Publications (34)227.87 Total impact
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Article: A double-flowered variety of lesser periwinkle (Vinca minor fl. pl.) that has persisted in the wild for more than 160 years.
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ABSTRACT: Homeotic transitions are usually dismissed by population geneticists as credible modes of evolution due to their assumed negative impact on fitness. However, several lines of evidence suggest that such changes in organ identity have played an important role during the origin and subsequent evolution of the angiosperm flower. Better understanding of the performance of wild populations of floral homeotic varieties should help to clarify the evolutionary potential of homeotic mutants. Wild populations of plants with changes in floral symmetry, or with reproductive organs replacing perianth organs or sepals replacing petals have already been documented. However, although double-flowered varieties are quite popular as ornamental and garden plants, they are rarely found in the wild and, if they are, usually occur only as rare mutant individuals, probably because of their low fitness relative to the wild-type. We therefore investigated a double-flowered variety of lesser periwinkle, Vinca minor flore pleno (fl. pl.), that is reported to have existed in the wild for at least 160 years. To assess the merits of this plant as a new model system for investigations on the evolutionary potential of double-flowered varieties we explored the morphological details and distribution of the mutant phenotype. The floral morphology of the double-flowered variety and of a nearby population of wild-type plants was investigated by means of visual inspection and light microscopy of flowers, the latter involving dissected or sectioned floral organs. The double-flowered variety was found in several patches covering dozens of square metres in a forest within the city limits of Jena (Germany). It appears to produce fewer flowers than the wild-type, and its flowers are purple rather than blue. Most sepals in the first floral whorl resemble those in the wild-type, although occasionally one sepal is broadened and twisted. The structure of second-whorl petals is very similar to that of the wild-type, but their number per flower is more variable. The double-flowered character is due to partial or complete transformation of stamens in the third whorl into petaloid organs. Occasionally, 'flowers within flowers' also develop on elongated pedicels in the double-flowered variety. The flowers of V. minor fl. pl. show meristic as well as homeotic changes, and occasionally other developmental abnormalities such as mis-shaped sepals or loss of floral determinacy. V. minor fl. pl. thus adds to a growing list of natural floral homeotic varieties that have established persistent populations in the wild. Our case study documents that even mutant varieties that have reproductive organs partially transformed into perianth organs can persist in the wild for centuries. This finding makes it at least conceivable that even double-flowered varieties have the potential to establish new evolutionary lineages, and hence may contribute to macroevolutionary transitions and cladogenesis.Annals of Botany 06/2011; 107(9):1445-52. · 4.03 Impact Factor -
Article: The Selaginella genome identifies genetic changes associated with the evolution of vascular plants.
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ABSTRACT: Vascular plants appeared ~410 million years ago, then diverged into several lineages of which only two survive: the euphyllophytes (ferns and seed plants) and the lycophytes. We report here the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first nonseed vascular plant genome reported. By comparing gene content in evolutionarily diverse taxa, we found that the transition from a gametophyte- to a sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, whereas secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in posttranscriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the trans-acting small interfering RNA pathway, and extensive RNA editing of organellar genes.Science 05/2011; 332(6032):960-3. · 31.20 Impact Factor -
Article: Conserved differential expression of paralogous DEFICIENS- and GLOBOSA-like MADS-box genes in the flowers of Orchidaceae: refining the 'orchid code'.
