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Pseudomonas savastanoi pv. savastanoi Contains Two iaaL Paralogs, One of Which Exhibits a Variable Number of a Trinucleotide (TAC) Tandem Repeat
No full textIn this study, Pseudomonas savastanoi pv. savastanoi isolates were demonstrated to contain two iaaL paralogs, which are both chromosomally located in most strains. Comparative analysis of iaaL nucleotide sequences amplified from these two paralogs revealed that one paralog, iaaL(Ps)n, is 100% identical to iaaL from P. savastanoi pv. nerii, while the other paralog, iaaL(Psv), exhibited 93% identity to iaaL from Pseudomonas syringae pv. tomato (iaaL(Pto)). A 3-nucleotide motif (TAC) comprised of 3 to 15 repeats, which remained stable after propagation of the strains in olive plants, was found in iaaL(Psv). Based on the observed nucleotide sequence variations, a restriction fragment length polymorphism assay was developed that allowed differentiation among iaaL(Psn), iaaL(Psv), and iaaL(Pto). In addition, reverse transcriptase PCR on total RNA from P. savastanoi pv. savastanoi strains demonstrated that both iaaL(Psv) and iaaL(Psn) containing 14 or fewer TAC repeats are transcribed. Capillary electrophoresis analysis of PCR-amplified DNA fragments containing the TAC repeats from iaaL(Psv) allowed the differentiation of P. savastanoi pv. savastanoi isolates
Chromosomal and Ti plasmid characterization of tumorigenic strains of three Agrobacterium species isolated from grapevine tumours
No full textFifty-six tumorigenic Spanish grapevine strains of Agrobacterium spp. were tested for biovar classification, pathogenicity on several hosts, opine utilization, 16S rRNA gene sequencing and PCR amplifications using five primer sets targeting chromosomal and Ti plasmid genes. Fifty of them belonged to A. vitis (biovar 3), three to A. tumefaciens (biovar 1) and three to A. rhizogenes (biovar 2). All strains were tumorigenic on grapevines. Most A. vitis strains were also pathogenic on tomato and tobacco plants, while the three A. tumefaciens strains were only pathogenic on grapevine. Although most A. vitis strains used octopine, 12 utilized neither octopine nor nopaline. 16S rRNA gene sequencing clearly distinguished between strains belonging to the three species. Those of A. vitis could be further divided into three chromosomal backgrounds according to their 16S ribosomal RNA gene sequences. No universal primer pair was found for the detection of all three Agrobacterium species isolated from grapevine. DNA from all A. vitis strains was amplified with the chromosomally-encoded pehA primer pair. In both A. vitis and A. tumefaciens a correlation was observed between the amplifications obtained using the tmr and the virA Ti-plasmid-targeting primer pairs. Three types of Ti plasmid were found in A. vitis strains according to their PCR amplifications and opine utilization profiles. A given chromosomal background harboured only one type of Ti plasmid within the strains from each analysed sample, showing a strong association between chromosomal backgrounds and Ti plasmids in A. viti
Erwinia amylovora: Características generales. métodos de diagnóstico de la enfermedad e identificación de E. amylovora
Get PDFEl género Erwinia, que debe su nombre a la memoria del fitopatólogo Erwin F. Smith, se creó inicialmente para agrupar a las enterobacterias asociadas a las plantas, Gram negativas, bacilares, no formadoras de esporas y móviles (Winslow et al., 1920). Por ello, los miembros de este género incluían además enterobacterias saprofitas ecológicamente asociadas a plantas, así como
patógenos oportunistas del hombre y los animales (Brenner, 1984). Esta heterogeneidad de especies fue la causa de que el género Erwinia fuera objeto de varias reclasificaciones. Finalmente, gracias al avance de las técnicas moleculares, las especies del género Erwinia se clasificaron en cuatro grupos filogenéticos basados en la comparación de secuencias del ADN ribosómico
16S (Hauben et al., 1998). El grupo I (género Erwinia) representa a las verdaderas erwinias e incluye diversas especies, que producen necrosis o marchitamientos en plantas, o que pueden ser epifitas. Erwinia amylovora es la especie tipo de este género. El grupo II (actuales géneros Pectobacterium y Dickeya) agrupa especies que originan podredumbres blandas en
un amplio rango de hospedadores debido a su gran actividad pectolítica. El grupo III (actual género Brenneria y la especie Dickeya paradisiaca) incluye varias especies que afectan a plantas leñosas produciendo generalmente chancros y exudados. El grupo IV (género Pantoea) contiene especies que son saprofitas o patógenos más o menos frecuentemente oportunistas de plantas, animales y del hombre. Entre ellas destaca la antigua Erwinia herbicola, actualmente denominada Pantoea agglomerans, frecuentemente asociada en rosáceas a E. amylovora
Evaluación de la resistencia a Plum Pox Virus en albaricoquero (Prunus armeniaca l.), mediante sintomatología y RT-PACR en tiempo real
