ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
Not a member yet
2747 research outputs found
Sort by
ACTA HORTICULTURAE
No full textCopper compounds, used to control Erwinia amylovora, have a strong effect on the culturability of plant-associated bacteria. Recent studies have shown that some phytopathogenic bacteria enter into a viable but nonculturable (VBNC) state in the presence of copper. This state, in which cells progressively lose their culturability on non-selective solid media, is considered to be a survival strategy under adverse environmental conditions. To determine whether copper kills or induces a VBNC state in E. amylovora cells, mineral medium without copper or supplemented with 0.005, 0.01 and 0.05 mM Cu2+ was inoculated with 10(7) cfu/ml of the pathogen. Aliquots were taken regularly for four months, and the total and viable cell counts were determined using the Live/Dead staining kit and culturable cell counts were determined on King's B medium. E. amylovora entered into a VBNC state in the presence of the three copper concentrations assayed. It entered faster the VBNC state with increased copper concentration: it entered at days 36, 1 and 0 (immediately after being introduced in the medium) with 0.005, 0.01 and 0.05 mm Cu2+ respectively. Afterwards, the restoration of culturability or resuscitation of copper-induced VBNC E. amylovora cells was achieved by the addition of different copper complexing agents that could remove the free-copper ions. Dilution studies were also performed to demonstrate that the resuscitated cells came from a true resuscitation and not from the regrowth of any undetectable culturable cell. Finally, the pathogenicity of both VBNC and resuscitated cells was evaluated by inoculation on immature pear fruits. Copper-induced VBNC cells were virulent only for five days while resuscitated cells held their pathogenicity for more than four months. Understanding the effect of copper against E. amylovora cells could help to optimize fireblight control strategies
Integration under commercial conditions of antifungal treatments and CA-storage to control gray mold and maintain quality of 'Wonderful' pomegranates
No full text
Vitrification of pre-pubertal ovine cumulus-oocyte complexes: Effect of cytochalasin B pre-treatment
No full textThe aim of this study was to evaluate the effect of cytochalasin B (CCB) pre-treatment before vitrification on ability of immature oocytes from lamb ovaries to progress until metaphase II (MII) stage after vitrification/warming procedure. Cumulus-oocyte complexes (COCs) were obtained from ovaries of lambs, from 80 to 90 days old, collected from a local slaughterhouse. Before vitrification, COCs were randomly distributed in two experimental groups corresponding to the incubation with or without 7.5 mu g/ml CCB for 30 min. In order to study cryoprotectant and CCB pre-treatment toxicity (toxicity test), oocytes were exposed to cryoprotectants, with or without CCB pre-treatment, but without plunging into N-2 liquid. Vitrification solution was composed by 4.48 M EG plus 3.50 M DMSO supplemented with 0.25 M sucrose. Two-step addition was performed. After vitrification or toxicity test, COCs were matured in bicarbonate-buffered TCM 199 containing 10% foetal calf serum and 10 ng/ml epidermal growth factor. A sample of CCICs was directly in vitro matured (control group). Rates of M11 oocytes of toxicity groups both, with or without CCB pre-treatment were lower than control group (41.1-50.0 versus 79.9, respectively; P < 0.05). After vitrification, a lower number of oocytes progressed to MII stage in comparison with non-vitrification groups (P < 0.05). In vitrified groups both with or without CCB pre-treatment 8.0 and 12.7%, respectively, of immature oocytes reached MII stage by the end of in vitro maturation culture. No effect of CCB was observed, either in the toxicity or vitrified groups. In conclusion, no effect of CCB pre-treatment before vitrification was detected in this study with immature oocytes of pre-pubertal sheep. More studies are needed in order to increase ovine oocyte survival after vitrification. (c) 2005 Elsevier B.V. All rights reserved
The GH3 family in plants: Genome wide analysis in rice and evolutionary history based on EST analysis
