RESUMO
The genomic nucleotide sequences of the cloned agroinfectious genomes of three South African mastreviruses obtained from Zea mays, a Setaria sp., and Panicum maximum (designated MSV-Kom, MSV-Set, and PanSV-Kar respectively), were determined. Additionally, their relative infectivities and virulence were analysed in a range of differentially susceptible wheat, maize, and barley genotypes. MSV-Kom produced moderate to severe streak symptoms in all maize genotypes tested, but only moderate to very mild symptoms in the wheat and barley genotypes. MSV-Set infected only the susceptible to tolerant maize genotypes, but was generally more severe in the barley and wheat genotypes than MSV-Kom. PanSV-Kar was incapable of infecting any of the wheat and barley genotypes and only produced very mild symptoms on the three most sensitive maize genotypes. Genomic characteristics in common with related mastreviruses were identified. Phylogenetic analysis indicated that while MSV-Kom was closely related to previously sequenced MSV isolates, MSV-Set and PanSV-Kar represented distinctly novel strains of MSV and PanSV respectively. In the case of MSV-Set, this is the most distantly related MSV strain yet characterised.
Assuntos
Geminiviridae/genética , Geminiviridae/patogenicidade , Genoma Viral , Animais , Sequência de Bases , DNA Intergênico/genética , DNA Viral/genética , Geminiviridae/isolamento & purificação , Hemípteros/virologia , Hordeum/virologia , Dados de Sequência Molecular , Panicum/virologia , Filogenia , Doenças das Plantas/virologia , África do Sul , Especificidade da Espécie , Triticum/virologia , Virulência , Zea mays/virologiaRESUMO
Homozygous glabra2 (gl2) mutant Arabidopsis thaliana Landsberg erecta plants with only a few rudimentary single spiked trichomes on the leaf margin were transformed with a genomic clone of GL2, resulting in partial restoration of the normal leaf trichome phenotype. The introduced GL2 transgene was configured as part of an FLP recombinase-responsive gene switch, which permitted visibly marked gl2 mutant clonal sectors to be generated by FLP recombinase-mediated deletion of the GL2 transgene with concomitant activation of a previously silent beta-glucuronidase (GUS) marker gene. GUS marked sectors extending through all three leaf cell layers (L1, L2, and L3) displayed the anticipated gl2 mutant phenotype, whereas immediately adjacent unmarked tissue, and unmarked tissues overlaying GUS sectors restricted to the L2 and/or L3 cell layers, retained the GL2 restored phenotype. These data support the view that the GL2 gene product acts in a region-autonomous manner within a single cell layer and indicate that GL2 gene expression in the L1 layer is sufficient for GL2-directed outgrowth of trichomes.
Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Proteínas de Homeodomínio/genética , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Arabidopsis/crescimento & desenvolvimento , Diferenciação Celular , Sobrevivência Celular , DNA Nucleotidiltransferases , Regulação da Expressão Gênica de Plantas/genética , Genes de Plantas/genética , Genes Reporter/genética , Glucuronidase/genética , Glucuronidase/metabolismo , Proteínas de Homeodomínio/metabolismo , Morfogênese/fisiologia , Mutagênese/genética , Fenótipo , Folhas de Planta/citologia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Transformação GenéticaRESUMO
Stably transformed Arabidopsis lines in which GUS marked cell clones are readily produced in response to heat-shock have been established and characterized. Control of GUS activation is achieved by heat-shock-induced FLP recombinase activity which "switches on" expression of a GUS marker gene previously held transcriptionally silent. To obtain efficient GUS sectoring, single insert Arabidopsis lines carrying FLP recombinase under the control of a heat-shock-inducible promoter and an FLP-activatable GUS construct were generated. Analysis of GUS sectoring in lines hemizygous and homozygous for both inserts was conducted after various regimes of heat-shock were given at various developmental stages. It is shown that GUS sectoring events can be efficiently induced in most vegetative, aerial and sexual structures in Arabidopsis. Furthermore, the frequency of sectoring events, sector size and, to some extent, the tissues in which sectors are generated can be readily controlled by choice of the conditions and timing of heat-shock used.
