RESUMEN
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.
Asunto(s)
Ácido Abscísico/farmacología , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas Portadoras/genética , Membrana Celular/metabolismo , Fosfoproteínas Fosfatasas/metabolismo , Cloruro de Sodio/farmacología , Estrés Fisiológico/efectos de los fármacos , Adaptación Fisiológica/efectos de los fármacos , Adaptación Fisiológica/genética , Arabidopsis/fisiología , Proteínas de Arabidopsis/metabolismo , Proteínas Portadoras/metabolismo , Membrana Celular/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Técnicas de Silenciamiento del Gen , Genes de Plantas/genética , Glucuronidasa/metabolismo , Tamaño de los Órganos/efectos de los fármacos , Tamaño de los Órganos/genética , Oxidación-Reducción/efectos de los fármacos , Fenotipo , Fosfoproteínas Fosfatasas/genética , Hojas de la Planta/anatomía & histología , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/genética , Raíces de Plantas/anatomía & histología , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Plantas Modificadas Genéticamente , Transporte de Proteínas/efectos de los fármacos , ARN sin Sentido/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Estrés Fisiológico/genética , Fracciones Subcelulares/efectos de los fármacos , Fracciones Subcelulares/metabolismo , Dedos de ZincRESUMEN
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.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de la Membrana/metabolismo , Estrés Oxidativo , Secuencia de Aminoácidos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Membrana Celular/metabolismo , Regulación de la Expresión Génica de las Plantas , Peróxido de Hidrógeno/metabolismo , Proteínas de la Membrana/genética , Datos de Secuencia MolecularRESUMEN
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.
Asunto(s)
Ácido Abscísico/genética , Adaptación Fisiológica/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Transducción de Señal/genética , Factores de Transcripción/metabolismo , Ácido Abscísico/fisiología , Acetiltransferasas/genética , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , ADN Complementario , Deshidratación , Biblioteca de Genes , Genes de Plantas , Genes Reporteros , Germinación , Humanos , Manitol , Mutación , Cebollas , Ósmosis , Fenotipo , Plantas Modificadas Genéticamente , Tolerancia a la Sal/genética , Cloruro de Sodio , Estrés Fisiológico/genética , Factores de Transcripción/genética , Levaduras/genética , Zea mays/genéticaRESUMEN
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.