The Experts below are selected from a list of 4263 Experts worldwide ranked by ideXlab platform
Teemu H Teeri - One of the best experts on this subject based on the ideXlab platform.
-
Floral developmental genetics of Gerbera (Asteraceae)
Advances in Botanical Research, 2020Co-Authors: Teemu H Teeri, Roosa A E Laitinen, Mika Kotilainen, Satu Ruokolainen, Yan Peng Ng, Suvi K Broholm, Anne Uimari, Ursula Malm, Eija Pöllänen, Paula ElomaaAbstract:Abstract Inflorescence development in the angiosperm family Asteraceae has distinct features not found in the traditional model systems (e.g., Arabidopsis, Petunia , and Zea ). In Gerbera hybrida , inflorescences are composed of morphologically different types of flowers tightly packed into a flower head (capitulum) that overtly resembles a single flower. Individual floral organs, such as pappus bristles (sepals), are developmentally specialized, petals and anthers form fused structures, stamens are aborted in marginal flowers, and ovaries are located inferior to other floral organs. These specific features have made Gerbera a rewarding target for comparative studies. We have shown that Gerbera MADS‐box genes that group phylogenetically with B‐ and C‐function genes from Arabidopsis and Antirrhinum function in organ determination in a very similar manner to their respective homologs from these model plants. However, MADS‐box genes encoding proteins that interact with those of the ABC‐genes behave differently. In Arabidopsis , three SEPALLATA ( SEP ) genes have redundant functions and are needed for development of petals, stamens, and carpels. Homologs of these SEP genes are found in Gerbera ( GRCD1, GRCD2 ), but they show functional specialization. GRCD1 is necessary for stamen development, but not for petal or carpel development. Similarly, GRCD2 has a homeotic function restricted to carpel development. Remarkably, downregulation of the latter also results in floral reversion (which occurs in ovaries) and alters inflorescence architecture by switching off terminal, determinate growth. This integrated SEP‐like control over reproductive meristem fate has not been detected in the well‐known model systems, which have a different carpel design and normally bear indeterminate inflorescences. Moreover, the organization of flowers on the Gerbera capitulum reveals the presence of a radial morphogenetic gradient that appears to regulate ABC and other MADS‐box genes differentially in a cell‐nonautonomous manner. As such, there is some commonality in gene regulatory features between Gerbera flowers and inflorescences, which suggests that Gerbera capitula are more than simple analogs of the flowers they bear.
-
functional characterization and expression of gascl1 and gascl2 two anther specific chalcone synthase like enzymes from Gerbera hybrida
Phytochemistry, 2017Co-Authors: Juha Kontturi, Xianbao Deng, Hany Bashandy, Victor A Albert, Raisa Osama, Teemu H TeeriAbstract:Abstract The chalcone synthase superfamily consists of type III polyketidesynthases (PKSs), enzymes responsible for producing plant secondary metabolites with various biological and pharmacological activities. Anther-specific chalcone synthase-like enzymes (ASCLs) represent an ancient group of type III PKSs involved in the biosynthesis of sporopollenin, the main component of the exine layer of moss spores and mature pollen grains of seed plants. In the latter, ASCL proteins are localized in the tapetal cells of the anther where they participate in sporopollenin biosynthesis and exine formation within the locule. It is thought that the enzymes responsible for sporopollenin biosynthesis are highly conserved, and thus far, each angiosperm species with a genome sequenced has possessed two ASCL genes, which in Arabidopsis thaliana are PKSA and PKSB. The Gerbera hybrida (Gerbera) PKS protein family consists of three chalcone synthases (GCHS1, GCHS3 and GCHS4) and three 2-pyrone synthases (G2PS1, G2PS2 and G2PS3). In previous studies we have demonstrated the functions of chalcone synthases in flavonoid biosynthesis, and the involvement of 2-pyrone synthases in the biosynthesis of antimicrobial compounds found in Gerbera. In this study we expanded the Gerbera PKS-family by functionally characterizing two Gerbera ASCL proteins. In vitro enzymatic studies using purified recombinant proteins showed that both GASCL1 and GASCL2 were able to use medium and long-chain acyl-CoA starters and perform two to three condensation reactions of malonyl-CoA to produce tri- and tetraketide 2-pyrones, usually referred to as alpha-pyrones in sporopollenin literature. Both GASCL1 and GASCL2 genes were expressed only in floral organs, with most expression observed in anthers. In the anthers, transcripts of both genes showed strict tapetum-specific localization.
