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Early gene expression events in the laminar abscission zone of abscission-promoted citrus leaves after a cycle of water stress/rehydration: involvement of CitbHLH1
Get PDFLeaf abscission is a common response of plants to drought stress. Some species, such as citrus, have evolved a specific behaviour in this respect, keeping their leaves attached to the plant body during water stress until this is released by irrigation or rain. This study successfully reproduced this phenomenon under controlled conditions (24h of water stress followed by 24h of rehydration) and used it to construct a suppression subtractive hybridization cDNA library enriched in genes involved in the early stages of rehydration-promoted leaf abscission after water stress. Sequencing of the library yielded 314 unigenes, which were spotted onto nylon membranes. Membrane hybridization with petiole (Pet)- and laminar abscission zone (LAZ)-enriched RNA samples corresponding to early steps in leaf abscission revealed an almost exclusive preferential gene expression programme in the LAZ. The data identified major processes such as protein metabolism, cell-wall modification, signalling, control of transcription and vesicle production, and transport as the main biological processes activated in LAZs during the early steps of rehydration-promoted leaf abscission after water stress. Based on these findings, a model for the early steps of citrus leaf abscission is proposed. In addition, it is suggested that CitbHLH1, the putative citrus orthologue of Arabidopsis BIGPETAL, may play major roles in the control of abscission-related events in citrus abscission zones
Acta Horticulturae
No full textIn the old-world viticulture autochthonous varieties are an important inheritance because they can provide wines with authenticity and distinction. Cultivar Mandó is an almost extinguished variety from the south-east of Spain with very large and tight clusters. The aim of this study was to assess the usefulness of early defolia¬tion as a possible tool to reduce cluster compactness, improving fruit composition. With this in mind, an experiment was conducted with ‘Mandó’ in deficit irrigated vines trained with a divided Lyre system. Control (C), non-defoliated vines, were compared with defoliation carried out either just before anthesis (phenological phase H, (Def-H)), at flowering (phenological phase I, (Def-I)) or at fruit set (phenological stage J, (Def-J)). In all the defoliation treatments, leaves from the first eight nodes, including laterals, were removed. The experimental design was a complete randomized block with three replicates per treatment and 24 experimental vines per experimental plot. As an average for all defoliation treatments, berry number per cluster, berry weight and yield were reduced by 44%, 16% and 45%,in Def-H, Def-I and Def-J respectively. Defoliation increased berry soluble solids concentration only in the Def-H treatment. On the other hand, berry acidity was only decreased in the Def-H treatment. In the ED and LD defoliation treatments, leaf pulling improved berry quality determined by a berry tasting panel. In agreement, berries from the ED and LD also had higher total phenolics, anthocyanins and tannin concentration. Results obtained were judged positively by the winery owners and defoliation, particularly at stage J, will now be more widely conducted in the vineyards planted with the ‘Mandó’ cultivar. The research is indeed an example of a successful transfer of a research technique under commercial situations
Yield components and grape composition responses to seasonal water deficits in Tempranillo grapevines
No full textA field experiment was carried out over three seasons on Vitis vinifera cv. Tempranillo in order to compare pre-veraison and post-veraison water restrictions on vine performance and fruit composition. Rain-fed vines were compared with a treatment named MAX that was constantly irrigated at 75 % of the estimated crop evapotranspiration (ETc). In addition, an early (pre-veraison) water deficit strategy (ED) was applied by withholding irrigation until plant water stress experienced by vines surpassed a threshold value of midday stem water potential of -1.0 MPa. After that, 75 % of ETc was applied. A late season deficit (LD) treatment was irrigated as per the MAX up to veraison, and thereafter, water application was reduced to approximately 37 % of ETc. All irrigation regimes increased vine yield up to 58 % with respect to the rain-fed treatment, and no differences in yield among the irrigated treatments occurred. However, there were differences in berry composition among the different irrigation strategies. The ED strategy was more effective than the LD one in reducing berry growth leading to more concentrated berries in terms of sugars and anthocyanins. The LD water shortage impaired berry sugar accumulation due to the detrimental effect of water stress on leaf photosynthesis
Impact of pig diets with different fibre contents on the composition of excreta and their gaseous emissions and anaerobic digestion
