ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Biofilm-associated proteins
No full textAlthough exopolysaccharides are important and often essential compounds of the biofilm matrix, recent evidences suggest that a group of surface proteins plays a leading role during the development of the microbial communities. The first member of this group of proteins was described in a Stophylococcus aureus bovine mastitis isolate and was named Bap, for biofilm-associated protein. Later on, other surface proteins homologous to Bap and involved in biofilm development have been described in many gram-positive and gram-negative bacteria. In this review, we have summarized our knowledge about three members of this group of proteins: Bap of S. aureus, Esp of Enterococcus faecalis and BapA of Salmonella enterica ser. Enteritidis
Characterisation of potato isolates of Dickeya chrysanthemi in Spain by a microtitre system for biovar determination
No full textThirteen Spanish potato isolates of Dickeya chrysanthemi obtained from different cultivars, regions and years have been characterised by biochemical, physiological, serological, molecular and pathogenicity tests. Isolates studied have been classified into biovars 1, 3, 5 and 6 by a microtitre system that correlates with the conventional tests in tubes. This is the first description of the characteristics of D. chrysanthemi isolated from potato in Spain and of the development of a microtitre system for biovar determination
The complete nucleotide sequence of a severe stem pitting isolate of Citrus tristeza virus from Spain: comparison with isolates from different origins
No full textThe genomic RNA of the severe stem pitting Citrus tristeza virus (CTV) isolate T318A from Spain (19252 nt) was completely sequenced. It showed strong sequence similarities with the severe isolates SY568 from California and NUagA from Japan, and distant relationships with mild non-stem pitting isolates T385 from Spain and T30 from Florida. Contrasting with other severe CTV isolates, T318A had a predominant sequence variant even in the highly variable 5'-terminal untranslated region, in which a unique sequence variant (type II) previously associated with severe stem pitting isolates was detected. The high homogeneity of the T318A population suggests that the sequence obtained is probably responsible for the symptoms induced and makes it a useful tool to delimit pathogenicity determinants
Effect of solid storage on caprine semen conservation at 5 degrees C
No full textIn this work, we investigated the effect of storage in solid-phase extender on buck semen conserved at 5 degrees C. Furthermore, we studied the effect of addition of cysteine to the extender and the washing of seminal plasma on sperm survival. In Experiment 1, milk-based extender (M) was used as a control to study the effect of solid media storage (G) and cysteine supplementation (C), and the combination of both (GC), on in vitro sperm survival of washed and non-washed semen, conserved up to 72 h at 5 degrees C. Motility, acrosome integrity (NAR) and hypo-osmotic swelling tests (HOST) were evaluated to assess in vitro sperm survival. In Experiment 2, an artificial insemination (AI) field trial was performed to compare G versus M. Solid media (G) maintained motility of spermatozoa during storage higher than any other extender (67% G versus 62% GC; 61% M and 59% C; P 0.05). No improvement in sperm viability was obtained by addition of cysteine to the media. Washing of semen improved motility (65% versus 60%; P 0.05). No improvement in sperm viability was obtained by addition of cysteine to the media. Washing of semen improved motility (65% versus 60%; P 0.05). No improvement in sperm viability was obtained by addition of cysteine to the media. Washing of semen improved motility (65% versus 60%; P 0.05). In conclusion, washing of semen and dilution in gelatin- supplemented milk extender (solid storage) appears to be a successful method for goat semen storage at 5 degrees C. (c) 2006 Elsevier Inc. All rights reserved
ACTA HORTICULTURAE
