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Detection, Characterization, Epidemiology and Eradication of Plum Pox Virus Marcus Type in Spain
No full textSharka disease caused by Plum pox virus (PPV) is widespread in a number of Spanish stone fruit-growing areas; only the common Dideron type (PPV-D) is prevalent. Systematic surveys of field and packing houses were conducted in 2002 for detection of the aggressive Marcus type (PPV-M). The focus of PPV-M was an infected cv. Royal Gem peach (Prunus persica L.) orchard in Zaragoza province (Ebro Valley, Aragon). Over three years, the virus has spread from this orchard to distant plots by means of grafting of infected plant material and to neighbouring plots by aphid transmission. Serological and molecular analyses of symptomatic trees and fruits confirmed the presence of PPV-M in these plots and segregation of the initial viral population into three serogroups and seven different haplotypes as a consequence of host/individual change or vector transmission. Not only did peach cv. Royal Gem become infected, but also cvs Calante and Gladys, in 4 orchards with a total area of 19.5 ha. Spatial analysis of the spread of infection showed a compound contagion process with long-range (up to 150 meters) and short-range movements to adjacent trees in the same row. The main aphid vectors present in the area were Aphis spiraecola Pagenstecher, A. gossypii Glover and Myzus persicae Sulz.. Experimental aphid transmission assays showed that the introduced PPV-M isolate was more efficiently transmitted to other peach cultivars from GF305 peach seedlings, rather than to P persica cv. Gladys young trees. All tree blocks infected with PPV-M were uprooted. Eight years later (2010) no more PPV-M has been detected in commercial Prunus orchards in the area suggesting successful eradication
Acta Horticulturae
No full textThe use of high rates of manure application before solarization is an increasingly accepted practice by Spanish vegetable crops growers. Nevertheless the EU directive 91/676/CEE establishes a limit of 170 kg N/ha in the applied manure, to reduce nitrate leaching. This directive does not distinguish among different kind of soils, nor climates. In order to study the possible increase in nitrate leaching due to solarization combined with manure application, we set up an experiment on a greenhouse with a loamy-clay soil and also under tunnel with loamy sand soil at the IVIA Experiment Station of Carcaixent (Valencia, Spain). Every year, three manure application rates equivalent to 0, 170 and 340 kg N/ha were applied. Manure was incorporated to the soil and then solarisation was applied from the 1st of August to mid September. The statistical design was with complete blocks with three replicates. Soil temperatures were monitored during solarization at 10 and 20 cm depth. Fungicidal effect was determined by biological probes containing infested roots at 10, 20 and 30 cm depth. On 1st October an escarole crop was planted, and was grown until the end of December or beginning of January, followed by a pepper crop up to mid July. As the nitrate content in irrigation water was high (about 200 mg L-1) and soil levels of P2O5 and K2O were high, no mineral fertilizers were added during the study. In order to reduce the nitrate input in irrigation water, the crop was irrigated with rainwater whenever it was possible. Sclerotinia sclerotiorum was isolated every year from the escaroles plants whereas Meloidogyne incognita was isolated in pepper only on the third and forth year. In the loamy sand soil the healthier escaroles were frequently produced on the 340 kg/ha of N treatment. Generally there were not yield differences on pepper, except in 2008 when pepper plants suffered an attack by Meloidogyne incognita with a significant yield reduction in the check treatments with loamy sand soil. Check treatment, without manure, did not affect the incidence of Meloidogyne on pepper crop in the loamy sand soil, while higher rates of manure reduced gall number in roots. There were no clear differences in NO3-N content in soil (0-60 cm depth) throughout the experiment between treatments. However, soil nitrate levels in the loamy sand soil were much lower than in the loamy clay soil. No cumulative effects of treatments on soil nitrate levels in the 0-60 cm layer were found after 5 years, with a total N application of 340 kg/ha/year in the highest N rate treatment
Development of Ssr Markers from Citrus Clementina (Rutaceae) Bac End Sequences and Interspecific Transferability in Citrus
No full textPremise of the study: Microsatellite primers were developed from bacterial artificial chromosome (BAC) end sequences of Citrus clementina and their transferability and polymorphism tested in the genus Citrus for future anchorage of physical and genetic maps and comparative interspecific genetic mapping. Methods and Results: Using PAGE and DNA silver staining, 79 primer pairs were selected for their transferability and polymorphism among 526 microsatellites mined in BES. A preliminary diversity study in Citrus was conducted with 18 of them, in C. reticulata, C. maxima, C. medica, C. sinensis, C. aurantium, C. paradisi, C. lemon, C. aurantifolia, and some papedas (wild citrus), using a capillary electrophoresis fragment analyzer. Intra- and interspecific polymorphism was observed, and heterozygous markers were identified for the different genotypes to be used for genetic mapping. Conclusions: These results indicate the utility of the developed primers for comparative mapping studies and the integration of physical and genetic maps
Dextran vitrification media prevents mucin coat and zona pellucida damage in rabbit embryo.