No full textTwo diets with the same net energy and digestible lysine content were compared in growing pigs: a control diet with soybean meal as the main protein source, and an experimental high fibre (HF) diet with 15% of dried distiller's grain with solubles and 15% rapeseed meal as the main protein source. The animals (10 castrated males) were housed individually in metabolism cages, and urine and faeces were collected separately from each pig in order to measure nutrient digestibility and the excretory patterns of nitrogen (N) and carbon (C). Ammonia (NH3) volatilisation was measured from samples of slurry and urine, over a 16-day storage period in a laboratory pilot scale system. The methane (CH4) production from effluents (fresh faeces and slurry) was measured using three methods: a biomethanogene test to obtain the ultimate CH4 potential (B-0), a simulation of storage over 100 days, and with a lab scale anaerobic digester. The addition of biofuel by-products as fibre source had no significant effect on the animal growth performance, but it significantly reduced organic matter (OM), N and C digestibility by 7%, 8% and 9%, respectively. The HF diet significantly increased the amount of faeces excreted by 40%, whereas the amount of urine was not affected. Concurrently, the HF diet significantly increased the C content of the faeces by 51% and the amount of OM excreted per pig by 65%, compared to the control diet. NH3 emissions from slurry and urine were significantly reduced for the HF diet by 31% and 26%, respectively, compared to the control diet. The B-0 expressed in L CH4 kg(-1) OM was not affected by the type of diet. During the simulation of storage, the CH4 production expressed in L CH4 kg(-1) OM was significantly affected by the diet and the type of effluent. With the lab-scale anaerobic digester, CH4 production per kg OM was higher for faeces than for slurry (333 L kg(-1) OM vs. 219 L kg(-1) OM, respectively) whereas the difference between the HF and the control diet was small. (C) 2011 Elsevier B.V. All rights reserved
On-line UV-C prototype for postharvest antifungal treatment of citrus fruits
Get PDFSynthetic fungicides used for postharvest treatment of citrus fruits are considered by
consumers as a risk to human health and environment and alternatives to these chemicals
that leave no residue on fruit are increasingly demanded. UV-C light irradiation is a clean and
safe technology that when applied at the right doses may induce fruit resistance to
postharvest diseases, reducing the need for chemical treatments.
The objective of present study was to evaluate the preventive effect of UV-C light treatments
against citrus postharvest green mould caused by the pathogen Penicillium digitatum. For
this purpose, ‘Lanelate’ oranges and ‘Ortanique’ mandarins were puncture-injured in one
side of the equatorial zone, treated with UV-C light at doses of 2.5 or 5 kJ/m2 and held at
20ºC and 90% RH for 6 days before inoculation with P. digitatum at 103 or 104 spores/ml.
Control fruit was inoculated but not treated. Four replicates of 10 fruit each were used for
each treatment.
A new UV-C reactor prototype was used for postharvest treatment of citrus fruits. This
prototype was able to treat the fruit while rolling, therefore exposing the surface of the fruit
more homogeneously to UV-C light. The reactor, assembled on a commercial 3-m long roller
conveyor, consisted of three low pressure 55-W mercury-vapour lamps, mounted on an
aluminium frame placed 16 cm above the conveyor belt. UV-C average power supplied by
the lamps at 6 cm above the conveyor belt was 5 mW/cm2. In order to regulate the flow rate
and thus the UV-C exposure dose, the speed of the conveyor belt was set to provide a
treatment time from 25 s to 2 min, which yielded a UV-C light dose from 2.25 to 5 kJ/m2,
respectively.
The number of infected fruit (disease incidence) as well as the diameter of the lesion
(disease severity) and the percentage of fruit showing sporulated lesions (pathogen
sporulation) were assessed after 3 and 7 days of incubation at 20ºC. Green mould incidence
on ‘Lanelate’ oranges treated with a UV-C dose of 5 kJ/m2 was 64 and 42% lower than on
control fruit after 3 and 7 days of incubation, respectively. Pathogen sporulation was 70 and
45% lower than on control fruit after these incubation periods. Disease severity was not
significantly affected by UV-C treatments. On ‘Ortanique’ mandarins, treatments with UV-C
light at 2.5 kJ/m2 reduced green mould incidence by 56% compared to non-treated fruit after
7 days of incubation. However, disease incidence and pathogen sporulation on ‘Ortanique’
mandarins treated with UV-C light at 5 kJ/m2 were similar to those on control fruit. In this
case, although no rind damage was observed at the naked eye, UV-C light application
probably resulted on slight phytotoxicity that counteracted the resistance induction. It can be
concluded from these experiments that the election of the right UV-C dose was essential for
the suitability of the treatments
Actas de Horticultura
Get PDFLa floricultura española sigue un lento retroceso en las últimas décadas, ya
que la globalización de los mercados ha reducido la rentabilidad de las explotaciones
nacionales y es imposible competir vía costes con las producciones procedentes de
otras latitudes. Sin embargo el consumo de especies ornamentales en España ha ido
creciendo paulatinamente, por lo que cada vez hay mayor dependencia de las
importaciones. Una de las especies mediterráneas más relevantes de la floricultura
del sureste español es el estátice (Limonium sinuatum). El objetivo del presente
trabajo es dar a conocer los aspectos técnicos y agronómicos que caracterizan a este
cultivo, así como los resultados del análisis de sus costes de producción en
