/s41437-019-0250-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/27/2019] [Accepted: 06/27/2019] [Indexed: 12/14/2022] Open
Abstract
Distyly is a genetically controlled flower polymorphism that has intrigued both botanists and evolutionary biologists ever since Darwin's time. Despite extensive reports on the pollination and evolution of distylous systems, the genetic basis and mechanism of molecular regulation remain unclear. In the present study, comparative transcriptome profiling was conducted in primrose (Primula oreodoxa), the prime research model for heterostyly. Thirty-six transcriptomes were sequenced for styles at different stages and corolla tube in the three morphs of P. oreodoxa. Large numbers of differentially expressed genes (DEGs) were detected in the transcriptomes of styles across different morphs. Several transcription factors (TFs) and phytohormone metabolism-related genes were highlighted in S-morphs. A growing number of genes showed differential expression patterns along with the development of styles, suggesting that the genetic control of distyly may be more complicated than ever expected. Analysis of co-expression networks and module-trait relationships identified modules significantly associated with style development. CYP734A50, a key S-locus gene whose products degrade brassinosteroids, was co-expressed with many genes in the module and showed significant negative association with style length. In addition, crucial TFs involved in phytohormone signaling pathways were found to be connected with CYP734A50 in the co-expression module. Our global transcriptomic analysis has identified DEGs that are potentially involved in regulation of style length in P. oreodoxa, and may shed light on the evolution and broad biological processes of heterostyly.
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20
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Wang X, Zhong L, Wu Z, Sun H, Wang H, Li D, Barrett SCH, Zhou W. Characterization of 30 microsatellite markers in distylous Primula sinolisteri (Primulaceae) using HiSeq sequencing. APPLICATIONS IN PLANT SCIENCES 2019; 7:e01208. [PMID: 30693154 PMCID: PMC6342175 DOI: 10.1002/aps3.1208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Accepted: 10/23/2018] [Indexed: 06/09/2023]
Abstract
PREMISE OF THE STUDY Microsatellite markers were developed for Primula sinolisteri, a perennial distylous herb belonging to section Obconicolisteri (Primulaceae), to facilitate future investigations of the population genetics and mating patterns of populations in this species. METHODS AND RESULTS We developed 30 microsatellite markers for P. sinolisteri using HiSeq X-Ten sequencing and measured polymorphism and genetic diversity in a sample of 36 individuals from three natural populations. The markers displayed relatively high polymorphism, with the number of observed alleles per locus ranging from one to 19 (mean = 4.42). The observed and expected heterozygosity ranged from 0-1.000 and 0.083-0.882, respectively. Twenty-nine of the loci were also successfully amplified in homostylous P. sinolisteri var. aspera. CONCLUSIONS The microsatellite markers we have identified in P. sinolisteri provide powerful tools for investigating patterns of population genetic diversity and the evolutionary relationships between heterostyly and homostyly in this species.
