RESUMO
A highly efficient and convenient method for the Agrobacterium rhizogenes-dependent production of transformed roots of Saponaria vaccaria L. (Caryophyllaceae) is described. The parameters tested and optimized include S. vaccaria cultivar, explant type, Agrobacterium rhizogenes strain and culture conditions. For cotransformation using additional recombinant T-DNA-containing A. rhizogenes strains, use of neomycin phosphotransferase and enhanced green fluorescent protein genes as selectable markers were tested alone and in combination. Optimal results, yielding a minimum of one transformed root per explant, were obtained using the cultivar Pink Beauty, the A. rhizogenes strain LBA9402 and internode explants precultured on a phytohormone mixture. Selection of cotransformed roots by observation of enhanced green fluorescent protein fluorescence alone was highly effective and convenient.
Assuntos
Caryophyllaceae/genética , Técnicas Genéticas , Rhizobium/fisiologia , Seleção Genética , Transformação Genética , Resistência Microbiana a Medicamentos , Fluorescência , Proteínas de Fluorescência Verde/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase , Espectrometria de FluorescênciaRESUMO
Elicitor-induced sanguinarine accumulation in opium poppy (Papaver somniferum) cell cultures provides a responsive model system to profile modulations in gene transcripts and metabolites related to alkaloid biosynthesis. An annotated expressed sequence tag (EST) database was assembled from 10,224 random clones isolated from an elicitor-treated opium poppy cell culture cDNA library. The most abundant ESTs encoded defense proteins, and enzymes involved in alkaloid metabolism and S-adenosylmethionine-dependent methyl transfer. ESTs corresponding to 40 enzymes involved in the conversion of sucrose to sanguinarine were identified. A corresponding DNA microarray was probed with RNA from cell cultures collected at various time-points after elicitor treatment, and compared with RNA from control cells. Several diverse transcript populations were coordinately induced, with alkaloid biosynthetic enzyme and defense protein transcripts displaying the most rapid and substantial increases. In addition to all known sanguinarine biosynthetic gene transcripts, mRNAs encoding several upstream primary metabolic enzymes were coordinately induced. Fourier transform-ion cyclotron resonance-mass spectrometry was used to characterize the metabolite profiles of control and elicitor-treated cell cultures. Principle component analysis revealed a significant and dynamic separation in the metabolome, represented by 992 independent detected analytes, in response to elicitor treatment. Identified metabolites included sanguinarine, dihydrosanguinarine, and the methoxylated derivatives dihydrochelirubine and chelirubine, and the alkaloid pathway intermediates N-methylcoclaurine, N-methylstylopine, and protopine. Some of the detected analytes showed temporal changes in abundance consistent with modulations in the profiles of alkaloid biosynthetic gene transcripts.
Assuntos
Regulação da Expressão Gênica de Plantas , Papaver/genética , Transcrição Gênica , Técnicas de Cultura de Células , Clonagem Molecular , DNA Complementar/genética , DNA de Plantas/genética , Enzimas/genética , Etiquetas de Sequências Expressas , Perfilação da Expressão Gênica , Biblioteca Gênica , Análise de Sequência com Séries de Oligonucleotídeos , Papaver/citologia , Papaver/metabolismo , Proteínas de Plantas/genética , RNA de Plantas/genéticaRESUMO
Tropane alkaloids are valuable pharmaceutical drugs derived from solanaceous plants such as Hyoscyamus niger (black henbane). The biosynthesis of these molecules, including the nature of the enigmatic rearrangement of (R)-littorine to (S)-hyoscyamine, is not completely understood. To test the hypothesis that a cytochrome P450 enzyme is involved in this rearrangement, we used virus-induced gene silencing to silence a cytochrome P450, CYP80F1, identified from H. niger roots by EST sequencing. Silencing CYP80F1 resulted in reduced hyoscyamine levels and the accumulation of littorine. Hyoscyamine was observed in CYP80F1-expressing tobacco hairy roots supplied with (R)-littorine. Expression in yeast confirmed that CYP80F1 catalyzes the oxidation of (R)-littorine with rearrangement to form hyoscyamine aldehyde, a putative precursor to hyoscyamine, and without rearrangement to form 3'-hydroxylittorine. Our data strongly support the involvement of CYP80F1 in the rearrangement of littorine to hyoscyamine.
