RESUMO
St. John's wort (Hypericum perforatum L., 2n = 4x = 32) is a medicinal plant that produces pharmaceutically important metabolites with antidepressive, anticancer and antiviral activities. It is also regarded as a serious weed in many countries. H. perforatum is furthermore an attractive model system for the study of apomixis. Natural populations of H. perforatum are predominantly composed of tetraploid individuals, although diploids and hexaploids are known to occur. It has been demonstrated that while diploids are sexual, polyploids are facultative apomictic whereby a single individual can produce both sexual and apomictic seeds. Despite our increasing understanding of gamete formation in sexually reproducing species, relatively little is known regarding the cytological basis of reproduction in H. perforatum. Here, we have studied embryo sac formation and the genetic constitution of seeds by means of staining-clearing of ovules/ovaries, DIC microscopy and flow cytometric seed screening (FCSS) of embryo and endosperm DNA contents. Comparisons of female sporogenesis and gametogenesis between sexual and apomictic accessions have enabled the identification of major phenotypic differences in embryo sac formation, in addition to complex fertilization scenarios entailing reduced and unreduced male and female gametes. These data provide new insights into the production of aposporous seeds in H. perforatum, and complement ongoing population genetic, genomic and transcriptomic studies.
Assuntos
Hypericum/citologia , Hypericum/metabolismo , Endosperma/citologia , Endosperma/metabolismo , Endosperma/fisiologia , Citometria de Fluxo , Gametogênese Vegetal/genética , Gametogênese Vegetal/fisiologia , Hypericum/fisiologia , Ploidias , Poliploidia , TetraploidiaRESUMO
Iron homeostasis is vital for many cellular processes and requires a precise regulation. Several iron efficient plants respond to iron starvation with the excretion of riboflavin and other flavins. Basic helix-loop-helix transcription factors (TF) are involved in the regulation of many developmental processes, including iron assimilation. Here we describe the isolation and characterisation of two Arabidopsis bHLH TF genes, which are strongly induced under iron starvation. Their heterologous ectopic expression causes constitutive, iron starvation independent excretion of riboflavin. The results show that both bHLH TFs represent an essential component of the regulatory pathway connecting iron deficiency perception and riboflavin excretion and might act as integrators of various stress reactions.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Ferro/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas , Riboflavina/metabolismo , Plântula , Nicotiana/genética , Nicotiana/metabolismoRESUMO
The plant hormone gibberellin (GA) is known to modulate various aspects of plant cell differentiation and development. The current model of GA-mediated regulation is based on a de-repressible system and includes specific protein modification and degradation. HRT, a zinc finger protein from barley has been shown to have GA-dependent transcriptional repressing activity on the seed-specific alpha-amylase promoter [Raventos, D., Skriver, K., Schlein, M., Karnahl, K., Rogers, S.W., Rogers, J.C. and Mundy, J. 1998. J. Biol. Chem. 273: 23313-23320]. Here we report the characterization of a dicot homologue from Brassica napus (BnET) and provide evidence for its role in GA response modulation suggesting that this could be a conserved feature of this gene family. When BnET is ectopically expressed in either Arabidopsis or tobacco the phenotypes include dwarfism due to shorter internodes and late flowering, reduced germination rate, increased anthocyanin content and reduced xylem lignification as a marker for terminal cell differentiation. Transient expression in protoplasts supports the notion that this most likely is due to a transcriptional repression of GA controlled genes. Finally, histological analysis showed that in contrast to other GA deficient mutants the shorter internodes were due to fewer but not smaller cells, suggesting a function of BnET in GA-mediated cell division control.