-
two polyketide synthases are necessary for 4 hydroxy 5 methylcoumarin biosynthesis in Gerbera hybrida
Plant Journal, 2016Co-Authors: Milla Pietiainen, Xianbao Deng, Miia Ainasoja, Juha Kontturi, Tanja Paasela, Paulina Nyberg, Hannu Hotti, Teemu H TeeriAbstract:Summary Gerbera (Gerbera hybrida) is an economically important ornamental species and a model plant of the Asteraceae family for flower development and secondary metabolism. Gerberin and parasorboside, two bitter tasting glucosidic lactones, are produced in high amounts in nearly all Gerbera tissues. Gerbera and its close relatives also produce a rare coumarin, 4-hydroxy-5-methylcoumarin (HMC). Unlike most coumarins, 5-methylcoumarins have been suggested to be derived through the acetate-malonate pathway. All of these polyketide-derived glucosylated molecules are considered to have a role in defense against herbivores and phytopathogens in Gerbera. Gerbera expresses three genes encoding 2-pyrone synthases (G2PS1–3). The enzymes are chalcone synthase-like polyketide synthases with altered starter substrate specificity. We have shown previously that G2PS1 is responsible for the synthesis of 4-hydroxy-6-methyl-2-pyrone (triacetolactone), a putative precursor of gerberin and parasorboside. Here we show that polyketide synthases G2PS2 and G2PS3 are necessary for the biosynthesis of HMC in Gerbera, and that a reductase enzyme is likely required to complete the pathway to HMC. G2PS2 is expressed in the leaf blade and inflorescences of Gerbera, while G2PS3 is strictly root specific. Heterologous expression of G2PS2 or G2PS3 in tobacco leads to the formation of 4,7-dihydroxy-5-methylcoumarin, apparently an unreduced precursor of HMC, while ectopic expression in Gerbera leads to HMC formation in tissues where nontransgenic tissue does not express the genes and does not accumulate the compound. Using protein modelling and site-directed mutagenesis we identified the residues I203 and T344 in G2PS2 and G2PS3 to be critical for pentaketide synthase activity.
-
anthocyanin biosynthesis in Gerbera cultivar estelle and its acyanic sport ivory
Planta, 2015Co-Authors: Hany Bashandy, Milla Pietiainen, Paula Elomaa, Elisabete Carvalho, Stefan Martens, Teemu H TeeriAbstract:Identification of distinct allelic versions for dihydroflavonol 4-reductase in Gerbera cultivars reveals that Gerbera DFR enzymes have strong substrate preference in vivo that is not reflected to the activity in vitro. Flavonoids in the model ornamental plant Gerbera hybrida consist of flavones, flavonols and anthocyanins. Anthocyanins accumulate in the adaxial epidermis of petals and give the different cultivars their characteristic red and violet colour. Both pelargonidin and cyanidin derivatives are found in Gerbera, but none of the cultivars contain delphinidin. ‘Ivory’, a cultivar with white petals, is a sport of the pelargonidin-containing pink cultivar ‘Estelle’, i.e. it originates from an acyanic branch of ‘Estelle’. In this work, four different alleles encoding dihydroflavonol 4-reductase (DFR) were identified in Gerbera cultivars. We found that, in contrast to ‘Estelle’ with the functional allele GDFR1-2, ‘Ivory’ carries a mutation in this gene that results in an inactive enzyme. Interestingly, ‘Ivory’ also expresses a second, nonmutated allele (GDFR1-3) in petal epidermi, leading to extractable DFR activity but not to anthocyanin biosynthesis. The second allele encodes a protein identical in amino acid sequence to the DFR of the cyanidin-containing variety ‘President’. Pelargonidin-containing cultivars do not react to the flavonoid 3′-hydroxylase inhibitor tetcyclacis, but cyanidin-containing cultivars lose their colour, instead of starting to synthesise pelargonidins, indicating the specificity of GDFR1-3 for the cyanidin pathway. This explains why petals of ‘Ivory’ are white, even when it has lost only one of the two enzymatically functional DFR forms, and shows that anthocyanin biosynthesis in Gerbera is under more complex regulation than earlier thought.
-
virus induced gene silencing for asteraceae a reverse genetics approach for functional genomics in Gerbera hybrida
Plant Biotechnology Journal, 2012Co-Authors: Xianbao Deng, Jari P T Valkonen, Paula Elomaa, Cuong X Nguyen, Timo Hytonen, Teemu H TeeriAbstract:Summary Virus-induced gene silencing (VIGS) is a natural defence mechanism in plants which leads to sequence-specific degradation of viral RNA. For identifying gene functions, Tobacco rattle virus (TRV)-based VIGS has been applied for silencing of endogenous genes in many plant species. Gerbera hybrida (Asteraceae) has emerged as a novel model for studies in flower development and secondary metabolism. For this highly heterozygous species, functional studies have been conducted through reverse genetic methods by producing stable transgenic lines, which, however, is labour-intensive and time-consuming. For the development of TRVbased VIGS system for Gerbera, and for the first time for an Asteraceaeous species, we screened several Gerbera cultivars and optimized the agroinfiltration methods for efficient silencing. Gene fragments for Gerbera phytoene desaturase (GPDS) and Mg-chelatase subunits (GChl-H and GChl-I), expressed from a TRV vector, induced silencing phenotypes in leaves, scapes, and involucral bracts indicating their feasibility as markers for green tissues. In addition, robust silencing symptoms were achieved in Gerbera floral tissues by silencing the anthocyanin pathway gene for chalcone synthase (GCHS1) and a Gerbera B-type MADS-box gene globosa (GGLO1), confirming the phenotypes previously observed in stable transgenic lines. Unexpectedly, photobleaching induced by GPDS and GChl-H or GChl-I silencing, or by the herbicide norflurazon, resulted in silencing of the polyketide synthase gene G2PS1, which has no apparent connections to carotenoid or chlorophyll biosynthesis. We have shown feasibility of VIGS for functional studies in Gerbera, but our results also show that selection of the marker gene for silencing must be critically evaluated.
Paula Elomaa - One of the best experts on this subject based on the ideXlab platform.
