The Experts below are selected from a list of 558 Experts worldwide ranked by ideXlab platform
Angela Hay - One of the best experts on this subject based on the ideXlab platform.
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Fine-scale empirical data on niche divergence and homeolog expression patterns in an allopolyploid and its diploid progenitor species.
The New phytologist, 2020Co-Authors: Reiko Akiyama, Angela Hay, Miltos Tsiantis, Xiangchao Gan, Hiroshi Kudoh, Jianqiang Sun, Masaomi Hatakeyama, Heidi E. L. Lischer, Roman Briskine, Masahiro M. KanaokaAbstract:Polyploidization is pervasive in plants, but little is known about the niche divergence of wild allopolyploids (species that harbor polyploid genomes originating from different diploid species) relative to their diploid progenitor species and the gene expression patterns that may underlie such ecological divergence. We conducted a fine-scale empirical study on habitat and gene expression of an allopolyploid and its diploid progenitors. We quantified soil properties and light availability of habitats of an allotetraploid Cardamine flexuosa and its diploid progenitors Cardamine amara and Cardamine Hirsuta in two seasons. We analyzed expression patterns of genes and homeologs (homeologous gene copies in allopolyploids) using RNA sequencing. We detected niche divergence between the allopolyploid and its diploid progenitors along water availability gradient at a fine scale: the diploids in opposite extremes and the allopolyploid in a broader range between diploids, with limited overlap with diploids at both ends. Most of the genes whose homeolog expression ratio changed among habitats in C. flexuosa varied spatially and temporally. These findings provide empirical evidence for niche divergence between an allopolyploid and its diploid progenitor species at a fine scale and suggest that divergent expression patterns of homeologs in an allopolyploid may underlie its persistence in diverse habitats.
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seed coat development in explosively dispersed seeds of Cardamine Hirsuta
Annals of Botany, 2020Co-Authors: Ulla Neumann, Angela HayAbstract:BACKGROUND AND AIMS Seeds are dispersed by explosive coiling of the fruit valves in Cardamine Hirsuta. This rapid coiling launches the small seeds on ballistic trajectories to spread over a 2 m radius around the parent plant. The seed surface interacts with both the coiling fruit valve during launch and subsequently with the air during flight. We aim to identify features of the seed surface that may contribute to these interactions by characterizing seed coat differentiation. METHODS Differentiation of the outermost seed coat layers from the outer integuments of the ovule involves dramatic cellular changes that we characterize in detail at the light and electron microscopical level including immunofluorescence and immunogold labelling. KEY RESULTS We found that the two outer integument (oi) layers of the seed coat contributed differently to the topography of the seed surface in the explosively dispersed seeds of C. Hirsuta vs. the related species Arabidopsis thaliana where seed dispersal is non-explosive. The surface of A. thaliana seeds is shaped by the columella and the anticlinal cell walls of the epidermal oi2 layer. In contrast, the surface of C. Hirsuta seeds is shaped by a network of prominent ridges formed by the anticlinal walls of asymmetrically thickened cells of the sub-epidermal oi1 layer, especially at the seed margin. Both the oi2 and oi1 cell layers in C. Hirsuta seeds are characterized by specialized, pectin-rich cell walls that are deposited asymmetrically in the cell. CONCLUSIONS The two outermost seed coat layers in C. Hirsuta have distinct properties: the sub-epidermal oi1 layer determines the topography of the seed surface, while the epidermal oi2 layer accumulates mucilage. These properties are influenced by polar deposition of distinct pectin polysaccharides in the cell wall. Although the ridged seed surface formed by oi1 cell walls is associated with ballistic dispersal in C. Hirsuta, it is not restricted to explosively dispersed seeds in the Brassicaceae.
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Seed coat development in explosively dispersed seeds of Cardamine Hirsuta.