No full textVitrification of embryos is being increasingly important for cryopreservation in mammals. However, damage and toxicity has to be reduced even more. The composition of cryoprotective medium used to immerse the embryos affects viability and developmental potential. The aim of this work was to assess the effect of the Polyvinylalcohol-PVA- and Dextran addition to vitrification media on the in vitro development of rabbit embryos from superovulated and non-superovulated females. Superovulation group were treated intramuscularly with 25 IU rhFSH. The vitrification media contained the same permeable cryoprotectans (Ethylene Glycol-ET- and Dimethyl Sulfoxide-Me₂SO-) and different macromolecules (PVA and Dextran) in different combinations. There was a significantly higher proportion of embryos without damages in mucin coat or zona pellucida after warming (undamaged embryos) in the control than in the superovulation group (95.8% vs. 83.2%, respectively). The proportion of undamaged embryos was significantly affected by the vitrification solution composition. The rate of undamaged embryos after warming in media containing 20% Me₂SO was significantly lower in media supplemented with PVA than in media with dextran (67.3 vs. 93.8, respectively). However, the proportion of undamaged embryos for the medium supplemented with dextran was similar for media with 15 or 20% Me₂SO. In conclusion, the addition of dextran to the vitrification media improve the preservation of rabbit embryos and permits to reduce the amount of Me₂SO for vitrification. Additionally, in vitro developmental ability of undamaged embryos were not affected by superovulation treatment nor vitrification media
Potencial del compost de restos verdes en la elaboración de sustratos ecológicos para viverismo en horticultura
Get PDFUno de los grandes retos del viverismo ecológico es la progresiva eliminación de
la turba para sustituirla por otros sustratos que provengan de fuentes renovables, dando
especial atención a aquellos que impliquen un mayor aprovechamiento de los residuos o
subproductos orgánicos que se originan a escala local. Entre los materiales más
prometedores para su uso en agricultura ecológica se encuentra el compost de restos
verdes. Si este compost se elaborase a partir de residuos de cultivo y restos de poda de
frutales y setos procedentes de las explotaciones ecológicas, se podría convertir en una
fuente de materia orgánica muy adecuada para generar un compost de calidad destinado
a sustrato ecológico.
Con el objeto de estudiar sus características y su posible uso en semillero de
hortícolas, se llevaron a cabo dos experiencias de invernadero, utilizando tomate y col
lombarda, empleando compost vegetales provenientes de tres instalaciones comerciales
con distintos tratamientos de fertilización orgánica y mineral. De los tres productos
ensayados, uno afectó claramente al crecimiento de las plantas produciendo una
significativa disminución en el porcentaje de germinación, la altura de planta y peso de la
parte aérea y raíces, lo que puso en evidencia la importancia de partir de un compost de
buena calidad. Ni la fertilización mineral ni la orgánica han presentado una clara
respuesta positiva, lo que parece indicar que la limitación de estos productos como
sustratos no reside en su contenido de nutrientes, sino más bien en sus características
físicas y químicas.
