ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Current situation and characterization of Pseudomonas syringae pv. actinidiae on kiwifruit in Galicia (northwest Spain)
No full textBacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae (Psa), is a disease that is spreading rapidly in several kiwifruit‐producing countries, causing significant economic losses. In 2011, it was detected for the first time in Spain, in the south of Galicia (northwest Spain). Kiwifruit orchards were therefore inspected and sampled in 2011 and 2012 to determine the pathogen distribution, and the isolates obtained were characterized by morphology, fatty acids profile, biochemical tests and molecular techniques. Isolates were obtained from Actinidia deliciosa ‘Hayward’ (from leaves, canes, flower buds, fruits and roots), from A. deliciosa ‘Summer’, from Actinidia chinensis ‘Jin Tao’ (from canes and leaves) and from A. chinensis pollinator ‘Belén’ (from canes). Results of the analysis of the cfl gene (phytotoxin production‐related), the tox–argK gene cluster and phylogenetic analysis of the cts gene demonstrated that all Psa isolates from northwest Spain correspond to the Psa3 population, which includes strains of haplotype 2. This is the first record of Psa3 and haplotype 2 in Spain
Effectiveness of gene silencing induced by viral vectors based on Citrus leaf blotch virus is different in Nicotiana benthamiana and citrus plants
No full textVirus induced gene silencing (VIGS) is an effective technology for gene function analysis in plants. We assessed the VIGS effectiveness in Nicotiana benthamiana and citrus plants of different Citrus leaf blotch virus (CLBV)-based vectors, using insets of the phytoene desaturase (pds) gene. While in N. benthamiana the silencing phenotype was induced only by the construct carrying a 58-nt pds hairpin, in citrus plants all the constructs induced the silencing phenotype. Differences in the generation of secondary small interfering RNAs in both species are believed to be responsible for differential host-species effects. The ability of CLBV-based vectors to silence different endogenous citrus genes was further confirmed. Since CLBV-based vectors are known to be stable and induce VIGS in successive flushes for several months, these vectors provide an important genomic tool and it is expected that they will be useful to analyze gene function by reverse genetics in the long-lived citrus plants
¿Es posible incrementar la eficiencia en el uso del agua modificando la orientación de las filas y la inclinación de la espaldera de los viñedos?
Get PDFEn este trabajo se resumen las investigaciones realizadas encaminadas a
cuantificar la influencia que tienen la orientación de las filas del viñedo y la
inclinación de las espalderas con respecto a la vertical sobre la transpiración, la
productividad, la eficiencia en el uso del agua y la composición de la uva. Las
investigaciones se llevaron a cabo en vides de la variedad Bobal tanto en maceta
como en campo. Los resultados ponen de manifiesto que la orientación de las filas
este-oeste permite reducir la transpiración en un 15% con respecto a la orientación
norte-sur. Por otro lado, en viñedos plantados norte-sur, inclinar la espaldera 30º
hacia el oeste para reducir la radiación interceptada por las cepas a primera hora de
la tarde cuando la demanda evaporativa es mayor, no permite reducir el consumo
diario de agua. Sin embargo, la inclinación de las espalderas hacia el oeste, puede
incrementar la productividad del viñedo, seguramente debido a la mayor cantidad
de radiación interceptada por las cepas a primera hora de la mañana cuando la
capacidad fotosintética de las vides es mayor. Los resultados obtenidos muestran el
papel que puede jugar el diseño del viñedo y la arquitectura del dosel vegetal sobre
la eficiencia en el uso del agua a nivel de planta entera
Application of nondestructive impedance spectroscopy to determination of the effect of temperature on potato microstructure and texture