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ABSTRACT: In flowering plants, class-B floral homeotic genes encode MADS-domain transcription factors, which are key in the specification of petal and stamen identity, and have two ancient clades: DEF-like and GLO-like genes. Many species have one gene of each clade, but orchids have typically four DEF-like genes, representing ancient gene clades 1, 2, 3 and 4. We tested the 'orchid code', a combinatorial genetic model suggesting that differences between the organs of the orchid perianth (outer tepals, inner lateral tepals and labellum) are generated by the combinatorial differential expression of four DEF-like genes. Our experimental test involves highly sensitive and specific measurements, with qRT-PCR of the expression of DEF- and GLO-like genes from the distantly related Vanilla planifolia and Phragmipedium longifolium, as well as from wild-type and peloric Phalaenopsis hybrid flowers. Our findings support the first 'orchid code' hypothesis, in that absence of clade-3 and -4 gene expression distinguishes the outer tepals from the inner tepals. In contrast to the original hypothesis, however, mRNA of both clade-3 and -4 genes accumulates in wild-type inner lateral tepals and the labellum, and in labellum-like inner lateral tepals of peloric flowers, albeit in different quantities. Our data suggest a revised hypothesis where high levels of clade-1 and -2, and low levels of clade-3 and -4, gene expression specify inner lateral tepals, whereas labellum development requires low levels of clade-1 and -2 expression and high levels of clade-3 and -4 expression.The Plant Journal 03/2011; 66(6):1008-19. · 6.16 Impact Factor -
Article: SplamiR--prediction of spliced miRNAs in plants.
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ABSTRACT: MicroRNAs (miRNAs) are important regulators of biological processes in plants and animals. Recently, miRNA genes have been discovered, whose primary transcripts are spliced and which cannot be predicted directly from genomic sequence. Hence, more sophisticated programs for the detection of spliced miRNAs are required. Here, we present the first method for the prediction of spliced miRNAs in plants. For a given genomic sequence, SplamiR creates a database of complementary sequence pairs, which might encode for RNAs folding into stem-loop structures. Next, in silico splice variants of database sequences with complementarity to an mRNA of interest are classified as to whether they could represent miRNAs targeting this mRNA. Our method identifies all known cases of spliced miRNAs in rice, and a previously undiscovered miRNA in maize which is supported by an expressed sequence tag (EST). SplamiR permits identification of spliced miRNAs for a given target mRNA in many plant genomes. The program is freely available at http://www.uni-jena.de/SplamiR.html.Bioinformatics 03/2011; 27(9):1215-23. · 5.47 Impact Factor -
Article: MADS and more: transcription factors that shape the plant.
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ABSTRACT: All major processes of life depend on differential gene expression, which is largely controlled by the activity of transcription factors (TFs). In plants many TFs are encoded by members of multigene families that expanded much more dramatically during land plant evolution than during the evolution of animals and fungi. Here we review typical features such as domain structure, DNA binding, and protein interactions of TFs from some families that have contributed to the development and evolution of plant-specific structures in especially important ways. Our survey includes the MADS-domain protein family involved in specifying meristem and organ identity; YABBY proteins controlling lamina outgrowth; TCP proteins controlling floral zygomorphy and apical dominance; and finally homeodomain proteins involved in stem-cell maintenance and many other processes. Common themes as well as interesting differences between these "molecular architects of plant body plans" will become apparent.Methods in molecular biology (Clifton, N.J.) 01/2011; 754:3-18. -
Article: Molecular interactions of orthologues of floral homeotic proteins from the gymnosperm Gnetum gnemon provide a clue to the evolutionary origin of 'floral quartets'.
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ABSTRACT: Several lines of evidence suggest that the identity of floral organs in angiosperms is specified by multimeric transcription factor complexes composed of MADS-domain proteins. These bind to specific cis-regulatory elements ('CArG-boxes') of their target genes involving DNA-loop formation, thus constituting 'floral quartets'. Gymnosperms, angiosperms' closest relatives, contain orthologues of floral homeotic genes, but when and how the interactions constituting floral quartets were established during evolution has remained unknown. We have comprehensively studied the dimerization and DNA-binding of several classes of MADS-domain proteins from the gymnosperm Gnetum gnemon. Determination of protein-protein and protein-DNA interactions by yeast two-hybrid, in vitro pull-down and electrophoretic mobility shift assays revealed complex patterns of homo- and heterodimerization among orthologues of floral homeotic class B, class C and class E proteins and B(sister) proteins. Using DNase I footprint assays we demonstrate that both orthologues of class B with C proteins, and orthologues of class C proteins alone, but not orthologues of class B proteins alone can loop DNA in floral quartet-like complexes. This is in contrast to class B and class C proteins from angiosperms, which require other factors such as class E floral homeotic proteins to 'glue' them together in multimeric complexes. Our findings suggest that the evolutionary origin of floral quartet formation is based on the interaction of different DNA-bound homodimers, does not depend on class E proteins, and predates the origin of angiosperms.The Plant Journal 10/2010; 64(2):177-90. · 6.16 Impact Factor -
Article: GORDITA (AGL63) is a young paralog of the Arabidopsis thaliana B(sister) MADS box gene ABS (TT16) that has undergone neofunctionalization.