explotaciones comerciales del sureste de Alicante. En el presente trabajo se describe
el itinerario de cultivo del estátice, la distribución de la mano de obra necesaria para
la ejecución de las principales labores y las características tecnológicas de los
principales tipos de invernaderos donde se cultiva. Los costes variables alcanzan casi
el 80% de los costes totales. Entre los factores de producción que más inciden en los
costes destaca la adquisición del material vegetal y el coste de la mano de obra, en la
que este cultivo es muy exigente a lo largo de todo su ciclo
Pomegranate improvement through clonal selection and hybridization in Elche
Get PDFSpain is one of the most important pomegranate producers and exporters in the Mediterranean Basin. In spite of various pomegranate cultivars grown, sweet and soft seeds ‘Mollar de Elche’ and ‘Valenciana’ are the main varieties-population. This paper reports the activities in progress on pomegranate germplasm and breeding in the last ten years at Valencian Agricultural Research Institute (IVIA) in Elche. A collection of 35 accessions collected from different parts of Alicante was established and characterised. The collection has been implemented with new accessions. Hybridization between ‘Mollar de Elche’ and other foreign varieties was done in order to obtain darker skin and early ripening. Crossbred progenies were selected and they are being examined in an experimental orchard
Comparison of four steady-state models of increasing complexity for assessing the leaching requirement in agricultural salt-threatened soils
Get PDFIrrigation scheduling in salt-threatened soils must include an estimation of the leaching requirement (LR). Many models have been developed over the last 40 years for assessing the LR, and they should be compared on common grounds to guide potential users. The LR for salts (LR gamma), chloride (LRCI) and SAR (LRSAR) and therefore the eventual LR was assessed with simple equations and three steady-state computer models of increasing complexity, WATSUIT, SALSODIMAR and SALTIRSOIL. These models were assessed in 30 scenarios characterised by different crops and water qualities in the irrigated area of the Vega Baja del Segura (SE Spain). The simple equations, WATSUIT and SALTIRSOIL calculated quite similar eventual LRs, which were between 0.99 depending on crop species and water quality. The SALSODIMAR gave remarkably higher eventual LRs (between 0.31 and > 0.99). This occurred because SALSODIMAR uses the hypothesis that the saturation extract is more concentrated than the drainage water, contrary to what is assumed by the simple equations or calculated by WATSUIT and SALTIRSOIL. Rainfall, which is not taken into account by the simple equations and WATSUIT, and soil calcite weathering, which is not taken into account by SALSODIMAR, were revealed, respectively, as important and very important aspects to be included in steady-state models. Although the SALTIRSOIL appears to be the most complete model, the simple equations give acceptably similar irrigation doses for many of the situations considered in this study. Irrigation doses lower than presently used could be profitably applied in the Vega Baja del Segura
Recombination profiles between Tomato yellow leaf curl virus and Tomato yellow leaf curl Sardinia virus in laboratory and field conditions: evolutionary and taxonomic implications
No full textTomato yellow leaf curl Sardinia virus and Tomato yellow leaf curl virus have co-existed in Italian tomato crops since 2002 and have reached equilibrium, with plants hosting molecules of both species plus their recombinants being the most frequent case. Recombination events are studied in field samples, as well as in experimental co-infections, when recombinants were detected as early as 45 days following inoculation. In both conditions, recombination breakpoints were essentially absent in regions corresponding to ORFs V2, CP and C4, whereas density was highest in the 3'-terminal portion of ORF C3, next to the region where the two transcription units co-terminate. The vast majority of breakpoints were mapped at antisense ORFs, supporting speculation that the rolling-circle replication mechanism, and the existence of sense and antisense ORFs on the circular genome, may result in clashes between replication and transcription complexes
Annual Review of Phytopathology
No full textAccurate plant disease diagnoses and rapid detection and identification of plant pathogens are of utmost importance for controlling plant diseases and mitigating the economic losses they incur. Technological advances have increasingly simplified the tools available for the identification of pathogens to the extent that, in some cases, this can be done directly by growers and producers themselves. Commercially available immunoprinting kits and lateral flow devices (LFDs) for detection of selected plant pathogens are among the first tools of what can be considered grower-friendly pathogen monitoring methods. Research efforts, spurned on by point-of-care needs in the medical field, are paving the way for the further development of on-the-spot diagnostics and multiplex technologies in plant pathology. Grower-friendly methods need to be practical, robust, readily available, and cost-effective. Such methods are not restricted to on-the-spot testing but extend to laboratory services, which are sometimes more practicable for growers, extension agents, regulators, and other users of diagnostic tests