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Actas de Horticultura
Get PDFEl cultivo de los cítricos comenzó en Extremo Oriente hace unos 4.000 años, en las regiones que ocupan actualmente China y Japón. Los grandes movimientos migratorios que ocasionaron las conquistas de Alejandro Magno, la expansión del Islam y el descubrimiento de América favorecieron la expansión de este cultivo por todo el mundo. Sin embargo, fue a partir del siglo XVIII cuando la citricultura adquirió una relevancia económica, tanto desde el punto de vista industrial como ornamental. El movimiento de plantas fue acompañado por la difusión de diversos patógenos, aunque afortunadamente, sólo una parte de los presentes en las regiones de origen han llegado en las nuevas áreas de cultivo. En Italia, la superficie cultivada con cítricos es de aproximadamente 160.000 Ha y de éstas, alrededor del 60% se encuentran en Sicilia. En los últimos años ha cobrado relevancia la producción de cítricos destinados a fines ornamentales, con una producción media anual en Sicilia de unos 4,5 millones de plantas, lo que la convierte en el máximo productor de cítricos ornamentales de Europa. Entre estos se encuentran los limones ornamentales, distintos kumquats, calamondín, naranjo amargo, cidro, naranjo dulce, mandarinos y pomelos. Desde el punto de vista sanitario, hay que tener en cuenta que las plantas ornamentales que se venden por todo el territorio Europeo pueden actuar como reservorios y facilitar el tráfico y emergencia de nuevas enfermedades. Entre las enfermedades más comunes en los cítricos ornamentales se encuentra la exocortis, las protuberancias nerviales (vein enation), las manchas anulares (ringspot), la psoriasis, la tristeza, la variegación, las concavidades gomosas (concave gum), la impietratura, el stubborn y el Huanglongbing. En este artículo se describen las principales enfermedades que afectan a los cítricos ornamentales y que representan un riesgo en la Comunidad Europea
Guía de gestión integrada de plagas de cítricos
No full textLa enfermedad de la tristeza de los cítricos está causada por Citrus tristeza virus (CTV), Fam.
Closteroviridae, Gen. Closterovirus. Se han descrito numerosas razas o aislados virales que
difieren en su agresividad y causan distintos síndromes. CTV está presente en todos los países
citrícolas con una prevalencia e incidencia variable. En los países citrícolas del Mediterráneo no
son mayoritarias las razas agresivas del virus. CTV puede infectar de forma natural exclusivamente
a miembros de la familia Rutáceas y en particular de los géneros Citrus y Fortunella utilizados para
producción comercial de fruta (naranjo dulce y amargo, mandarinos, pomelos, limas, limoneros,
kunquats, pumelos, tangors, cidros...) y a otras especies utilizadas como patrones (C. macrophylla,
C. volkameriana, citranges, limonero rugoso...). CTV se transmite por injerto y propagación
vegetativa en general y en condiciones naturales de forma semipersistente por diversas especies de pulgone
Deastringency treatment with CO2 induces oxidative stress in persimmon fruit
No full textBecause of astringency at harvest, 'Rojo Brillante' persimmons are regularly submitted to deastringency treatment based on exposing fruit to a high CO2 concentration. The treatment conditions that ensure total astringency removal throughout the various maturity stages have been determined to be 95% CO2, 20 degrees C, 24 h. The aim of this study was to investigate changes in the redox state of persimmon fruit associated with this deastringency treatment. The levels of reactive oxygen species (ROS) (O-2(-) and H2O2), and the activities of the main ROS scavenging enzymes (CAT, POD, APX, and SOD), were determined at harvest and after deastringency in fruit at three different maturity stages. Our results showed that during 'Rojo Brillante' persimmon maturation, the level of O-2(-) gradually increased, while APX activity was lowered. The deastringency treatment with CO2 induced oxidative stress in the fruit, observed as an over-accumulation of O-2(-) and H2O2. As a response to ROS accumulation, the activities of the CAT, APX and SOD scavenging enzymes were up-regulated after deastringency treatment. The response of POD enzyme was dependent on maturity stage, showing enhanced activity after CO2 treatment only for the fruit at the most mature stage. (C) 2014 Elsevier B.V. All rights reserved
Evolution and Molecular Epidemiology of Citrus tristeza virus on Crete: Recent Introduction of a Severe Strain