No full textThe GH3 gene family in Arabidopsis, implicated in hormonal homeostasis through the conjugation of indolacetic and jasmonic acids to amino acids, is involved in a broad range of plant growth and development processes. In this work, the analysis of the GH3 family in the genome of Oryza sativa identified 13 hypothetical ORFs. EST analysis and RT-PCR assays demonstrated that 12 of them were active genes. An extensive EST analysis of the GH3 family performed on 26 plant species was used to estimate the minimum number of GH3 genes en each one. The data indicated that the members of the GH3 family progressively increased in the different plant divisions from Chlorophyta (0), Bryophyta (3), and Coniferophyta (4), to Magnoliophyta (7-19). Phylogenetic analyses showed a high degree of conservation between Arabidopsis and rice GH3 proteins and, in general, in the plant kingdom. The data revealed a homology Clustering consistent with the functional classification of the Arabidopsis proteins, since most of the 110 sequences analyzed grouped into 2 main clusters, corresponding to the Arabidopsis functional groups I (jasmonic acid adenylation) and II (indolacetic acid adenylation). And additional cluster including group III (non-adenylation ability) was exclusively composed of proteins from Arabidopsis thaliana, Brassica napus and Gossypium hirsutum
ACTA HORTICULTURAE
No full textThe EU-funded project DIAGPRO has developed diagnostic protocols for 18 quarantine pests including Erwinia amylovora. The protocol for this organism includes a diagnosis scheme for detection of the bacterium in symptomatic and asymptomatic plants with details of the different techniques as isolation in three media, direct tissue print-ELISA, enrichment DASI-ELISA, immunofluorescence, conventional PCR and nested-PCR in a single closed tube (before and after enrichment of the samples in two liquid media). A ring test was conducted to evaluate and standardize some techniques and protocols. Testing was performed independently at 10 plant health laboratories analysing 15 samples (healthy, spiked or inoculated). The reliability of the diagnosis across all laboratories decreased with inoculum concentration. The accuracy of the different techniques, defined as (true positive diagnosis + true negatives)/total number of samples, was: 0.88, 0.92 and 0.92 respectively for isolation on King’s B, SNA and CCT media; 0.70, 0.72 and 0.66 for immunofluorescence performed with one monoclonal and two polyclonal antibodies commercially available; 0.79 and 0.83 for enrichment-ELISA with a commercial kit after enrichment in two media; 0.51 for conventional PCR and 0.69 for nested-PCR in a single tube, both techniques increasing their accuracy up to 0.78 and 0.86, respectively, after enrichment. The designed protocol is freely available at the web site: www.csl.gov.uk/science/organ/ph/diagpro
Diagnosis of "maladie des feuilles cassantes" or brittle leaf disease of date palms by detection of associated chloroplast encoded double stranded RNAs
No full textThe “Maladie des feuilles cassantes” (MFC) or “Brittle leaf disease” of date palms is associated with the accumulation of two populations of small, chloroplast-encoded RNAs. A plasmid vector containing a cDNA with partial sequences of both of these RNA populations was used to synthesize a DIG-labeled bifunctional probe by PCR. The probe has been tested to detect, by molecular hybridization, MFC-associated RNAs from dsRNA-enriched palm leaflet preparations. Leaflet samples from MFC-affected date palm trees consistently gave a positive hybridization signal regardless of the date palm cultivar, severity of symptoms, or geographical location, whereas samples from date palm trees affected by other biotic and abiotic stresses tested negative. The assay is specific for MFC and can be used for early diagnostic purposes
Nuevas técnicas aplicadas al riego localizado
Get PDFCon el aumento de la población se está produciendo un crecimiento de la demanda de agua, con lo que ésta se convierte en un bien cada vez más escaso y, en la zona mediterránea, en el factor más limitante de la producción agrícola. La creciente escasez de este recurso exige, cada día más, un mayor control de la eficiencia, necesaria para una utilización racional de los recursos hídricos disponibles
Control biológico de Panonychus citri en plantones de cítricos mediante liberaciones del fitoseido Neoseiulus californicus
No full textUna alternativa interesante a los tratamientos químicos para el control de Panonychus citri, en plantones de cítricos en viveros y en cítricos ornamentales, podría ser la liberación de enemigos naturales. En el presente trabajo se ensayaron, en dos experiencias similares, tres dosis de suelta del fitoseido N. californicus (1 individuo por cada 10, 20 y 30 individuos móviles de P. citri) sobre plantones de naranjo amargo infestados con P. citri en condiciones controladas en invernadero y se compararon con un tratamiento control sin suelta de fitoseidos. En la primera de las experiencias se hicieron dos sueltas de fitoseidos separadas una semana en el tiempo, mientras que en la segunda sólo se hizo una suelta. En ambas experiencias las poblaciones de P. citri disminuyeron de manera natural. Sin embargo en los tratamientos con suelta de fitoseidos esta disminución fue mucho más drástica, especialmente en el primer conteo tras la suelta. Los porcentajes de reducción de P. citri alcanzaron el 95% y el 59% en la primera y segunda experiencia respectivamente
