Green Strategies of Powdery Mildew Control in Hop: From Organic Products to Nanoscale Carriers.

Humulus lupulus L. is a long-lived, perennial, herbaceous, and dioecious climbing plant. The foremost producers in the European Union are Germany, the Czech Republic, Poland, Slovenia, and Spain. The Spanish cultivated area is concentrated in the province of León. Powdery mildew, caused by Podosphaera macularis, menaces hop production and quality in all hop growing regions located in the Northern hemisphere, colonizing leaves, petioles, inflorescences, and finally cones. In this work, powdery mildew control was monitored, comparing nine fungicide strategies: five organics, two integrated disease management (IDM)-based, with and without Nutragreen® nanoscale carrier, and two conventional treatments (CON) with and without Nutragreen® nanoscale carrier. The organic treatments were able to diminish P. macularis on leaves, but no effect was observed in cones. CON treatments reduced the infection on leaves and cones and increased the cone quantity and quality. Likewise, IDM-based treatments provided satisfactory results as they diminished powdery mildew on leaves and cones. Finally, dose reduction using a Nutragreen® nanoscale carrier showed beneficial effects in the control of powdery mildew compared to the commercial dose. Hence, the use of nanoscale carries permits a 30% reduction in pesticide dose, which optimizes yield and hop quality, reduces risks linked to pesticides, and aids in compliance with public and international policy demands.

Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7.

The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7.

Endophytic colonization and biocontrol performance of Pseudomonas fluorescens†PICF7 in olive (Olea europaea L.) are determined neither by pyoverdine production nor swimming motility.

Pseudomonas fluorescens PICF7 is an indigenous inhabitant of olive (Olea europaea L.) rhizosphere, able to display endophytic lifestyle in roots, to induce a wide range of defence responses upon colonization of this organ and to exert effective biological control against Verticillium wilt of olive (VWO) (Verticillium dahliae). We aimed to evaluate the involvement of specific PICF7 phenotypes in olive root colonization and VWO biocontrol effectiveness by generating mutants impaired in swimming motility (fliI) or siderophore pyoverdine production (pvdI). Besides, the performance of mutants with diminished in vitro growth in potato dextrose agar medium (gltA) and cysteine (Cys) auxotrophy was also assessed. Results showed that olive root colonization and VWO biocontrol ability of the fliI, pvdI and gltA mutants did not significantly differ from that displayed by the parental strain PICF7. Consequently, altered in vitro growth, swimming motility and pyoverdine production contribute neither to PICF7 VWO suppressive effect nor to its colonization ability. In contrast, the Cys auxotroph mutant showed reduced olive root colonization capacity and lost full biocontrol efficacy. Moreover, confocal laser scanning microscopy revealed that all mutants tested were able to endophytically colonize root tissue to the same extent as wild-type PICF7, discarding these traits as relevant for its endophytic lifestyle.

The -174G/C and -572G/C interleukin 6 promoter gene polymorphisms in mexican patients with rheumatoid arthritis: a case-control study.

OBJECTIVE: There is a lack of information about the genotype frequencies of IL-6 -174G/C and -572G/C polymorphisms in Mexicans with rheumatoid arthritis (RA). Therefore, the aim of this study was to evaluate the association of the IL-6 -174G/C and -572G/C polymorphisms in Mexican mestizo with RA. METHODS: We included 137 patients with RA and 102 healthy controls. Patients were assessed for clinical characteristics. IL-6 -174G/C and -572G/C polymorphisms were genotyped using PCR-RFLP analysis. Allele and genotype frequencies and the Hardy-Weinberg equilibrium were computed. Odds ratios (ORs) were computed to identify the risk for RA associated with the presence of GG genotype in comparison with the GC or CC genotypes. RESULTS: The genotype -174GG occurred at a higher frequency in cases and controls (77.4% versus 78.4%, P = 0.845). We found similar results for the genotype -572GG (54% in patients versus 60.8% in controls, P = 0.295). CONCLUSIONS: This is the first study to evaluate the association of -174G/C and -572G/C polymorphisms of the IL-6 gene with RA in Mexican mestizo patients. These two polymorphisms were not associated with RA in the studied sample. Additional studies are required to evaluate if these IL-6 polymorphisms have relevance to the development of more severe disease.

From the root to the stem: interaction between the biocontrol root endophyte Pseudomonas fluorescens†PICF7 and the pathogen Pseudomonas savastanoi†NCPPB 3335 in olive knots.

Olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi, is one of the most important biotic constraints for olive cultivation. Pseudomonas fluorescens PICF7, a natural colonizer of olive roots and effective biological control agent (BCA) against Verticillium wilt of olive, was examined as potential BCA against olive knot disease. Bioassays using in vitro-propagated olive plants were carried out to assess whether strain PICF7 controlled knot development either when co-inoculated with the pathogen in stems or when the BCA (in roots) and the pathogen (in stems) were spatially separated. Results showed that PICF7 was able to establish and persist in stem tissues upon artificial inoculation. While PICF7 was not able to suppress disease development, its presence transiently decreased pathogen population size, produced less necrotic tumours, and sharply altered the localization of the pathogen in the hyperplasic tissue, which may pose epidemiological consequences. Confocal laser scanning microscopy combined with fluorescent tagging of bacteria revealed that when PICF7 was absent the pathogen tended to be localized at the knot surface. However, presence of the BCA seemed to confine P. savastanoi at inner regions of the tumours. This approach has also enabled to prove that the pathogen can moved systemically beyond the hypertrophied tissue.

Use of Arabidopsis thaliana to study mechanisms of control of Verticillium wilt by Pseudomonas fluorescens PICF7.

Verticillium wilt (VW), caused by Verticillium dahliae Kleb., is an important disease in many crops and its effective management has proven difficult. Among the various disease control measures to be implemented, the use of microbial antagonists (biological control agents, BCAs) constitutes an environmentally-friendly approach fitting criteria of modern sustainable agriculture. Pseudomonas fluorescens PICF7 was isolated from root tissues of nursery--propagated olive plants. Selection of this strain was based on in vitro growth inhibition of V. dahliae, colonizing ability of olive roots, endophytic lifestyle, and control of the highly-virulent defoliating (D) pathotype of V. dahliae in olive planting stocks. The mode of action by which PICF7 controls VW in olive is as yet unknown; moreover, to uncover potential biocontrol mechanisms poses additional difficulties in this pathosystem because the target is a tree. Therefore we used the model plant Arabidopsis thaliana to study: i) if PICF7 colonizes the rhizosphere of A. thaliana; ii) disease symptoms caused by V. dahliae in A. thaliana; iii) control of VW by PICF7 in different accessions and mutants of A. thaliana; and iv) if motility, antibiosis and/or siderophores are involved in control of V. dahliae by PICF7. Diverse bioassays were conducted and in all of them both the BCA and the pathogen were introduced in the rhizosphere of A. thaliana. Both D and non-defoliating isolates of V. dahliae caused disease symptoms in A. thaliana. PICF7 colonized and persisted in the rhizosphere of different Arabidopsis accessions and could control the D pathotype in some of them. PICF7 mutants affected in antibiosis significantly lost their ability to control VW in A. thaliana. We conclude that the model plant A. thaliana is useful to unravel interactions between this BCA and V. dahliae.

Autoantibodies to a miRNA-binding protein Argonaute2 (Su antigen) in patients with hepatitis C virus infection.

OBJECTIVES: Chronic liver diseases caused by hepatitis B (HBV) or C virus (HCV) are common worldwide. Despite reports on autoimmunity in viral hepatitis, studies on autoantibodies associated with systemic rheumatic diseases are inconsistent. Testing of a small number of selected autoantibody specificities using ELISA appears to be one reason for inconsistency. Sera from patients with viral hepatitis were tested by immunoprecipitation that will allow unbiased screening of autoantibodies found in systemic rheumatic diseases. METHODS: Ninety Mexican patients (37 male, 53 female, 26 HBV, 6 HBV+HCV, 58 HCV) with chronic viral hepatitis, confirmed by nested or RT-nested-PCR, HBsAg and anti-HCV antibodies, were studied. Autoantibodies were tested by immunofluorescence, immunoprecipitation and ELISA. Specificities were verified using reference sera. RESULTS: Antinuclear antibodies were found in 38% HBV, 17% HBV+HCV, and 28% in HCV. Autoantibodies to Argonaute (Ago2, Su antigen), a microRNA binding protein that plays a key role in RNA-induced silencing complex (RISC), was found in 5% (4/64) of HCV or HBV+HCV coinfected patients but not in HBV (0/26). Anti-Ago2/Su was found in 1/2 of I-IFN-treated case vs. 3/62 in cases without I-IFN. HCV did not have other lupus autoantibodies whereas 19% (5/26) of HBV had anti-U1RNP+Ku, Ro+La, RNA polymerase II, or possible U5snRNPs. CONCLUSIONS: Lupus autoantibodies were uncommon in HCV except anti-Ago2/Su. HCV and I-IFN have many ways to affect TLR signaling, miRNA and miRNA binding protein Ago2/Su. To understand the mechanism of specific targeting of Ago2 in HCV may provide a clue to understand the mechanism of specific autoantibody production.