RESUMO
Heat shock proteins are associated with protection against various abiotic stresses. Here, the isolation of a chrysanthemum cDNA belonging to the HSP70 family is reported. The cDNA, designated CgHSP70, encodes a 647-residue polypeptide, of estimated molecular mass 70.90 kDa and pI 5.12. A sub-cellular localization assay indicated that the cDNA product is deposited in the cytoplasm and nucleus. The performance of Arabidopsis thaliana plants constitutively expressing CgHSP70 demonstrated that the gene enhances tolerance to heat, drought and salinity. When CgHSP70 was stably over-expressed in chrysanthemum, the plants showed an increased peroxidase (POD) activity, higher proline content and inhibited malondialdehyde (MDA) content. After heat stress, drought or salinity the transgenic plants were better able to recover, demonstrating CgHSP70 positive effect.
Assuntos
Adaptação Fisiológica/genética , Chrysanthemum/genética , Proteínas de Choque Térmico HSP70/genética , Proteínas de Plantas/genética , Estresse Fisiológico , Sequência de Aminoácidos , Arabidopsis/genética , Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Chrysanthemum/metabolismo , Secas , Regulação da Expressão Gênica de Plantas , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Temperatura Alta , Microscopia Confocal , Dados de Sequência Molecular , Peróxidos/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Prolina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Salinidade , Homologia de Sequência de AminoácidosRESUMO
Zinc finger proteins (ZFPs) play an important role in plant growth and development. Here, we describe the isolation of CgZFP1, a Cys2/His2 (C(2)H(2)) ZFP gene, using RACE PCR from chrysanthemum, and the investigation of its function with ectopic expression in Arabidopsis. CgZFP1 contains two conserved C(2)H(2) regions, a nuclear localization domain (B box), a Leu-rich domain (L box) and a conserved DLN sequence (DLN box) close to its C-terminus. Its expression in the chrysanthemum leaf was strongly induced by salinity or drought, but not by ABA. Subcellular localization assay indicated that CgZFP1 protein is localized in nucleus in vivo. Yeast-one hybrid assay showed that CgZFP1 possesses transcriptional activation ability, heterologous expression of CgZFP1 conferred tolerance of transgenic Arabidopsis plants to both salinity and drought stresses. Under salinity stress, genes involved in osmotic adjustment, ROS scavenging, and ion homeostasis: Atlea3, AtP5CS2, AtProT1, and AtMnSOD, AtPOD, AtAPX1, and AtSOS1, AtSOS2, AtSOS3, AtNHX1 were enhanced in CgZFP1 transgenic Arabidopsis plants. Moreover, genes involved in the osmotic adjustment and oxidative stress responses: Atlea3, AtP5CS2, AtProT1, the aquaporin AtPIP2A, and AtMnSOD, AtPOD, AtAPX1 were induced in CgZFP1 transgenic Arabidopsis under drought stress. These results indicate CgZFP1 is an important regulator involved in the salt and drought stress response in plants.
Assuntos
Adaptação Fisiológica/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Estresse Fisiológico/genética , Dedos de Zinco/genética , Chrysanthemum/genética , Chrysanthemum/metabolismo , Secas , Genes de Plantas , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Salinidade , Tolerância ao Sal/genéticaRESUMO
Knowledge on genes related to plant responses to adverse growth conditions and development is essential for germplasm improvement. In this study, a chrysanthemum R2R3-MYB transcription factor gene, designated CmMYB2 (GenBank accession No. JF795918), was cloned and functionally characterized. Expression of CmMYB2 in chrysanthemum leaves was up-regulated in response to drought, salinity and cold stress, as well as by treatment with exogenous abscisic acid (ABA). When the gene was constitutively expressed in Arabidopsis thaliana, it increased plant sensitivity to ABA and reduced stomatal aperture. Plant survival under drought was improved than in the wild type, as was the plants' salinity tolerance. The level of expression of a number of genes associated with the stress response, including RD22, RD29A, RAB18, COR47, ABA1 and ABA2, was raised in the CmMYB2 transgenic Arabidopsis plants. CmMYB2 transgenic Arabidopsis plants were also delayed in flowering. The expression of CONSTANS (CO), FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), LEAFY (LFY) and APETALA1 (AP1) genes involved in flowering was down-regulated in the CmMYB2 transgenics. Together, these results suggest that CmMYB2 may be a promising gene for the drought and salt tolerance improvement and flowering-time modulation.