-
Floral developmental genetics of Gerbera (Asteraceae)
Advances in Botanical Research, 2020Co-Authors: Teemu H Teeri, Roosa A E Laitinen, Mika Kotilainen, Satu Ruokolainen, Yan Peng Ng, Suvi K Broholm, Anne Uimari, Ursula Malm, Eija Pöllänen, Paula ElomaaAbstract:Abstract Inflorescence development in the angiosperm family Asteraceae has distinct features not found in the traditional model systems (e.g., Arabidopsis, Petunia , and Zea ). In Gerbera hybrida , inflorescences are composed of morphologically different types of flowers tightly packed into a flower head (capitulum) that overtly resembles a single flower. Individual floral organs, such as pappus bristles (sepals), are developmentally specialized, petals and anthers form fused structures, stamens are aborted in marginal flowers, and ovaries are located inferior to other floral organs. These specific features have made Gerbera a rewarding target for comparative studies. We have shown that Gerbera MADS‐box genes that group phylogenetically with B‐ and C‐function genes from Arabidopsis and Antirrhinum function in organ determination in a very similar manner to their respective homologs from these model plants. However, MADS‐box genes encoding proteins that interact with those of the ABC‐genes behave differently. In Arabidopsis , three SEPALLATA ( SEP ) genes have redundant functions and are needed for development of petals, stamens, and carpels. Homologs of these SEP genes are found in Gerbera ( GRCD1, GRCD2 ), but they show functional specialization. GRCD1 is necessary for stamen development, but not for petal or carpel development. Similarly, GRCD2 has a homeotic function restricted to carpel development. Remarkably, downregulation of the latter also results in floral reversion (which occurs in ovaries) and alters inflorescence architecture by switching off terminal, determinate growth. This integrated SEP‐like control over reproductive meristem fate has not been detected in the well‐known model systems, which have a different carpel design and normally bear indeterminate inflorescences. Moreover, the organization of flowers on the Gerbera capitulum reveals the presence of a radial morphogenetic gradient that appears to regulate ABC and other MADS‐box genes differentially in a cell‐nonautonomous manner. As such, there is some commonality in gene regulatory features between Gerbera flowers and inflorescences, which suggests that Gerbera capitula are more than simple analogs of the flowers they bear.
-
anthocyanin biosynthesis in Gerbera cultivar estelle and its acyanic sport ivory
Planta, 2015Co-Authors: Hany Bashandy, Milla Pietiainen, Paula Elomaa, Elisabete Carvalho, Stefan Martens, Teemu H TeeriAbstract:Identification of distinct allelic versions for dihydroflavonol 4-reductase in Gerbera cultivars reveals that Gerbera DFR enzymes have strong substrate preference in vivo that is not reflected to the activity in vitro. Flavonoids in the model ornamental plant Gerbera hybrida consist of flavones, flavonols and anthocyanins. Anthocyanins accumulate in the adaxial epidermis of petals and give the different cultivars their characteristic red and violet colour. Both pelargonidin and cyanidin derivatives are found in Gerbera, but none of the cultivars contain delphinidin. ‘Ivory’, a cultivar with white petals, is a sport of the pelargonidin-containing pink cultivar ‘Estelle’, i.e. it originates from an acyanic branch of ‘Estelle’. In this work, four different alleles encoding dihydroflavonol 4-reductase (DFR) were identified in Gerbera cultivars. We found that, in contrast to ‘Estelle’ with the functional allele GDFR1-2, ‘Ivory’ carries a mutation in this gene that results in an inactive enzyme. Interestingly, ‘Ivory’ also expresses a second, nonmutated allele (GDFR1-3) in petal epidermi, leading to extractable DFR activity but not to anthocyanin biosynthesis. The second allele encodes a protein identical in amino acid sequence to the DFR of the cyanidin-containing variety ‘President’. Pelargonidin-containing cultivars do not react to the flavonoid 3′-hydroxylase inhibitor tetcyclacis, but cyanidin-containing cultivars lose their colour, instead of starting to synthesise pelargonidins, indicating the specificity of GDFR1-3 for the cyanidin pathway. This explains why petals of ‘Ivory’ are white, even when it has lost only one of the two enzymatically functional DFR forms, and shows that anthocyanin biosynthesis in Gerbera is under more complex regulation than earlier thought.
-
functional diversification of duplicated chalcone synthase genes in anthocyanin biosynthesis of Gerbera hybrida
New Phytologist, 2014Co-Authors: Xianbao Deng, Hany Bashandy, Miia Ainasoja, Juha Kontturi, Milla Pietiainen, Roosa A E Laitinen, Victor A Albert, Jari P T Valkonen, Paula ElomaaAbstract:• Chalcone synthase (CHS) is the key enzyme in the first committed step of the flavonoid biosynthetic pathway and catalyzes the stepwise condensation of 4-coumaroyl-CoA and malonyl-CoA to naringenin chalcone. In plants, CHS is often encoded by a small family of genes that are temporally and spatially regulated. Our earlier studies have shown that GCHS4 is highly activated by ectopic expression of an MYB-type regulator GMYB10 in Gerbera (Gerbera hybrida). • The tissue- and development-specific expression patterns of three Gerbera CHS genes were examined. Virus-induced gene silencing (VIGS) was used to knock down GCHS1 and GCHS4 separately in Gerbera inflorescences. • Our data show that GCHS4 is the only CHS encoding gene that is expressed in the cyanidin-pigmented vegetative tissues of Gerbera cv Terraregina. GCHS3 expression is pronounced in the pappus bristles of the flowers. Expression of both GCHS1 and GCHS4 is high in the epidermal cells of Gerbera petals, but only GCHS1 is contributing to flavonoid biosynthesis. • Gerbera contains a family of three CHS encoding genes showing different spatial and temporal regulation. GCHS4 expression in Gerbera petals is regulated post-transcriptionally, at the level of either translation elongation or protein stability.
