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Effect of antioxidants in controlling enzymatic browning of minimally processed persimmon 'Rojo Brillante'
No full text'Rojo Brillante' is an important variety of persimmon that after removal of the astringency with high levels of CO2, maintains firmness and sweetness, making possible its commercialization as a fresh-cut commodity. However, the commercial success of the product is limited mainly by enzymatic browning. This work presents the effect of a wide range of antioxidants on enzymatic browning of 'Rojo Brillante' persimmon combining in vitro (extracts and precipitates) and in vivo (cut tissue) studies. Preliminary screening of the antioxidants, determined by absorbance and color measurements of persimmon extracts and pellets, showed that 4-hexylresorcinol (Hexyl), citric acid (CA) and calcium chloride (CaCl2) were effective at controlling browning at 10 mM; whereas, ascorbic acid (AA) required a higher concentration (25 mM). Peracetic acid, cyclodextrin, cysteine, and hexametaphosphate were not effective at controlling browning, even at a concentration of 50 mM. In in vivo studies, AA (1.12%) and CA (0.21%) were the most effective treatments to control enzymatic browning of fresh-cut material, reaching the limit of marketability in 5-7 days, whereas, Hexyl and CaCl2 did not reach 1 day of storage. The results showed that optimum concentrations in cut tissue did not always correlate with the in vitro studies, indicating that antioxidants have an effect not only in browning reactions, but also in metabolic activity and cell wall changes during wound-induced reactions. The results provide relevant information for further development of minimally processed 'Rojo Brillante' persimmon during storage at 5 degrees C. (C) 2013 Elsevier B.V. All rights reserved
Real-time multiplex RT-PCR for the simultaneous detection of the five main grapevine viruses
No full textA real-time multiplex RT-PCR has been developed for the simultaneous detection and identification of the major RNA viruses that infect grapevines (Grapevine fanleaf virus, Arabis mosaic virus, Grapevine leafroll-associated virus 1, Grapevine leafroll-associated virus 3 and Grapevine fleck virus). Serial dilutions of infected plant extracts were tested using the new method, and the results were compared with those obtained using a commercially available ELISA and real-time singleplex RT-PCR. The two real-time RT-PCR versions detected up to the same level of dilution and were at least 10,000 times more sensitive than the ELISA. In addition, 158 grapevine plants collected in a survey of the Protected Designation of Origin in Alicante, Spain were compared using the three methods. The results of the molecular methods were very similar, with only four discordant results, and both were able to detect many more infected plants than the. ELISA. The high prevalence of Grapevine fleck virus, Grapevine leafroll-associated virus 3 and Grapevine fanleaf virus suggests that the main pathways of viral introduction are infected plant material that has escaped controls and/or uncontrolled traffic of propagating plant material. Real-time multiplex RT-PCR could be used to facilitate a better control of grapevine viruses. (C) 2012 Elsevier B.V. All rights reserved
Pre-adaptive shift of a native predator (Araneae, Zodariidae) to an abundant invasive ant species (Hymenoptera, Formicidae)
Get PDFInvasive species often displace native species and can affect ecological processes in invaded habitats. If invasive species become abundant, changes in prey availability may be particularly harmful to specialist predators. The Argentine ant, Linepithema humile Mayr, is an important invasive species on nearly all continents. Spiders of the genus Zodarion are specialised ant-eating predators native to the Mediterranean yet it is unknown if they can exploit invasive ant species. Here we studied spatial and temporal abundance of this invasive ant and the native spider, Zodarion cesari Pekar, during 4 years in four citrus groves. Circadian activity of both spiders and ants, and capture efficiency and prey specificity of the predator were also evaluated. The abundance of Z. cesari was strongly correlated to L. humile abundance. The predatory activity of spiders varied seasonally with differences on the relative frequency of spiders capturing ants depending on the time of the year. In laboratory, Z. cesari displayed most efficient capture upon the native ant Tapinoma nigerrimum (Nylander) and the invasive ant L. humile in comparison with five other native ant species. These results demonstrate that the native spider Z. cesari is successfully exploiting the invasive ant species L. humile and is likely a locally monophagous predator. We suggest that Z. cesari shifted away from native T. nigerrimum post invasion as both ant species are phylogenetically related and of similar size
Estudios sobre la resistencia a la piriculariosis
Get PDFLa “piriculariosis”, causada por el hongo Magnaporthe oryzae Couch, es la
enfermedad del arroz más importante a escala mundial; también en España ha causado
pérdidas importantes algunos años. Se han obtenido diversas variedades resistentes,
principalmente al incorporar genes de resistencia completa (genes Pi), pero la mayoría se
han vuelto susceptibles en pocos años. Actualmente, para conseguir una resistencia efectiva y
duradera, se busca incorporar resistencia parcial, o una combinación de ambos tipos de
resistencia; la resistencia parcial está controlada, generalmente, por un tipo de genes a los
que se denomina OTLs.