Assuntos
Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Brassica napus/genética , Giberelinas/farmacologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sequência de Aminoácidos , Antocianinas/biossíntese , Antocianinas/metabolismo , Arabidopsis/citologia , Arabidopsis/genética , Núcleo Celular/metabolismo , Clonagem Molecular , Citocininas/farmacologia , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Germinação , Ácidos Indolacéticos/farmacologia , Lignina/metabolismo , Dados de Sequência Molecular , Caules de Planta/citologia , Caules de Planta/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Nicotiana/citologia , Nicotiana/efeitos dos fármacos , Nicotiana/genética , Nicotiana/crescimento & desenvolvimento , Zinco/metabolismoRESUMO
When seeds germinate nearly all the proteins are degraded in senescing storage tissue cells. All these proteins act as amino acid reserves which are mobilized to nourish the seedling. Nevertheless, the major amount of the seeds' protein reserve consists of a few enzymatically inactive, abundant, genuine storage proteins. In their metabolism the conflicting processes of biosynthesis, protein turnover and breakdown, are temporally separated. No degradation of correctly formed storage proteins was observed at the time of synthesis and accumulation during seed maturation. Breakdown takes place after a (long) period of rest when seeds germinate and seedlings start growing. At that time genuine storage proteins are no longer synthesized. Genuine storage proteins have evolved structural features permitting controlled temporal patterns of protection and proteolysis. The acquisition of inserted sequence stretches as sites accessible to limited proteolysis played a key role in the evolution of this control system and happened in coevolution of genuine storage proteins with specific proteinases. This can be deduced from the results of current research on the mechanisms of limited and unlimited proteolysis of storage globulins and on storage globulin evolution. The evolved system of controlled structure-function interplay between storage globulins and proteinases is part of a syndrome that, in addition, comprises differential compartmentation and gene expression of storage proteins and proteinases for controlling the total spatial and temporal patterns of globulin storage and mobilization in maturing and germinating seeds.
Assuntos
Evolução Molecular , Globulinas/metabolismo , Proteínas de Plantas/genética , Sementes/metabolismo , Sequência de Aminoácidos , Globulinas/química , Globulinas/genética , Glicoproteínas/química , Glicoproteínas/genética , Glicoproteínas/metabolismo , Dados de Sequência Molecular , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Proteínas de Armazenamento de Sementes , Sementes/genética , Sementes/crescimento & desenvolvimento , Homologia de Sequência de Aminoácidos , LeguminasRESUMO
The control of epidermal cell fate is a complex molecular process and requires the regulatory activity of different transcription factors. Here, we describe the isolation of a member of the Arabidopsis MYB transcription factor family, AtMYB23, that is involved in trichome development. Expression of the AtMYB23 gene under the control of the viral CaMV 35S promoter causes the development of ectopic trichomes. The formation of ectopic trichomes depends on TRANSPARENT TESTA GLABRA1 but not on GLABRA1. The absence of the negative regulator TRIPTYCHON leads to branching of the ectopic trichomes on cotyledons and the formation of ectopic trichomes in the leaf subepidermal cell layer. The CaMV 35S promoter-controlled expression of AtMYB23 can partially rescue the glabra1 mutant phenotype. Together, the presented data indicate that the AtMYB23 gene has partially overlapping functions with GLABRA1 in controlling the initiation of trichome development.
Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Genes myb/genética , Proteínas de Plantas/biossíntese , Proteínas de Plantas/genética , Proteínas Proto-Oncogênicas c-myb , Arabidopsis/ultraestrutura , Diferenciação Celular , DNA Complementar/metabolismo , Vetores Genéticos , Microscopia Eletrônica de Varredura , Fenótipo , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transformação GenéticaRESUMO
The 'Salmon' system of wheat comprises three isogenic alloplasmic lines with either zygotic (aS) or autonomous, fertilisation-independent (cS kS) embryo development. While the initiation of embryogenesis from the isolated sexual egg cell depends on in vitro fertilisation, the corresponding parthenogenetic egg cell develops into an early embryo without fertilisation. This demonstrates that parthenogenesis is an inherent feature of the isolated egg cell. Based on this observation, we have constructed egg-cell-specific cDNA libraries and report first results of a sequencing project aimed at the isolation of putative egg-cell-specific and parthenogenesis-related genes.