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ABSTRACT: MIKC-type MADS domain proteins are key regulators of flower development in angiosperms. B(sister) genes constitute a clade with a close relationship to class B floral homeotic genes, and have been conserved for more than 300 million years. The loss-of-function phenotype of the A. thaliana B(sister) gene ABS is mild: mutants show reduced seed coloration and defects in endothelium development. This study focuses on GORDITA (GOA, formerly known as AGL63), the most closely related paralog of ABS in A. thaliana, which is thought to act redundantly with ABS. Phylogenetic trees reveal that the duplication leading to ABS and GOA occurred during diversification of the Brassicaceae, and further analyses show that GOA has evolved under relaxed selection pressure. The knockdown phenotype of GOA suggests a role for this gene in fruit longitudinal growth, while over-expression of GOA results in disorganized floral structure and addition of carpel-like features to sepals. Given the phylogeny and function of other B(sister) genes, our data suggest that GOA has evolved a new function as compared to ABS. Protein analysis reveals that the GOA-specific 'deviant' domain is required for protein dimerization, in contrast to other MIKC-type proteins that require the K domain for dimerization. Moreover, no shared protein interaction partners for ABS and GOA could be identified. Our experiments indicate that modification of a protein domain and a shift in expression pattern can lead to a novel gene function in a relatively short time, and highlight the molecular mechanism by which neofunctionalization following gene duplication can be achieved.The Plant Journal 09/2010; 63(6):914-24. · 6.16 Impact Factor -
Article: Cooperation and cheating in microbial exoenzyme production--theoretical analysis for biotechnological applications.
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ABSTRACT: The engineering of microorganisms to produce a variety of extracellular enzymes (exoenzymes), for example for producing renewable fuels and in biodegradation of xenobiotics, has recently attracted increasing interest. Productivity is often reduced by "cheater" mutants, which are deficient in exoenzyme production and benefit from the product provided by the "cooperating" cells. We present a game-theoretical model to analyze population structure and exoenzyme productivity in terms of biotechnologically relevant parameters. For any given population density, three distinct regimes are predicted: when the metabolic effort for exoenzyme production and secretion is low, all cells cooperate; at intermediate metabolic costs, cooperators and cheaters coexist; while at high costs, all cells use the cheating strategy. These regimes correspond to the harmony game, snowdrift game, and Prisoner's Dilemma, respectively. Thus, our results indicate that microbial strains engineered for exoenzyme production will not, under appropriate conditions, be outcompeted by cheater mutants. We also analyze the dependence of the population structure on cell density. At low costs, the fraction of cooperating cells increases with decreasing cell density and reaches unity at a critical threshold. Our model provides an estimate of the cell density maximizing exoenzyme production.Biotechnology Journal 07/2010; 5(7):751-8. -
Article: On the origin of MADS-domain transcription factors.
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ABSTRACT: MADS-domain transcription factors are involved in signal transduction and developmental control in plants, animals and fungi. Because their diversification is linked to the origin of novelties in multicellular eukaryotes, the early evolution of MADS-domain proteins is of interest, but has remained enigmatic. Employing whole genome sequence information and remote homology detection methods, we demonstrate that the MADS domain originated from a region of topoisomerases IIA subunit A. Furthermore, we provide evidence that gene duplication occurred in the lineage that led to the MRCA of extant eukaryotes, giving rise to SRF-like and MEF2-like MADS-box genes.Trends in Genetics 03/2010; 26(4):149-53. · 10.06 Impact Factor -
Article: Developmental robustness by obligate interaction of class B floral homeotic genes and proteins.
