RESUMO
Gibberellins (GAs) play important roles in the regulation of plant growth and development. The green revolution gene SD1 encoding gibberellin 20-oxidase 2 (GA20ox2) has been widely used in modern rice breeding. However, the molecular mechanism of how SD1/OsGA20ox2 expression is regulated remains unclear. Here, we report a Cys2/His2 zinc finger protein ZFP207 acting as a transcriptional repressor of OsGA20ox2. ZFP207 was mainly accumulated in young tissues and more specifically in culm nodes. ZFP207-overexpression (ZFP207OE) plants displayed semidwarfism phenotype and small grains by modulating cell length. RNA interference of ZFP207 caused increased plant height and grain length. The application of exogenous GA3 could rescue the semidwarf phenotype of ZFP207OE rice seedlings. Moreover, ZFP207 repressed the expression of OsGA20ox2 via binding to its promoter region. Taken together, ZFP207 acts as a transcriptional repressor of SD1/OsGA20ox2 and it may play a critical role in plant growth and development in rice through the fine-tuning of GA biosynthesis .
Assuntos
Regulação da Expressão Gênica de Plantas , Genes de Plantas/fisiologia , Oryza/metabolismo , Proteínas de Plantas/fisiologia , Dedos de Zinco/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Genes de Plantas/genética , Oryza/genética , Proteínas Repressoras/metabolismo , Proteínas Repressoras/fisiologia , Plântula/metabolismoRESUMO
The CDF family is a ubiquitous family that has been identified in prokaryotes, eukaryotes, and archaea. Members of this family are important heavy metal transporters that transport metal ions out of the cytoplasm. In this research, a full length cDNA named Oryza sativa Zn Transporter 1 (OZT1) that closely related to rat ZnT-2 (Zn Transporter 2) gene was isolated from rice. The OZT1 encoding a CDF family protein shares 28.2 % ~ 84.3 % of identities and 49.3 % ~ 90.9 % of similarities with other zinc transporters such as RnZnT-2, HsZnT-8, RnZnT-8 and AtMTP1. OZT1 was constitutively expressed in various rice tissues. The OZT1 expression was significantly induced both in the seedlings of japonica rice Nipponbare and indica rice IR26 in response to Zn(2+) and Cd(2+) treatments. Besides, OZT1 expression was also increased when exposed to other excess metals, such as Cu(2+), Fe(2+) and Mg(2+). Subcellular localization analysis indicated that OZT1 localized to vacuole. Heterologous expression of OZT1 in yeast increased tolerance to Zn(2+) and Cd(2+) stress but not the Mg(2+) stress. Together, OZT1 is a CDF family vacuolar zinc transporter conferring tolerance to Zn(2+) and Cd(2+) stress, which is important to transporting and homeostasis of Zn, Cd or other heavy metals in plants.
Assuntos
Proteínas de Transporte/genética , Oryza/genética , Proteínas de Plantas/genética , Vacúolos/metabolismo , Adaptação Fisiológica , Sequência de Aminoácidos , Cloreto de Cádmio/metabolismo , Proteínas de Transporte/biossíntese , Proteínas de Transporte/química , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Homeostase , Modelos Moleculares , Dados de Sequência Molecular , Oryza/metabolismo , Filogenia , Proteínas de Plantas/biossíntese , Proteínas de Plantas/química , Estrutura Secundária de Proteína , Proteínas Recombinantes , Saccharomyces cerevisiae , Plântula , Análise de Sequência de DNA , Estresse Fisiológico , Ativação Transcricional , Sulfato de Zinco/metabolismoRESUMO
In the present paper, we identified and cloned OsDHODH1 encoding a putative cytosolic dihydroorotate dehydrogenase (DHODH) in rice. Expression analysis indicated that OsDHODH1 is upregulated by salt, drought and exogenous abscisic acid (ABA), but not by cold. By prokaryotic expression, we determined the enzymatic activity of OsDHODH1 and found that overproduction of OsDHODH1 significantly improved the tolerance of Escherichia coli cells to salt and osmotic stresses. Overexpression of the OsDHODH1 gene in rice increased the DHODH activity and enhanced plant tolerance to salt and drought stresses as compared with wild type and OsDHODH1-antisense transgenic plants. Our findings reveal, for the first time, that cytosolic dihydroorotate dehydrogenase is involved in plant stress response and that OsDHODH1 could be used in engineering crop plants with enhanced tolerance to salt and drought.
Assuntos
Secas , Oryza/enzimologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/enzimologia , Cloreto de Sódio/farmacologia , Ácido Abscísico/farmacologia , Sequência de Aminoácidos , Clorofila/metabolismo , Di-Hidro-Orotato Desidrogenase , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Dados de Sequência Molecular , Oryza/efeitos dos fármacos , Oryza/genética , Oxidantes/farmacologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/química , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/classificação , Fenótipo , Filogenia , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/química , Proteínas de Plantas/classificação , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Prolina/metabolismo , TemperaturaRESUMO
The A20/AN1-type zinc finger protein family is conserved in animals and plants. Using human AWP1 protein as a query, we identified twelve A20/AN1-type zinc finger proteins in japonica rice. Most of these genes were constitutively expressed in leaves, roots, culms and spikes. Through microarray analysis, it was found that four genes (ZFP177, ZFP181, ZFP176, ZFP173), two genes (ZFP181 and ZFP176) and one gene (ZFP157) were significantly induced by cold, drought and H(2)O(2) treatments, respectively. Further expression analysis showed that ZFP177 was responsive to both cold and heat stresses, but down-regulated by salt. The subcellular localization assay indicated that ZFP177 was localized in cytoplasm in tobacco leaf and root cells. Yeast-one hybrid assay showed that ZFP177 lacked trans-activation potential in yeast cells. Overexpression of ZFP177 in tobacco conferred tolerance of transgenic plants to both low and high temperature stresses, but increased sensitivity to salt and drought stresses. Further we found expression levels of some stress-related genes were inhibited in ZFP177 transgenic plants. These results suggested that ZFP177 might play crucial but differential roles in plant responses to various abiotic stresses.