No full textThe role of irrigation water in disseminating Erwinia amylovora is not fully recognized, and the survival of the bacterium in natural water has not been carefully investigated. This risk has been underestimated, since it is generally considered that E. amylovora survives only for a short period in water and its isolation from natural water samples has not been reported. The main goal of this study has been to clarify whether E. amylovora could survive under nutrient starvation conditions usually found in aquatic environments and if it is nonculturable on solid media when recovered from sterile natural water. Infectivity of E. amylovora cells in water was evaluated by using immature pear fruits. Total and viable cell counts were monitored by the Live/Dead viability kit, and culturability by plate counts on King's B medium. E. amylovora was able to survive in water from different sources showing a long persistence in irrigation water and maintaining its infectivity for green pears. However, a progressive loss of culturability on solid media by 2 to 3 logarithmic units during storage time was observed, the rate at which cells became nonculturable dependent on the type of water used. A significant difference in the time to nonculturability between cells maintained in irrigation water and those kept in deionized water was observed, associated with the content of dissolved compounds, which differ for these two types of water. Since bacterial cells maintained their viability, it seems that the oligotrophic conditions found in natural aquatic environments could allow the survival of the fireblight pathogen. Further, the maintenance of the pathogenicity of E. amylovora supports the possible role of water as a reservoir and vehicle for transmission of this pathogen
Systemic movement of Agrobacterium tumefaciens in several plant species
No full textAims: The systemic movement of Agrobacterium spp. inside plants of different species was studied to determine the most valuable diagnostic methodology for their detection. Methods and Results: Pathogenic agrobacteria were detected by isolation and PCR in tissue away from primary tumours in tomato plants grown in the presence of Agrobacterium spp. Moreover, this bacterium was also able to induce secondary tumours beyond the inoculation site. In addition, the capacity of agrobacteria to translocate and induce secondary tumours was analysed in rose, grapevine, chrysanthemum, cherry and peach x almond hybrid GF677. No differences among strains of Agrobacterium spp. were detected in secondary tumour development, although some of them induced a significantly higher number of primary tumours in some species. Movement of inoculated pathogenic cells of four strains was also demonstrated in symptomless portions of the plant stems by isolation and PCR. Finally, pathogenic agrobacteria were detected in root, crown and stem portions of naturally infected walnuts. In all assays, PCR was the most efficient technique for detecting the movement of Agrobacterium spp. within the plants. Conclusions: Migration of agrobacteria inside plants is a complex phenomenon and more extensive than previously reported. Therefore, efficient and sensitive detection methods such as PCR must be used to select clean plants to avoid latent infections of Agrobacterium spp. Significance and Impact of the Study: The results show that migration of Agrobacterium spp. could be relatively frequent in several cultivated fruit trees, and systemic infections should be taken into account when designing strategies for controlling crown gall disease
An Indigenous Virulent Strain of Erwinia amylovora Lacking the Ubiquitous Plasmid pEA29
No full textAn atypical strain of Erwinia amylovora was isolated near an outbreak of fire blight at a nursery in Spain in 1996. It was obtained from a Crataegus plant showing typical symptoms and was identified as E. amy-lovora by biochemical tests and enrichment-enzyme-linked immuno-sorbent assay, but not by polymerase chain reaction using primers based on the pEA29 sequence. Nevertheless, with primers from chromosomal regions, the isolate gave the expected amplification band. This strain carries one plasmid of ≈70 kb, with no homology with the 29-kb plasmid common to all pathogenic strains, or with a large plasmid present in some E. amylovora strains. Growth of the strain in minimal medium without thiamine was slower compared with cultures in the same medium with thiamine, a characteristic typical of strains cured of the 29-kb plasmid. Nevertheless, aggressiveness assays on pear, apple, and Pyracantha plants and in immature pear fruit showed that this strain exhibited a virulence level similar to other strains containing pEA29. To the best of our knowledge, this is the first report of the isolation from naturally infected plant material of a pathogenic strain of E. amylovora without pEA29, but with a plasmid of ≈70 kb not previously described
The Rosaceae Genome Database: A Tool for Improving Apricot Genetics and Culture