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ABSTRACT: DEF-like and GLO-like class B floral homeotic genes encode closely related MADS-domain transcription factors that act as developmental switches involved in specifying the identity of petals and stamens during flower development. Class B gene function requires transcriptional upregulation by an autoregulatory loop that depends on obligate heterodimerization of DEF-like and GLO-like proteins. Because switch-like behavior of gene expression can be displayed by single genes already, the functional relevance of this complex circuitry has remained enigmatic. On the basis of a stochastic in silico model of class B gene and protein interactions, we suggest that obligate heterodimerization of class B floral homeotic proteins is not simply the result of neutral drift but enhanced the robustness of cell-fate organ identity decisions in the presence of stochastic noise. This finding strongly corroborates the view that the appearance of this regulatory mechanism during angiosperm phylogeny led to a canalization of flower development and evolution.PLoS Computational Biology 02/2009; 5(1):e1000264. · 5.22 Impact Factor -
Article: MADS about the evolution of orchid flowers.
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ABSTRACT: Orchids have unique flowers involving three types of perianth organs: outer tepals, lateral inner tepals, and a lip. Expression studies indicate that the identity of these organs is specified by the combinatorial interaction of four different DEFICIENS-like MADS-box genes. We suggest that clarifying the evolution of these genes provides a rational framework for reconstructing the enigmatic origin and unique diversification of the orchid flower. For example, two rounds of gene duplications during early orchid evolution might have generated the genes that were probably recruited to distinguish the different types of perianth organs. This hypothesis suggests intriguing, experimentally testable mechanisms by which gene duplications followed by sub- and neo-functionalization events might have contributed to the evolutionary origin of morphological novelties in orchids - and well beyond.Trends in Plant Science 03/2008; 13(2):51-9. · 11.05 Impact Factor -
Article: Germline transformation of Shepherd's purse (Capsella bursa-pastoris) by the 'floral dip' method as a tool for evolutionary and developmental biology.
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ABSTRACT: Capsella bursa-pastoris is an attractive model system for evolutionary and developmental biology. To facilitate future studies on gene function, the 'floral dip' method was adapted to achieve germline transformation of C. bursa-pastoris. The GFP and BASTA-resistance (BAR (r)) genes were used as markers for screening or selecting, respectively, putative transgenic C. bursa-pastoris plants and the beta-glucuronidase (GUS) gene as well as the GFP gene for monitoring transgene expression level. We tested two Agrobacterium strains, LBA4404 and GV3101, for their ability to transform C. bursa-pastoris. In contrast to Arabidopsis thaliana, for which both strains were able to transform different ecotypes, only GV3101 gave satisfactory transformation rates with C. bursa-pastoris. Furthermore, we evaluated the effects of different concentrations of sucrose and the surfactant Silwet L-77 on the efficiency to generate transgenic C. bursa-pastoris plants and identified an efficient medium containing 10% (w/v) sucrose and 0.02-0.05% (v/v) Silwet L-77. Using Southern hybridisation, we confirmed the integration of the marker gene in the plant genome and the stable heredity of the introduced genes in the next generation.Gene 03/2008; 409(1-2):11-9. · 2.34 Impact Factor -
Article: Petaloidy and petal identity MADS-box genes in the balsaminoid genera Impatiens and Marcgravia.
