ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
Not a member yet
2747 research outputs found
Sort by
Transmission of Tomato spotted wilt virus isolates able and unable to overcome tomato or pepper resistance by its vector Frankliniella occidentalis
Get PDFTomato spotted wilt virus (TSWV) causes serious diseases of many economically important crops. Disease control has been achieved by breeding tomato and pepper cultivars with the resistance genes Sw-5 and Tsw, respectively. However, TSWV isolates overcoming these genetic resistances have appeared in several countries. To evaluate the risk of spread of these resistance-breaking isolates, we tested their ability of transmission by the main vector of TSWV, the thrips Frankliniella occidentalis. We compared the transmission rate by thrips of six TSWV isolates of different biotype (able or unable to overcome this resistance in pepper and tomato), and with divergent genotype (A and B). Our results indicate that the transmission rate was related to the amount of virus accumulated in thrips but not to virus accumulation in the source plants on which thrips acquired the virus. No correlation was found between transmission efficiency by thrips and the genotype or between transmission efficiency and the ability of overcoming both resistances. This result suggests that resistance-breaking isolates have the same potential to be transmitted as the isolates unable to infect resistant tomato and pepper cultivars
Aplicación de la biotecnología en los programas actuales de mejora
Get PDFLa disponibilidad de una secuencia genómica bien anotada y de un transcriptoma completo facilita enormemente la localización e identificación de los genes involucrados en los caracteres de interés. Conocer la variación en estas secuencias génicas y genómicas es un paso previo necesario para asociarla a la variabilidad fenotípica que se observa en los cultivos, lo que resulta esencial para su mejora. Desde hace varios años venimos asistiendo a una revolución de las técnicas de secuenciación, con el desarrollo de plataformas de secuenciación a gran escala, denominadas colectivamente “Next Generation Sequencing” (NGS) technologies (Shendure y Ji, 2008; Metzker, 2010). Las más empleadas son las denominadas de segunda generación, como la plataforma Roche 454®, el sistema Illumina®, el más utilizado en la actualidad, la tecnología de Applied Biosystems SOLiD® o la estrategia Ion Torrent TM de Life technologies. Además, se están poniendo a punto otras técnicas NGS de tercera generación, como Helicos Heliscope®, Complete Genomics®, and Pacific Biosciences SMRT®, algunas basadas en la secuenciación de moléculas individuales de mayor longitud (Niedringhaus et al., 2011). Todas estas
técnicas llevan a cabo millones de reacciones de secuenciación en paralelo y, asociadas al avance en las estrategias bioinformáticas de análisis, han permitido obtener grandes cantidades de secuencia genómica y transcriptómica en numerosos cultivos y especies silvestres relacionadas, a muy bajo costo y en un tiempo récord. Las secuencias generadas suelen depositarse en la base de datos “Sequence Read Archive” del NCBI (http://www.ncbi.nlm.nih.gov/sra/). Aparte de la información del NCBI, resultan de interés las bases de datos del PLantGDB Phytozome y EnsemblPlants; http://www.plantgdb.org; http://www.phytozome.net; http://plants.ensembl.org/index.html. Los avances también se describen en revisiones recientes (Pérez de Castro et al., 2012; Gao et al., 2012)
Un nuevo método para la evaluación de la compacidad del racimo mediante análisis de imagen
Get PDFLa compacidad del racimo es una característica clave que puede influir de
manera importante en la calidad de la uva y del vino. El descriptor OIV, método
más utilizado para la evaluación de la compacidad del racimo, requiere una
inspección visual por evaluadores entrenados y proporciona valores subjetivos y
cualitativos. Este trabajo presenta una nueva metodología basada en análisis de
imagen para determinar la compacidad del racimo de manera no invasiva, objetiva
y cuantitativa. El modelo PLS construido a partir de algunas características
morfológicas extraídas de forma automática mediante técnicas de análisis de imagen
mostró una capacidad de predicción del 85,3% en la evaluación de la compacidad
respecto a la evaluación visual
Estimación de los componentes del racimo mediante análisis de imagen
Get PDFEl peso de baya, así como el número de bayas y peso del racimo son
parámetros fundamentales en la estimación del rendimiento en la industria
vitivinícola y de uva de mesa. En la actualidad, los métodos utilizados para estimar y
predecir el rendimiento productivo del viñedo son destructivos, lentos, y requieren
elevada cantidad de mano de obra. En este trabajo se presenta una nueva
metodología, basada en el análisis de imagen, para determinar los componentes del
racimo de forma rápida y económica.
Se fotografiaron racimos de siete variedades de uva (Vitis vinifera L.)
distintas en condiciones de laboratorio y se determinaron los componentes del
racimo de forma manual después de la adquisición de imágenes. El tratamiento de
las imágenes incluyó el desarrollo de dos algoritmos basados en las estrategias de
Canny y LIP (Logarithmic Image Processing) para encontrar los contornos de las
bayas, como paso previo a la detección de las mismas mediante la Transformada de
Hough. Asimismo, se comparó la capacidad de los algoritmos desarrollados
utilizando una única imagen por racimo o cuatro imágenes por racimo, obtenidas de
diferentes orientaciones. Los mejores resultados (R2
entre 69%-95% en detección
del número de bayas por racimo, y R2 entre 65%-97% en la estimación del peso de
racimo) se obtuvieron utilizando cuatro imágenes por racimo y aplicando el
algoritmo de Canny. Asimismo, la capacidad del modelo basado en análisis de
imagen para predecir el peso de baya fue 84%.