No full textThe objective of this study was to use impedance spectroscopy to evaluate microstructural changes in potato tissue caused by heat treatments. Potato samples were subjected to 30 min treatments at room temperature, 30, 40, 50, 60 and 70 degrees C. Changes in microstructure were evaluated by texture, electrolyte leakage and color measurements, and confocal laser scanning microscopy (CLSM). Samples processed at 60 and 70 degrees C showed significantly different module of impedance and phase values than those processed at <= 50 degrees C. Texture decreased and electrolyte leakage increased after treating potato at temperatures above 60 degrees C, indicating loss of turgor pressure and rupture of both membranes and cell walls. Significant changes in tissue microstructure and progressive cell wall degradation as temperature increased were visualized using CLSM. Real-time nondestructive impedance spectroscopy proved to be a quantitative means of following the effects of process temperature on potato cell walls and starch, and subsequently on textural properties. (C) 2014 Elsevier Ltd. All rights reserved
LIDAR as an alternative to passive collectors to measure pesticide spray drift
Get PDFPesticide spray drift entails a series of risks and costs in terms of human, animal and environmental wellbeing. A proper understanding of this phenomenon is essential to minimise these risks. However, most conventional methods used in drift measurement are based on point collectors which are unable to obtain information concerning the temporal or spatial evolution of the pesticide cloud. Such methods are also costly, labour-intensive, and require a considerable amount of time. The aim of this paper is to propose a method to measure the spray drift based on lidar (Light Detection And Ranging) and to prove that it can be an alternative to passive collectors. An analytical model is proposed to relate the measurements obtained through passive collectors and those obtained with lidar systems considering several spray application and meteorological parameters. The model was tested through an experimental campaign involving multiple ground spray tests. A lidar system and two types of passive collectors (nylon strings and water-sensitive paper) were used simultaneously to measure the drift. The results showed for each test a high coefficient of determination (R-2 approximate to 0.90) between the lidar signal and the tracer mass captured by the nylon strings. This coefficient decreased (R-2 = 0.77) when all tests were considered together. Lidar measurements were also used to study the evolution of the pesticide cloud with high range (1.5 m) and temporal resolution (1 s) and to estimate its velocity. Furthermore, a very satisfactory adjustment (R-2 = 0.89) was observed between the tracer mass collected by the nylon lines and the coverage on water-sensitive paper sheets. These results are in accordance with the proposed analytical model and allow the conclusion that the application and meteorological parameters can be considered spatially invariant for a given test but are not invariant for different tests. C) 2013 Elsevier Ltd. All rights reserved
Non-invasive tools to estimate stress-induced changes in photosynthetic performance in plants inhabiting Mediterranean areas
No full textIn Mediterranean areas, plants are concomitantly exposed to various abiotic stresses such as light intensity, water deficit, extremes in air temperature, air pollutants, etc. These environmental pressures adversely affect plant development. Changes in photosystem activity are an early response of plants to abiotic stresses. Therefore, chlorophyll (Chl) fluorescence and gas exchange, two non-invasive, rapid and inexpensive techniques for measuring photosynthesis in leaves, have been widely used by plant eco-physiologists to analyse plant responses to stressful conditions. Chl a fluorescence and gas exchange parameters can be indeed used to evaluate changes in photochemical and non-photochemical processes in photosystems associated with electron transport, CO2 fixation, and heat dissipation. In this review, we focus our analysis on the effects of different abiotic stresses on the photochemistry of Mediterranean plants using Chl a fluorescence and gas exchange measurements. Since changes in photosynthetic parameters are observed in the absence of visual injuries, these methodologies constitute fundamental tools to predict and evaluate the extent to which abiotic stresses damage photosynthesis. (C) 2014 Elsevier B.V. All rights reserved
Actas de Horticultura