-
virus induced gene silencing for asteraceae a reverse genetics approach for functional genomics in Gerbera hybrida
Plant Biotechnology Journal, 2012Co-Authors: Xianbao Deng, Jari P T Valkonen, Paula Elomaa, Cuong X Nguyen, Timo Hytonen, Teemu H TeeriAbstract:Summary Virus-induced gene silencing (VIGS) is a natural defence mechanism in plants which leads to sequence-specific degradation of viral RNA. For identifying gene functions, Tobacco rattle virus (TRV)-based VIGS has been applied for silencing of endogenous genes in many plant species. Gerbera hybrida (Asteraceae) has emerged as a novel model for studies in flower development and secondary metabolism. For this highly heterozygous species, functional studies have been conducted through reverse genetic methods by producing stable transgenic lines, which, however, is labour-intensive and time-consuming. For the development of TRVbased VIGS system for Gerbera, and for the first time for an Asteraceaeous species, we screened several Gerbera cultivars and optimized the agroinfiltration methods for efficient silencing. Gene fragments for Gerbera phytoene desaturase (GPDS) and Mg-chelatase subunits (GChl-H and GChl-I), expressed from a TRV vector, induced silencing phenotypes in leaves, scapes, and involucral bracts indicating their feasibility as markers for green tissues. In addition, robust silencing symptoms were achieved in Gerbera floral tissues by silencing the anthocyanin pathway gene for chalcone synthase (GCHS1) and a Gerbera B-type MADS-box gene globosa (GGLO1), confirming the phenotypes previously observed in stable transgenic lines. Unexpectedly, photobleaching induced by GPDS and GChl-H or GChl-I silencing, or by the herbicide norflurazon, resulted in silencing of the polyketide synthase gene G2PS1, which has no apparent connections to carotenoid or chlorophyll biosynthesis. We have shown feasibility of VIGS for functional studies in Gerbera, but our results also show that selection of the marker gene for silencing must be critically evaluated.
-
evolution and diversification of the cyc tb1 gene family in asteraceae a comparative study in Gerbera mutisieae and sunflower heliantheae
Molecular Biology and Evolution, 2012Co-Authors: Sari Tahtiharju, Victor A Albert, Teemu H Teeri, Anneke S Rijpkema, Adrien Vetterli, Paula ElomaaAbstract:Plant-specific TCP domain transcription factors have been shown to regulate morphological novelties during plant evolution, including the complex architecture of the Asteraceae inflorescence that involves different types of flowers. We conducted comparative analysis of the CYCLOIDEA/TEOSINTE BRANCHED1 (CYC/TB1) gene family in Gerbera hybrida (Gerbera) and Helianthus annuus (sunflower), two species that represent distant tribes within Asteraceae. Our data confirm that the CYC/TB1 gene family has expanded in Asteraceae, a condition that appears to be connected with the increased developmental complexity and evolutionary success of this large plant family. Phylogenetic analysis of the CYC/TB1 gene family revealed both shared and lineage-specific duplications in Gerbera and sunflower, corresponding to the three gene lineages previously identified as specific to core eudicots: CYC1, CYC2, and CYC3. Expression analyses of early stages of flower primordia development indicated that especially within the CYC2 clade, with the greatest number of secondary gene duplications, gene expression patterns are conserved between the species and associated with flower and inflorescence development. All sunflower and Gerbera CYC2 clade genes showed differential expression between developing flower types, being upregulated in marginal ray (and trans) flowers. One gene in Gerbera (GhCYC3) and two in sunflower (HaCYC2d and HaCYC2c) were indicated to be strong candidates as regulators of ray flower identity, a function that is specific for Asteraceae. Our data further showed that other CYC2 clade genes are likely to have more specialized functions at the level of single flowers, including the late functions in floral reproductive organs that may be more conserved across plant families. The expression patterns of CYC1 and CYC3 clade genes showed more differences between the two species but still pointed to possible conserved functions during vegetative plant development. Pairwise protein– protein interaction assays gave the first molecular evidence that CYC/TB1-like proteins function in complexes. Compared with sunflower, the Gerbera proteins showed higher capacity for dimerization, between as well as within CYC clades. Our data from two distant species within the Asteraceae suggest that the expansion and the apparent conservation of especially the CYC2 clade CYC/TB1-like genes are associated with the evolution of the increased complexity of the Asteraceae inflorescence architecture.
Victor A Albert - One of the best experts on this subject based on the ideXlab platform.
