ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Chilling and GA3 Effects on Growth and Development of “Nemaguard" and “GF 305” Peaches
No full textThe effect of different chilling and gibberellin treatments on growth and development of the peach rootstocks ‘Nemaguard’ and ‘GF305’ was studied. A factorial experiment was designed combining cold treatments (0, 5, 15 and 30 days at 4°C temperature) and GA3 concentrations (0, 100 and 200 mg/L). The variables considered were: percentage of germination, number of internodes, plant height and the ratio plant height/number of internodes. Results showed an overall growth increase as a consequence of chilling and gibberellin addition; however the behaviour of the two assayed rootstocks was slightly different. In general terms, ‘Nemaguard’ responded well to 5 days cold and chilling treatments did not improve growth in a relevant way, whereas ‘GF305’ showed a more gradual effect of the chilling and gibberellin treatments on the studied parameters
Fate of N-15-Labeled Potassium Nitrate in Different Citrus-Cultivated Soils: Influence of Spring and Summer Application
No full textThe fate of N-15-labeled potassium nitrate (8.5% N-15 excess) was determined in 3-year-old Valencia orange trees grown in 1-m(3) containers filled with different textured soils (sandy and loamy). The trees were fertilized either in spring (24 March) or summer (24 July). Spring fertilized trees gave higher fruit yields in sandy than in loamy soils, which exceeded summer fertilized trees in both cases. Summer fertilized trees had greater leaf biomass than spring fertilized trees. Fibrous root weight was 1.9-fold higher in sandy than in loamy soil. At the end of the cycle, tree N recovery from spring application was 45.7% for sandy and 37.7% for loamy soil; from summer fertilization, N recovery was 58.9% and 51.5% for sandy and loamy soils, respectively. The N-15 recovered in the inorganic soil fraction (0-90 cm) was higher for loamy (1.3%) than for sandy soil (0.4%). Fertilizer N immobilized in the organic matter was lower in sandy (2.5%) than in loamy soil (6.0%). Potential nitrate leaching from fertilizer ((NO)-N-15 (3) (-) -N in the 90-110-cm soil layer plus (NO)-N-15 (3) (-) -N in drainage water) was 34.8% higher in sandy than in loamy soil. The low N levels in sandy soil resulted from both higher NO (3) (-) -N leaching losses and higher N uptake of plants grown in the former. The great root mass and higher soil temperatures could account for raised plant N uptake in sandy soil and in summer, respectively
Estimation of the accuracy of two diagnostic methods for the detection of Plum pox virus in nursery blocks by latent class models
No full textThe control of Plum pox virus (PPV), the most important viral disease that affects stone fruit trees, requires the use of reliable detection methods. The effectiveness of spot real-time reverse transcriptase polymerase chain reaction (RT-PCR) for the detection of PPV in samples collected from nursery blocks was compared with a validated PPV detection technique, the double antibody sandwich indirect enzyme-linked immunosorbent assay (DASI-ELISA) using the PPV-specific monoclonal antibody 5B-IVIA/AMR. In total, 5047 nursery plants were analysed by both techniques. The agreement between the techniques was almost perfect (Cohens kappa index of 0.88 +/- 0.01). The diagnostic parameters (sensitivity, specificity and likelihood ratios) of both techniques were simultaneously evaluated in 2473 nursery plants by latent class models using maximum likelihood functions and a Bayesian approach. The sensitivity and specificity of both techniques did not vary according to the latent model applied. Spot real-time RT-PCR was more sensitive while DASI-ELISA was more specific for PPV detection. In addition, the findings demonstrate that latent class models are a flexible and potent statistical method to estimate the accuracy of diagnostic tests for plant pathology
Advances in validating SALTIRSOIL at plot scale: First results
No full textSALTIRSOIL (SALTS in IRrigated SOILs) is a model for the medium to long term simulation of soil salinity in irrigated, well-drained lands. Once the algorithms were verified, the objective of our study was to validate SALTIRSOIL under one of several water quality and management scenarios in Mediterranean agriculture. Because drip and surface are the most common irrigation systems in irrigated agriculture in Valencia (Spain), the validation was performed with climate, soil, irrigation water (composition and management) and crop (species and management) information from an experimental plot surface irrigated with well water and planted with watermelon that has been monitored since the late spring of 2007. To carry out the validation, first we performed a global sensitivity analysis (GSA). Second, we compared simulated soil saturation extract composition against measured data. According to the GSA, SALTIRSOIL calculations of soil salinity seem to be most affected by climate (rainfall and evapotranspiration) with 60% of explained soil salinity variance, water salinity with 26% of explained variance, and then irrigation with 4%. According to the closeness of the first comparisons between predictions and measurements, SALTIRSOIL does not seem to be affected by any systematic error, and as a consequence, neither inclusion of new parameters nor calibration of the others already included would be needed at least for surface irrigation. The validation of SALTIRSOIL continues under other water quality and irrigation management scenarios
Physical mapping of a pollen modifier locus controlling self-incompatibility in apricot and synteny analysis within the Rosaceae