Annals of botany, 2019Co-Authors: Ulla Neumann, Angela HayAbstract:Seeds are dispersed by explosive coiling of the fruit valves in Cardamine Hirsuta. This rapid coiling launches the small seeds on ballistic trajectories to spread over a 2 m radius around the parent plant. The seed surface interacts with both the coiling fruit valve during launch and subsequently with the air during flight. We aim to identify features of the seed surface that may contribute to these interactions by characterizing seed coat differentiation. Differentiation of the outermost seed coat layers from the outer integuments of the ovule involves dramatic cellular changes that we characterize in detail at the light and electron microscopical level including immunofluorescence and immunogold labelling. We found that the two outer integument (oi) layers of the seed coat contributed differently to the topography of the seed surface in the explosively dispersed seeds of C. Hirsuta vs. the related species Arabidopsis thaliana where seed dispersal is non-explosive. The surface of A. thaliana seeds is shaped by the columella and the anticlinal cell walls of the epidermal oi2 layer. In contrast, the surface of C. Hirsuta seeds is shaped by a network of prominent ridges formed by the anticlinal walls of asymmetrically thickened cells of the sub-epidermal oi1 layer, especially at the seed margin. Both the oi2 and oi1 cell layers in C. Hirsuta seeds are characterized by specialized, pectin-rich cell walls that are deposited asymmetrically in the cell. The two outermost seed coat layers in C. Hirsuta have distinct properties: the sub-epidermal oi1 layer determines the topography of the seed surface, while the epidermal oi2 layer accumulates mucilage. These properties are influenced by polar deposition of distinct pectin polysaccharides in the cell wall. Although the ridged seed surface formed by oi1 cell walls is associated with ballistic dispersal in C. Hirsuta, it is not restricted to explosively dispersed seeds in the Brassicaceae. © The Author(s) 2019. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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The role of APETALA1 in petal number robustness.
eLife, 2018Co-Authors: Marie Monniaux, Bjorn Pieper, Sarah M. Mckim, Daniel Kierzkowski, Richard S. Smith, Anne-lise Routier-kierzkowska, Angela HayAbstract:Invariant floral forms are important for reproductive success and robust to natural perturbations. Petal number, for example, is invariant in Arabidopsis thaliana flowers. However, petal number varies in the closely related species Cardamine Hirsuta, and the genetic basis for this difference between species is unknown. Here we show that divergence in the pleiotropic floral regulator APETALA1 (AP1) can account for the species-specific difference in petal number robustness. This large effect of AP1 is explained by epistatic interactions: A. thaliana AP1 confers robustness by masking the phenotypic expression of quantitative trait loci controlling petal number in C. Hirsuta. We show that C. Hirsuta AP1 fails to complement this function of A. thaliana AP1, conferring variable petal number, and that upstream regulatory regions of AP1 contribute to this divergence. Moreover, variable petal number is maintained in C. Hirsuta despite sufficient standing genetic variation in natural accessions to produce plants with four-petalled flowers.
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Seasonal Regulation of Petal Number.
Plant physiology, 2017Co-Authors: Sarah M. Mckim, Miltos Tsiantis, Bjorn Pieper, Marie Monniaux, Daniel Kierzkowski, Richard S. Smith, Anne-lise Routier-kierzkowska, Angela HayAbstract:Four petals characterize the flowers of most species in the Brassicaceae family, and this phenotype is generally robust to genetic and environmental variation. A variable petal number distinguishes the flowers of Cardamine Hirsuta from those of its close relative Arabidopsis (Arabidopsis thaliana), and allelic variation at many loci contribute to this trait. However, it is less clear whether C. Hirsuta petal number varies in response to seasonal changes in environment. To address this question, we assessed whether petal number responds to a suite of environmental and endogenous cues that regulate flowering time in C. Hirsuta We found that petal number showed seasonal variation in C. Hirsuta, such that spring flowering plants developed more petals than those flowering in summer. Conditions associated with spring flowering, including cool ambient temperature, short photoperiod, and vernalization, all increased petal number in C. Hirsuta Cool temperature caused the strongest increase in petal number and lengthened the time interval over which floral meristems matured. We performed live imaging of early flower development and showed that floral buds developed more slowly at 15°C versus 20°C. This extended phase of floral meristem formation, coupled with slower growth of sepals at 15°C, produced larger intersepal regions with more space available for petal initiation. In summary, the growth and maturation of floral buds is associated with variable petal number in C. Hirsuta and responds to seasonal changes in ambient temperature.
Miltos Tsiantis - One of the best experts on this subject based on the ideXlab platform.
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Fine-scale empirical data on niche divergence and homeolog expression patterns in an allopolyploid and its diploid progenitor species.