-
functional characterization and expression of gascl1 and gascl2 two anther specific chalcone synthase like enzymes from Gerbera hybrida
Phytochemistry, 2017Co-Authors: Juha Kontturi, Xianbao Deng, Hany Bashandy, Victor A Albert, Raisa Osama, Teemu H TeeriAbstract:Abstract The chalcone synthase superfamily consists of type III polyketidesynthases (PKSs), enzymes responsible for producing plant secondary metabolites with various biological and pharmacological activities. Anther-specific chalcone synthase-like enzymes (ASCLs) represent an ancient group of type III PKSs involved in the biosynthesis of sporopollenin, the main component of the exine layer of moss spores and mature pollen grains of seed plants. In the latter, ASCL proteins are localized in the tapetal cells of the anther where they participate in sporopollenin biosynthesis and exine formation within the locule. It is thought that the enzymes responsible for sporopollenin biosynthesis are highly conserved, and thus far, each angiosperm species with a genome sequenced has possessed two ASCL genes, which in Arabidopsis thaliana are PKSA and PKSB. The Gerbera hybrida (Gerbera) PKS protein family consists of three chalcone synthases (GCHS1, GCHS3 and GCHS4) and three 2-pyrone synthases (G2PS1, G2PS2 and G2PS3). In previous studies we have demonstrated the functions of chalcone synthases in flavonoid biosynthesis, and the involvement of 2-pyrone synthases in the biosynthesis of antimicrobial compounds found in Gerbera. In this study we expanded the Gerbera PKS-family by functionally characterizing two Gerbera ASCL proteins. In vitro enzymatic studies using purified recombinant proteins showed that both GASCL1 and GASCL2 were able to use medium and long-chain acyl-CoA starters and perform two to three condensation reactions of malonyl-CoA to produce tri- and tetraketide 2-pyrones, usually referred to as alpha-pyrones in sporopollenin literature. Both GASCL1 and GASCL2 genes were expressed only in floral organs, with most expression observed in anthers. In the anthers, transcripts of both genes showed strict tapetum-specific localization.
-
functional diversification of duplicated chalcone synthase genes in anthocyanin biosynthesis of Gerbera hybrida
New Phytologist, 2014Co-Authors: Xianbao Deng, Hany Bashandy, Miia Ainasoja, Juha Kontturi, Milla Pietiainen, Roosa A E Laitinen, Victor A Albert, Jari P T Valkonen, Paula ElomaaAbstract:• Chalcone synthase (CHS) is the key enzyme in the first committed step of the flavonoid biosynthetic pathway and catalyzes the stepwise condensation of 4-coumaroyl-CoA and malonyl-CoA to naringenin chalcone. In plants, CHS is often encoded by a small family of genes that are temporally and spatially regulated. Our earlier studies have shown that GCHS4 is highly activated by ectopic expression of an MYB-type regulator GMYB10 in Gerbera (Gerbera hybrida). • The tissue- and development-specific expression patterns of three Gerbera CHS genes were examined. Virus-induced gene silencing (VIGS) was used to knock down GCHS1 and GCHS4 separately in Gerbera inflorescences. • Our data show that GCHS4 is the only CHS encoding gene that is expressed in the cyanidin-pigmented vegetative tissues of Gerbera cv Terraregina. GCHS3 expression is pronounced in the pappus bristles of the flowers. Expression of both GCHS1 and GCHS4 is high in the epidermal cells of Gerbera petals, but only GCHS1 is contributing to flavonoid biosynthesis. • Gerbera contains a family of three CHS encoding genes showing different spatial and temporal regulation. GCHS4 expression in Gerbera petals is regulated post-transcriptionally, at the level of either translation elongation or protein stability.
-
evolution and diversification of the cyc tb1 gene family in asteraceae a comparative study in Gerbera mutisieae and sunflower heliantheae
Molecular Biology and Evolution, 2012Co-Authors: Sari Tahtiharju, Victor A Albert, Teemu H Teeri, Anneke S Rijpkema, Adrien Vetterli, Paula ElomaaAbstract:Plant-specific TCP domain transcription factors have been shown to regulate morphological novelties during plant evolution, including the complex architecture of the Asteraceae inflorescence that involves different types of flowers. We conducted comparative analysis of the CYCLOIDEA/TEOSINTE BRANCHED1 (CYC/TB1) gene family in Gerbera hybrida (Gerbera) and Helianthus annuus (sunflower), two species that represent distant tribes within Asteraceae. Our data confirm that the CYC/TB1 gene family has expanded in Asteraceae, a condition that appears to be connected with the increased developmental complexity and evolutionary success of this large plant family. Phylogenetic analysis of the CYC/TB1 gene family revealed both shared and lineage-specific duplications in Gerbera and sunflower, corresponding to the three gene lineages previously identified as specific to core eudicots: CYC1, CYC2, and CYC3. Expression analyses of early stages of flower primordia development indicated that especially within the CYC2 clade, with the greatest number of secondary gene duplications, gene expression patterns are conserved between the species and associated with flower and inflorescence development. All sunflower and Gerbera CYC2 clade genes showed differential expression between developing flower types, being upregulated in marginal ray (and trans) flowers. One gene in Gerbera (GhCYC3) and two in sunflower (HaCYC2d and HaCYC2c) were indicated to be strong candidates as regulators of ray flower identity, a function that is specific for Asteraceae. Our data further showed that other CYC2 clade genes are likely to have more specialized functions at the level of single flowers, including the late functions in floral reproductive organs that may be more conserved across plant families. The expression patterns of CYC1 and CYC3 clade genes showed more differences between the two species but still pointed to possible conserved functions during vegetative plant development. Pairwise protein– protein interaction assays gave the first molecular evidence that CYC/TB1-like proteins function in complexes. Compared with sunflower, the Gerbera proteins showed higher capacity for dimerization, between as well as within CYC clades. Our data from two distant species within the Asteraceae suggest that the expansion and the apparent conservation of especially the CYC2 clade CYC/TB1-like genes are associated with the evolution of the increased complexity of the Asteraceae inflorescence architecture.