Hemos realizado diversos estudios para conocer mejor la población del patógeno presente en
la zona de la Albufera, y qué genes y QTLs de resistencia pueden ser efectivos en varias
zonas arroceras de España. Para ello, por un lado se ensayaron durante varios años 31
variedades diferenciales, que son líneas con un gen Pi diferente cada una. Estos estudios
demostraron que la estructura de la población del hongo varía con los años, incluso en una
misma parcela; además, ninguno de los genes Pi ensayados confirió inequívocamente una
resistencia efectiva. Por otro lado, realizamos estudios genéticos sobre la resistencia a M.
oryzae en varias poblaciones, procedentes del cruzamiento entre variedades con buenas
características agronómicas, por variedades resistentes. Aquí presentamos los resultados de
dos de ellas: la procedente de un cruzamiento entre Sivert y CNA-6159 (SixCNA), y la
derivada del cruzamiento entre Jsendra y Gigante Vercelli (JSxGV). En ambas se determinó
la resistencia en campo, en condiciones favorables para el ataque del hongo, en hojas y
órganos productivos de líneas F3 de cada población: en SixCNA, en una parcela de la
Albufera, y en JSxGV, en 4 localidades de Valencia, el Delta del Ebro y Sevilla. En la
segunda población, además, se realizaron inoculaciones en condiciones controladas. Se
detectaron 10 OTLs en SixCNA, y 55 OTLs en JSxGV, la mayoría de los cuales sólo se
expresan en una localidad. Todos los parentales aportan alelos de resistencia, no sólo los
que, a priori, se consideran resistentes; pero los OTLs identificados son de efectos pequeños
y, a menudo, con un notable componente dominante. Muchos de ellos co-localizan con OTLs
identificados en otros estudios. Hemos encontrado pocas coincidencias entre QTLs que
controlan la incidencia en panículas y los que determinan la severidad en las hojas, lo que
apoya la hipotesis de que los mecanismos de resistencia en ambos órganos son diferentes, y
explicaría porqué la correlación entre ambos caracteres es baja.