No full textSporadic incidences of Citrus tristeza virus (CTV) in western Crete resulting from the introduction of a mild strain (Spanish isolate T385) have been reported previously. Further analysis within this region has identified an emerging second CTV strain with minimal genetic divergence, sharing 99% nucleotide identity with the severe stem-pitting isolate Taiwan-Pum/SP/T1. Other severe isolates from the Mediterranean region appear in the same phylogenetic cluster, indicating movement or new introductions and the need for targeted control actions and improved phytosanitary measures in this area
Detection and identification of Fabavirus species by one-step RT-PCR and multiplex RT-PCR
No full textThe genus Fabavirus of the family Secoviridae comprises a group of poorly characterized viruses. To date, only five species have been described: Broad bean wilt virus 1 (BBWV-1), Broad bean wilt virus 2 (BBWV-2), Lamium mild mosaic virus (LMMV), Gentian mosaic virus (GeMV) and Cucurbit mild mosaic virus (CuMMV). The development is described of two RT-PCR procedures for the detection and identification of Fabavirus species: a one-step RT-PCR using a single pair of conserved primers for the detection of all fabaviruses, and a one-step multiplex RT-PCR using species-specific primers for the simultaneous detection and identification of the above-mentioned species of the genus Fabavirus. These methods were applied successfully to field samples and the results were compared with those obtained by molecular hybridization and ELISA. The combination of the two techniques enables rapid, sensitive and reliable identification of the five known fabavirus species, as well as the possibility of discovering new species of this genus. (C) 2013 Elsevier B.V. All rights reserved
The movement protein (NSm) of Tomato spotted wilt virus is the avirulence determinant in the tomato Sw-5 gene-based resistance
Get PDFThe avirulence determinant triggering the resistance conferred by the tomato gene Sw-5 against Tomato spotted wilt virus (TSWV) is still unresolved. Sequence comparison showed two substitutions (C118Y and T120N) in the movement protein NSm present only in TSWV resistance-breaking (RB) isolates. In this work, transient expression of NSm of three TSWV isolates [RB1 (T120N), RB2 (C118Y) and non-resistance-breaking (NRB)] in Nicotiana benthamiana expressing Sw-5 showed a hypersensitive response (HR) only with NRB. Exchange of the movement protein of Alfalfa mosaic virus (AMV) with NSm supported cell-to-cell and systemic transport of the chimeric AMV RNAs into N.tabacum with or without Sw-5, except for the constructs with NBR when Sw-5 was expressed, although RB2 showed reduced cell-to-cell transport. Mutational analysis revealed that N120 was sufficient to avoid the HR, but the substitution V130I was required for systemic transport. Finally, co-inoculation of RB and NRB AMV chimeric constructs showed different prevalence of RB or NBR depending on the presence or absence of Sw-5. These results indicate that NSm is the avirulence determinant for Sw-5 resistance, and mutations C118Y and T120N are responsible for resistance breakdown and have a fitness penalty in the context of the heterologous AMV system
Mecanismo implicado en la formación de gametos masculinos no reducidos de un híbrido diploide de mandarino clementino x naranjo
Get PDFEl análisis genético realizado con marcadores Simple Sequence Repeat (SSR) en dos poblaciones de híbridos tetraploides obtenidos en hibridaciones sexuales 4x X 2x nos ha permitido identificar un híbrido de clementino x naranjo (C. clementina x C. sinensis) que produce gametos masculinos no reducidos y que el mecanismo implicado en la formación de los gametos 2n es la restitución de la primera división meiótica (FDR). Este fenómeno se describe por primera vez en los cítricos-en el presente trabajo
A combined equation to estimate the soil pore-water electrical conductivity: calibration with the WET and 5TE sensors
