RESUMO
CCCH-type zinc finger proteins are important for developmental and environmental responses. However, the precise roles of these proteins in plant stress tolerance are poorly understood. Arabidopsis thaliana Oxidation-related Zinc Finger 2 (AtOZF2) (At4g29190) is an AtOZF1 homolog previously isolated from Arabidopsis, which confers oxidative stress tolerance on plants. The AtOZF2 protein is localized in the plasma membrane, as is AtOZF1. Disruption expression of AtOZF2 led to reduced root length and leaf size. AtOZF2 was implicated to be involved in the ABA and salinity responses. atozf2 antisense lines were more sensitive to ABA and salt stress during the seed germination and cotyledon greening processes. In contrast, AtOZF2-overexpressing plants were more insensitive to ABA and salt stress than the wild type. Interestingly, in the presence of ABA and salt stress, the transcript level of ABA insensitive 2 (ABI2), but not that of ABI1, in AtOZF2-overexpressing plants was lower than that in the wild type, whereas the expression of ABI2 in atozf2 was significantly enhanced. Thus, AtOZF2 is involved in the ABA and salt stress response through the ABI2-mediated signaling pathway. Taken together, these findings provide compelling evidence that AtOZF2 is an important regulator for plant tolerance to abiotic stress.
Assuntos
Ácido Abscísico/farmacologia , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas de Transporte/genética , Membrana Celular/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Adaptação Fisiológica/efeitos dos fármacos , Adaptação Fisiológica/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Proteínas de Transporte/metabolismo , Membrana Celular/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Genes de Plantas/genética , Glucuronidase/metabolismo , Tamanho do Órgão/efeitos dos fármacos , Tamanho do Órgão/genética , Oxirredução/efeitos dos fármacos , Fenótipo , Fosfoproteínas Fosfatases/genética , Folhas de Planta/anatomia & histologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Raízes de Plantas/anatomia & histologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , Transporte Proteico/efeitos dos fármacos , RNA Antissenso/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Estresse Fisiológico/genética , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismo , Dedos de ZincoRESUMO
The CCCH-type zinc finger proteins are a superfamily containing tandem zinc-binding motifs involved in many aspects of plant growth and development. However, the precise role of these proteins involved in plant stress tolerance is poorly understood. This study was to examine the regulatory and functional role of the CCCH-type zinc finger protein, AtOZF1 (At2g19810), under oxidative stress. Interestingly, the AtOZF1 protein was localized in the plasma membrane. The AtOZF1 transcripts were highly induced by treatment with hydrogen peroxide, abscisic acid and salinity. The AtOZF1-overexpressing plants were relatively resistant to oxidative stress than wild-type and T-DNA insertion mutant atozf1. Malondialdehyde, a decomposition product of lipid peroxidation, accumulated in atozf1 mutants more than in wild-type and AtOZF1-overexpressing plants. Furthermore, atozf1 mutants displayed lower activities of catalase and guaiacol peroxidase, higher chlorosis, and down-regulated expression of antioxidant genes under oxidative stress. Taken together, these observations demonstrate that AtOZF1 is required for the tolerance of Arabidopsis to oxidative stress.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Membrana/metabolismo , Estresse Oxidativo , Sequência de Aminoácidos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Membrana Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/metabolismo , Proteínas de Membrana/genética , Dados de Sequência MolecularRESUMO
We identified and functionally characterized the AtSKIP gene (At1g77180), an Arabidopsis homologue of SNW/SKIP, under abiotic stresses. Although the SNW/SKIP protein has been implicated as a critical transcription cofactor, its biological functions have yet to be reported in any plant. Recently, we have isolated Salt-tolerance genes (SATs) via the overexpression screening of yeast with a maize cDNA library. One of the selected genes (SAT2) appeared to confer elevated tolerance to salt. Maize SAT2 cDNA encodes a homologue of the human SNW/SKIP transcriptional coregulator. Treatment with salt, mannitol and abscisic acid induced AtSKIP expression. Ectopic expression of the AtSKIP gene modulated the induction of salt tolerance, dehydration resistance and insensitivity towards abscisic acid under stress conditions. By contrast, atskip antisense lines displayed reduced tolerance to abiotic stresses during germination. Moreover, a decrease in AtSKIP expression resulted in an abnormal phenotype. We further determined that the AtSKIP protein activated the transcription of a reporter gene in yeast. Green fluorescent protein-tagged AtSKIP was localized in the nuclei of both onion cells and transgenic Arabidopsis cells. Taken together, these results suggest that AtSKIP functions as both a positive regulator and putative potential transcription factor in the abiotic stress signalling pathway.
Assuntos
Ácido Abscísico/genética , Adaptação Fisiológica/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Transdução de Sinais/genética , Fatores de Transcrição/metabolismo , Ácido Abscísico/fisiologia , Acetiltransferases/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , DNA Complementar , Desidratação , Biblioteca Gênica , Genes de Plantas , Genes Reporter , Germinação , Humanos , Manitol , Mutação , Cebolas , Osmose , Fenótipo , Plantas Geneticamente Modificadas , Tolerância ao Sal/genética , Cloreto de Sódio , Estresse Fisiológico/genética , Fatores de Transcrição/genética , Leveduras/genética , Zea mays/genéticaRESUMO
An antifungal protein, AFP-J, was purified from tubers of the potato (Solanum tuberosum cv. L Jopung) by various chromatographic columns. AFP-J strongly inhibited yeast fungal strains, including Candida albicans, Trichosporon beigelii, and Saccharomyces cerevisiae, whereas it exhibited no activity against crop fungal pathogens. Automated Edman degradation determined the partial N-terminal sequence of AFP-J to be NH2-Leu-Pro-Ser-Asp-Ala-Thr-Leu-Val-Leu-Asp-Gln-Thr-Gly-Lys-G lu-Leu-Asp-Ala-Arg-Leu-. The partially sequence had 83% homology with a serine protease inhibitor belonging to the Kunitz family, and the protein inhibited chymotrypsin, pepsin, and trypsin. Mass spectrometry showed that its molecular mass was 13 500.5 Da. This protease inhibitor suppressed over 50% the proteolytic activity at 400 microg/mL. These results suggest that AFP-J is an excellent candidate as a lead compound for the development of novel antiinfective agents.
