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Effects of High CO2 Levels on Fermentation, Peroxidation, and Cellular Water Stress in Fragaria vesca Stored at Low Temperature in Conditions of Unlimited O-2
No full textTo better understand the tolerance of strawberries (Fragaria vesca L.) to high CO2 in storage atmospheres, fermentation and cellular damage were investigated. Fruits were stored for 3 and 6 days at 0 degrees C in the presence of different CO2 levels (0, 20, or 40%) with 20% O-2. Changes in pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) gene expression and in fermentative metabolites, as well as in bound water and malondialdehyde (MDA) concentrations, were analyzed. In strawberries stored without added CO2, up-regulation of PDC and ADH was not associated with an increase in fermentative metabolites. By contrast, moderate ethanol fermentation in fruits exposed to 20% CO2 seems to be essential to maintain fruit metabolism, reducing both lipid peroxidation and cellular water stress. However, if the CO2 concentration increases (40%), the excess acetaldehyde and ethanol produced were closely correlated with a decrease in bound water and production of MDA
Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying
Get PDFPatterns of root abscisic acid (ABA) accumulation ([ABA](root)), root water potential (psi(root)), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0-10 d, RWU and Psi(root) were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22 cm(3) cm(-3) for both spatial distributions of soil moisture. However, [ABA](root) increased in response to decreasing Psi(root) in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (similar to 4 cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Psi(root) than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA](root). Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA](root) and relatively high RWU fraction
Design and validation of a 2D CFD model of the airflow produced by an airblast sprayer during pesticide treatments of citrus
Get PDFDuring plant protection treatments using airblast sprayers, part of the chemical is lost in the atmosphere (spray drift), ground, surface water, etc., causing risks to the environment. Although there is a growing interest in quantifying these losses, field measurements are extraordinarily complex and expensive. Computational Fluid Dynamics (CFD) generates mathematical models of this phenomenon that may help to understand and quantify it. The air flow produced by the fan is affected by the tree canopies, which modify the trajectories of spray droplets. Current state of the art in CFD considers canopies as porous bodies and uses the k-epsilon turbulence model. In a first step, this work proposes and validates a two dimensional CFD model to be applied in citrus tree applications from experimental data. This new CFD model considers canopies as solid bodies. Four different geometries for the first tree are compared using three different turbulence models: k-epsilon, SST k-omega and Reynolds Stress Model. Air velocities measured in front of a canopy in a previous field test are introduced as boundary conditions. We used the experimental data to adjust the model and select the geometry and the turbulence model. In order to test the validity of the model, air velocities obtained with the model are compared with the experimental data obtained in other experiment. The final CFD model was able to reproduce the airflow behaviour around the tree canopy, with the same turbulent structures. The solid body with the new turbulence model (SST k-omega) was considered as a good approximation to the real life
Acta Horticulturae
No full textThe most important economic Citrus species originated from natural interspecific hybridization between four ancestral taxa (C. reticulata, C. maxima, C. medica and C. micrantha) with limited further interspecific recombination due to apomixis and vegetative propagation. Such reticulate evolution coupled with vegetative propagation results in genomes that are mosaics of large chromosome fragments of the basic taxa, in frequent interspecific heterozygosity. Breeding of these species is hampered by their complex heterozygous genomic structures. Haplotyping of multiple gene fragments along the genome should be a powerful approach to resolve the evolutionary history of the gene pools, to reveal the admixture genomic structure of current species and to develop innovative breeding schemes. We have analysed the efficiency of parallel sequencing with 454 methodology to decipher the hybrid structure of modern citrus species and cultivars along chromosome 2. Four hundred