RESUMO
The Arabidopsis mutants fus3 and abi3 show pleiotropic effects during embryogenesis including reduced levels of transcripts encoding embryo-specific seed proteins. To investigate the interaction between the B3-domain-containing transcription factors FUS3 and ABI3 with the RY cis-motif, conserved in many seed-specific promoters, a promoter analysis as well as band-shift experiments were performed. The analysis of promoter mutants revealed the structural requirements for the function of the RY cis-element. It is shown that both the nucleotide sequence and the alternation of purin and pyrimidin nucleotides (RY character) are essential for the activity of the motif. Further, it was shown that FUS3 and ABI3 can act independently of each other in controlling promoter activity and that the RY cis-motif is a target for both transcription factors. For FUS3, which is so far the smallest known member of the B3-domain family, a physical interaction with the RY motif was established. The functional and biochemical data demonstrate that the regulators FUS3 and ABI3 are essential components of a regulatory network acting in concert through the RY-promoter element to control gene expression during late embryogenesis and seed development.
Assuntos
Proteínas de Arabidopsis , Fabaceae/genética , Proteínas Fúngicas/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Proteínas Quinases Ativadas por Mitógeno/genética , Plantas Medicinais , Regiões Promotoras Genéticas , Proteínas de Saccharomyces cerevisiae , Albuminas 2S de Plantas , Sequência de Bases , Biolística , Células Cultivadas , DNA de Plantas , Dados de Sequência Molecular , Mutação , Proteínas de Plantas/genética , Sementes/crescimento & desenvolvimento , Fatores de TranscriçãoRESUMO
Basic cellular processes such as electron transport in photosynthesis and respiration require the precise control of iron homeostasis. To mobilize iron, plants have evolved at least two different strategies. The nonproteinogenous amino acid nicotianamine which is synthesized from three molecules of S-adenosyl-L-methionine, is an essential component of both pathways. This compound is missing in the tomato mutant chloronerva, which exhibits severe defects in the regulation of iron metabolism. We report the purification and partial characterization of the nicotianamine synthase from barley roots as well as the cloning of two corresponding gene sequences. The function of the gene sequence has been verified by overexpression in Escherichia coli. Further confirmation comes from reduction of the nicotianamine content and the exhibition of a chloronerva-like phenotype due to the expression of heterologous antisense constructs in transgenic tobacco plants. The native enzyme with an apparent Mr of approximately 105 000 probably represents a trimer of S-adenosyl-L-methionine-binding subunits. A comparison with the recently cloned chloronerva gene of tomato reveals striking sequence homology, providing support for the suggestion that the destruction of the nicotianamine synthase encoding gene is the molecular basis of the tomato mutation.
Assuntos
Alquil e Aril Transferases/genética , Hordeum/genética , Ferro/metabolismo , Alquil e Aril Transferases/biossíntese , Sequência de Aminoácidos , Elementos Antissenso (Genética) , Clonagem Molecular , DNA Complementar/genética , Escherichia coli/genética , Homeostase , Hordeum/enzimologia , Deficiências de Ferro , Dados de Sequência Molecular , Peso Molecular , Fenótipo , Raízes de Plantas/enzimologia , Plantas Geneticamente Modificadas , Plantas Tóxicas , Estrutura Quaternária de Proteína , Proteínas Recombinantes/biossíntese , Análise de Sequência de DNA , Análise de Sequência de Proteína , Homologia de Sequência de Aminoácidos , NicotianaRESUMO
The uptake of iron in plants is a highly regulated process that is induced on iron starvation. In tomato, the mutant chloronerva exhibits constitutive expression of iron uptake responses and intercostal chlorosis. Biochemically, chloronerva is an auxotroph for nicotianamine, a key polyamine in plant iron uptake metabolism. The chloronerva gene has been fine-mapped onto the long arm of chromosome 1 in a large segregating tomato population and yeast artificial chromosome clones encompassing the region were isolated by using flanking markers. A cosmid contig containing the chloronerva gene was established, and complementing cosmids were identified by transformation into the mutant. The chloronerva transcript was identified by cDNA isolation using the complementing cosmids. The gene encodes a unique protein of 35 kDa. The mutant harbors a single base change compared with the wild type. Based on enzyme activity and sequence similarity to the coding DNA sequence of the purified barley enzyme the chloronerva gene encodes the enzyme nicotianamine synthase.