La novedosa metodología desarrollada y presentada en este trabajo ha
permitido la estimación de los componentes del racimo de forma rápida y económica,
en comparación con los métodos manuales actuales
Association of 'Candidatus Liberibacter solanacearum' with a Vegetative Disorder of Celery in Spain and Development of a Real-Time PCR Method for Its Detection
No full textA new symptomatology was observed in celery (Apium graveolens) in Villena, Spain in 2008. Symptomatology included an abnormal amount of shoots per plant and curled stems. These vegetative disorders were associated with ‘Candidatus Liberibacter solanacearum’ and not with phytoplasmas. Samples from plant sap were immobilized on membranes based on the spot procedure and tested using a newly developed real-time polymerase chain reaction assay to detect ‘Ca. L. solanacearum’. Then, a test kit was developed and validated by intralaboratory assays with an accuracy of 100%. Bacterial-like cells with typical morphology of ‘Ca. Liberibacter’ were observed using electron microscopy in celery plant tissues. A fifth haplotype of ‘Ca. L. solanacearum’, named E, was identified in celery and in carrot after analyzing partial sequences of 16S and 50S ribosomal RNA genes. From our results, celery (family Apiaceae) can be listed as a new natural host of this emerging bacterium
Irrigation recommendation in a semi-arid drip-irrigated artichoke orchard using a one-dimensional monthly transient-state model
No full textIrrigation in semi-arid areas can be optimally scheduled using models that maximize accuracy while minimizing data requirements. In this work, the validation of the one-dimensional transient-state SALTIR-SOIL_M model able to monthly simulate the soil water content (theta), downward water flux (D), and the electrical conductivity in the saturation extract (ECe) is presented. The theta and the ECe were monthly monitored at 15 and 45 cm depth in a plot in commercial production of globe artichoke under semi-arid climate and drip-irrigation in SE Spain during the 2011-2012 growing season. Data on water quality, weather, irrigation management, crop development and soil were also collected and used to simulate the theta, D, and ECe throughout the growing season at both depths with the SALTIRSOIL_M model. Reference and simulations of theta and D reasonably agreed with one another at both depths. ECe at 45 cm depth was estimated correctly enough by the model but was underestimated at 15 cm depth. The higher concentrations of nitrate, potassium, and hence other cations, which were observed at 15 cm as a consequence of fertilization could explain this. The model was subsequently used to estimate the optimum water management in the plot. Use of 325-450 mm yr(-1) instead of 694 mm yr(-1), and by means of evenly distributed pulse irrigations instead of continuous ones, would have met the crop evapotranspiration requirements while avoiding excessive drainage, and maintaining soil salinity well below damaging values. (C) 2014 Elsevier B.V. All rights reserved
Employing evolutionary theory to improve biological pest control: Causes of non-adaptive sex allocation behavior in parasitoid wasps and implications
No full textModels based on sex allocation theory predict that when the fitness gains from larger size differ between male and female offspring, mothers should produce the sex that will offer the greatest investment return. Behavioral studies on parasitoid wasps have confirmed predictions of models, which additionally have practical implications because of their relevance in biological control. We investigated how a parasitoid attacking a scale insect matches theoretical model predictions in a 2-year field study. As predicted by Charnov's host quality model, mothers laid female eggs in hosts above a threshold size. This threshold was absolute, i.e. independent of the host size distribution, independently of the sampling site and date. Further laboratory assays confirmed field results for at least one parasitoid generation and, moreover, excluded the possibility that the observed behavior was a consequence of immature mortality. By comparing the characteristics of our system with others, we hypothesize that this short-term absolute threshold might be favored in polyphagous parasitoids that attack multivoltine hosts. We propose three measures to mitigate the negative implications of this sex allocation behavior in classical and augmentative biological control programs
A new method for pedicel/peduncle detection and size assessment of grapevine berries and other fruits by image analysis
Get PDFThe berry size of wine-grapes has often been considered to influence wine composition and quality, as it is related to the skin-to-pulp ratio of the berry and the concentration of skin-located compounds that play a key role in the wine quality. The size and weight of wine-grapes are usually measured by hand, making it a slow, tedious and inaccurate process. This paper focuses on two main objectives aimed at automating this process using image analysis: (1) to develop a fast and accurate method for detecting and removing the pedicel in images of berries, and (2) to accurately determine the size and weight of the berry. A method to detect the peduncle of fruits is presented based on a novel signature of the contour. This method has been developed specifically for grapevine berries, and was later extended and tested with an independent set of other fruits with different shapes and sizes such as peppers, pears, apples or mandarins. Using this approach, the system has been capable of correctly estimating the berry weight (R2 > 0.96) and size (R2 > 0.97) of wine-grapes and of assessing the size of other fruits like mandarins, apples, pears and red peppers (R2 > 0.93). The proven performance of the image analysis methodology developed may be easily implemented in automated inspection systems to accurately estimate the weight of a wide range of fruits including wine-grapes. In this case, the implementation of this system on sorting tables after de-stemming may provide the winemaker with very useful information about the potential quality of the wine
Evolutionary analysis of Citrus tristeza virus outbreaks in Calabria, Italy: two rapidly spreading and independent introductions of mild and severe isolates
No full textThe evolution of citrus tristeza virus (CTV) from outbreaks occurred in Calabria, Italy, was compared with that of CTV outbreaks reported previously in another two proximal Italian regions, Sicily and Apulia. Examination of four genomic regions (genes p20, p25 and p23, and one fragment of open reading frame 1) showed two recombination events, and phylogenetic analysis disclosed two divergent CTV groups in Calabria: one formed by severe and the other by mild isolates. This analysis, together with others involving population genetic parameters, revealed a low migration rate of CTV between the three Italian regions, as well as significant differences in selective pressures, epidemiology and demography, all affecting the genetic structure of CTV populations