RESUMO
D-ononitol epimerase (OEP) catalyzes the conversion of D-ononitol to D-pinitol, which is the last step in the biosynthetic pathway, where myo-inositol is converted to pinitol in higher plants. In this study, OEP cDNA was isolated from Glycine max (GmOEP) and was functionally characterized, which confirmed that GmOEP expression was induced by high salinity and drought stress treatments. To understand the biological function of GmOEP, transgenic Arabidopsis plants overexpressing this protein were constructed. The transgenic Arabidopsis plants displayed enhanced tolerance to high salinity and drought stress treatments.
Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , Inositol/análogos & derivados , Sais/química , Proteínas de Arabidopsis/metabolismo , Secas , Etiquetas de Sequências Expressas , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Inositol/biossíntese , Inositol/química , Plantas Geneticamente Modificadas/metabolismo , Tolerância ao Sal/genética , Plântula/metabolismo , Cloreto de Sódio/química , Glycine max/metabolismo , Estresse FisiológicoRESUMO
Protein phosphatase 2Cs (PP2Cs) have been referred to act as negative modulators of the protein kinase pathways involved in different environmental stress responses and developmental processes. In Arabidopsis, PP2Cs have been extensively studied and some are known to negatively regulate abscisic acid signaling. In rice, PP2Cs are scarcely characterized functionally. Here, we identified a novel PP2C from rice (OsPP2C34), which is highly inducible by gibberellin (GA) and expressed in various tissues. Subcellular localization analysis in maize protoplasts using a green fluorescence protein fusion vector localized OsPP2C34 to the cytosol. Genetic analysis of T-DNA insertional mutants revealed that plant height and internode length were significantly shorter in mutants than in corresponding wild types under GA treatment. The induction of the GA-inducibleα-amylase genes RAmy3E and OsAmy was delayed in mutant plants. The substrate of OsPP2C34 was identified by immunoblotting using anti serine/threonine antibodies. A 65â¯kDa protein was phosphorylated in Ospp2c34-1 but dephosphorylated in the wild type during early germination stage. Overall, the present results indicated that OsPP2C34 is involved inα-amylase expression of GA signal transduction pathway.
Assuntos
Giberelinas/farmacologia , Oryza/efeitos dos fármacos , Oryza/enzimologia , Proteína Fosfatase 2C/isolamento & purificação , Proteína Fosfatase 2C/metabolismo , Transdução de Sinais/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Proteína Fosfatase 2C/químicaRESUMO
A number of basic leucine zipper (bZIP) transcription factors are known to function in stress signaling in plants but few have thus far been functionally characterized in rice. In our current study in rice, we have newly isolated and characterized the OsABF1 (Oryza sativa ABA responsive element binding factor 1) gene that encodes a bZIP transcription factor. Its expression in seedling shoots and roots was found to be induced by various abiotic stress treatments such as anoxia, salinity, drought, oxidative stress, cold and abscisic acid (ABA). Subcellular localization analysis in maize protoplasts using GFP fusion vectors indicated that OsABF1 is a nuclear protein. In a yeast experiment, OsABF1 was shown to bind to ABA responsive elements (ABREs) and its N-terminal region was necessary to transactivate the downstream reporter gene. The homozygous T-DNA insertional mutants Osabf1-1 and Osabf1-2 were more sensitive in response to drought and salinity treatments than wild type plants. Furthermore, the upregulated expression of some ABA/stress-regulated genes in response to ABA treatment was suppressed in these Osabf1 mutants. Our current results thus suggest that OsABF1 is involved in abiotic stress responses and ABA signaling in rice.
Assuntos
Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Ácido Abscísico/metabolismo , Sequência de Bases , Fatores de Transcrição de Zíper de Leucina Básica/genética , Sondas de DNA , DNA de Plantas/genética , Genes de Plantas , Mutação , Oryza/genética , Filogenia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais , Estresse Fisiológico , Zea mays/genética , Zea mays/metabolismoRESUMO
Abscisic acid (ABA) is an important phytohormone involved in abiotic stress tolerance in plants. The group A bZIP transcription factors play important roles in the ABA signaling pathway in Arabidopsis but little is known about their functions in rice. In our current study, we have isolated and characterized a group A bZIP transcription factor in rice, OsABF2 (Oryza sativa ABA-responsive element binding factor 2). It was found to be expressed in various tissues in rice and induced by different types of abiotic stress treatments such as drought, salinity, cold, oxidative stress, and ABA. Subcellular localization analysis in maize protoplasts using a GFP fusion vector indicated that OsABF2 is a nuclear protein. In yeast experiments, OsABF2 was shown to bind to ABA-responsive elements (ABREs) and its N-terminal region found to be necessary to transactivate a downstream reporter gene. A homozygous T-DNA insertional mutant of OsABF2 is more sensitive to salinity, drought, and oxidative stress compared with wild type plants. In addition, this Osabf2 mutant showed a significantly decreased sensitivity to high levels of ABA at germination and post-germination. Collectively, our present results indicate that OsABF2 functions as a transcriptional regulator that modulates the expression of abiotic stress-responsive genes through an ABA-dependent pathway.