Get PDFLa resistencia a la enfermedad de la Sharka causada por Plum Pox Virus (PPV) es uno de los objetivos prioritarios en la mejora del albaricoquero a escala mundial. Los bioensayos para evaluar este carácter resultan muy costosos lo que ha despertado el interés por el desarrollo de la selección asistida. Sin embargo, este objetivo requiere cartografiar la resistencia a PPV con cierta precisión y, en este sentido, se hace necesaria una clasificación fenotípica más detallada que la clasificación binaria entre individuos resistentes y susceptibles. En este trabajo, se han evaluado dos familias obtenidas a partir de fuentes de resistencia a PPV distintas, una F1 (“Goldrich” x “Currot) y una F2 (“Lito” x “Lito”) en base a una anotación de síntomas más pormenorizada y RT-PCR en tiempo real para incrementar la sensibilidad de la detección de PPV tanto en hojas sintomáticas como asintomáticas. Frente a la clasificación binaria determinada por el protocolo tradicional, los resultados obtenidos según la nueva evaluación sugieren que, una vez recopilados los datos del segundo ciclo de observaciones, podría establecerse un número discreto de clases fenotípicas de susceptibilidad con cierta consistencia. En conjunto, se ha mejorado la descripción fenotípica de la resistencia a PPV lo que podría ser de gran ayuda en el estudio de su control genético y facilitar la selección asistida en el futuro
Chemical Alternatives to Malathion for Controlling Ceratitis capitata (Diptera: Tephritidae), and Their Side Effects on Natural Enemies in Spanish Citrus Orchards
No full textThe Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is one of the most important fruit pests worldwide. Mediterranean fruit fly control in Spain has been based on organophosphate sprays, especially malathion, mixed with protein baits. However, this insecticide has recently been excluded from annex 1 of the Directive 91/414 CEE, which lists authorized active ingredients for pest control in the European Union. This article reports on the efficacy of four alternative baited insecticides on Mediterranean fruit fly and their side effects on three natural enemies [Cryptolaemus montrouzieri (Mulsant), Neoseiulus californicus (McGregor), and Aphidius colemani (Viereck)] relevant for pest control in citrus agroecosystems. A high Mediterranean fruit fly mortality was obtained for all baited insecticides (phosmet and spinosad) except lambdacyhalothrin, which caused the lowest mortality and showed a novel disabling effect on surviving Mediterranean fruit fly adults. Spinosad proved to be the most selective bait treatment for C. montrouzieri and N. californicus, whereas for A. colemani the most selective bait was phosmet and lambda-cyhalothrin. These findings would contribute to a sustainable chemical control of C. capitata populations under an integrated pest management system in Spanish citrus orchards
Genetics and Genomics of Rosaceae
No full textLoquat (Eriobotrya japonica Lindl., Rosaceae, Maloideae) is a subtropical evergreen fruit tree that blooms in fall and early winter. Records on loquat in China spanover 2,000 years. Loquat species are native to the South East of China (Fig. 1). The medium and low region of Dahube river and South East of the Gongga Montains are considered the primary center of origin for Eriobotrya japonica (Zhang et al., 1990), with the Yunnan region as a secondary center (Yang et al., 2005). The loquat cultivated in Japan was introduced from China in ancient times and
its cultivation in Japan was described as early as 1180 (Ichinose, 1995). In 1784, the loquat was introduced from Guangdong into the National Garden at Paris, and in 1787 it was introduced into the Royal Botanical Gardens at Kew, England. Thereafter, loquat was distributed around the Mediterranean countries, including Algeria, Cyprus, Egypt, Greece, Israel, Italy, Spain, Tunisia and Turkey. Sometime
between 1867 and 1870, loquat was introduced to Florida from Europe, and to California from Japan. Chinese immigrants are assumed to have carried the loquat to Hawaii (Morton, 1987). Cultivation spread to India and Southeastern Asia, the East Indies, Australia, New Zealand, Madagascar, and South Africa. Loquats are now distributed in many Asian countries, for example, Laos, Nepal, Pakistan, South Korea, and Vietnam; in Armenia, Azerbaiian and Georgia; and in the Americas,
including Argentina, Brazil, Chile, the mountains of Ecuador, Guatemala, Mexico, and Venezuela. Generally, loquats are found between latitudes 20 and 35. North or
South. but can be cultivated up to latitude 45. under marine climates (Lin et al., 1999). Currently, the crop is grown in temperate and subtropical areas, sharing the same environmental areas as citrus
Addition of food preservatives to hydroxypropyl methylcellulose-lipid edible coatings to control postharvest penicillium molds of citrus fruit
No full textNew hydroxypropyl methylcellulose (HPMC)-lipid edible composite
emulsions containing food additives or GRAS compounds with antifungal
properties were developed. Film disks containing sodium salts of parabens,
potassium sorbate (PS), or sodium benzoate (SB) were the most effective to
inhibit in vitro the pathogens Penicillium digitatum and Penicillium italicum,
the causal agents of citrus postharvest green and blue molds, respectively.
