RESUMO
In plants, the bZIP (basic leucine zipper) transcription factors regulate diverse functions, including processes such as plant development and stress response. However, few have been functionally characterized in maize (Zea mays). In this study, we cloned ZmbZIP72, a bZIP transcription factor gene from maize, which had only one copy in the maize genome and harbored three introns. Analysis of the amino acid sequence of ZmbZIP72 revealed a highly conserved bZIP DNA-binding domain in its C-terminal region, and four conserved sequences distributed in N- or C-terminal region. The ZmbZIP72 gene expressed differentially in various organs of maize plants and was induced by abscisic acid, high salinity, and drought treatment in seedlings. Subcellular localization analysis in onion epidermal cells indicated that ZmbZIP72 was a nuclear protein. Transactivation assay in yeast demonstrated that ZmbZIP72 functioned as a transcriptional activator and its N terminus (amino acids 23-63) was necessary for the transactivation activity. Heterologous overexpression of ZmbZIP72 improved drought and partial salt tolerance of transgenic Arabidopsis plants, as determined by physiological analyses of leaf water loss, electrolyte leakage, proline content, and survival rate under stress. In addition, the seeds of ZmbZIP72-overexpressing transgenic plants were hypersensitive to ABA and osmotic stress. Moreover, overexpression of ZmbZIP72 enhanced the expression of ABA-inducible genes such as RD29B, RAB18, and HIS1-3. These results suggest that the ZmbZIP72 protein functions as an ABA-dependent transcription factor in positive modulation of abiotic stress tolerance and may be a candidate gene with potential application in molecular breeding to enhance stress tolerance in crops.
Assuntos
Arabidopsis/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Plantas Tolerantes a Sal/genética , Zea mays/genética , Ácido Abscísico/farmacologia , Sequência de Aminoácidos , Arabidopsis/efeitos dos fármacos , Arabidopsis/fisiologia , Fatores de Transcrição de Zíper de Leucina Básica/classificação , Fatores de Transcrição de Zíper de Leucina Básica/genética , Clonagem Molecular , Sequência Conservada , Secas , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Germinação/efeitos dos fármacos , Dados de Sequência Molecular , Cebolas/genética , Cebolas/fisiologia , Pressão Osmótica , Filogenia , Epiderme Vegetal/genética , Epiderme Vegetal/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/fisiologia , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/fisiologia , Sementes/efeitos dos fármacos , Sementes/fisiologia , Cloreto de Sódio/farmacologia , Estresse Fisiológico , Ativação Transcricional , Leveduras/genética , Leveduras/metabolismoRESUMO
SnRK2 (sucrose non-fermenting 1-related protein kinases 2) represents a unique family of protein kinase in regulating signaling transduction in plants. Although the regulatory mechanisms of SnRK2 have been well demonstrated in Arabidopsis thaliana, their functions in maize are still unknown. In our study, we cloned an SnRK2 gene from maize, ZmSAPK8, which encoded a putative homolog of the rice SAPK8 protein. ZmSAPK8 had two copies in the maize genome and harbored eight introns in its coding region. We demonstrated that ZmSAPK8 expressed differentially in various organs of maize plants and was up-regulated by high-salinity and drought treatment. A green fluorescent protein (GFP)-tagged ZmSAPK8 showed subcellular localization in the cell membrane, cytoplasm and nucleus. In vitro kinase assays indicated that ZmSAPK8 preferred Mn(2+) to Mg(2+) as cofactor for phosphorylation, and Ser-182 and Thr-183 in activation loop was important for its activity. Heterologous overexpression of ZmSAPK8 in Arabidopsis could significantly strengthen tolerance to salt stress. Under salt treatment, ZmSAPK8-overexpressed transgenic plants exhibited higher germination rate and proline content, low electrolyte leakage and higher survival rate than wild type. Further analysis indicated that transgenic plants showed increased transcription of the stress-related genes, RD29A, RD29B, RAB18, ABI1, DREB2A and P5CS1, under high-salinity conditions. The results demonstrated that ZmSAPK8 was involved in diverse stress signal transduction. Moreover, no obvious adverse effects on growth and development in the ZmSAPK8-overexpressed transgenic plants implied that ZmSAPK8 was potentially useful in transgenic breeding to improve salt tolerance in crops.
Assuntos
Arabidopsis/genética , Proteínas Serina-Treonina Quinases/genética , Tolerância ao Sal , Zea mays/genética , Sequência de Aminoácidos , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Clonagem Molecular , DNA Complementar/genética , Eletrólitos/metabolismo , Ativação Enzimática , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Germinação , Manganês/metabolismo , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Fosforilação , Filogenia , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais , Cloreto de Sódio/farmacologia , Estresse Fisiológico , Transcrição Gênica , Regulação para Cima , Zea mays/efeitos dos fármacos , Zea mays/metabolismoRESUMO
TCM terms of diseases and symptoms are important elements of traditional Chinese medical nomenclature. Good English translation of these terms plays an active role in standardizing English translation of TCM terms. Through comparing the names of diseases and symptoms in Chinese and Western medicine and sorting, the author put forward in this paper several methods for translating TCM terms into English.