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Genetically Based Location from Triploid Populations and Gene Ontology of a 3.3-Mb Genome Region Linked to Alternaria Brown Spot Resistance in Citrus Reveal Clusters of Resistance Genes
Get PDFGenetic analysis of phenotypical traits and marker-trait association in polyploid species is generally considered as a challenge. In the present work, different approaches were combined taking advantage of the particular genetic structures of 2n gametes resulting from second division restitution (SDR) to map a genome region linked to Alternaria brown spot (ABS) resistance in triploid citrus progeny. ABS in citrus is a serious disease caused by the tangerine pathotype of the fungus Alternaria alternata. This pathogen produces ACT-toxin, which induces necrotic lesions on fruit and young leaves, defoliation and fruit drop in susceptible genotypes. It is a strong concern for triploid breeding programs aiming to produce seedless mandarin cultivars. The monolocus dominant inheritance of susceptibility, proposed on the basis of diploid population studies, was corroborated in triploid progeny. Bulk segregant analysis coupled with genome scan using a large set of genetically mapped SNP markers and targeted genetic mapping by half tetrad analysis, using SSR and SNP markers, allowed locating a 3.3 Mb genomic region linked to ABS resistance near the centromere of chromosome III. Clusters of resistance genes were identified by gene ontology analysis of this genomic region. Some of these genes are good candidates to control the dominant susceptibility to the ACT-toxin. SSR and SNP markers were developed for efficient early marker-assisted selection of ABS resistant hybrids
Antibrowning effect of antioxidants on extract, precipitate, and fresh-cut tissue of artichokes
No full textThe effect of antioxidants controlling enzymatic browning of artichokes cv. 'Blanca de Tudela' was studied in extracts and fresh-cut tissue. Initially, the effect of ascorbic acid (AA), citric acid (CA), peracetic acid (PA), calcium chloride (CaCl2), cyclodextrin (CD), cysteine (Cys), hexametaphosphate (HMP), and 4-hexylresorcinol (Hexyl) at different concentrations was studied in extracts and precipitates. Absorbance at 450 nm of artichoke extract and color of the pellets were measured, as a preliminary screening of antioxidants controlling browning. AA at 10 mol/m(3) was the most effective controlling browning in the extract and pellet; whereas, Cys and 4-Hexyl were effective at a higher concentration (50 mol/m(3)) and CA was only effective in the extract. Application of AA, CA, Cys, and Hexyl at different concentrations was studied on fresh-cut artichokes during storage at 5 degrees C. Samples treated with Cys (0.1, 0.3, 0.5, 1%) showed the highest L* and lowest a* values. An increase in Cys concentration decreased a* and increased b* values, which correlated with a decrease in browning and an increase in yellowness of the tissue. Application of CA (1, 2.7, 5.3%), AA (0.5, 1, 1.5, 2%) and Hexyl (0.002, 0.005%) did not inhibit enzymatic browning. Visual evaluation confirmed these results. (C) 2012 Elsevier Ltd. All rights reserved
Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+/K+ homeostasis
Get PDFThe location of major quantitative trait loci (QTL) contributing to stem and leaf [Na+] and [K+] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na+-selective class I-HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single-nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near-isogenic lines (NILs): 157-14 (double homozygote for the cheesmaniae alleles) and 157-17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157-14 in comparison with 157-17. A significant difference between NILs was also found for [K+] and the [Na+]/[K+] ratio in leaf and stem but not for [Na+] arising a disagreement with the corresponding RIL population. Their association with leaf [Na+] and salt tolerance in tomato is also discussed
Could sterile males be used to vector a microbiological control agent? The case of Rhynchophorus ferrugineus and Beauveria bassiana
No full textRhynchophorus ferrugineus (Coleoptera, Curculionidae) is the most threatening pest of palms worldwide. The potential of gamma-irradiated males to spread a pathogenic strain of the entomopathogenic fungus Beauveria bassiana (Ascomycota: Clavicipitaceae) to control this pest was studied. First, the effects of gamma irradiation (15 and 25 Gy) on the mating success and performance of adult males irradiated at age one day were studied in the laboratory. Although male longevity decreased after irradiation (118.6 vs. 244.7 days for irradiated and control males, respectively) and their testes suffered from the treatment, fecundity of mated females did not depend on the irradiation status of the male (86.8 +/- 5.5 eggs in 15 days). However, egg hatching was significantly lower in couples with irradiated males (31.4% vs. 86.5% for irradiated and control couples, respectively), and this value decreased after a second mating (6.1% vs. 85.9%). Therefore, irradiation did not affect male sexual competiveness but sperm quality. Second, a semi-field assay was carried out to evaluate infestation in young Phoenix canariensis caused by different combinations of couples with irradiated and/or B. bassiana-challenged males. The number of immature stages found in infested palms was significantly higher when females mated with untreated males and lower when mated with irradiated males (either B. bassiana-infected or not). Some females from the fungus-challenged treatments showed post-mortem hyphal growth, and this horizontal transmission proves that irradiated males could act as a vector for B. bassiana and should be considered as a new method to improve the biological control of R. ferrugineus