-
over expression of the Gerbera hybrida at soc1 like1 gene gh soc1 leads to floral organ identity deterioration
Annals of Botany, 2011Co-Authors: Satu Ruokolainen, Victor A Albert, Paula Elomaa, Yan Peng Ng, Teemu H TeeriAbstract:Background and Aims The family of MADS box genes is involved in a number of processes besides controlling floral development. In addition to supplying homeotic functions defined by the ABC model, they influence flowering time and transformation of vegetative meristem into inflorescence meristem, and have functions in roots and leaves. Three Gerbera hybrida At-SOC1-like genes (Gh-SOC1–Gh-SOC3) were identified among Gerbera expressed sequence tags.
-
characterization of squamosa like genes in Gerbera hybrida including one involved in reproductive transition
BMC Plant Biology, 2010Co-Authors: Satu Ruokolainen, Victor A Albert, Paula Elomaa, Yan Peng Ng, Suvi K Broholm, Teemu H TeeriAbstract:The flowering process in plants proceeds through the induction of an inflorescence meristem triggered by several pathways. Many of the genes associated with both the flowering process and floral architecture encode transcription factors of the MADS domain family. Gerbera, a member of the sunflower family, Asteraceae, bears compressed inflorescence heads (capitula) with three different flower types characterized by differences in both sexuality and floral symmetry. To understand how such a complex inflorescence structure is achieved at the molecular level, we have characterized the array of Gerbera MADS box genes. The high number of SQUAMOSA-like genes in Gerbera compared to other model species raised the question as to whether they may relate to Gerbera's complex inflorescence structure and whether or not a homeotic A function is present. In this paper we describe six Gerbera genes related to the SQUAMOSA/APETALA1/FRUITFULL genes of snapdragon and Arabidopsis. Based on phylogenetic analysis of the entire gene lineage, our data indicates that GSQUA1 and GSQUA3 are members of the SQUA/AP1 clade, while GSQUA2, GSQUA4, GSQUA5 and GSQUA6 are co-orthologs of the Arabidopsis FUL gene. GSQUA1/GSQUA3 and GSQUA4/GSQUA5/GSQUA6, respectively, represent several gene duplication events unknown in the model systems that may be specific to either Gerbera or Asteraceae. GSQUA genes showed specific expression profiles. GSQUA1, GSQUA2, and GSQUA5 were inflorescence abundant, while GSQUA3, GSQUA4, and GSQUA6 expression was also detected in vegetative organs. Overexpression of GSQUA2 in Gerbera led to accelerated flowering, dwarfism and vegetative abnormalities, all new and specific phenomena observed in transgenic Gerbera plants with modified MADS box gene expression. Based on expression patterns, none of the Gerbera SQUA-like genes are likely to control flower organ identity in the sense of the floral A function. However, our data shows that the FUL-like gene GSQUA2 plays a vital role in meristem transition. The roles of other GSQUA-genes in Gerbera floral development are intriguing, but require still further study.
Hany Bashandy - One of the best experts on this subject based on the ideXlab platform.
-
functional characterization and expression of gascl1 and gascl2 two anther specific chalcone synthase like enzymes from Gerbera hybrida
Phytochemistry, 2017Co-Authors: Juha Kontturi, Xianbao Deng, Hany Bashandy, Victor A Albert, Raisa Osama, Teemu H TeeriAbstract:Abstract The chalcone synthase superfamily consists of type III polyketidesynthases (PKSs), enzymes responsible for producing plant secondary metabolites with various biological and pharmacological activities. Anther-specific chalcone synthase-like enzymes (ASCLs) represent an ancient group of type III PKSs involved in the biosynthesis of sporopollenin, the main component of the exine layer of moss spores and mature pollen grains of seed plants. In the latter, ASCL proteins are localized in the tapetal cells of the anther where they participate in sporopollenin biosynthesis and exine formation within the locule. It is thought that the enzymes responsible for sporopollenin biosynthesis are highly conserved, and thus far, each angiosperm species with a genome sequenced has possessed two ASCL genes, which in Arabidopsis thaliana are PKSA and PKSB. The Gerbera hybrida (Gerbera) PKS protein family consists of three chalcone synthases (GCHS1, GCHS3 and GCHS4) and three 2-pyrone synthases (G2PS1, G2PS2 and G2PS3). In previous studies we have demonstrated the functions of chalcone synthases in flavonoid biosynthesis, and the involvement of 2-pyrone synthases in the biosynthesis of antimicrobial compounds found in Gerbera. In this study we expanded the Gerbera PKS-family by functionally characterizing two Gerbera ASCL proteins. In vitro enzymatic studies using purified recombinant proteins showed that both GASCL1 and GASCL2 were able to use medium and long-chain acyl-CoA starters and perform two to three condensation reactions of malonyl-CoA to produce tri- and tetraketide 2-pyrones, usually referred to as alpha-pyrones in sporopollenin literature. Both GASCL1 and GASCL2 genes were expressed only in floral organs, with most expression observed in anthers. In the anthers, transcripts of both genes showed strict tapetum-specific localization.