No full textThe importance of high-quality fruit and the intrinsic difficulties of breeding in a perennial species require the development and application of structural and functional genomic databases for the sustained improvement of Rosaceaous fruit crops. Identification and characterisation of genes controlling the genetic basis of the traits, and their tagging with molecular markers, permits facilitated introgression of important characters, speeding development of new breeding material combining the best traits formerly isolated in separate varieties. Currently, there are two major bottlenecks to the identification, characterisation and direct manipulation of genes important to Rosaceae crop cultivation. These are the lack of a candidate gene database and a genetic/physical map resource in which to search for the genes. In co-operation with other researchers world-wide, we are developing such databases for peach as a genome index species for the Rosaceae. The work towards this Rosaceae genome database is presented here in order to update Rosaceae community researchers on the progress of this database and its application to problems in apricot breeding and sustainability
Programa de mejora genética del melocotonero del IVIA
Get PDFEntre las distintas especies frutales, el melocotonero es la más dinámica en cuanto a
renovación varietal, En parte, es debido a la amplia gama varietal disponible. Así, se pueden
encontrar frutos del tipo melocotón o nectarina, de carne blanda o firme, de color de la carne
blanca o amarilla, de forma redondeada o achatada (paraguayos) etc. La época de recolección
se inicia en las zonas cálidas a finales de abril y se alarga hasta principios de noviembre en
las zonas más tardías. Esta diversidad fenotípica es posible debido a la existencia de cientos
de variedades comerciales que combinan características distintas. Uno de los mayores problemas
que afectan al cultivo de esta especie en los países desarrollados es la superproducción,
no sólo debida al aumento del rendimiento por hectárea, a causa de las mejoras en las
técnicas de cultivo, sino a la expansión del cultivo a zonas tradicionalmente no frutícolas como
las subtropicales, en las cuales las nuevas variedades de bajos requerimientos en frío se
han adaptado y son una alternativa real y económicamente rentable frente a los cultivos tropicales.
El principal mercado para la producción española son los países europeos, los cuales
son a su vez grandes productores a nivel mundial, lo que representa una competencia muy
importante. Sin embargo, en Valencia, Murcia y parte de Andalucía la climatología permite la
producción de variedades más precoces que las de los países competidores. Para aprovechar
esta ventaja, se inició en el IVIA en 1997 un programa de mejora cuyos objetivos son la
obtención de nuevas variedades de melocotón y nectarina precoces y extraprecoces que
superen en calidad del fruto a las actualmente disponibles
Evaluación en campo de la resistencia de líneas transgénicas de ciruelo europeo (Prunus domestica L.) a Plum pox virus
Get PDFLa sharka es la enfermedad viral más grave de frutales de hueso. Afecta especialmente a
albaricoquero, melocotonero y ciruelo produciendo deformación, pérdida de calidad y caída
prematura de los frutos. Esto causa importantes pérdidas económicas en la industria de frutales
de hueso. El agente causante de la sharka es Plum pox virus (PPV). PPV se transmite a través de pulgones y mediante injerto, siendo el transporte y uso ilegal de material infectado la principal causa de la dispersión de la enfermedad a larga distancia. Existen programas de mejora encaminados a la obtención de variedades de prunus resistentes
a PPV. Sin embargo, el largo tiempo que requiere esta técnica unido a la naturaleza poligénica de la resistencia y a la falta de fuentes de resistencia compatibles han hecho que se obtengan escasos éxitos y únicamente en albaricoquero. Una técnica alternativa o complementaria es el uso de la resistencia derivada del patógeno (PDR) mediante la obtención de plantas transgénicas que expresan un gen viral. Esto confiere a la planta resistencia frente al virus del cual procede el gen y frente a virus relacionados. En este sentido, Scorza et al.
(1994) obtuvieron líneas de ciruelo europeo (Prunus domestica L.) que expresan el gen de la proteína de la cápsida de PPV. En condiciones de invernadero estas líneas transgénicas mostraron distintos grados de sensibilidad a la infección por PPV, con excepción de la línea C5 que demostró ser altamente resistente a la infección natural (a través de pulgones) de PPV. Cuando las plantas CS se inocularon mediante injerto, se desarrolló una infección muy leve y sólo en zonas localizadas de las plantas