The New phytologist, 2020Co-Authors: Reiko Akiyama, Angela Hay, Miltos Tsiantis, Xiangchao Gan, Hiroshi Kudoh, Jianqiang Sun, Masaomi Hatakeyama, Heidi E. L. Lischer, Roman Briskine, Masahiro M. KanaokaAbstract:Polyploidization is pervasive in plants, but little is known about the niche divergence of wild allopolyploids (species that harbor polyploid genomes originating from different diploid species) relative to their diploid progenitor species and the gene expression patterns that may underlie such ecological divergence. We conducted a fine-scale empirical study on habitat and gene expression of an allopolyploid and its diploid progenitors. We quantified soil properties and light availability of habitats of an allotetraploid Cardamine flexuosa and its diploid progenitors Cardamine amara and Cardamine Hirsuta in two seasons. We analyzed expression patterns of genes and homeologs (homeologous gene copies in allopolyploids) using RNA sequencing. We detected niche divergence between the allopolyploid and its diploid progenitors along water availability gradient at a fine scale: the diploids in opposite extremes and the allopolyploid in a broader range between diploids, with limited overlap with diploids at both ends. Most of the genes whose homeolog expression ratio changed among habitats in C. flexuosa varied spatially and temporally. These findings provide empirical evidence for niche divergence between an allopolyploid and its diploid progenitor species at a fine scale and suggest that divergent expression patterns of homeologs in an allopolyploid may underlie its persistence in diverse habitats.
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Adjustment of the PIF7-HFR1 transcriptional module activity controls plant shade adaptation.
The EMBO journal, 2020Co-Authors: Sandi Paulišić, Miltos Tsiantis, Christiane Then, Wenting Qin, Benjamin Alary, Harshul Arora Verasztó, Fabien Nogué, Michael Hothorn, Jaime F. Martínez-garcíaAbstract:Shade caused by the proximity of neighboring vegetation triggers a set of acclimation responses to either avoid or tolerate shade. Comparative analyses between the shade-avoider Arabidopsis thaliana and the shade-tolerant Cardamine Hirsuta revealed a role for the atypical basic-helix-loop-helix LONG HYPOCOTYL IN FR 1 (HFR1) in maintaining the shade tolerance in C. Hirsuta, inhibiting hypocotyl elongation in shade and constraining expression profile of shade-induced genes. We showed that C. Hirsuta HFR1 protein is more stable than its A. thaliana counterpart, likely due to its lower binding affinity to CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), contributing to enhance its biological activity. The enhanced HFR1 total activity is accompanied by an attenuated PHYTOCHROME INTERACTING FACTOR (PIF) activity in C. Hirsuta. As a result, the PIF-HFR1 module is differently balanced, causing a reduced PIF activity and attenuating other PIF-mediated responses such as warm temperature-induced hypocotyl elongation (thermomorphogenesis) and dark-induced senescence. By this mechanism and that of the already-known of phytochrome A photoreceptor, plants might ensure to properly adapt and thrive in habitats with disparate light amounts.
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Adaptation to plant shade relies on rebalancing the transcriptional activity of the PIF-HFR1 regulatory module
2020Co-Authors: Sandi Paulišić, Miltos Tsiantis, Christiane Then, Benjamin Alary, Fabien Nogué, Jaime F. Martínez-garcíaAbstract:Shade caused by the proximity of neighboring vegetation triggers a set of acclimation responses to either avoid or tolerate shade. Comparative analyses between the shade avoider Arabidopsis thaliana and the shade tolerant Cardamine Hirsuta, revealed a role for the atypical basic-helix-loop-helix LONG HYPOCOTYL IN FR 1 (HFR1) in maintaining the shade-tolerance in C. Hirsuta, inhibiting hypocotyl elongation in shade and constraining expression profile of shade induced genes. We showed that C. Hirsuta HFR1 protein is more stable than its A. thaliana counterpart, contributing to enhance its biological activity. The enhanced HFR1 activity is accompanied by an attenuated PHYTOCHROME INTERACTING FACTOR (PIF) activity in C. Hirsuta. As a result, the PIF-HFR1 module is imbalanced, causing a reduced PIF activity and attenuating other PIF-mediated responses such as warm temperature-induced hypocotyl elongation (thermomorphogenesis) and dark-induced senescence. By this mechanism and that of the already-known of phytochrome A photoreceptor, plants might ensure to properly adapt and thrive in habitats with disparate light amounts.