-
anthocyanin biosynthesis in Gerbera cultivar estelle and its acyanic sport ivory
Planta, 2015Co-Authors: Hany Bashandy, Milla Pietiainen, Paula Elomaa, Elisabete Carvalho, Stefan Martens, Teemu H TeeriAbstract:Identification of distinct allelic versions for dihydroflavonol 4-reductase in Gerbera cultivars reveals that Gerbera DFR enzymes have strong substrate preference in vivo that is not reflected to the activity in vitro. Flavonoids in the model ornamental plant Gerbera hybrida consist of flavones, flavonols and anthocyanins. Anthocyanins accumulate in the adaxial epidermis of petals and give the different cultivars their characteristic red and violet colour. Both pelargonidin and cyanidin derivatives are found in Gerbera, but none of the cultivars contain delphinidin. ‘Ivory’, a cultivar with white petals, is a sport of the pelargonidin-containing pink cultivar ‘Estelle’, i.e. it originates from an acyanic branch of ‘Estelle’. In this work, four different alleles encoding dihydroflavonol 4-reductase (DFR) were identified in Gerbera cultivars. We found that, in contrast to ‘Estelle’ with the functional allele GDFR1-2, ‘Ivory’ carries a mutation in this gene that results in an inactive enzyme. Interestingly, ‘Ivory’ also expresses a second, nonmutated allele (GDFR1-3) in petal epidermi, leading to extractable DFR activity but not to anthocyanin biosynthesis. The second allele encodes a protein identical in amino acid sequence to the DFR of the cyanidin-containing variety ‘President’. Pelargonidin-containing cultivars do not react to the flavonoid 3′-hydroxylase inhibitor tetcyclacis, but cyanidin-containing cultivars lose their colour, instead of starting to synthesise pelargonidins, indicating the specificity of GDFR1-3 for the cyanidin pathway. This explains why petals of ‘Ivory’ are white, even when it has lost only one of the two enzymatically functional DFR forms, and shows that anthocyanin biosynthesis in Gerbera is under more complex regulation than earlier thought.
-
functional diversification of duplicated chalcone synthase genes in anthocyanin biosynthesis of Gerbera hybrida
New Phytologist, 2014Co-Authors: Xianbao Deng, Hany Bashandy, Miia Ainasoja, Juha Kontturi, Milla Pietiainen, Roosa A E Laitinen, Victor A Albert, Jari P T Valkonen, Paula ElomaaAbstract:• Chalcone synthase (CHS) is the key enzyme in the first committed step of the flavonoid biosynthetic pathway and catalyzes the stepwise condensation of 4-coumaroyl-CoA and malonyl-CoA to naringenin chalcone. In plants, CHS is often encoded by a small family of genes that are temporally and spatially regulated. Our earlier studies have shown that GCHS4 is highly activated by ectopic expression of an MYB-type regulator GMYB10 in Gerbera (Gerbera hybrida). • The tissue- and development-specific expression patterns of three Gerbera CHS genes were examined. Virus-induced gene silencing (VIGS) was used to knock down GCHS1 and GCHS4 separately in Gerbera inflorescences. • Our data show that GCHS4 is the only CHS encoding gene that is expressed in the cyanidin-pigmented vegetative tissues of Gerbera cv Terraregina. GCHS3 expression is pronounced in the pappus bristles of the flowers. Expression of both GCHS1 and GCHS4 is high in the epidermal cells of Gerbera petals, but only GCHS1 is contributing to flavonoid biosynthesis. • Gerbera contains a family of three CHS encoding genes showing different spatial and temporal regulation. GCHS4 expression in Gerbera petals is regulated post-transcriptionally, at the level of either translation elongation or protein stability.
Roosa A E Laitinen - One of the best experts on this subject based on the ideXlab platform.
-
Floral developmental genetics of Gerbera (Asteraceae)
Advances in Botanical Research, 2020Co-Authors: Teemu H Teeri, Roosa A E Laitinen, Mika Kotilainen, Satu Ruokolainen, Yan Peng Ng, Suvi K Broholm, Anne Uimari, Ursula Malm, Eija Pöllänen, Paula ElomaaAbstract:Abstract Inflorescence development in the angiosperm family Asteraceae has distinct features not found in the traditional model systems (e.g., Arabidopsis, Petunia , and Zea ). In Gerbera hybrida , inflorescences are composed of morphologically different types of flowers tightly packed into a flower head (capitulum) that overtly resembles a single flower. Individual floral organs, such as pappus bristles (sepals), are developmentally specialized, petals and anthers form fused structures, stamens are aborted in marginal flowers, and ovaries are located inferior to other floral organs. These specific features have made Gerbera a rewarding target for comparative studies. We have shown that Gerbera MADS‐box genes that group phylogenetically with B‐ and C‐function genes from Arabidopsis and Antirrhinum function in organ determination in a very similar manner to their respective homologs from these model plants. However, MADS‐box genes encoding proteins that interact with those of the ABC‐genes behave differently. In Arabidopsis , three SEPALLATA ( SEP ) genes have redundant functions and are needed for development of petals, stamens, and carpels. Homologs of these SEP genes are found in Gerbera ( GRCD1, GRCD2 ), but they show functional specialization. GRCD1 is necessary for stamen development, but not for petal or carpel development. Similarly, GRCD2 has a homeotic function restricted to carpel development. Remarkably, downregulation of the latter also results in floral reversion (which occurs in ovaries) and alters inflorescence architecture by switching off terminal, determinate growth. This integrated SEP‐like control over reproductive meristem fate has not been detected in the well‐known model systems, which have a different carpel design and normally bear indeterminate inflorescences. Moreover, the organization of flowers on the Gerbera capitulum reveals the presence of a radial morphogenetic gradient that appears to regulate ABC and other MADS‐box genes differentially in a cell‐nonautonomous manner. As such, there is some commonality in gene regulatory features between Gerbera flowers and inflorescences, which suggests that Gerbera capitula are more than simple analogs of the flowers they bear.