Con los resultados del análisis, se seleccionaron con marcadores (MAS) los genotipos de
JSxGV con el mayor número de alelos favorables en los OTLs, y se comprobó la respuesta a
la selección en líneas F4, en dos localidades. Estas líneas mostraron una resistencia
mejorada, tanto en caracteres de hoja como de panícula; aunque los cambios en la población
de M. oryzae con los años nos hacen ser prudentes con esta conclusión. Esto demostraría
que, aunque los QOTLs detectados en estos estudios no aportan, individualmente, una
resistencia significativa, la combinación en un mismo genotipo de diversos factores que
ayuden a controlar el hongo podría ser efectiva. Pero para poder utilizar la MAS en
programas de mejora, de manera eficaz, deberíamos poder realizar las diversas fases
(genotipado, evaluación, análisis y selección) en una sola generación; esto es algo que van a
permitir los avances técnicos más recientes, tales como la secuenciación masiva o el
“genotipado en profundidad”
Postharvest Anthracnose of Persimmon Fruit Caused by Colletotrichum gloeosporioides First Reported in Spain
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Litter aeration and spread of Salmonella in broilers
Get PDFLitter quality in the poultry sector is one of the main parameters of health, productivity, and animal welfare. Therefore, innovative management methods have been developed to improve the quality of litter. One of them is litter aeration (LA) by tumbling. However, there is little information related to the effect of this technique on the spreading of pathogens of public health importance such as Salmonella. In this context, the objective of this study was to determine the epidemiology of Salmonella in poultry farms, when serial LA were implemented during the rearing cycle of broilers. For this purpose, an experimental broiler farm with 3 identical rooms was used in the study. Two rooms were assigned to the LA treatment, and the other one served as the control room. Environmental samples were taken in poultry houses after LA in 4 consecutive weeks at the end of the cycle. All samples collected were analyzed according to the standards of the International Organization for Standardization (ISO 6579:2002, Annex D). The results of this study showed that in the control and treated rooms, the percentage of positive samples for Salmonella decreased in the first 3 LA sessions (LA 1, LA 2, and LA 3). However, in the last LA session of rearing (LA 4), the percentage of positive samples increased from 8.2 to 33.2% in the control room instead the treated rooms where the positive samples decreased (P = 0.017). Thus, the aeration of the litter as litter management technique in poultry broiler production does not increase the shedding or the spread of Salmonella throughout broiler houses. In addition, it could be an effective technique to reduce the infective pressure of this bacterium in several areas of the farm or in certain moments of the rearing period with more risk of multiplication and spreading of Salmonella
A new mechanised cultural practice to reduce Ceratitis capitata Wied. populations in area-wide IPM
Get PDFThe Mediterranean fruit fly (or medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), affects most of the fruit species grown in temperate and tropical climate regions, causing significant economic damage. One of the classical cultural strategies against this pest is to gather and bury the remaining fruit after harvest, but this is economically unfeasible today. Wood shredders already available in current Spanish groves can be used to grind or crush fruits laying on the soil as an alternative to this practice and to the use of pesticides in area-wide integrated pest management (IPM). With the purpose of evaluating this alternative, the initial step of this study was to perform laboratory tests to assess the efficacy of crushing and grinding as a method for controlling medflies. The results showed that grinding was 78% effective against larval stages, while crushing resulted in a 17% efficacy, leading us to choose the first alternative. As a second step, the operational parameters (type of cutting tool, shaft rotation speed and tractor speed) of the wood shredders were adjusted to efficiently carry out this practice under field conditions. Finally, the effect of the mechanised grinding of fallen fruit on C. capitata populations was evaluated for two consecutive years in commercial citrus orchards. The results showed a significant 27-46% reduction in C. capitata populations the following spring, thus demonstrating that the newly proposed mechanised alternative can be included in the current area-wide IPM of the pest in Spain
Characterization of Erwinia amylovora strains from Middle Atlas Mountains in Morocco by PCR based on tandem repeat sequences
No full textForty Erwinia amylovora strains isolated from the Middle Atlas Mountains in Morocco have been characterized using sequences from tandem repeat of variable numbers (VNTR) as chromosomal markers. Three VNTR sequences were identified and used for studying the genetic diversity of the strains using a PCR fingerprinting method. Thirty nine strains showed high genetic homogeneity, but one strain displayed a profile quite different. We were able to obtain reproducible and characteristic profiles in strains from remote geographical areas, and associated them with each of the primers. Comparative analyses of Moroccan strains with three reference strains from Spain, France and England, were performed. The results revealed some polymorphisms compared with the English and the French strains, but notable similarities were observed with a Spanish strain obtained from plants imported from Belgium. The developed methodology has demonstrated its usefulness for being applied in epidemiological studies