fifty four amplicon libraries were established with the fluidigm array system for 48 genotypes and 16 gene fragments of chromosome 2. Haplotypes were established from the reads of each accession and phylogenetic analyses were performed from the haplotypic data of each gene fragment. The length of 454 reads and the level of differentiation between the ancestral taxa of modern citrus allowed efficient haplotype phylogenetic assignations for 12 of the 16 gene fragments. The analysis of the mixed genomic structure of modern species and cultivars (i) revealed C. maxima introgressions in modern mandarins; (ii) was consistent with previous hypothesis regarding the origin of secondary species; and (iii) provided a new picture of the evolution of chromosome 2. Perspectives to rebuild the main secondary species from the basic taxa are discussed
Detection and molecular characterisation of Grapevine Syrah virus-1 isolates from Central Europe
No full textGrapevine Syrah virus-1 (GSyV-1) was identified by small-RNA deep sequencing in Slovak grapevine co-infected by several other viruses. The RT-PCR assays developed in this work substantially improved the virus detection and allowed the identification of GSyV-1 in tested grapevine samples from Slovakia and the Czech Republic at an unexpectedly high rate (ca. 30 %). Subsequently, complete genome sequences of 3 GSyV-1 isolates (2 Slovak and 1 Czech) were determined by Sanger sequencing, showing a typical marafivirus genome organization. Analyses of complete genome sequences showed a higher intra-group diversity among these 3 central European GSyV-1 isolates (differences reaching 7.1 % at the nucleotide level) in comparison to 3 previously characterized North American isolates (only 1.2 % intra-group divergence). A substantially higher divergence among central European isolates and their clustering into two major phylogenetic groups was further confirmed by the partial genome analysis of additional 26 isolates. The CP-centered study did not support the geography-based clustering among central European and American isolates. Nevertheless, the sequence data of the highly variable 5′-proximal portion of the genome obtained for few additional isolates from Slovakia and Czech Republic showed the presence of both, “European-” and “north American-like”, GSyV-1 isolates in the analyzed grapevine samples
Acta Horticulturae
No full textSeven-year-old trees of ‘Lane Late’ grafted on three new citrus rootstocks: ‘Forner-Alcaide n°5’ (‘FA5’), ‘Forner Alcaide n°13’ (‘FA13’) and ‘Forner-Alcaide n°41’ (‘FA41’) (hybrids of ‘Cleopatra’ mandarin × Poncirus trifoliate), and three traditional rootstocks: ‘Carrizo’ citrange (Citrus sinensis × Poncirus trifoliate), ‘Alemow’ (Citrus macrophylla) and ‘Cleopatra’ mandarin (Citrus reshni), cultivated in Andalusia (Spain), were evaluated in the season 2010-2011. They were characterized as their effects on fruit appearance, taste and nutritional compounds. ‘FA5’ and ‘Cleopatra’ madarin maintained fruit quality on the tree for longer time, indicating that they are the most suitable for late harvested cultivars such as ‘Lane Late’. ‘Alemow’ and ‘Carrizo’ citrange showed a faster loss of organoleptic quality due to their lower acidity of the juice. ‘Alemow’ produced larger fruits than ‘Cleopatra’ mandarin and ‘FA13’, although it also produced the lowest juice content and the poorest organoleptic quality. In relation to the remaining quality parameters, ‘Alemow’ and ‘Carrizo’ citrange had the lowest values in fruit firmness, total polyphenols content and antioxidant activity. ‘Cleopatra’ mandarin, ‘FA13’ and ‘FA5’ had the highest antioxidant activity, while ‘FA13’ showed the highest fruit firmness, similar to ‘FA41’ and ‘FA5
Acta Horticulturae
No full textThe main application of shoot-tip grafting in vitro (STG) is to control graft-transmissible pathogens that requires the use of healthy trees in the new plantings. The routine application of STG using 0.1-0.2 mm shoot tips is very efficient for elimination of all citrus graft-transmissible pathogens from local or imported varieties. It has allowed the recovery of hundreds of healthy cultivars and the planting of hundreds of millions of healthy certified trees worldwide. Only in Spain about 140 million certified nursery plants propagated from micrografted plants have been planted. STG is also a very useful technique for regeneration of elite genotypes in several research areas. In vitro grafting for these purposes may be done using larger shoots (up to 1 cm). STG is being routinely used for the following purposes: (i) Regeneration of somatic hybrids from embryos difficult to germinate; (ii) Regeneration of plants from irradiated shoots to produce seedless varieties; (iii) Regeneration of plants from haploid embryos that are very difficult to germinate. STG was used to regenerate the 'Clemenules' haploid plant that has been used by the International Citrus Genome Consortium to sequence the whole citrus genome; (iv) Production of stable tetraploid plants of non-apomictic genotypes, which are very useful for triploid breeding; (v) Regeneration of transgenic plants from shoots that are very difficult to root in vitro. STG has become a routine application in citrus genetic transformation