Selected coatings were tested in vivo on ‘Valencia’ oranges and ‘Ortanique’
mandarins to determine their curative (fruit coated after fungal inoculation)
and preventive (fruit coated before fungal inoculation) antifungal activity. In
general, the curative activity after incubation at 20°C for 7 days was higher on
oranges than on mandarins. On coated oranges, coatings prepared with the
mixture PS+SB reduced disease incidence and severity up to 85 and 95%,
respectively, with respect to uncoated controls. On coated mandarins, the
incidence of green and blue molds was reduced by about 65 and 80%,
respectively, by the application of a PS+SP (sodium propionate)-based
coating. The tested coatings did not provide any preventive activity against
both molds. These (HPMC)-lipid edible coatings effectively preserved fruit
quality during cold storage and showed promise as nonpolluting commercial
alternatives to conventional citrus waxes
Principal component analysis of chemical properties of soil saturation extracts from an irrigated Mediterranean area: Implications for calcite equilibrium in soil solutions
No full textCalcite equilibrium characterisation of soil solutions is needed in order to provide soil salinity modellers with reliable solubility constants in solutions where the hypothesis of equilibrium can be accepted. A total of 134 soil samples were taken from 39 sites at 2, 3, or 4 depths per site, down to a maximum depth of 95 cm, during a survey in the irrigated agricultural area of the Segura River Lowland (SE Spain). Soil saturation extracts obtained from each sample were analysed for thirteen chemical properties: Na, NH(4), K, Mg, Ca, Cl, NO(2), NO(3), SO(4), alkalinity, chemical oxygen demand, and electrical conductivity. A principal component analysis (PCA) was then done on the correlation matrix from the log-transformed data set. Three principal components, accounting for 76% of the variance in the correlation matrix, were retained after eigenvector extraction. These components were interpreted as representing salinisation, soil superficiality as opposed to soil depth, and fertilisation status. Sodium, chloride, magnesium, calcium and sulphate concentrations were highly correlated with the first principal component and were interpreted as explaining the variance in electrical conductivity of the soil saturation extracts, and by proxy soil salinity. Alkalinity, pH, chemical oxygen demand, and nitrite were correlated with the second principal component. Nitrate, potassium and ammonium concentrations were correlated with the third principal component, and their variation in soil was independent of soil saturation extract salt content and soil depth. According to the interpretation of the second principal component, soil saturation extracts are further than the solutions in the saturated pastes from being in equilibrium with calcite. The calcite oversaturation status of soil saturation extracts is related to soil organic matter content. (C) 2009 Elsevier B.V. All rights reserved
Situación del material vegetal de melocotonero utilizado en España
Get PDFThe peach species is the most important stone fruit grown in Spain. The acreage devoted to this crop has increased lightly in the last 15 years, however the production has been doubled in this period as a consequence of the use of drip irrigation and introduction of new varieties and more efficient rootstocks. The range of varieties in Spain is very dinamic, there is a substantial increase of nectarines and platicarpa types, a light increase of melting peaches and a decrease of non-melting varieties. The main problems of this crop are the bad adaptability of many varieties from foreign countries to the Spanish environment, the dependency from varieties bred in other countries, the lack of internal quality of the fruits in many commercial cultivars, the incidence of pests, diseases and abiotic stresses and the high cost of the crop management. These problems might be overcame by means of breeding programs based on specific crosses. Currently, there are 14 active peach breeding programs in Spain. in terms of accomplishing the objectives of these programs new sources of variability carrying the desired traits are needed. The search and use of new sources of variation implies a high investment in research and characterization of the new plant material along with inheritance studies of those traits of interest