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CRISPR/Cas9-Mediated Mutagenesis of RCO in Cardamine Hirsuta
Plants (Basel Switzerland), 2020Co-Authors: Claire Lessa Alvim Kamei, Miltos Tsiantis, Bjorn Pieper, Stefan Laurent, Peter HuijserAbstract:The small crucifer Cardamine Hirsuta bears complex leaves divided into leaflets. This is in contrast to its relative, the reference plant Arabidopsis thaliana, which has simple leaves. Comparative studies between these species provide attractive opportunities to study the diversification of form. Here, we report on the implementation of the CRISPR/Cas9 genome editing methodology in C. Hirsuta and with it the generation of novel alleles in the RCO gene, which was previously shown to play a major role in the diversification of form between the two species. Thus, genome editing can now be deployed in C. Hirsuta, thereby increasing its versatility as a model system to study gene function and evolution.
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crispr cas9 mediated mutagenesis of rco in Cardamine Hirsuta
Plants (Basel Switzerland), 2020Co-Authors: Claire Lessa Alvim Kamei, Miltos Tsiantis, Bjorn Pieper, Stefan Laurent, Peter HuijserAbstract:The small crucifer Cardamine Hirsuta bears complex leaves divided into leaflets. This is in contrast to its relative, the reference plant Arabidopsis thaliana, which has simple leaves. Comparative studies between these species provide attractive opportunities to study the diversification of form. Here, we report on the implementation of the CRISPR/Cas9 genome editing methodology in C. Hirsuta and with it the generation of novel alleles in the RCO gene, which was previously shown to play a major role in the diversification of form between the two species. Thus, genome editing can now be deployed in C. Hirsuta, thereby increasing its versatility as a model system to study gene function and evolution.
Ulla Neumann - One of the best experts on this subject based on the ideXlab platform.
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seed coat development in explosively dispersed seeds of Cardamine Hirsuta
Annals of Botany, 2020Co-Authors: Ulla Neumann, Angela HayAbstract:BACKGROUND AND AIMS Seeds are dispersed by explosive coiling of the fruit valves in Cardamine Hirsuta. This rapid coiling launches the small seeds on ballistic trajectories to spread over a 2 m radius around the parent plant. The seed surface interacts with both the coiling fruit valve during launch and subsequently with the air during flight. We aim to identify features of the seed surface that may contribute to these interactions by characterizing seed coat differentiation. METHODS Differentiation of the outermost seed coat layers from the outer integuments of the ovule involves dramatic cellular changes that we characterize in detail at the light and electron microscopical level including immunofluorescence and immunogold labelling. KEY RESULTS We found that the two outer integument (oi) layers of the seed coat contributed differently to the topography of the seed surface in the explosively dispersed seeds of C. Hirsuta vs. the related species Arabidopsis thaliana where seed dispersal is non-explosive. The surface of A. thaliana seeds is shaped by the columella and the anticlinal cell walls of the epidermal oi2 layer. In contrast, the surface of C. Hirsuta seeds is shaped by a network of prominent ridges formed by the anticlinal walls of asymmetrically thickened cells of the sub-epidermal oi1 layer, especially at the seed margin. Both the oi2 and oi1 cell layers in C. Hirsuta seeds are characterized by specialized, pectin-rich cell walls that are deposited asymmetrically in the cell. CONCLUSIONS The two outermost seed coat layers in C. Hirsuta have distinct properties: the sub-epidermal oi1 layer determines the topography of the seed surface, while the epidermal oi2 layer accumulates mucilage. These properties are influenced by polar deposition of distinct pectin polysaccharides in the cell wall. Although the ridged seed surface formed by oi1 cell walls is associated with ballistic dispersal in C. Hirsuta, it is not restricted to explosively dispersed seeds in the Brassicaceae.
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Seed coat development in explosively dispersed seeds of Cardamine Hirsuta.