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Affiliation(s)
- Xinjia Wang
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunming650201YunnanPeople's Republic of China
- University of the Chinese Academy of SciencesBeijing100049People's Republic of China
| | - Li Zhong
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunming650201YunnanPeople's Republic of China
- University of the Chinese Academy of SciencesBeijing100049People's Republic of China
| | - Zhikun Wu
- Department of PharmacyGuiyang University of Traditional Chinese MedicineGuiyang550002GuizhouPeople's Republic of China
| | - Huaying Sun
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunming650201YunnanPeople's Republic of China
| | - Hong Wang
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunming650201YunnanPeople's Republic of China
| | - Dezhu Li
- Plant Germplasm and Genomics CenterGermplasm Bank of Wild SpeciesKunming Institute of BotanyChinese Academy of SciencesKunming650201YunnanPeople's Republic of China
| | - Spencer C. H. Barrett
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioM5S 3B2Canada
| | - Wei Zhou
- Plant Germplasm and Genomics CenterGermplasm Bank of Wild SpeciesKunming Institute of BotanyChinese Academy of SciencesKunming650201YunnanPeople's Republic of China
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21
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Cocker JM, Wright J, Li J, Swarbreck D, Dyer S, Caccamo M, Gilmartin PM. Primula vulgaris (primrose) genome assembly, annotation and gene expression, with comparative genomics on the heterostyly supergene. Sci Rep 2018; 8:17942. [PMID: 30560928 PMCID: PMC6299000 DOI: 10.1038/s41598-018-36304-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 11/14/2018] [Indexed: 11/24/2022] Open
Abstract
Primula vulgaris (primrose) exhibits heterostyly: plants produce self-incompatible pin- or thrum-form flowers, with anthers and stigma at reciprocal heights. Darwin concluded that this arrangement promotes insect-mediated cross-pollination; later studies revealed control by a cluster of genes, or supergene, known as the S (Style length) locus. The P. vulgaris S locus is absent from pin plants and hemizygous in thrum plants (thrum-specific); mutation of S locus genes produces self-fertile homostyle flowers with anthers and stigma at equal heights. Here, we present a 411 Mb P. vulgaris genome assembly of a homozygous inbred long homostyle, representing ~87% of the genome. We annotate over 24,000 P. vulgaris genes, and reveal more genes up-regulated in thrum than pin flowers. We show reduced genomic read coverage across the S locus in other Primula species, including P. veris, where we define the conserved structure and expression of the S locus genes in thrum. Further analysis reveals the S locus has elevated repeat content (64%) compared to the wider genome (37%). Our studies suggest conservation of S locus genetic architecture in Primula, and provide a platform for identification and evolutionary analysis of the S locus and downstream targets that regulate heterostyly in diverse heterostylous species.
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Affiliation(s)
- Jonathan M Cocker
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom.,Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ, United Kingdom
| | - Jonathan Wright
- Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ, United Kingdom
| | - Jinhong Li
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom.,Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ, United Kingdom
| | - David Swarbreck
- Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ, United Kingdom
| | - Sarah Dyer
- National Institute for Agricultural Botany, Huntingdon Road, Cambridge, CB3 0LE, United Kingdom
| | - Mario Caccamo
- National Institute for Agricultural Botany, Huntingdon Road, Cambridge, CB3 0LE, United Kingdom
| | - Philip M Gilmartin
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom. .,Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ, United Kingdom.
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22
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Transcriptomics Investigation into the Mechanisms of Self-Incompatibility between Pin and Thrum Morphs of Primula maximowiczii. Int J Mol Sci 2018; 19:ijms19071840. [PMID: 29932122 PMCID: PMC6073747 DOI: 10.3390/ijms19071840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 06/13/2018] [Accepted: 06/17/2018] [Indexed: 11/17/2022] Open
Abstract
Heteromorphic self-incompatibility (SI) is an important system for preventing inbreeding in the genus Primula. However, investigations into the molecular mechanisms of Primula SI are lacking. To explore the mechanisms of SI in Primula maximowiczii, the pollen germination and fruiting rates of self- and cross-pollinations between pin and thrum morphs were investigated, and transcriptomics analyses of the pistils after pollination were performed to assess gene expression patterns in pin and thrum SI. The results indicated that P. maximowiczii exhibits strong SI and that the mechanisms of pollen tube inhibition differ between pin and thrum morphs. While self-pollen tubes of the pin morph were able to occasionally, though rarely, enter the style, those of the thrum morph were never observed to enter the style. The transcriptomics analysis of the pistils revealed 1311 and 1048 differentially expressed genes (DEGs) that were identified by comparing pin self-pollination (PS) vs. pin cross-pollination (PT) and thrum self-pollination (TS) vs. thrum cross-pollination (TP). Notably, about 90% of these DEGs exhibited different expression patterns in the two comparisons. Moreover, pin and thrum DEGs were associated with different Gene Ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways following enrichment analyses. Based on our results, the molecular mechanisms underlying the pin and thrum SI in P. maximowiczii appear to be distinct. Furthermore, the genes involved in the SI processes are commonly associated with carbohydrate metabolism and environmental adaptation. These results provide new insight into the molecular mechanisms of Primula SI.