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ABSTRACT: Impatiens and Marcgravia have striking morphological innovations associated with the flowers. One of the sepals in Impatiens is spurred and petaloid, while in Marcgravia the petals are fused into a cap and nectary cups are associated with the inflorescence. Balsaminaceae (Impatiens) and Marcgraviaceae have surprisingly been shown to be closely related, since both belong to the balsaminoid clade of Ericales (basal asterids). However, several thorough morphological studies thus far have not revealed shared derived characters (synapomorphies) that support a close relationship between these families. In the balsaminoid clade, transitions from entirely green flowers to flowers with heterotopic petaloid organs can be observed. The primary role of class B genes in core eudicots is to specify the identity of petal and stamen floral organs. E-class genes, of which SEP3 is a representative, have been identified as redundant mediators that confer transcriptional activation potential on protein complexes that specify organ identity. Given the conserved function of organ-identity MADS-box genes in model plants, but the rapid molecular evolution in angiosperms, it remains controversial whether these genes have been involved in shaping floral diversity. We have identified a SEP3-like gene and a total of five class B genes from Impatiens hawkeri and Marcgravia umbellata and report their quantitative expression in the floral organs. In Impatiens, two AP3/DEF-like genes were identified with strongly divergent C-terminal domains, one truncated and one unusually long. Both genes show a gradual decrease in expression towards the outer perianth organs, but no GLO-like gene expression is observed in the petaloid sepal. Remarkably, SEP3-like gene expression in the Impatiens perianth is absent from the green sepals but present in the petaloid sepal and in the petals. Dimeric protein interactions of the cloned Impatiens genes were studied in yeast and by using gel retardation. In Marcgravia, strong overlapping class B gene expression is limited to the stamens, but a SEP3-like gene is strongly expressed in the Marcgravia nectary, indicating that both Impatiens and Marcgravia show heterotopic expression of a SEP3-like gene. We discuss several candidate mechanisms for heterotopic petaloidy involving modified gene expression and protein interaction of SEP3-like and class B genes.The Plant Journal 09/2006; 47(4):501-18. · 6.16 Impact Factor -
Article: The proper place of hopeful monsters in evolutionary biology.
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ABSTRACT: Hopeful monsters are organisms with a profound mutant phenotype that have the potential to establish a new evolutionary lineage. The Synthetic Theory of evolutionary biology has rejected the evolutionary relevance of hopeful monsters, but could not fully explain the mechanism and mode of macroevolution. On the other hand, several lines of evidence suggest that hopeful monsters played an important role during the origin of key innovations and novel body plans by saltational rather than gradual evolution. Homeotic mutants are identified as an especially promising class of hopeful monsters. Examples for animal and plant lineages that may have originated as hopeful monsters are given. Nevertheless, a brief review of the history of the concept of hopeful monsters reveals that it needs refinements and empirical tests if it is to be a useful addition to evolutionary biology. While evolutionary biology is traditionally zoocentric, hopeful monsters might be more relevant for plant than for animal evolution. Even though during recent years developmental genetics has provided detailed knowledge about how hopeful monsters can originate in the first place, we know almost nothing about their performance in natural populations and thus the ultimate difference between hopeful and hopeless. Studying the fitness of candidate hopeful monsters (suitable mutants with profound phenotype) in natural habitats thus remains a considerable challenge for the future.Theory in Biosciences 04/2006; 124(3-4):349-69. · 0.98 Impact Factor -
Article: Catching a 'hopeful monster': shepherd's purse (Capsella bursa-pastoris) as a model system to study the evolution of flower development.
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ABSTRACT: Capsella is a small genus within the mustard family (Brassicaceae). Its three species, however, show many evolutionary trends also observed in other Brassicaceae (including Arabidopsis) and far beyond, including transitions from a diploid, self-incompatible, obligatory outcrossing species with comparatively large and attractive flowers but a restricted distribution to a polyploid, self-compatible, predominantly selfing, invasive species with floral reductions. All these evolutionary transitions may have contributed to the fact that Capsella bursa-pastoris (shepherd's purse) has become one of the most widely distributed flowering plants on our planet. In addition, Capsella bursa-pastoris shows a phenomenon that, although rare, could be of great evolutionary importance, specifically the occurrence of a homeotic variety found in relatively stable populations in the wild. Several lines of evidence suggest that homeotic changes played a considerable role in floral evolution, but how floral homeotic varieties are established in natural populations has remained a highly controversial topic among evolutionary biologists. Due to its close relationship with the model plant Arabidopsis thaliana, numerous experimental tools are available for studying the genus Capsella, and further tools are currently being developed. Hence, Capsella provides great opportunities to investigate the evolution of flower development from molecular developmental genetics to field ecology and biogeography, and from morphological refinements to major structural transitions.Journal of Experimental Botany 02/2006; 57(13):3531-42. · 5.36 Impact Factor -
Article: Birth, life and death of developmental control genes: new challenges for the homology concept.