Pese al carácter exploratorio de este ensayo, se han obtenido resultados bastante
prometedores a la hora de plantear este tipo de productos orgánicos para su uso en la
elaboración de sustrato de hortícolas
Analysis of genetic diversity among persimmon cultivars using microsatellite markers
No full textIn the Mediterranean area, the production of persimmon (Diospyros kaki Thumb) [2n = 6x = 90] has increased recently as an alternative to the major fruit crops. In Spain, production relies almost exclusively on the cultivar “Rojo Brillante” which accounts for 83% of the crop. A crop based on a monovarietal culture implies several commercial risks that can compromise the future of the crop. Although the species was introduced in Europe very recently, it is well adapted to the climate of southern Europe. However, the recent introduction from Japan, the mistakes on the identity of varieties in the collections due to a bad translation of variety names from Japanese, and the lack of genetic characterization of many varieties have caused difficulties for effective management of the available genetic resources. The present paper was aimed at exploring the genetic diversity among different persimmon cultivars, including those collected in the European survey as well as Japanese cultivars. Seventy-one persimmon cultivars coming from two European collections that included accessions from Japan, Italy, and Spain were analyzed using 19 polymorphic microsatellite markers. A total of 206 alleles were obtained, with a mean value of 10.8 alleles per locus. A neighbor joining dendrogram and a principal coordinate analysis arranged the cultivars according to their genetic relationships. Analysis of molecular variance revealed significant genetic variability between and within groups, 73.3% and 85.2% for astringent-type and country origin, respectively. The simple sequence repeat markers classified the persimmon cultivars according to their genetic relationship
Characterization of technological levels in Mediterranean horticultural greenhouses
Get PDFThe technology existing in Spanish horticultural greenhouses is highly diverse; however, low levels predominate. Therefore urgent improvements and conversions are required to increase yields and quality to maintain competitive production. To define the equipment and investment required, it is necessary to establish the current levels of technology and the extent to which it is developing. To do so, information has been collected using a survey based on stratified random sampling in the three most important greenhouse horticultural areas in Spain: Almeria, Murcia and Southern Alicante. Based on information from 242 farms, five groups of technological levels with a gradual variation in technology were identified by cluster analysis. Of the five groups, three relate to cultivation in soil and the other two to soilless culture. In this study, we have applied the test for independence in order to relate the levels obtained with certain relevant characteristics of the farm. The results display the usefulness of grouping the greenhouses by levels, and reveal which are the most characteristic components in level formation with their percentage distribution. Thus, current characteristics of technology, and its development, have been identified, and priority assigned to the different components
Recovery of citrus triploid hybrids by embryo rescue and flow cytometry from 2x x 2x sexual hybridisation and its application to extensive breeding programs
No full textSeedlessness is one of the most important characteristics for mandarins for the fresh-fruit market and mandarin triploid hybrids have this trait. Citrus triploid plants can be recovered by 2x x 2x sexual hybridisations as a consequence of the formation of unreduced gametes at low frequency. Triploid embryos are found in small seeds that do not germinate under greenhouse conditions. Extensive breeding programs based on this type of hybridisation require very effective methodologies for embryo rescue and ploidy evaluation. In this work, we describe an effective methodology to recover triploid hybrids from 2x x 2x hybridisations based on in vitro embryo rescue and ploidy level determination by means of flow cytometry. The influence of parents and environmental conditions on obtaining triploid hybrids has been analysed. The strongest effect was associated with the genotype of the female parent while a strong interaction was found between the male parent genotype and environmental conditions. The effect of the female parent genotype on the length of the juvenile phase was also demonstrated by observing a large number of progenies over the last 10 years. The methodology described here has enabled us to obtain over 4,000 triploid hybrids so far, of which 13 have been protected in the European Union and two are being extensively planted by citrus growers to establish new commercial plots. These triploid hybrids have been analysed with simple sequence repeats markers to differentiate all the new triploid varieties and their parents, and thus molecular identification will help defend plant breeders' rights
Pseudomonas Savastanoi Endophytic Bacteria in Olive Tree Knots and Antagonistic Potential of Strains of Pseudomonas Fluorescens and Bacillus Subtilis
No full textForty nine endophytic bacterial isolates were obtained from knots on olive sterns induced by Pseudomonas savastanoi pv. savastanoi (Pss) and from symptomless leaves of olive trees naturally infected with Pss from six orchards from different locations in Tunisia. Populations of all endophytic bacteria were higher in knots (1-14 10(6) CFU/g) than in leaves (5-21 10(4) CFU/g). A 16S rDNA sequence analysis revealed the presence of many saprophytic bacteria associated with Pss, such as Pantoea agglomerans, Enterobacter sp., Pseudomonas sp., P fluorescens, Stenotropbomonas maltophilia and Burkolderia cepacia. In the leaves, however Pss was often associated with Bacillus subtilis and an Acinetobacter species. Screening of antagonistic activity of 18 isolates associated with Pss in knots or leaves showed that only one strain of P fluorescens and one strain of B. subtilis were highly antagonistic against Pss. The active compound produced by B. subtilis is a protein whereas that produced by P. fluorescens is not