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Yuan S, Barrett SCH, Li C, Li X, Xie K, Zhang D. Genetics of distyly and homostyly in a self-compatible Primula. Heredity (Edinb) 2018; 122:110-119. [PMID: 29728676 DOI: 10.1038/s41437-018-0081-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 03/16/2018] [Accepted: 03/17/2018] [Indexed: 12/23/2022] Open
Abstract
The transition from outcrossing to selfing through the breakdown of distyly to homostyly has occurred repeatedly among families of flowering plants. Homostyles can originate by major gene changes at the S-locus linkage group, or by unlinked polygenic modifiers. Here, we investigate the inheritance of distyly and homostyly in Primula oreodoxa, a subalpine herb endemic to Sichuan, China. Controlled self- and cross-pollinations confirmed that P. oreodoxa unlike most heterostylous species is fully self-compatible. Segregation patterns indicated that the inheritance of distyly is governed by a single Mendelian locus with the short-styled morph carrying at least one dominant S-allele (S-) and long-styled plants homozygous recessive (ss). Crossing data were consistent with a model in which homostyly results from genetic changes at the distylous linkage group, with the homostylous allele (Sh) dominant to the long-styled allele (s), but recessive to the short-styled allele (S). Progeny tests of open-pollinated seed families revealed high rates of intermorph mating in the L-morph but considerable selfing and possibly intramorph mating in the S-morph and in homostyles. S-morph plants homozygous at the S-locus (SS) occurred in several populations but may experience viability selection. The crossing data from distylous and homostylous plants are consistent with either recombination at the S-locus governing distyly, or mutation at gene(s) controlling sex-organ height; both models predict the same patterns of segregation. Recent studies on the molecular genetics of distyly in Primula demonstrating the hemizygous nature of genes at the S-locus make it more likely that homostyles have resulted from mutation rather than recombination.
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Affiliation(s)
- Shuai Yuan
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.,University of Chinese Academy of Sciences, Beijing, 10049, China
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, M5S 3B2, Canada
| | - Cehong Li
- Biological Resources Research Station at E'mei Mountain, Sichuan, Leshan, 614201, China
| | - Xiaojie Li
- Biological Resources Research Station at E'mei Mountain, Sichuan, Leshan, 614201, China
| | - Kongping Xie
- Biological Resources Research Station at E'mei Mountain, Sichuan, Leshan, 614201, China
| | - Dianxiang Zhang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
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Examination of S-Locus Regulated Differential Expression in Primula vulgaris Floral Development. PLANTS 2018; 7:plants7020038. [PMID: 29724049 PMCID: PMC6027539 DOI: 10.3390/plants7020038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/24/2018] [Accepted: 04/25/2018] [Indexed: 12/02/2022]
Abstract
Recent findings on the molecular basis of heteromorphic self-incompatibility in Primula have shown that the controlling self-incompatibility (S)-locus is not allelic, but is instead a small hemizygous region of only a few genes in the thrum genotype. How these genes alter the development of floral morphology and the specificity of self-incompatibility is still not completely clear. In order to start to identify genes regulated by the S-locus and elucidate the large-scale biological processes affected, we used RNA-seq data from floral buds of heteromorphic P. vulgaris pin (long style, short anthers) and thrum (short style, long anthers) morphs at early and late developmental time points. Differential expression between the two morphs was assessed at both time points and Gene Ontology term analyses of these gene sets were conducted. Our findings suggest that the S-locus regulates a large number of genes outside its physical bounds and likely sets up a cascade of expression changes. Additionally, we found evidence to suggest that there may be a timing difference in pollen development between the morphs, with pin pollen development proceeding earlier than thrum pollen development. This finding provides insight into how morphological differences in pollen between the morphs may be established, but intriguingly, could also be related to the self-incompatibility phenotype.