Acta Horticulturae
No full textA proteomic study was used to know how the primary metabolism in Citrus leaves is affected by the fruit load. To this end, we researched the differential expression of proteins related to these processes between on-crop and off-crop ‘Moncada’ mandarin leaves. Samples were collected in November and proteins were extracted. From 2D DIGE gel of these extracts, 33 spots related to primary metabolism were isolated: 26 spots being associated with photosynthesis and carbohydrate metabolism, 4 spots related to Krebs cycle, 1 spot related to pentose phosphate pathway, and 2 spots related to nutrient reservoir activity. These spots were identified by MALDI-MS or LC-MS-MS. Between the proteins related to photosynthesis and carbohydrate metabolism, 16 were up-expressed in off-crop leaves, such as NADP-dependent glyceraldehyde-3-phosphate dehydrogenase, RuBisCO large subunit, ADP-glucose pyrophosphorylase, cinnamoyl-CoA reductase, and carbonic anhydrase; while 10 proteins were up-expressed in on-crop leaves such as NADP-dependent malic enzyme, and 3,4-dihydroxy-2-butanone kinase. The isolated proteins related to pentose phosphate pathway (6-phosphogluconate dehydrogenase) and to nutrient reservoir activity (Granule-bound starch synthase Ib precursor) were up-expressed in off-crop leaves. Regarding the proteins related to Krebs cycle, only malate dehydrogenase was up-expressed in off-crop leaves, while the other proteins were up-expressed in on-crop leaves (citrate synthase and NADP-isocitrate dehydrogenase). According to these results, the primary metabolism seems to be more active in off-crop leaves, suggesting that fruit load inhibits the primary metabolism in ‘Moncada’ mandarins
Injertos y portainjertos en sandía
Get PDFEl injerto en la sandía en España es, desde hace más de 20 años, una práctica habitual. Se impuso, porque era competitivo, cuando el bromuro de metilo era un desinfectante de suelo autorizado. El injerto es verdaderamente eficaz para el control de las enfermedades de suelo que afectan a la sandía: la fusariosis (Fusarium oxysporum f. sp. niveum), el colapso por destrucción del sistema radicular producida por Monosporascus cannonballus y el virus del cribado del melón (Melon Necrotic Spot Virus), entre otros de menor importancia. Además, contribuye a la reducción de inóculo de la enfermedad en el suelo. El injerto, como técnica no contaminante para el producto final ni para el medioambiente (es «eco» y es «bio») y no peligrosa en su manejo, se ha extendido en numerosos países como alternativa al empleo del bromuro de metilo. El injerto en la sandía aumenta sustancialmente el vigor de la planta, lo cual repercute muy favorablemente en el coste de esta práctica. La mayor parte del importe de la planta injertada corresponde a mano de obra y ciertamente el injerto es una parte sustancial de la industria de producción de planta hortícola
Acta Horticulturae
No full textThe Spanish citrus industry has a long and worldwide known tradition. Citrons (Citrus medica) were introduced by the Romans during the V century, sour oranges (C. aurantium), lemons (C. limon), and pummelos (C. maxima) by the Arabs during the X and XI centuries, sweet oranges (C. sinensis) by Genoese traders during the XV century and a reintroduction of higher quality varieties by the Portuguese in the XVI century and finally, the mandarins (C. reticulata) during the XIX century. Initially citrus were used as ornamental plants and for medicinal purposes, and after the introduction of sweet oranges also for direct consumption at very local scale. Commercial plantings started at the end of the XVIII century and exports of fresh fruit to other European countries were done from this time. Today the Spain has 330.000 ha producing 6.3 million tons. About 50% of the production is exported as fresh fruit, 20% is consumed in the internal market also as fresh fruit, 18% is processed and the rest are wastes. Spain is the fifth production country and the first fresh fruit citrus exporting country in the world