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ABSTRACT: Understanding the interrelationship between the phylogeny of developmental control genes and the evolution of morphological features is a central goal of evolutionary developmental biology (evo-devo). It requires that one distinguishes properly between gene genealogy and function. Gene duplication, gene loss and speciation in combination with differential changes in gene function can generate complex evolutionary scenarios that require additional terms beyond homology for a proper description. Use and possible misuse of these terms, including "orthology", "paralogy" and "subfunctionalization", is exemplified with AGAMOUS-like genes encoding transcription factors involved in flower and fruit development. This MADS-box gene subfamily demonstrates that homologous genes in different species with (almost) identical functions can be paralogues rather than orthologues, corroborating that functional similarity of genes is not a valid criterion for orthology. Homeosis fails some tests of homology, but might be of greater evolutionary importance than previously assumed, justifying yet another term, "homocracy". It describes organs that share the expression of the same patterning genes, irrespective of the homology of these organs. All in all this article opts for a careful use of a limited and well-chosen set of terms describing gene relationships and function, rather than the inflationary production of novel terms that may seem to be precise, but whose obscurity hampers communication.Theory in Biosciences 12/2005; 124(2):199-212. · 0.98 Impact Factor -
Article: Mutant analysis, protein-protein interactions and subcellular localization of the Arabidopsis B sister (ABS) protein.
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ABSTRACT: Recently, close relatives of class B floral homeotic genes, termed B(sister) genes, have been identified in both angiosperms and gymnosperms. In contrast to the B genes themselves, B(sister) genes are exclusively expressed in female reproductive organs, especially in the envelopes or integuments surrounding the ovules. This suggests an important ancient function in ovule or seed development for B(sister) genes, which has been conserved for about 300 million years. However, investigation of the first loss-of-function mutant for a B(sister) gene (ABS/TT16 from Arabidopsis) revealed only a weak phenotype affecting endothelium formation. Here, we present an analysis of two additional mutant alleles, which corroborates this weak phenotype. Transgenic plants that ectopically express ABS show changes in the growth and identity of floral organs, suggesting that ABS can interact with floral homeotic proteins. Yeast-two-hybrid and three-hybrid analyses indicated that ABS can form dimers with SEPALLATA (SEP) floral homeotic proteins and multimeric complexes that also include the AGAMOUS-like proteins SEEDSTICK (STK) or SHATTERPROOF1/2 (SHP1, SHP2). These data suggest that the formation of multimeric transcription factor complexes might be a general phenomenon among MIKC-type MADS-domain proteins in angiosperms. Heterodimerization of ABS with SEP3 was confirmed by gel retardation assays. Fusion proteins tagged with CFP (Cyan Fluorescent Protein) and YFP (Yellow Fluorescent Protein) in Arabidopsis protoplasts showed that ABS is localized in the nucleus. Phylogenetic analysis revealed the presence of a structurally deviant, but closely related, paralogue of ABS in the Arabidopsis genome. Thus the evolutionary developmental genetics of B(sister) genes can probably only be understood as part of a complex and redundant gene network that may govern ovule formation in a conserved manner, which has yet to be fully explored.Molecular and General Genetics 10/2005; 274(2):103-18. · 2.63 Impact Factor -
Article: MIKC-type MADS-domain proteins: structural modularity, protein interactions and network evolution in land plants.