Assuntos
Alquil e Aril Transferases/genética , Genes de Plantas , Plantas/genética , Sequência de Aminoácidos , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Dados de Sequência Molecular , Alinhamento de SequênciaRESUMO
The development of seeds as a specialized organ for the nutrition, protection, and dispersal of the next generation was an important step in the evolution of land plants. Seed maturation is accompanied by massive synthesis of storage compounds such as proteins, starch, and lipids. To study the processes of seed storage protein evolution we have partially sequenced storage proteins from maturing seeds of representatives from the gymnosperm genera Gnetum, Ephedra, and Welwitschia-morphologically diverse and unusual taxa that are grouped in most formal systems into the common order Gnetales. Based on partial N-terminal amino acid sequences, oligonucleotide primers were derived and used for PCR amplification and cloning of the corresponding cDNAs. We also describe the structure of the nuclear gene for legumin of Welwitschia mirabilis. This first gnetalean nuclear gene structure contains introns in only two of the four conserved positions previously characterized in other spermatophyte legumin genes. The distinct phylogenetic status of the gnetalean taxa is also reflected in a sequence peculiarity of their legumin genes. A comparative analysis of exon/intron sequences leads to the hypothesis that legumin genes from Gnetales belong to a monophyletic evolutionary branch clearly distinct from that of legumin genes of extant Ginkgoales and Coniferales as well as from all angiosperms.
Assuntos
Cycadopsida/classificação , Cycadopsida/genética , Evolução Molecular , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Sequência de Aminoácidos , Dados de Sequência Molecular , RNA Mensageiro/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Sementes , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , LeguminasRESUMO
Metallothioneins are small cysteine-rich proteins with strong binding capacity for heavy metals. In animals and fungi they are involved in cellular detoxification processes. Although genes for similar proteins exist in plants, less is known about the putative functions of their protein products. Here, we describe the characterisation of cDNAs specific for four genes (LEMT1, LEMT2, LEMT3 and LEMT4) encoding metallothionein-like proteins from tomato. Based on the characteristic cysteine pattern, the LEMT1, LEMT3 and LEMT4 gene products represent type 2 proteins. In contrast, the LEMT2 protein might establish a new structural pattern of metallothionein-like proteins not described before. Mapping experiments demonstrate that all four genes are localised at different genetic loci within the tomato genome. The members of the small gene family show a differential organ specific expression pattern. Expression of these genes is also influenced by heavy metals and by treatment with the thiol-oxidising drug diamide. We further describe the expression of the LEMT genes under different iron supply conditions both in tomato wild type as well as in the mutant chloronerva, which is defective in metal uptake regulation and exhibits a characteristic 'apparent iron deficiency syndrome'.
Assuntos
Genes de Plantas , Metalotioneína/genética , Família Multigênica , Proteínas de Plantas/genética , Solanum lycopersicum/genética , Sequência de Aminoácidos , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Primers do DNA/genética , DNA Complementar/genética , DNA de Plantas/genética , Diamida/farmacologia , Expressão Gênica/efeitos dos fármacos , Ferro/metabolismo , Solanum lycopersicum/efeitos dos fármacos , Solanum lycopersicum/metabolismo , Metalotioneína/metabolismo , Metais Pesados/metabolismo , Metais Pesados/farmacologia , Dados de Sequência Molecular , Mutação , Proteínas de Plantas/metabolismo , Técnica de Amplificação ao Acaso de DNA Polimórfico , Homologia de Sequência de AminoácidosRESUMO
The Arabidopsis thaliana mutants fus3, lec1 and abi3 have pleiotropic defects during late embryogenesis. Mutant embryos fail to enter the maturation programme and initiate a vegetative germination pathway instead. Screening for genes which are differentially expressed in the fus3 mutant of Arabidopsis resulted in the isolation of several members of the MYB family. MYB domain proteins in plants represent an extended gene family of transcription factors, suggesting their participation in a variety of plant specific cellular functions. Here, the authors describe one of these genes, designated AtMYB13, representing a novel member of the MYB gene family. The structure of the gene as well as its genomic organisation and localisation are reported. The expression of the gene is regulated by dehydration, exogenous abscisic acid, light and wounding. A chimeric AtMYB13 promoter/GUS gene is tissue-specifically expressed in transgenic Arabidopsis plants. The GUS staining was predominantly detected in the shoot apex zone and at the basis of developing flowers. In addition, the AtMYB13 gene promoter is active at branching points of the inflorescence. Furthermore, ectopic expression of the AtMYB13 gene has a characteristic impact on the architecture of the inflorescence leading to peculiar hook structures at pedicel branching points. In addition, some transgenic plants exhibit a reversed order of first flowers and axillary buds. These data suggest a function of the AtMYB13 gene product in linking shoot morphogenic activity with environmental as well as intrinsic signals.