Early decay detection in citrus fruit using laser-light backscattering imaging
No full textEarly detection of fungal infections in citrus fruit still remains one of the major problems in postharvest technology. The potential of laser-light backscattering imaging was evaluated for detecting decay in citrus fruit after infection with the pathogen Penicillium digitatum, before the appearance of fruiting structures (green mould). Backscattering images of oranges cv. Navelate with and without decay were obtained using diode lasers emitting at five different wavelengths in the visible and near infrared range for addressing the absorption of fruit carotenoids, chlorophylls and water/carbohydrates. The apparent region of backscattered photons captured by a camera had radial symmetry with respect to the incident point of the light, being reduced to a one-dimensional profile after radial averaging. The Gaussian-Lorentzian cross product (GL) distribution function with five independent parameters described radial profiles accurately with average R-2 values higher or equal to 0.998, pointing to differences in the parameters at the five wavelengths between sound and decaying oranges. The GL parameters at each wavelength were used as input vectors for classifying samples into sound and decaying oranges using a supervised classifier based on linear discriminant analysis. Ranking and combination of the laser wavelengths in terms of their contribution to the detection of decay resulted in the minimum detection average success rate of 80.4%, which was obtained using laser light at 532 nm that addresses differences in scattering properties of the infected tissue and carotenoid contents. However, the best results were achieved using the five laser wavelengths, increasing the classifier average success rate up to 96.1%. The results highlight the potential of laser-light backscattering imaging for advanced citrus grading. (C) 2013 Elsevier B.V. All rights reserved
Relationship between hydraulic conductance and citrus dwarfing by the Flying Dragon rootstock (Poncirus trifoliata L. Raft var. monstruosa)
No full textThis work studied the hydraulic characteristics and physiological behavior of two trifoliate orange (Poncirus trifoliata L. Raft) varieties-Flying Dragon (FD) and Rubidoux (RT)-with contrasting size-controlling potential when used as rootstocks for citrus trees. Thus, Valencia orange scions growing on RT root system develop about 40 % more biomass than scions on FD. The anatomical study of xylem root tissue of both rootstocks showed that the number of vessels per cross-sectional area in RT almost doubled that found in FD, whereas diameter distribution did not vary significantly. Hydraulic resistance determined in rootstocks, and bud union segments were, respectively, 2- and 3.4-fold higher in trees on FD than in trees on RT. Root systems accounted for 46.5 and 55.2 % of whole-plant hydraulic resistance, whereas bud union segments represented 7.5 and 14.6 % of this parameter, the dwarfing rootstock (FD) having the highest values. Reduced hydraulic conductance in plants on FD rootstock diminished water potential in high evaporative demand periods, causing a reduction in stomatal conductance with respect to plants on RT. This leads to lower net photosynthetic CO2 assimilation, which may affect biomass production. Translocation of C-13-labeled photoassimilates from leaves to roots was lower in plants on FD than in plants on RT, indicating that in the dwarfing rootstock (FD) there may be a vascular resistance to sucrose transport at the budding union level. Findings show that reduced hydraulic conductance may be the main cause of rootstock-induced dwarfing in citrus grafted onto FD
Quantitative estimation of the impact of caprine arthritis encephalitis virus infection on milk production by dairy goats
No full textThis retrospective study investigated milk production losses associated with serological evidence (serostatus) of caprine arthritis encephalitis virus (CAEV) infection over one lactation in 4543 Murciano-Granadina goats from 22 herds in Spain. The seroprevalence of infection was 18%, ranging from 0% to 2% in 11 herds, 7% to 60% in 10 herds and was 100% in one herd. Seropositive does had significantly shorter lactations, produced less milk and milk fat, lactose and dry extract and had higher somatic cell counts than their seronegative counterparts, although differences in milk production between seropositive and seronegative animals were noted between herds. Mixed regression models confirmed the association between CAEV seropositivity and reduced milk production. The adjusted, least squares mean (LSM) test-day milk yield was 10% less in seropositive compared to seronegative does and this difference varied according to lactation number. In contrast, differences in the LSM of milk fat, lactose and dry extract percentages between seropositive and seronegative goats were only between 0.1% and 0.2% and did not increase with lactation number. The findings of this study provide strong evidence that CAEV-infection can be a major cause of reduction in milk yield in goats and its control should be considered as part of dairy goat herd health schemes. (C) 2013 Elsevier Ltd. All rights reserved
Effect of handling on stress-induced hyperthermia in adult rabbits
Get PDFAnimals perceive humans as a threat, therefore handling could cause stress reactions and fear in
rabbits. Stress induced hyperthermia (SIH) is a physiological response produced when a stressful situation
takes place and is supposed to occur in rabbits. In this work, the SIH response is assessed when different
groups of rabbits (young males, nulliparous does and multiparous does) are handled. A benzodiazepine
(Midazolam®) was administered to half of the animals to assess handling response also under drug effects.
