RESUMO
Junenol based-eudesmanolides have been detected in many compositae plant species and were reported to exhibit various pharmacological activities. So far, the gene encoding junenol synthase has never been isolated. Here we report the molecular cloning and functional analysis of a 10-epi-junenol synthase from Inula hupehensis (designated IhsTPS1). IhsTPS1 converts the substrate farnesyl diphosphate into multiple sesquiterpenes with the product 10-epi-junenol being predominant. The transcript levels of IhsTPS1 correlate well with the accumulation pattern of 10-epi-junenol in I. hupehensis organs, supporting its biochemical roles in vivo.
Assuntos
Alquil e Aril Transferases/genética , Inula/enzimologia , Inula/genética , Proteínas de Plantas/genética , Alquil e Aril Transferases/metabolismo , Vias Biossintéticas/genética , Clonagem Molecular , DNA Complementar/genética , Cromatografia Gasosa-Espectrometria de Massas , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Filogenia , Proteínas de Plantas/metabolismo , Fosfatos de Poli-Isoprenil/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Sesquiterpenos/química , Sesquiterpenos/metabolismoRESUMO
The 5' fragment (1 647 bp) of the cotton glucuronosyltransferase gene (GhGlcAT1) was transcriptionally fused to the beta-glucuronidase (GUS) gene, and functionally analyzed for important regulatory regions controlling gene expression in transgenic tobacco plants. GUS activity analysis revealed that the full-length promoter drives efficient expression of the GUS gene in the root cap, seed coat, pollen grains and trichomes. Exposure of the transgenic tobacco to various abiotic stresses showed that the promoter was mainly responsive to the sugars (glucose and sucrose) as well as gibberellic acid. Progressive upstream deletion analyses of the promoter showed that the region from -281 to +30 bp is sufficient to drive strong GUS expression in the trichomes of shoot, suggesting that the 311 bp region contains all cis-elements needed for trichome-specific expression. Furthermore, deletion analysis also revealed that the essential cis-element(s) for sucrose induction might be located between -635 and -281 bp. In addition, sequence analysis of the regulatory region indicated several conserved motifs among which some were shared with previously reported seed-specific elements and sugar-responsive elements, while others were related with trichome expression. These findings indicate that a 1 647-bp fragment of the cotton GhGlcAT1 promoter contains specific transcription regulatory elements, and provide clues about the roles of GhGlcAT1 in cotton fiber development. Further analyses of these elements will help to elucidate the molecular mechanisms regulating the expression of the GhGlcAT1 gene during fiber elongation.