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Random Genome Sequencing of Ralstonia solanacearum Strain IVIA 1602 and Comparative Analysis with Strain GMI1000
No full textRalstonia solanacearum is a β-proteobacterium which affects several hundred plant species and provokes important agronomic losses. Five biovars of this bacterium have been described and they show behavioural differences. In this study a random sequencing of the genome of R. solanacearum strain IVIA 1602 (race 3, biovar 2), isolated from potato, was performed. The resulting 730 Genomic Survey Sequences (GSSs), representing 6.38% of the complete genome, were compared against the completely sequenced genome of strain GMI1000 (race 1, biovar 3), isolated from tomato, which is the only strain of this species sequenced until now. This comparative analysis showed, as expected, a high degree of similarity, but it also revealed strain-specific regions of the genome as well as a number of insertion/deletion events and chromosomal rearrangements. All together, this comparative analysis gives an overview of the genomic divergence between these two biovars of the R. solanacearum species complex
Criterios para identificar variedades y patrones de cítricos en el campo
No full textEsta publicación pretende servir de ayuda para aquellas personas que se inicien en el mundo de la citricultura, lleguen a distinguir variedades, considerando las características de la planta que puedan ser fácilmente reconocibles y que aquí se exponen de la manera más sencilla posible. Refiriéndonos a especies, las podemos diferenciar según la forma de las hojas. En algunos casos concretos estrujándolas, se puede percibir el aroma característico que desprenden. La identificación se complica cuando se desea reconocer la variedad, sobre todo si el fruto ha sido recolectado o se encuentra evolucionando hacia su tamaño, color y madurez natural. Además, el estado vegetativo que pueden presentar los árboles de una misma variedad, puede ser algo distinto en función de la textura del suelo, la profundidad, las labores de cultivo que se realicen, etc. Sin embargo, una vez se va adquiriendo experiencia, es posible conseguir distinguirlas, en base a la observación de una serie de caracteres y parámetros representativos de cada una de ellas. Estos caracteres y parámetros se presentan en porcentajes variables entre campos distintos de una misma variedad, e incluso entre árboles de un mismo campo. La experiencia nos ha demostrado que para distinguir las variedades de una forma práctica, en primer lugar, se debe observar el conjunto del arbolado desde cierta distancia, lo que nos puede indicar la forma del árbol, el hábito de crecimiento, el color en conjunto, el tamaño, etc. A continuación, diferenciar las especies por la forma de las hojas y encuadrar las variedades en cada especie: y por último, confirmar si reúnen o no los caracteres y parámetros propios de las variedades descritas
Cloning and Mapping of Resistance Gene Homologues in Apricot (Prunus armeniaca L..)
No full textGenomic DNA sequences, sharing homology with the NBS-LRR (Nucleotide Binding Site - Leucine Rich Repeat) resistance genes, were isolated and cloned from apricot using a PCR approach with degenerate primers designed from conserved regions of the NBS domain. RGA-specific primers were developed from the consensus sequences of each apricot RGA family and were used to develop AFLP-RGA markers by means of an AFLP-modified procedure, where one standard primer is substituted by an RGA-specific primer. Using this method, 27 polymorphic markers, six of which shared homology with the TIR class of the NBS-LRR R-genes, were obtained from 17 different primer combinations. Sixteen of the 27 mapped in an apricot genetic map previously constructed from the self-pollination of the cultivar ‘Lito’
Hongos asociados al decaimiento de los bosques de enebros (Juniperus spp.) en áreas de montaña del mediterráneo español
Get PDFEn el transcurso de 2004, tuvimos conocimiento de que los bosques de enebros (Juniperus spp.) de áreas de montaña de la Comunidad Valenciana (SE España) llevaban años afectados por severos procesos de decaimiento. Dicha sintomatología fue principalmente observada e investigada en la Puebla de San Miguel del Rincón de Ademuz (Valencia) y en el macizo de Penyagolosa y L’Alt Maestrat (Castellón). Las áreas afectadas consistían en pies de planta infectados o sintomáticos que mostraban varios grados de afección, desde clorosis primaria, hasta la existencia de individuos completamente desfoliados y muertos. Las muestras recolectadas en las áreas afectadas fueron estudiadas para caracterizar e identificar los diferentes agentes fúngicos que pudieran ser la causa primaria o secundaria de la sintomatología observada en las masas de enebros prospectadas. Algunos de los hongos repetidamente aislados fueron: Phaeostoma juniperina, Gymnosporangium clavariiforme, Phellinus ferruginosus y Coniophora arida. La presente contribución se centra en el estudio de los dos últimos táxones citados, los cuales parecen estar relacionados con el deterioro y el decaimiento de las masas de Juniperus spp. en las áreas de estudio. El estudio sistemático de estas especies ha incluido el empleo simultáneo de técnicas taxonómicas clásicas (morfología comparativa, estudio de cultivos, etc.) fitopatológicas (inoculación “in vitro” de material vegetal en laboratorio) y moleculares (identificación mediante la secuenciación directa del ADN ribosomal)
