RESUMO
The transcription factor DREB1A/CBF3 specifically interacts with the dehydration responsive element (DRE/CRT) and induces expression of genes involved in environmental stress tolerance in Arabidopsis: Overexpression of DREB1A improved drought- and low-temperature stress tolerance in tobacco. The stress-inducible rd29A promoter minimized the negative effects on the plant growth in tobacco. Furthermore, we detected overexpression of stress-inducible target genes of DREB1A in tobacco. These results indicate that a combination of the rd29A promoter and DREB1A is useful for improvement of various kinds of transgenic plants that are tolerant to environmental stress.
Assuntos
Aclimatação/genética , Proteínas de Arabidopsis/genética , Nicotiana/genética , Regiões Promotoras Genéticas/genética , Transativadores/genética , Fatores de Transcrição , Aclimatação/fisiologia , Proteínas de Arabidopsis/metabolismo , Temperatura Baixa , DNA Complementar/química , DNA Complementar/genética , Desastres , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Dados de Sequência Molecular , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Análise de Sequência de DNA , Nicotiana/crescimento & desenvolvimento , Transativadores/metabolismoRESUMO
The transcription factors DREBs/CBFs specifically interact with the dehydration-responsive element/C-repeat (DRE/CRT) cis-acting element (core motif: G/ACCGAC) and control the expression of many stress-inducible genes in Arabidopsis. In rice, we isolated five cDNAs for DREB homologs: OsDREB1A, OsDREB1B, OsDREB1C, OsDREB1D, and OsDREB2A. Expression of OsDREB1A and OsDREB1B was induced by cold, whereas expression of OsDREB2A was induced by dehydration and high-salt stresses. The OsDREB1A and OsDREB2A proteins specifically bound to DRE and activated the transcription of the GUS reporter gene driven by DRE in rice protoplasts. Over-expression of OsDREB1A in transgenic Arabidopsis induced over-expression of target stress-inducible genes of Arabidopsis DREB1A resulting in plants with higher tolerance to drought, high-salt, and freezing stresses. This indicated that OsDREB1A has functional similarity to DREB1A. However, in microarray and RNA blot analyses, some stress-inducible target genes of the DREB1A proteins that have only ACCGAC as DRE were not over-expressed in the OsDREB1A transgenic Arabidopsis. The OsDREB1A protein bound to GCCGAC more preferentially than to ACCGAC whereas the DREB1A proteins bound to both GCCGAC and ACCGAC efficiently. The structures of DREB1-type ERF/AP2 domains in monocots are closely related to each other as compared with that in the dicots. OsDREB1A is potentially useful for producing transgenic monocots that are tolerant to drought, high-salt, and/or cold stresses.