Annals of botany, 2019Co-Authors: Ulla Neumann, Angela HayAbstract:Seeds are dispersed by explosive coiling of the fruit valves in Cardamine Hirsuta. This rapid coiling launches the small seeds on ballistic trajectories to spread over a 2 m radius around the parent plant. The seed surface interacts with both the coiling fruit valve during launch and subsequently with the air during flight. We aim to identify features of the seed surface that may contribute to these interactions by characterizing seed coat differentiation. Differentiation of the outermost seed coat layers from the outer integuments of the ovule involves dramatic cellular changes that we characterize in detail at the light and electron microscopical level including immunofluorescence and immunogold labelling. We found that the two outer integument (oi) layers of the seed coat contributed differently to the topography of the seed surface in the explosively dispersed seeds of C. Hirsuta vs. the related species Arabidopsis thaliana where seed dispersal is non-explosive. The surface of A. thaliana seeds is shaped by the columella and the anticlinal cell walls of the epidermal oi2 layer. In contrast, the surface of C. Hirsuta seeds is shaped by a network of prominent ridges formed by the anticlinal walls of asymmetrically thickened cells of the sub-epidermal oi1 layer, especially at the seed margin. Both the oi2 and oi1 cell layers in C. Hirsuta seeds are characterized by specialized, pectin-rich cell walls that are deposited asymmetrically in the cell. The two outermost seed coat layers in C. Hirsuta have distinct properties: the sub-epidermal oi1 layer determines the topography of the seed surface, while the epidermal oi2 layer accumulates mucilage. These properties are influenced by polar deposition of distinct pectin polysaccharides in the cell wall. Although the ridged seed surface formed by oi1 cell walls is associated with ballistic dispersal in C. Hirsuta, it is not restricted to explosively dispersed seeds in the Brassicaceae. © The Author(s) 2019. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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The Cardamine Hirsuta genome offers insight into the evolution of morphological diversity
Nature Plants, 2016Co-Authors: Xiangchao Gan, Michiel Kwantes, Angela Hay, Georg Haberer, Asis Hallab, Raffaele Dello Ioio, Hugo Hofhuis, Bjorn Pieper, Maria Cartolano, Ulla NeumannAbstract:Finding causal relationships between genotypic and phenotypic variation is a key focus of evolutionary biology, human genetics and plant breeding. To identify genome-wide patterns underlying trait diversity, we assembled a high-quality reference genome of Cardamine Hirsuta , a close relative of the model plant Arabidopsis thaliana . We combined comparative genome and transcriptome analyses with the experimental tools available in C. Hirsuta to investigate gene function and phenotypic diversification. Our findings highlight the prevalent role of transcription factors and tandem gene duplications in morphological evolution. We identified a specific role for the transcriptional regulators PLETHORA5 / 7 in shaping leaf diversity and link tandem gene duplication with differential gene expression in the explosive seed pod of C. Hirsuta. Our work highlights the value of comparative approaches in genetically tractable species to understand the genetic basis for evolutionary change. By assembling the genome of Cardamine Hirsuta and conducting comparative genomic and transcriptomic analyses, a study reveals the prevalent role of transcription factors and gene duplication in morphological evolution.
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The Cardamine Hirsuta genome offers insight into the evolution of morphological diversity.
Nature plants, 2016Co-Authors: Xiangchao Gan, Michiel Kwantes, Angela Hay, Georg Haberer, Asis Hallab, Hugo Hofhuis, Bjorn Pieper, Maria Cartolano, Raffaele Dello Ioio, Ulla NeumannAbstract:Finding causal relationships between genotypic and phenotypic variation is a key focus of evolutionary biology, human genetics and plant breeding. To identify genome-wide patterns underlying trait diversity, we assembled a high-quality reference genome of Cardamine Hirsuta, a close relative of the model plant Arabidopsis thaliana. We combined comparative genome and transcriptome analyses with the experimental tools available in C. Hirsuta to investigate gene function and phenotypic diversification. Our findings highlight the prevalent role of transcription factors and tandem gene duplications in morphological evolution. We identified a specific role for the transcriptional regulators PLETHORA5/7 in shaping leaf diversity and link tandem gene duplication with differential gene expression in the explosive seed pod of C. Hirsuta. Our work highlights the value of comparative approaches in genetically tractable species to understand the genetic basis for evolutionary change.
