RESUMO
Transgenic arabidopsis plants were isolated that contained a T-DNA construct in which the promoter of an auxin-inducible glutathione S-transferase (GST) gene from tobacco was fused to the kanamycin resistance (nptII) as well as to the beta-glucuronidase (gusA) reporter gene. Subsequently, seeds were treated with EMS to obtain mutants in which both reporter gene fusions were up-regulated. Northern analysis showed that the mRNA level of a related, endogenous auxin-inducible GST gene of Arabidopsis was increased in some of these mutants as well. Two of the gup (GST up-regulated) mutants were characterized in more detail and roughly mapped. Both had epinastic cotyledons and leaves, a phenotype that turned out to be linked to the gup mutation.
Assuntos
Arabidopsis/genética , Glutationa Transferase/genética , Ácidos Indolacéticos/farmacologia , Regiões Promotoras Genéticas , Mapeamento Cromossômico , Cruzamentos Genéticos , DNA Bacteriano/genética , Indução Enzimática/efeitos dos fármacos , Metanossulfonato de Etila/farmacologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Mutagênese , Mutagênicos/farmacologia , Mutação , Fenótipo , Plantas Geneticamente Modificadas , Proteínas Recombinantes de Fusão/genética , Regulação para CimaRESUMO
Genes homologous to the auxin-inducible Nt103 glutathione S-transferase (GST) gene of tobacco, were isolated from a genomic library of Arabidopsis thaliana. We isolated a lambda clone containing an auxin-inducible gene, At103-1a, and part of a constitutively expressed gene, At103-1b. The coding regions of the Arabidopsis genes were highly homologous to each other and to the coding region of the tobacco gene but distinct from the GST genes that have been isolated from arabidopsis thusfar. Overexpression of a cDNA clone in Escherichia coli revealed that the AT103-1A protein had GST activity.
Assuntos
Arabidopsis/genética , Genes de Plantas , Glutationa Transferase/genética , Proteínas de Plantas/genética , Sequência de Aminoácidos , Arabidopsis/enzimologia , Sequência de Bases , Indução Enzimática , Escherichia coli/genética , Regulação da Expressão Gênica de Plantas , Biblioteca Genômica , Glutationa Transferase/biossíntese , Ácidos Indolacéticos/farmacologia , Dados de Sequência Molecular , Proteínas de Plantas/biossíntese , RNA Mensageiro/análise , RNA de Plantas/análise , Proteínas Recombinantes/biossíntese , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
Agrobacterium rhizogenes-mediated introduction of the wild-type allele of the gene encoding granulebound starch synthase (GBSS) into the amylose-free starch mutantamf of potato leads to restoration of GBSS activity and amylose synthesis, which demonstrates thatAmf is the structural gene for GBSS. Amylose was found in columella cells of root tips, in stomatal guard cells, tubers, and pollen, while in the control experiments using only vector DNA, these tissues remained amylose free. This confirms the fact that, in potato, GBSS is the only enzyme responsible for the presence of amylose, accumulating in all starch-containing tissues. Amylose-containing transformants showed no positive correlation between GBSS activity and amylose content, which confirms that the former is not the sole regulating factor in amylose metabolism.