Get PDFEn este trabajo se han localizado los centrómeros en los 9 grupos de ligamiento (GL) del mapa genético de mandarino clementino mediante Half Tetrad Analysis (HTA) y se ha determinadoel mecanismo implicado en la formación de los gametos femeninos no reducidos en 16 genotipos de mandarino y un genotipo de naranjo pigmentado. La determinación del mecanismo implicado en la formación de los gametos 2n sin el conocimiento de la posición de los centrómeros requiere del análisis de un elevado número de plantas con un elevado número de marcadores, mientras que conociendo la posición de los centrómeros es posible determinar el mecanismoa nivel individual y poblacional con un reducido número de marcadores próximos a los centrómeros. La restitución de la segunda división meiótica aparece como el mecanismo implicado en la formación de los gametos femeninos 2n en cítricos
Mandarino y naranjo
Get PDFDesde que aparece el virus de la tristeza en España (1957) se produce una reconversión varietal, desapareciendo multitud de variedades, sobre todo del grupo Blancas y permaneciendo aquellas que todavía son base de nuestra citricultura, como las naranjas de las variedades ‘W. Navel’, ‘Navelina’, ‘Salustiana’ y ‘Valencia late’ y las mandarinas de la variedad satsuma ‘Owari’. En ese momento el mejor patrón del mundo, el naranjo amargo (Citrus aurantium), debe reemplazarse por otros patrones tolerantes y/o resistentes al virus de la tristeza. En España se han replantado desde 1972 alrededor de 168 millones de plantas. Estos nuevos portainjertos son sensibles a enfermedades producidas por otros virus, que no afectaban al naranjo amargo, y a otras enfermedades producidas por hongos (Phythophthora spp.), que durante años hemos padecido sobre algunos patrones trifoliados (Citranges) por desconocimiento en el manejo de su cultivo
Segregación de la resistencia a la mancha marrón producida por alternaria alternata en poblaciones triploides de cítricos
Get PDFLa mancha marrón causada por el hongo Alternaria alternata (ABS) supone un problema importante en los genotipos susceptibles de cítricos, tanto a nivel diploide como triploide. La segregación de los caracteres en poblaciones triploides está principalmente afectada por la estrategia utilizada en su obtención, con importantes diferencias entre cruzamientos 2x x 2x y cruzamientos interploides. La resistencia a ABS está controlada por un alelo recesivo, cuyo locus que se encuentra a 10.5 cM del centrómero del cromosoma III. En este estudio se analiza la implicación que tiene la estrategia de obtención de nuevos genotipos triploides de cítricos en la segregación dela resistencia a ABS cuandose utilizan parentales susceptibles, dada la recesividad de la resistencia y la posición centromérica del locus ligado a la misma. Los resultados muestran que cuando se utilizan parentales heterocigotos susceptibles como donantes del gameto diploide, es mucho máseficiente usarlos en cruzamientos 2x x 2x que utilizarlos como parentales tetraploides en cruzamientos interploides
Comparative toxicity of pesticides in three phytoseiid mites with different life-style occurring in citrus: Euseius stipulatus, Neoseiulus californicus and Phytoseiulus persimilis
No full textConservation and augmentative biological control strategies have been developed to take full advantage of the natural enemies that occur in Spanish citrus orchards. Among them, the predatory mites Euseius stipulatus, Neoseiulus californicus and Phytoseiulus persimilis play an important role in the biological control of tetranychid mites. However, these predatory mites are often affected by pesticides and information about the side-effects of these products against these beneficial arthropods is essential to guarantee their efficacy. The side-effects of some pesticides remain unknown and the primary aim of this study was to fill this gap. We have further used this information and that collected from other sources to compare the response of these three mite species to pesticides. Based on this information, E. stipulatus has the most tolerant species, followed by N. californicus and P. persimilis. Therefore, using E. stipulatus as an indicator species in citrus may have led to the paradox of selecting presumed selective pesticides resulting in excessive impact on N. californicus and, especially on P. persimilis. Because these two latter species are considered key for the biological control of T. urticae in citrus, especially clementines, in Spain, we propose to use P. persimilis as the relevant indicator of such effects on predacious mites occurring in citrus instead of E. stipulatus. This change could have a dramatic impact on the satisfactory control of tetranychid mites in citrus in the near future