No abstract

The woodchuck post-transcriptional regulatory element (WPRE) can naturally accumulate hepatitis transcripts in the cytoplasm, and has been recently exploited as an enhancer of transgene expression. The retention of mutant myotonic dystrophy protein kinase (DMPK) transcripts in the nucleus of myotonic dystrophy (DM) cells has an important pathogenic role in the disease, resulting in pleiotropic effects including delayed myoblast differentiation. In this study, we report the first use of WPRE as a tool to enhance nuclear export of an aberrantly retained messenger RNA. Stable cell lines expressing the normal and mutant DMPK 3 0 UTR (3 0 untranslated region) complementary DNA, with or without WPRE, were produced. It is noteworthy that WPRE stimulated extensive transport of mutant transcripts to the cytoplasm. This was associated with repair of the defective cellular MyoD levels and a subsequent increase in myoblast differentiation. These results provide the basis for a cellular model that can be exploited in DM and in the study of RNA transport mechanisms.

The use of biocompatible chemical compounds that enhance plant disease resistance through Induced Resistance (IR) is an innovative strategy to improve the yield and quality of crops. Phosphites (Phi), inorganic salts of phosphorous acid, are environment friendly, and have been described to induce disease control. Phi, similar to other plant inductors, are thought to be effective against different types of biotic and abiotic stress, and it is assumed that the underlying signaling pathways probably overlap and interact. The signaling pathways triggered by UV-B radiation, for instance, are known to crosstalk with other signaling routes that respond that biotic stress. In the present work, the effect of potassium phosphite (KPhi) pre-treatment on UV-B stress tolerance was evaluated in potato leaves. Plants were treated with KPhi and, after 3 days, exposed to 2 h/day of UV-B (1.5 Watt m(-2)) for 0, 3 and 6 days. KPhi pre-treatment had a beneficial effect on two photosynthetic parameters, specifically chlorophyll content and expression of the psbA gene. Oxidative stress caused by UV-B was also prevented by KPhi. A decrease in the accumulation of hydrogen peroxide (H2O2) in leaves and an increase in guaiacol peroxidase (POD) and superoxide dismutase (SOD) activities were also observed. In addition, the expression levels of a gene involved in flavonoid synthesis increased in UV-B-stressed plants only when pre-treated with KPhi. Finally, accumulation of glucanases and chitinases was induced by UV-B stress and markedly potentiated by KPhi pre-treatment. Altogether, this is the first report that shows a contribution of KPhi in UV-B stress tolerance in potato plants.

Phosphite (Phi) compounds are salts derived from phosphorous acid. These compounds have the ability to protect plants against different pathogens. The aim of the present research was to assess the effect of Phi compounds on components of potato tuber periderm and cortex and to assess their effects on pathogen resistance in the postharvest stage. In a series of field experiments, potassium phosphite (KPhi) was applied to seed potato tubers and foliage. After harvest, several variables were analyzed in tubers obtained from these plants. An increase in pectin content was observed in both periderm and cortex tissue in tubers originating from KPhi-treated plants. After wounding and infection with Fusarium solani, a higher amount of pectin accumulation in cortical tissues was observed in tubers following treatment with KPhi. The content and/or activity of polygalacturonase and proteinase inhibitor also increased in tubers from KPhi-treated plants. A new isoform of chitinase was detected in the tuber periderm of treated plants.These results suggest that KPhi applied to seed tuber and foliage induces defense responses in tuber periderm and cortex and that these reactions are associated with structural and biochemical changes in these tissues.

A proteinase K inhibitor (PLPKI) was isolated from a potato 3.4.21.14) but poorly inhibits two serine proteinases of animal cultivar with a high level of field resistance (Solanum tubero-origin, trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1). A differential expression (determined by activity and im-sum L. cv. Pampeana INTA), after 24 h of infection with munoblotting assays) of PLPKI was observed between two Phytophthora infestans, when inhibitory activity waspotato cultivars with different degrees of field resistance to P. markedly increased. Purification was performed by heat treatment, gel filtration chromatography and affinity chromatogra-infestans. In the resistant cultivar (cv. Pampeana INTA) PLPKI induction (19-fold with respect to healthy leaves) phy. A size of 60 kDa was estimated by SDS-PAGE in partially denaturing conditions and by gel filtration. It is occurred 24 h after infection and remained over basal levels after 48 h infection. By contrast, in the susceptible cultivar multimeric and the monomer has a molecular mass of 8.5 -9.0 kDa. PLPKI is highly active against proteinase K (EC (cv. Bintje), no induction was observed.

No abstract

A 5‐kDa antifungal peptide (APS) was isolated from Helianthus annum L. (line HA89) leaves infected with a virulent isolate of Sclerotinia sclerotiorum (Lib.) de Bary. AP5 was purified by gel filtration, cation exchange chromatography and reverse phase FPLC and HPLC. This peptide in vitro inhibits ascospores germination of the fungal pathogen S. sclerotiorum or produces mycelial growth inhibition, depending on its concentration. The effective concentration of AP5 giving 50% growth inhibition (IC50) against S. sclerotiorum was 0.4 μM. The antifungal efficacy of AP5 is higher than that of other antimicrobial proteins already described that have no appreciable effect on S. sclemtiorum below 4 μM. The relevance of this finding with regard to the function of AP5 in sunflower resistance to pathogens is discussed.

A sunflower leaf antifungal peptide active against Sclerotinia sclerotiorum. -Physiol, Plant, 100: 178-182,A 5-kDa antifungal peptide (AP5) was isolated from Helianthus annuus L, (line HA89) leaves infected with a virulent isolate of Sclerotinia sclerotiorum (Lib,) de Bary, AP5 was purified by gel filtration, cation exchange chromatography and reverse phase FPLC and HPLC, This peptide in vitro inhibits ascospores germination of the fungal pathogen S. sclerotiorum or produces mycelial growth inhibition, depending on its concentration. The effective concentration of AP5 giving 50% growth inhibition (IC50) against 5, sclerotiorum was 0,4 \iM. The antifungal efficacy of AP5 is higher than that of other antimicrobial proteins already described that have no appreciable effect on S. sclerotiorum below 4 yM. The relevance of this finding with regard to the function of AP5 in sunflower resistance to pathogens is discussed.