Marie Monniaux - One of the best experts on this subject based on the ideXlab platform.
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The role of APETALA1 in petal number robustness.
eLife, 2018Co-Authors: Marie Monniaux, Bjorn Pieper, Sarah M. Mckim, Daniel Kierzkowski, Richard S. Smith, Anne-lise Routier-kierzkowska, Angela HayAbstract:Invariant floral forms are important for reproductive success and robust to natural perturbations. Petal number, for example, is invariant in Arabidopsis thaliana flowers. However, petal number varies in the closely related species Cardamine Hirsuta, and the genetic basis for this difference between species is unknown. Here we show that divergence in the pleiotropic floral regulator APETALA1 (AP1) can account for the species-specific difference in petal number robustness. This large effect of AP1 is explained by epistatic interactions: A. thaliana AP1 confers robustness by masking the phenotypic expression of quantitative trait loci controlling petal number in C. Hirsuta. We show that C. Hirsuta AP1 fails to complement this function of A. thaliana AP1, conferring variable petal number, and that upstream regulatory regions of AP1 contribute to this divergence. Moreover, variable petal number is maintained in C. Hirsuta despite sufficient standing genetic variation in natural accessions to produce plants with four-petalled flowers.
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Seasonal Regulation of Petal Number.
Plant physiology, 2017Co-Authors: Sarah M. Mckim, Miltos Tsiantis, Bjorn Pieper, Marie Monniaux, Daniel Kierzkowski, Richard S. Smith, Anne-lise Routier-kierzkowska, Angela HayAbstract:Four petals characterize the flowers of most species in the Brassicaceae family, and this phenotype is generally robust to genetic and environmental variation. A variable petal number distinguishes the flowers of Cardamine Hirsuta from those of its close relative Arabidopsis (Arabidopsis thaliana), and allelic variation at many loci contribute to this trait. However, it is less clear whether C. Hirsuta petal number varies in response to seasonal changes in environment. To address this question, we assessed whether petal number responds to a suite of environmental and endogenous cues that regulate flowering time in C. Hirsuta We found that petal number showed seasonal variation in C. Hirsuta, such that spring flowering plants developed more petals than those flowering in summer. Conditions associated with spring flowering, including cool ambient temperature, short photoperiod, and vernalization, all increased petal number in C. Hirsuta Cool temperature caused the strongest increase in petal number and lengthened the time interval over which floral meristems matured. We performed live imaging of early flower development and showed that floral buds developed more slowly at 15°C versus 20°C. This extended phase of floral meristem formation, coupled with slower growth of sepals at 15°C, produced larger intersepal regions with more space available for petal initiation. In summary, the growth and maturation of floral buds is associated with variable petal number in C. Hirsuta and responds to seasonal changes in ambient temperature.
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Conservation vs divergence in LEAFY and APETALA1 functions between Arabidopsis thaliana and Cardamine Hirsuta
The New phytologist, 2017Co-Authors: Marie Monniaux, Miltos Tsiantis, Maria Cartolano, Sarah M. Mckim, Emmanuel Thévenon, François Parcy, Angela HayAbstract:A conserved genetic toolkit underlies the development of diverse floral forms among angiosperms. However, the degree of conservation vs divergence in the configuration of these gene regulatory networks is less clear. We addressed this question in a parallel genetic study between the closely related species Arabidopsis thaliana and Cardamine Hirsuta. We identified leafy (lfy) and apetala1 (ap1) alleles in a mutant screen for floral regulators in C. Hirsuta. C. Hirsuta lfy mutants showed a complete homeotic conversion of flowers to leafy shoots, mimicking lfy ap1 double mutants in A. thaliana. Through genetic and molecular experiments, we showed that AP1 activation is fully dependent on LFY in C. Hirsuta, by contrast to A. thaliana. Additionally, we found that LFY influences heteroblasty in C. Hirsuta, such that loss or gain of LFY function affects its progression. Overexpression of UNUSUAL FLORAL ORGANS also alters C. Hirsuta leaf shape in an LFY-dependent manner. We found that LFY and AP1 are conserved floral regulators that act nonredundantly in C. Hirsuta, such that LFY has more obvious roles in floral and leaf development in C. Hirsuta than in A. thaliana.