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ABSTRACT: MIKC-type proteins represent a class of MADS-domain transcription factors and are defined by a unique domain structure: in addition to the highly conserved DNA-binding MADS-domain, they have three other domains ('I', 'K' and 'C'), with the keratin-like K-domain being the most highly conserved and characteristic one. The number and functional diversity of MIKC-type proteins increased considerably during land plant evolution, culminating in higher flowering plants, where they dominate the control of reproductive development from early to late stages. We wonder how one special class of proteins became important in the control of essentially all stages of a morphogenetic process. All MADS-domain proteins appear to bind to DNA as homo- or heterodimers and may function as part of ternary transcription factor complexes involving non-MADS-domain proteins. Only MIKC-type proteins, however, generate complex intrafamily interaction networks. These are based on the special potential of MIKC-type proteins to form complexes involving more than two homologous proteins constituting transcriptional regulators. We speculate that the potential to form heteromultimers of homologous proteins was achieved by the acquisition of the K-domain during evolution. There is emerging evidence that organismal complexity arises from progressively more elaborate regulation of gene expression. We hypothesize that combinatorial multimer formation of MIKC-type MADS-domain proteins facilitated an unusually efficient and rapid functional diversification based on gene duplication, sequence divergence and fixation. This 'networking' may have enabled a more sophisticated transcriptional control of target genes which was recruited for controlling increasingly complex and diverse developmental pathways during the rapid origin and diversification of plant reproductive structures. Therefore, MIKC-type proteins may owe their evolutionary 'success' and present-day developmental importance in part to their modular domain structure. Investigating the evolution of MIKC-type genes may thus help to better understand origin and diversification of gene regulatory networks.Gene 04/2005; 347(2):183-98. · 2.34 Impact Factor -
Article: Characterization of MADS-box genes in charophycean green algae and its implication for the evolution of MADS-box genes.
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ABSTRACT: The MADS-box genes of land plants are extensively diverged to form a superfamily and are important in various aspects of development including the specification of floral organs as homeotic selector genes. The closest relatives of land plants are the freshwater green algae charophyceans. To study the origin and evolution of land plant MADS-box genes, we characterized these genes in three charophycean green algae: the stonewort Chara globularis, the coleochaete Coleochaete scutata, and the desmid Closterium peracerosum-strigosum-littorale complex. Phylogenetic analyses suggested that MADS-box genes diverged extensively in the land plant lineage after the separation of charophyceans from land plants. The stonewort C. globularis mRNA was specifically detected in the oogonium and antheridium together with the egg and spermatozoid during their differentiation. The expression of the C. peracerosum-strigosum-littorale-complex gene increased when vegetative cells began to differentiate into gametangial cells and decreased after fertilization. These expression patterns suggest that the precursors of land plant MADS-box genes originally functioned in haploid reproductive cell differentiation and that the haploid MADS-box genes were recruited into a diploid generation during the evolution of land plants.Proceedings of the National Academy of Sciences 03/2005; 102(7):2436-41. · 9.68 Impact Factor -
Article: A simple method for predicting the functional differentiation of duplicate genes and its application to MIKC-type MADS-box genes.
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ABSTRACT: A simple statistical method for predicting the functional differentiation of duplicate genes was developed. This method is based on the premise that the extent of functional differentiation between duplicate genes is reflected in the difference in evolutionary rate because the functional change of genes is often caused by relaxation or intensification of functional constraints. With this idea in mind, we developed a window analysis of protein sequences to identify the protein regions in which the significant rate difference exists. We applied this method to MIKC-type MADS-box proteins that control flower development in plants. We examined 23 pairs of sequences of floral MADS-box proteins from petunia and found that the rate differences for 14 pairs are significant. The significant rate differences were observed mostly in the K domain, which is important for dimerization between MADS-box proteins. These results indicate that our statistical method may be useful for predicting protein regions that are likely to be functionally differentiated. These regions may be chosen for further experimental studies.Nucleic Acids Research 02/2005; 33(2):e12. · 8.03 Impact Factor
Top co-authors
Top Journals
Institutions
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2002–2011
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Friedrich-Schiller-Universität Jena
- Lehrstuhl für Genetik
Jena, Thuringia, Germany -
University of Florida
- Department of Botany
Gainesville, FL, USA
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2002–2003
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Max-Planck-Institut für Pflanzenzüchtungsforschung
Köln, North Rhine-Westphalia, Germany
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