Assuntos
Arabidopsis/embriologia , Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Genes de Plantas , Proteínas de Plantas/genética , Proteínas Proto-Oncogênicas c-myb , Sequência de Aminoácidos , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis , Sequência de Bases , Mapeamento Cromossômico , Primers do DNA/genética , DNA de Plantas/genética , DNA de Plantas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Glucuronidase/genética , Dados de Sequência Molecular , Família Multigênica , Mutação , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Regulação para CimaRESUMO
Two novel MYB genes (ATMYBR1 and ATMYBR2) were isolated from Arabidopsis thaliana. Binding to a conserved MYB recognition sequence is demonstrated for the ATMYBR1 protein. The expression of both genes is affected by the fus3, lec1 and abi3 mutations causing pleiotropic defects during late embryogenesis and seed maturation including the loss of dormancy and desiccation tolerance. The strong increase of the transcript levels of both MYB genes during very late stages of embryogenesis typically found in wild type is missing in the mutants. Furthermore, the expression of both MYB genes is developmentally regulated in vegetative tissues. The highly conserved repeats (R2 and R3) of the DNA binding MYB domain of both proteins represent chimeric structures combining features typical of plant and animal derived proteins. This demonstrates the existence of a distinct subfamily of animal-like MYB factors in plant genomes.
Assuntos
Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Proteínas de Plantas/genética , Sequência de Aminoácidos , Arabidopsis/embriologia , Proteínas de Arabidopsis , Sequência de Bases , Sítios de Ligação , Sequência Conservada , DNA Viral/metabolismo , Proteínas de Ligação a DNA/metabolismo , Elementos Facilitadores Genéticos/genética , Regulação da Expressão Gênica no Desenvolvimento , Genes de Plantas/genética , Genes de Plantas/fisiologia , Dados de Sequência Molecular , Mutação , Proteínas de Plantas/metabolismo , Polimorfismo de Fragmento de Restrição , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-myb , RNA Mensageiro/análise , RNA de Plantas/análise , Sementes/química , Homologia de Sequência de Aminoácidos , Vírus 40 dos Símios/genética , Transativadores/genéticaRESUMO
The isolation and characterisation of a cDNA coding for a vicilin-like protein of the fern Matteuccia struthiopteris is described. The corresponding gene is specifically expressed during late stages of spore development. Extensive sequence comparisons suggest that the fern protein can be considered as a molecular missing link between single-domain germin/spherulin-like proteins and two-domain seed storage globulins of gymnosperms and angiosperms. Further, evidence is provided for the existence of a superfamily of structurally related, functionally different proteins which includes storage globulins of the vicilin and legumin families, a membrane-associated sucrose-binding protein of soybean, a Forssman antigen-binding lectin of velvet bean, the precursor of the vacuolar membrane bound proteins MP27/MP32 of pumpkin, the embryogenesis-specific protein Gea8 of carrot, the fern-spore-specific protein described here as well as the functionally diverse family of germins/germin-like proteins and the spherulins of myxomycetes. We propose that seed storage globulins of spermatophytes evolved from desiccation-related single-domain proteins of prokaryotes via a duplicated two-domain ancestor that is best represented by the extant fern spore-specific vicilin-like protein.