-
functional diversification of duplicated chalcone synthase genes in anthocyanin biosynthesis of Gerbera hybrida
New Phytologist, 2014Co-Authors: Xianbao Deng, Hany Bashandy, Miia Ainasoja, Juha Kontturi, Milla Pietiainen, Roosa A E Laitinen, Victor A Albert, Jari P T Valkonen, Paula ElomaaAbstract:• Chalcone synthase (CHS) is the key enzyme in the first committed step of the flavonoid biosynthetic pathway and catalyzes the stepwise condensation of 4-coumaroyl-CoA and malonyl-CoA to naringenin chalcone. In plants, CHS is often encoded by a small family of genes that are temporally and spatially regulated. Our earlier studies have shown that GCHS4 is highly activated by ectopic expression of an MYB-type regulator GMYB10 in Gerbera (Gerbera hybrida). • The tissue- and development-specific expression patterns of three Gerbera CHS genes were examined. Virus-induced gene silencing (VIGS) was used to knock down GCHS1 and GCHS4 separately in Gerbera inflorescences. • Our data show that GCHS4 is the only CHS encoding gene that is expressed in the cyanidin-pigmented vegetative tissues of Gerbera cv Terraregina. GCHS3 expression is pronounced in the pappus bristles of the flowers. Expression of both GCHS1 and GCHS4 is high in the epidermal cells of Gerbera petals, but only GCHS1 is contributing to flavonoid biosynthesis. • Gerbera contains a family of three CHS encoding genes showing different spatial and temporal regulation. GCHS4 expression in Gerbera petals is regulated post-transcriptionally, at the level of either translation elongation or protein stability.
-
a tcp domain transcription factor controls flower type specification along the radial axis of the Gerbera asteraceae inflorescence
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Suvi K Broholm, Roosa A E Laitinen, Victor A Albert, Teemu H Teeri, Sari Tahtiharju, Paula ElomaaAbstract:Several key processes in plant development are regulated by TCP transcription factors. CYCLOIDEA-like (CYC-like) TCP domain proteins have been shown to control flower symmetry in distantly related plant lineages. Gerbera hybrida, a member of one of the largest clades of angiosperms, the sunflower family (Asteraceae), is an interesting model for developmental studies because its elaborate inflorescence comprises different types of flowers that have specialized structures and functions. The morphological differentiation of flower types involves gradual changes in flower size and symmetry that follow the radial organization of the densely packed inflorescence. Differences in the degree of petal fusion further define the distinct shapes of the Gerbera flower types. To study the role of TCP transcription factors during specification of this complex inflorescence organization, we characterized the CYC-like homolog GhCYC2 from Gerbera. The expression of GhCYC2 follows a gradient along the radial axis of the inflorescence. GhCYC2 is expressed in the marginal, bilaterally symmetrical ray flowers but not in the centermost disk flowers, which are nearly radially symmetrical and have significantly less fused petals. Overexpression of GhCYC2 causes disk flowers to obtain morphologies similar to ray flowers. Both expression patterns and transgenic phenotypes suggest that GhCYC2 is involved in differentiation among Gerbera flower types, providing the first molecular evidence that CYC-like TCP factors take part in defining the complex inflorescence structure of the Asteraceae, a major determinant of the family's evolutionary success.
-
reproductive meristem fates in Gerbera
Journal of Experimental Botany, 2006Co-Authors: Roosa A E Laitinen, Paula Elomaa, Teemu H Teeri, Mika Kotilainen, Anne Uimari, Hanna Help, Victor A AlbertAbstract:Flowering plants go through several phases between regular stem growth and the actual production of flower parts. The stepwise conversion of vegetative into inflorescence and floral meristems is usually unidirectional, but under certain environmental or genetic conditions, meristems can revert to an earlier developmental identity. Vegetative meristems are typically indeterminate, producing organs continuously, whereas flower meristems are determinate, shutting down their growth after reproductive organs are initiated. Inflorescence meristems can show either pattern. Flower and inflorescence development have been investigated in Gerbera hybrida, an ornamental plant in the sunflower family, Asteraceae. Unlike the common model species used to study flower development, Gerbera inflorescences bear a fixed number of flowers, and the architecture of the flowers differ in that Gerbera ovaries are inferior (borne below the perianth). This architectural difference has been exploited to show that floral meristem determinacy and identity are spatially and genetically distinct in Gerbera, and we have shown that a single SEPALLATA-like MADS domain factor controls both flower and inflorescence meristem fate in the plant. Although these phenomena have not been directly observed in Arabidopsis, the integrative role of the SEPALLATA function in reproductive meristem development may be general for all flowering plants.
-
patterns of mads box gene expression mark flower type development in Gerbera hybrida asteraceae
BMC Plant Biology, 2006Co-Authors: Roosa A E Laitinen, Victor A Albert, Teemu H Teeri, Suvi K Broholm, Paula ElomaaAbstract:Background The inflorescence of the cut-flower crop Gerbera hybrida (Asteraceae) consists of two principal flower types, ray and disc, which form a tightly packed head, or capitulum. Despite great interest in plant morphological evolution and the tractability of the Gerbera system, very little is known regarding genetic mechanisms involved in flower type specification. Here, we provide comparative staging of ray and disc flower development and microarray screening for differentially expressed genes, accomplished via microdissection of hundreds of coordinately developing flower primordia.