Spatial-temporal variations in rose leaves under water stress conditions studied by chlorophyll fluorescence imaging
No full textSpatial-temporal changes were examined by imaging chlorophyll (Chl) a fluorescence in four leaf areas, two central and two external of rose plants (Rosa x hybrida) cv. Grand Gala for 9 days, under progressive water stress. New fluorescence parameters based on the lake model have recently been used to determine Q(A) redox state and excitation energy fluxes in order to gain a better understanding of the mechanisms that occur under drought stress. Chlorophyll fluorescence images showed a spatial variation in the leaves. The lower values for F-o, F-M, phi(2), q(P) and q(L) were found in the internal leaf area while higher values of non-photochemical quenching calculated from Stern-Volmer quenching (NPQ) and phi(NPQ-)phi(Po) were more homogeneous throughout leaf Temporal changes were also observed during the experiment, a 10% decrease in relative water content (RWC) (between day I and 2), led to a decrease in photochemical quenching and an increase in non-photochemical processes. Chlorophyll fluorescence parameters were more or less constant till day 8. At the end of the experiment (day 9), energy dissipation by downregulation, electron transport and Q(A) redox state, decreased and phi(NO) increased to compensate the change. Chlorophyll fluorescence parameters based on the lake model q(L), phi(NPQ) and phi(NO) have been found more appropriate for estimating the fraction of open centres, the quantum yield of regulated energy dissipation in photosystem 11 (PSII) and the quantum yield of non-regulated energy dissipation in PSII, respectively. The F-s/F-o ratio is strongly correlated with NPQ and phi(NPQ) up to a RWC of 20%. This coincides with a greater decrease in photochemical quenching and non-photochemical quenching and an increase in phi(NO). (c) 2006 Elsevier Masson SAS. All rights reserved
Temperature requirements may explain why the introduced parasitoid Quadrastichus citrella failed to control Phyllocnistis citrella in Spain
No full textQuadrastichus citrella Reina and La Salle (Hymenoptera: Eulophidae) is a parasitoid of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), indigenous to South Eastern Asia where it is considered a key natural enemy of this pest. It was introduced in Spain in a classical biological control program and became established, but was not as successful as forecast. To check whether its biology could explain this lack of control, development and reproduction at different temperatures were studied. Quadrastichus citrella can survive at temperatures between 15 and 35°C. Lower development threshold was 12.3°C, which resulted in a thermal constant of 138.06 DD. The combination of development and reproduction into demographic parameters resulted in highest net reproduction occurring in the range 20-25°C (78.2 females per female), and highest intrinsic rate of increase at 30°C (0.2571 females per female per day). These values make Q. citrella an intrinsically superior natural enemy compared to other leaf miner parasitoids. However, overwintering of Q. citrella in Spain may present a barrier, especially in areas like Valencia, where average winter temperatures are around 11°C. This could account for the low recovery rates observed in Spain in spite of the key natural enemy status enjoyed by this species in its area of origin. © IOBC 2006
Abundance and population dynamics of ground-dwelling predators in Spanish citrus orchards
No full textSituación actual del cultivo del melocotonero. Tendencias
Get PDFEl melocotonero (Prunus persica L. Batsch), especie cuyos frutos reciben muchas denominaciones distintas, según una gran diversidad de tipos y formas (melocotones, nectarinas, pavías, paraguayos, duraznos, etc, CAMBRA, 1984), es con mucha diferencia el frutal de hueso de mayor importancia económica en España y en el mundo y el segundo árbol frutal de zonas templadas, después del manzano. Originario de China, su amplia diversificación varietal le ha permitido adaptarse a numerosas condiciones ambientales entre los 30 y 45” de latitud Norte y Sur. Fue introducido en España por los romanos, permaneciendo como un cultivo marginal hasta el siglo XIX. El injerto sobre diferentes patrones (ciruelos, híbridos melocotonero x almendro) permitió su expansión desde finales del citado siglo. Su rápida entrada en producción y su carácter claramente especulativo le confieren un alto valor agronómico y la preferencia de los fruticultores
Effect of Hydroxypropyl Methylcellulose–Lipid Edible Composite Coatings on Plum(cv.Autumn giant) Quality During Storage
No full text‘Autumn Giant’ plums were coated with edible hydroxypropyl methylcellulose-lipid composite coatings. The coatings consisted of beeswax or shellac, at 2 lipid content levels (20% and 60% dry basis). Weight loss of coated plums decreased as lipid content increased. No differences on weight loss were observed between uncoated and 20% lipid-coated plums, indicating that the natural waxes of plums are as effective as coatings having 20% lipid. Water-dipped plums experienced the highest weight loss. Fruit texture was not affected by coating after short-term storage at 20 °C. However, for prolonged storage at 20 °C, the coatings significantly reduced texture loss and internal breakdown compared to uncoated and water-dipped plums