Get PDFS-locus products (S-RNase and F-box proteins) are essential for the gametophytic self-incompatibility (GSI) specific recognition in Prunus. However, accumulated genetic evidence suggests that other S-locus unlinked factors are also required for GSI. For instance, GSI breakdown was associated with a pollen-part mutation unlinked to the S-locus in the apricot (Prunus armeniaca L.) cv. ‘Canino’. Fine-mapping of this mutated modifier gene (M-locus) and the synteny analysis of the M-locus within the Rosaceae are here reported. A segregation distortion loci mapping strategy, based on a selectively genotyped population, was used to map the M-locus. In addition, a bacterial artificial chromosome (BAC) contig was constructed for this region using overlapping oligonucleotides probes, and BAC-end sequences (BES) were blasted against Rosaceae genomes to perform micro-synteny analysis. The M-locus was mapped to the distal part of chr.3 flanked by two SSR markers within an interval of 1.8 cM corresponding to ~364 Kb in the peach (Prunus persica L. Batsch) genome. In the integrated genetic-physical map of this region, BES were mapped against the peach scaffold_3 and BACs were anchored to the apricot map. Micro-syntenic blocks were detected in apple (Malus × domestica Borkh.) LG17/9 and strawberry (Fragaria vesca L.) FG6 chromosomes. The M-locus fine-scale mapping provides a solid basis for self-compatibility marker-assisted selection and for positional cloning of the underlying gene, a necessary goal to elucidate the pollen rejection mechanism in Prunus. In a wider context, the syntenic regions identified in peach, apple and strawberry might be useful to interpret GSI evolution in Rosaceae
Complete nucleotide sequence of a severe isolate of cucumber vein yellowing virus from Jordan
No full textThe complete genome of a severe isolate of Cucumber vein yellowing virus (CVYV) from Jordan was sequenced. Comparison with the genome of a Spanish CVYV isolate inducing very mild symptoms in cucumber cultivars revealed a nucleotide identity of 94% for the complete genome and an amino acid identity of 96% for the coding region. Comparison of synonymous and non-synonymous substitutions suggested a negative selection at amino acid and nucleotide levels with different degrees depending on the different coding regions. Finally, specific amino acid changes in the zinc finger domain of P1b and in the P1-P3 proteolytic site were found which could be involved in the virulence of CVYV
Dynamic virulence in a parasitoid wasp: the influence of clutch size and sequential oviposition on egg encapsulation
No full textWe examined factors affecting the virulence of Metaphycus flavus (Hymenoptera: Encyrtidae), a facultatively gregarious endoparasitoid of Coccus hesperidum (Hemiptera: Coccidae). Clutch size significantly negatively influenced encapsulation rates of the parasitoid's eggs by the host (in some cases encapsulation rates increased two-fold in incomplete clutches of eggs). Clutches were smaller when individuals sequentially parasitized two hosts in a patch. This resulted in increased egg encapsulation rates in the second parasitized host. Our results suggest that increased encapsulation rates in second hosts are due not entirely to clutch size, but also possibly to the depletion of chemicals with immunosuppressive properties that individual wasps inject inside hosts during oviposition. This hypothesis is also supported by the fact that 4 h after the first oviposition experience wasp virulence decreased, whereas 48 h after oviposition experience virulence was regained. Our results suggest that parasitoid virulence is dynamic because it is directly linked with clutch size decisions. However, clutch size in synovigenic, egg-limited parasitoids such as M. flavus is influenced by several parameters such as egg load, experience, host availability and physiological state. This study has implications for understanding how constraints on the evolution of solitary to gregarious larval development have been overcome: the allocation of multiple eggs to suppress host immune defences could serve as the first step in the transition from solitary to gregarious development. We also discuss how larval immobility within a host and other life history characteristics of this species further facilitate this transition. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved
Acta Horticulturae
No full textTo better understand the molecular and physiological mechanisms underlying maintenance and release of seasonal bud dormancy in deciduous trees, we previously made four different libraries enriched in cDNA from dormant buds, dormancy-released buds, and buds from the peach ‘Springlady’ and ‘Zincal-5’, with different chilling requirements. In this work we analyze by RT-PCR the mRNA accumulation of some of these genes and describe the dormancy-dependent expression of two peach genes similar to Arabidopsis VIN3 and FT. As expected, DAM genes showed reduced expression during dormancy release in buds, whereas several peroxidase-like coding genes, among others, were drastically up-regulated after dormancy release. The peach homologues of VIN3 and FT genes increased their expression from November to January, suggesting a link with the vernalization pathway in Arabidopsis
Bacteria Associated with the Rhizosphere of Manganese-Deficient Date Palms Affected by Brittle Leaf Disease
No full textBrittle leaf disease or "Maladie des feuilles cassantes" (MFC) is a disorder affecting date palm (Phoenix dactylifera) orchards in oases of southern Tunisia. No causal pathogen has yet been identified, despite search for nematodes, fungi, bacteria, viruses and viroids. Although the soils of the oases in which affected palms grow have similar contents of total and exchangeable manganese (Mn) compared with oases with no disease, the leaflets of affected palms are deficient in this element. Here, we characterized the bacterial flora in the rhizosphere of three MFC-affected date palms and three non-affected controls. Our results show a high bacterial diversity in the date palm rhizosphere. From 201 clones corresponding to a 16S rDNA PCR fragment, we identified 177 different bacterial phylotypes. Some of them corresponded potentially to Mn-oxidizing bacteria that may be involved in soil Mn oxidation and, consequently, deplete this micronutrient in MFC-affected date palms. More detailed studies are necessary to establish the exact role of these bacteria in the disease syndrome