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Cells, walls, and endless forms
Current Opinion in Plant Biology, 2016Co-Authors: Marie Monniaux, Angela HayAbstract:A key question in biology is how the endless diversity of forms found in nature evolved. Understanding the cellular basis of this diversity has been aided by advances in non-model experimental systems, quantitative image analysis tools, and modeling approaches. Recent work in plants highlights the importance of cell wall and cuticle modifications for the emergence of diverse forms and functions. For example, explosive seed dispersal in Cardamine Hirsuta depends on the asymmetric localization of lignified cell wall thickenings in the fruit valve. Similarly, the iridescence of Hibiscus trionum petals relies on regular striations formed by cuticular folds. Moreover, NAC transcription factors regulate the differentiation of lignified xylem vessels but also the water-conducting cells of moss that lack a lignified secondary cell wall, pointing to the origin of vascular systems. Other novel forms are associated with modified cell growth patterns, including oriented cell expansion or division, found in the long petal spurs of Aquilegia flowers, and the Sarracenia purpurea pitcher leaf, respectively. Another good example is the regulation of dissected leaf shape in C. Hirsuta via local growth repression, controlled by the REDUCED COMPLEXITY HD-ZIP class I transcription factor. These studies in non-model species often reveal as much about fundamental processes of development as they do about the evolution of form. Address
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Cells, walls, and endless forms
Current opinion in plant biology, 2016Co-Authors: Marie Monniaux, Angela HayAbstract:A key question in biology is how the endless diversity of forms found in nature evolved. Understanding the cellular basis of this diversity has been aided by advances in non-model experimental systems, quantitative image analysis tools, and modeling approaches. Recent work in plants highlights the importance of cell wall and cuticle modifications for the emergence of diverse forms and functions. For example, explosive seed dispersal in Cardamine Hirsuta depends on the asymmetric localization of lignified cell wall thickenings in the fruit valve. Similarly, the iridescence of Hibiscus trionum petals relies on regular striations formed by cuticular folds. Moreover, NAC transcription factors regulate the differentiation of lignified xylem vessels but also the water-conducting cells of moss that lack a lignified secondary cell wall, pointing to the origin of vascular systems. Other novel forms are associated with modified cell growth patterns, including oriented cell expansion or division, found in the long petal spurs of Aquilegia flowers, and the Sarracenia purpurea pitcher leaf, respectively. Another good example is the regulation of dissected leaf shape in C. Hirsuta via local growth repression, controlled by the REDUCED COMPLEXITY HD-ZIP class I transcription factor. These studies in non-model species often reveal as much about fundamental processes of development as they do about the evolution of form.
Bjorn Pieper - One of the best experts on this subject based on the ideXlab platform.
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CRISPR/Cas9-Mediated Mutagenesis of RCO in Cardamine Hirsuta
Plants (Basel Switzerland), 2020Co-Authors: Claire Lessa Alvim Kamei, Miltos Tsiantis, Bjorn Pieper, Stefan Laurent, Peter HuijserAbstract:The small crucifer Cardamine Hirsuta bears complex leaves divided into leaflets. This is in contrast to its relative, the reference plant Arabidopsis thaliana, which has simple leaves. Comparative studies between these species provide attractive opportunities to study the diversification of form. Here, we report on the implementation of the CRISPR/Cas9 genome editing methodology in C. Hirsuta and with it the generation of novel alleles in the RCO gene, which was previously shown to play a major role in the diversification of form between the two species. Thus, genome editing can now be deployed in C. Hirsuta, thereby increasing its versatility as a model system to study gene function and evolution.
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crispr cas9 mediated mutagenesis of rco in Cardamine Hirsuta
Plants (Basel Switzerland), 2020Co-Authors: Claire Lessa Alvim Kamei, Miltos Tsiantis, Bjorn Pieper, Stefan Laurent, Peter HuijserAbstract:The small crucifer Cardamine Hirsuta bears complex leaves divided into leaflets. This is in contrast to its relative, the reference plant Arabidopsis thaliana, which has simple leaves. Comparative studies between these species provide attractive opportunities to study the diversification of form. Here, we report on the implementation of the CRISPR/Cas9 genome editing methodology in C. Hirsuta and with it the generation of novel alleles in the RCO gene, which was previously shown to play a major role in the diversification of form between the two species. Thus, genome editing can now be deployed in C. Hirsuta, thereby increasing its versatility as a model system to study gene function and evolution.