Assuntos
Proteínas de Plantas/química , Plantas/química , Esporos/química , Sequência de Aminoácidos , Clonagem Molecular , Sequência Conservada/genética , Evolução Molecular , Fabaceae , Glicoproteínas/química , Glicoproteínas/genética , Dados de Sequência Molecular , Plantas Medicinais , Proteínas de Armazenamento de Sementes , Sementes/química , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
The tomato mutant chloronerva exhibits a defect in iron-uptake regulation. Despite high apoplastic and symplastic iron concentrations, the mutant shows characteristic symptoms of iron deficiency. Using a subtractive-hybridisation approach, we have screened for cDNA clones specific for genes with altered expression in wild-type versus mutant root tissue. Based on this clone collection, we have isolated and characterised a 2075-bp full-length cDNA encoding a lysyl-tRNA-synthetase-like protein. The corresponding gene is localised as a single copy on chromosome 10. Its expression is strongly induced by changes in the iron status of the plant. This iron-dependent regulation is superimposed upon a strict root specificity of gene expression. Possible functions of the gene product other than in protein biosynthesis will be discussed.
Assuntos
Genes de Plantas , Ferro/metabolismo , Lisina-tRNA Ligase/genética , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Transporte Biológico Ativo/genética , Mapeamento Cromossômico , Clonagem Molecular , Primers do DNA/genética , DNA de Plantas/genética , Amplificação de Genes , Expressão Gênica , Humanos , Solanum lycopersicum/enzimologia , Dados de Sequência Molecular , Mutação , Homologia de Sequência de AminoácidosRESUMO
The 'Salmon system' consists of isogenic but alloplasmic wheat lines with either sexual or autonomous embryo development. Using two-dimensional gel electrophoresis these lines have been screened for proteins potentially involved in the initiation of parthenogenesis. A temporally altered expression of the polypeptide 'P 115.1' in the sexual and parthenogenetic 'Salmon' lines seems to be related with the autonomous embryo formation. Around anthesis when most of the egg cells begin the parthenogenetic development, the polypeptide 'P 115.1' was present in ovaries of the parthenogenetic lines but not in ovaries of the sexual line. Moreover, this polypeptide is only expressed in the ovaries of amphidiploid parthenogenetic plants containing differentiated embryo sacs. It is absent from ovaries of the analogous polyhaploid plants, which lack any embryo sac structure within their ovules. Furthermore, the polypeptide was neither detectable in meristematic tissue of root tips nor in leaves. N-terminal amino acid sequencing identified 'P 115.1' as an alpha-tubulin. Thus, 'P 115.1' apparently represents an embryo sac-specific isoform of alpha-tubulin involved in the initiation of embryo development.
Assuntos
Triticum/fisiologia , Tubulina (Proteína)/biossíntese , Sequência de Aminoácidos , Arabidopsis/genética , Partenogênese , Alinhamento de Sequência , Triticum/genética , Tubulina (Proteína)/químicaRESUMO
Three wheat sequences, shown to be homologous to pollen allergen encoding, DNA replication regulating, and DNA (cytosine-5)-methyltransferase genes were localized on chromosomes using nullisomic-tetrasomic wheat ('Chinese Spring') and wheat-rye ('Chinese Spring'/'Imperial') addition lines. Whereas the loci for the pollen allergen encoding sequence (Tri a III) were shown to be located on homoeologous group 4, the DNA replication regulating (Rep) and DNA (cytosine-5)-methyltransferase (Mtase) genes were located to homoeologous groups 1 and 7, respectively, of Triticeae. Chromosomal rearrangements in wheat and rye relative to each other are discussed.
Assuntos
Alérgenos/química , DNA (Citosina-5-)-Metiltransferases/genética , Replicação do DNA , Secale/genética , Triticum/genética , Eletroforese em Gel de Poliacrilamida , Regulação Enzimológica da Expressão Gênica , Pólen/química , Secale/enzimologia , Triticum/enzimologiaRESUMO
A novel myb-like gene (AtmybL2) was isolated from an Arabidopsis thaliana cDNA library. The single copy gene was localised on chromosome I. A gene specific transcript is preferentially found in leaves. The predicted gene product consists of a conservative N-terminal myb-domain known to be involved in DNA-binding and a unique proline-rich C-terminal part. Remarkably, the myb-domain includes only one of the typical two or three tryptophan repeats found in other myb-like proteins.