Rectal temperature was not increased by handling in male rabbits and multiparous does, whereas nulliparous
females showed presented SIH after 30 min of handling. In addition, Midazolam® has been revealed as useful
for pharmacological validation of SIH after 25 min from injection
Selección asistida por marcadores en la mejora del arroz
Get PDFLa selección asistida por marcadores (MAS) consiste en seleccionar los genotipos
deseados indirectamente, mediante marcadores ligados a los genes de interés. En los casos
en que está indicada (caracteres monogénicos o controlados por pocos genes, o de baja
heredabilidad, o cuando la evaluación directa del carácter presenta dificultades de tipo
práctico), el uso de MAS puede aumentar sustancialmente la eficacia del proceso.
Puesto que uno de los objetivos de mejora básicos para el Departamento del Arroz del IVIA
es la calidad del grano, en este trabajo se describe cómo el uso de marcadores moleculares
nos permite efectuar una selección más eficiente y temprana de algunos de estos caracteres:
la mejora de la textura y el aspecto del grano cocido (esponjosidad, brillo, humedad
superficial, integridad y adherencia entre granos), y la presencia de aroma. Lo primero,
mediante la selección de genotipos con un contenido de amilosa en el grano intermedio-alto,
lo cual logramos utilizando un marcador dentro del gen waxy. La selección de genotipos
aromáticos, por su parte, se efectúa cribando dos marcadores que flanquean al gen sk2, el
principal determinante de la presencia de aroma en nuestros cruzamientos. También se
discute en qué otros casos sería interesante la aplicación de esta metodología a la mejora del
arroz.
Ya que la utilización de MAS tiene interés cuando se puede realizar el cribado inicial en un
tamaño muestral importante, para descartar todos aquellos genotipos que no van a presentar
el carácter deseado, hemos diseñado un protocolo que nos permite analizar un gran número
de individuos de forma rápida y económica: podemos analizar entre 600 y 800 plántulas de
cada población F2, y las seleccionadas pueden ser trasplantadas en dos semanas desde la
siembra, con un coste reducido
Proteomic analysis of "Moncada" mandarin leaves with contrasting fruit load
No full textA proteomic approach was used to know more about the molecular mechanism related to Citrus alternate bearing. To this end, we researched protein expression differences between on-crop and off-crop “Moncada” [Clementine ‘Oroval’ (Citrus clementina Hort ex Tanaka) x ‘Kara’ mandarin (Citrus unshiu Marc. x Citrus nobilis Lou.)] mandarin leaves. This variety usually shows a remarkable behaviour in alternate production. Samples were collected in the period during which the fruit affect flowering induction. From 2D DIGE gel, 110 spots were isolated: 43 showed increased expression in the off-crop samples compared to on-crop samples, while 67 showed increased expression in the on-crop samples against off-crop samples. These spots were identified by MALDI-MS or LC-MS–MS. According to the up-expressed proteins in off-crop leaves such as proteins related to nutrient reservoir activity or to the pentose phosphate pathway, the primary metabolism was more active in off-crop trees than in on-crop trees. In contrast, the proteins up-expressed in on-crop samples such as catalase were related to the oxidoreductase activity and, therefore, the redox state seemed different for off-crop and for on-crop leaves. Other proteins with unknown functions were isolated, which could be also related to the alternate bearing and to the flowering induction