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The role of APETALA1 in petal number robustness.
eLife, 2018Co-Authors: Marie Monniaux, Bjorn Pieper, Sarah M. Mckim, Daniel Kierzkowski, Richard S. Smith, Anne-lise Routier-kierzkowska, Angela HayAbstract:Invariant floral forms are important for reproductive success and robust to natural perturbations. Petal number, for example, is invariant in Arabidopsis thaliana flowers. However, petal number varies in the closely related species Cardamine Hirsuta, and the genetic basis for this difference between species is unknown. Here we show that divergence in the pleiotropic floral regulator APETALA1 (AP1) can account for the species-specific difference in petal number robustness. This large effect of AP1 is explained by epistatic interactions: A. thaliana AP1 confers robustness by masking the phenotypic expression of quantitative trait loci controlling petal number in C. Hirsuta. We show that C. Hirsuta AP1 fails to complement this function of A. thaliana AP1, conferring variable petal number, and that upstream regulatory regions of AP1 contribute to this divergence. Moreover, variable petal number is maintained in C. Hirsuta despite sufficient standing genetic variation in natural accessions to produce plants with four-petalled flowers.
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Seasonal Regulation of Petal Number.
Plant physiology, 2017Co-Authors: Sarah M. Mckim, Miltos Tsiantis, Bjorn Pieper, Marie Monniaux, Daniel Kierzkowski, Richard S. Smith, Anne-lise Routier-kierzkowska, Angela HayAbstract:Four petals characterize the flowers of most species in the Brassicaceae family, and this phenotype is generally robust to genetic and environmental variation. A variable petal number distinguishes the flowers of Cardamine Hirsuta from those of its close relative Arabidopsis (Arabidopsis thaliana), and allelic variation at many loci contribute to this trait. However, it is less clear whether C. Hirsuta petal number varies in response to seasonal changes in environment. To address this question, we assessed whether petal number responds to a suite of environmental and endogenous cues that regulate flowering time in C. Hirsuta We found that petal number showed seasonal variation in C. Hirsuta, such that spring flowering plants developed more petals than those flowering in summer. Conditions associated with spring flowering, including cool ambient temperature, short photoperiod, and vernalization, all increased petal number in C. Hirsuta Cool temperature caused the strongest increase in petal number and lengthened the time interval over which floral meristems matured. We performed live imaging of early flower development and showed that floral buds developed more slowly at 15°C versus 20°C. This extended phase of floral meristem formation, coupled with slower growth of sepals at 15°C, produced larger intersepal regions with more space available for petal initiation. In summary, the growth and maturation of floral buds is associated with variable petal number in C. Hirsuta and responds to seasonal changes in ambient temperature.
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The Cardamine Hirsuta genome offers insight into the evolution of morphological diversity
Nature Plants, 2016Co-Authors: Xiangchao Gan, Michiel Kwantes, Angela Hay, Georg Haberer, Asis Hallab, Raffaele Dello Ioio, Hugo Hofhuis, Bjorn Pieper, Maria Cartolano, Ulla NeumannAbstract:Finding causal relationships between genotypic and phenotypic variation is a key focus of evolutionary biology, human genetics and plant breeding. To identify genome-wide patterns underlying trait diversity, we assembled a high-quality reference genome of Cardamine Hirsuta , a close relative of the model plant Arabidopsis thaliana . We combined comparative genome and transcriptome analyses with the experimental tools available in C. Hirsuta to investigate gene function and phenotypic diversification. Our findings highlight the prevalent role of transcription factors and tandem gene duplications in morphological evolution. We identified a specific role for the transcriptional regulators PLETHORA5 / 7 in shaping leaf diversity and link tandem gene duplication with differential gene expression in the explosive seed pod of C. Hirsuta. Our work highlights the value of comparative approaches in genetically tractable species to understand the genetic basis for evolutionary change. By assembling the genome of Cardamine Hirsuta and conducting comparative genomic and transcriptomic analyses, a study reveals the prevalent role of transcription factors and gene duplication in morphological evolution.