No full textAffordable, commercial dielectric sensors of the frequency domain reflectometry (FDR) and capacitance–conductance (CC) types estimate the dielectric permittivity (εb) and electrical conductivity (σb) of bulk soil. In this work, an equation was obtained to estimate the pore-water electrical conductivity (σp), which is closely related to the soil salinity in contact with plant roots, from εb and σb data, by combining the simplified dielectric mixing (SDM) model that relates εb to the soil volumetric water content (θ), with the Rhoades equation that relates θ and σb to σp. This equation was calibrated with measurements of εb and σb obtained with the Delta-T WET (FDR) and the Decagon 5TE (CC) sensors, in 20 pots filled with a clay loam soil and arranged as combinations of four levels of soil moisture with five levels of soil salinity. The calibrations were performed against reference θ and σp values. The σp was calculated with the chemical equilibrium model SALSOLCHEMEC and used as a more reliable reference than the electrical conductivity of the soil wetting water. For both sensors, the SDM model on the one hand, and the Rhoades equation on the other, provided the most accurate estimations using the least number of parameters regarding their respective alternatives, i.e. the third-order polynomial and the Hilhorst equation. The combined equation for estimation of σp subsequently provided root mean square deviations of 3.1 (WET) and 4.1 (5TE) dS m–1, which decreased to 1.5 and 2.6 dS m–1 for θ >0.22 m3 m–3, and σb 0.22 m3 m–3 and σb <3.7 dS m–1
Effect of freezing extender composition and male line on semen traits and reproductive performance in rabbits
Get PDFThis study was conducted to elucidate the effect of different freezing extenders on two lines selected for hyperprolificacy and longevity (H and LP, respectively). In extender A, dimethyl sulphoxide (Me2SO) and sucrose were used as cryoprotectants. In extenders B and C, the sucrose was replaced by 20% egg yolk, and in extender C the Me2SO was substituted by acetamide. Semen was packaged in 0.25 ml plastic straws and cooled at 5 degrees C for 45 min, and then was frozen in liquid nitrogen vapour for 10 min before being plunged into the liquid nitrogen. Thawing was carried out by immersing the straws in a water bath at 50 degrees C for 10 s. Frozen-thawed semen characteristics and reproductive parameters were affected by freezing. Extender C showed significantly lower post-thawing quality traits than any of the three extenders. Acrosome integrity was significantly improved when Me2SO was used as cryoprotectant. Sucrose replacement by 20% egg yolk had no effect on acrosome integrity but provided significantly lower sperm motility and viability. Freezing extender affected fertility rate, total born, number of implantation sites and gestational losses, obtaining better results when extender A was used. The acrosomal integrity after frozen-thawed process showed a significant correlation with fertility at 12(th) day and also at birth, indicating that an increase in acrosomal integrity leads to an increase in both fertilities (12(th) day and at birth). A positive correlation between motility of semen and implantation sites was found. The post-thawing quality traits of semen were not affected by the genetic line, although LP line showed higher total born and lower foetal and gestational losses. The findings of this study suggest that freezing extender composition has a significant effect on the success of rabbit sperm for preservation, and when Me2SO was used as permeable cryoprotectant sucrose provided better protection compared with egg yolk and improved reproductive traits, and, on the other hand, the male genotypes used in the present study had no effect on frozen-thawed sperm parameters but negatively affected some of the reproductive parameters
Organisms for the Control of Pathogens in Protected Crops. Cultural practices for Sustainable Agriculture
Get PDF“Whiteflies” is the common name of an insect group (Hemiptera:
Aleyrodidae) which has around 1556 described species (Martin & Mound,
2007), although only about thirty species have been mentioned in Spain
which are included in the table 1 (Martin et al., 2000). The origin of this
group of insects is very varied, as its current spread. But, in general,
these are organisms from hot climates: more than 724 species have been
described in tropical areas, and only 420 species in warm areas (BinkMoenen & Mound, 1990).
In general, there are two types of damage caused by whiteflies: direct and indirect. The first is caused by the insects feeding on the plant,
adults as well as nymphal stages (immature), causing the sap-sucking
that leads to weakening and reduction of plant yield, and also inducing
very different physiological disorders on plants. The indirect damages are
referred to as all the problems derived from the production of honeydew
by the insect immatures, and especially, the capacity of the adults of
some species to transmit very different vegetal viruses, that can lead to
the continuity of the crop being put at risk in a specific area