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Kappel C, Huu CN, Lenhard M. A short story gets longer: recent insights into the molecular basis of heterostyly. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:5719-5730. [PMID: 29099983 DOI: 10.1093/jxb/erx387] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 10/09/2017] [Indexed: 06/07/2023]
Abstract
Heterostyly is a fascinating adaptation to promote outbreeding and a classical paradigm of botany. In the most common type of heterostyly, plants either form flowers with long styles and short stamens, or short styles and long stamens. This reciprocal organ positioning reduces pollen wastage and promotes cross-pollination, thus increasing male fitness. In addition, in many heterostylous species selfing and the generation of unfit progeny due to inbreeding depression is limited by a self-incompatibility system, thus promoting female fitness. The two floral forms are genetically determined by the S locus as a complex supergene, namely a chromosomal region containing several individual genes that control the different traits, such as style or stamen length, and are held together by very tight linkage due to suppressed recombination. Recent molecular-genetic studies in several systems, including Turnera, Fagopyrum, Linum, and Primula have begun to identify and characterize the causal heterostyly genes residing at the S locus. An emerging theme from several families is that the dominant S haplotype represents a hemizygous region not present on the recessive s haplotype. This provides an explanation for the suppressed recombination and suggests a scenario for the chromosomal evolution of the S locus. In this review, we discuss the results from recent molecular-genetic analyses in light of the classical models on the genetics and evolution of heterostyly.
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Affiliation(s)
- Christian Kappel
- Institute for Biochemistry and Biology, University of Potsdam, Germany
| | - Cuong Nguyen Huu
- Institute for Biochemistry and Biology, University of Potsdam, Germany
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Yuan S, Barrett SCH, Duan T, Qian X, Shi M, Zhang D. Ecological correlates and genetic consequences of evolutionary transitions from distyly to homostyly. ANNALS OF BOTANY 2017; 120:775-789. [PMID: 28961784 PMCID: PMC5691548 DOI: 10.1093/aob/mcx098] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 07/29/2017] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND AIMS The outbreeding floral polymorphism heterostyly frequently breaks down, resulting in the evolution of self-fertilization as a result of homostyle formation. Here, the loss of floral polymorphism in distylous Primula oreodoxa, a sub-alpine species restricted to western Sichuan, China, was examined by investigating the ecological correlates and genetic consequences of mating system transitions. Several key questions were addressed. (1) What are the frequencies, geographical distribution and reproductive characteristics of floral morphs in distylous and homostylous populations? (2) Does increased elevation influence pollinator service and the likelihood of inbreeding in populations? (3) How often has homostyly originated and what are the consequences of the breakdown of distyly for the amounts and distribution of genetic diversity in populations? METHODS Fourteen populations throughout the range of P. oreodoxa were sampled, and morph frequencies and floral characteristics were recorded. Polymorphism at microsatellite loci and chloroplast DNA (cpDNA) variation were used to quantify population genetic structure and genetic relationships among populations. Controlled pollinations and studies of pollen tube growth and fertility were conducted to determine the compatibility status of populations and their facility for autonomous self-pollination. Finally, visitation rates of long- and short-tongued pollinators to distylous and homostylous populations at different elevations were compared to determine if increased elevation was associated with deterioration in pollinator service. KEY RESULTS In contrast to most heterostylous species, both distylous and homostylous morphs of P. oreodoxa are highly self-compatible, but only homostyles have the facility for autonomous self-pollination. Homostyles set significantly more fruit and seeds following open pollination than the distylous morphs. Visitation by long-tongued pollinators was significantly lower in homostylous populations, and overall rates of insect visitation decreased with elevation. Genetic diversity was significantly lower in homostylous populations, with evidence of increased inbreeding at higher elevation. Patterns of cpDNA variation were consistent with multiple transitions from distyly to homostyly and limited gene flow among populations. CONCLUSIONS The results of this study support the hypothesis that the multiple loss of floral polymorphism in distylous P. oreodoxa is associated with unsatisfactory pollinator service, with homostyles benefiting from reproductive assurance as a result of autonomous self-pollination.
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Affiliation(s)
- Shuai Yuan
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Tingting Duan
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Ocean University, Zhanjiang, China
| | - Xin Qian
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Miaomiao Shi
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Dianxiang Zhang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
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