ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Acta Horticulturae
No full textPomegranate (Punica granatum L.) is an expanding crop due to the high antioxidant activity and benefits for human health provided by this fruit. As new markets based on the manufacture of derived functional food products are arising, longer storage life of fresh pomegranates is required. An important factor limiting storability is postharvest decay due to grey mould, caused by Botrytis cinerea. In Spain and other important producing areas no postharvest chemical treatments of pomegranate are allowed and alternative antifungal treatments are required. Exposure to CO2-enriched atmospheres is known to provide fungistatic effects against major postharvest pathogens. In this work, pomegranates ‘Mollar de Elche’ were artificially inoculated with B. cinerea and exposed 24 h later to 0 (ambient atmosphere, control), 15, 50 or 95 kPa CO2 at 20°C and 90% RH for 48 h. Exposure of fruit to 0 and 95 kPa CO2 was also tested at 20°C for 24 h or 35°C for 48 h. Incidence and severity of grey mould were evaluated after 2, 5, 10 and 12 days of incubation at 20°C and 90% RH. After 5 days of incubation, the incidence of grey mould on fruit treated with 95 and 50 kPa CO2 at 20°C for 48 h was 92 and 82% lower than on control fruit, respectively. These reductions were 60 and 47% after 10 days. At the end of the incubation period, the severity of grey mould on fruit exposed to 95 and 50 kPa CO2 was reduced by 43 and 30% with respect to control fruit, respectively. Grey mould inhibition by treatment with 95 kPa CO2 for 48 h was lower at 35 than at 20°C. Exposure of pomegranates to 15 kPa CO2 for 48 h or 95 kPa CO2 for 24 h at 20°C did not affect the development of grey mould
Gibberellic Acid Reduces Flowering Intensity in Sweet Orange [Citrus sinensis (L.) Osbeck] by Repressing CiFT Gene Expression
No full textIn Citrus, gibberellic acid (GA(3)) applied at the floral bud inductive period significantly reduces flowering intensity. This effect is being used to improve the fruit set of parthenocarpic cultivars that tend to flower profusely. However, the molecular mechanisms involved in the process remain unclear. To contribute to the knowledge of this phenomenon, adult trees of 'Salustiana' sweet orange were sprayed at the floral bud inductive period with 40 mg L-1 of GA(3) and the expression pattern of flowering genes was examined up to the onset of bud sprouting. Trees sprayed with paclobutrazol (PBZ, 2,000 mg L-1), a gibberellin biosynthesis inhibitor, were used to confirm the effects, and untreated trees served as control. Bud sprouting, flowering intensity, and developed shoots were evaluated in the spring. GA(3) significantly reduced the number of flowers per 100 nodes by 72% compared to the control, whereas PBZ increased the number by 123%. Data of the expression pattern of flowering genes in leaves of GA(3)-treated trees revealed that this plant growth regulator inhibited flowering by repressing relative expression of the homolog of FLOWERING LOCUS T, CiFT, whereas PBZ increased flowering by boosting its expression. The activity of the homologs TERMINAL FLOWER 1, FLOWERING LOCUS C, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1, and APETALA1 was not affected by the treatments. The number of flowers per inflorescence, in both leafy and leafless inflorescences, was not altered by GA(3) but increased with PBZ; the latter paralleled LEAFY relative expression. These results suggest that GA(3) inhibits flowering in Citrus by repressing CiFT expression in leaves
Improved recovery of Erwinia amylovora-stressed cells from pome fruit on RESC, a simple, rapid and differential medium
No full textThe bacterium Erwinia amylovora causes fire blight, a serious and widespread disease of several pome fruit and ornamental plants. The use of suitable detection tools is essential for preventing its dissemination and, according to the protocol of the European and Mediterranean Plant Protection Organization, the isolation and further identification of E. amylovora is the only conclusive test of its presence. However, bacterial growth on solid media can be hampered when the pathogen is suffering stressful conditions in pome fruit or in other habitats. Since copper is an essential micronutrient that, in E. amylovora, also increases the exopolysaccharide production in rich-nutrient media, we have designed a non-selective differential medium containing 1.5 mM CuSO4 to improve the recovery of E. amylovora from plants under unfavorable conditions. In this new medium named Recovery Erwinia amylovora-Stressed Cells (RESC), its colonies were easily distinguished by a light yellow color and a high mucus production. The plating recovery of several E. amylovora strains in vitro and from naturally infected samples was significantly improved with respect to other media routinely employed, particularly when the pathogen was suffering stressful conditions. Thus, the recovery of stressed E. amylovora cells (after UV irradiation, nutrient deprivation, or the presence of copper ions in non-copper-complexing media) was significantly enhanced on RESC medium, and their culturability period extended. Therefore, RESC is a useful and valuable medium for the isolation of E. amylovora when adverse conditions in the natural environment are expected
Criteria for efficient prevention of dissemination and successful eradication of Erwinia amylovora (the cause of fire blight) in Aragon, Spain
Get PDFErwinia amylovora was detected on pome fruits in the Aragon region (North-Eastern Spain), in a ca. 5 km radius area located in the mid Jalon river (mid Ebro Valley) in the province of Zaragoza, during 2000-2003. Eight years have now passed since this pathogen was last detected, without new infections being reported in the same area. The bases for surveys and rapid eradication performed have been analyzed in detail to understand the reasons for the success in removing fireblight. The results demonstrate that intensive surveillance, risk assessment, plant analyses using accurate identification methods, and, especially, rapid total or selective eradication of infected trees in the plots have been very effective in preventing the generalized spread of fireblight and in delaying economic losses associated with this disease. Eradication and compensation to growers, estimated to cost approx. (sic) 467,000, were clearly counterbalanced by the economic value of apple and pear production in the 2000-2003 period (approx. (sic) 368 million). Fire blight risk-assessment, using the MARYBLYT system, showed that climatic conditions in the studied area were favourable to infections during the analyzed period (1997-2006). Molecular characterization of E. amylovora strains had revealed their homogeneity, suggesting that these fire blight episodes could have been caused by just one inoculum source, supporting the hypothesis that there was a unique introduction of E. amylovora in the studied area. Spatial spread of E. amylovora to trees was analyzed within six orchards, indicating an aggregated distribution model. This Spanish experience demonstrates the success of scientifically-based prevention methods that lead to the deployment of a fast and strict containment strategy, useful for other Mediterranean areas
Field performance of transgenic citrus trees: Assessment of the long-term expression of uidA and nptII transgenes and its impact on relevant agronomic and phenotypic characteristics
Get PDFBackground: The future of genetic transformation as a tool for the improvement of fruit trees depends on the development of proper systems for the assessment of unintended effects in field-grown GM lines. In this study, we used eight transgenic lines of two different citrus types (sweet orange and citrange) transformed with the marker genes beta-glucuronidase (uidA) and neomycin phosphotransferase II (nptII) as model systems to study for the first time in citrus the long-term stability of transgene expression and whether transgene-derived pleiotropic effects occur with regard to the morphology, development and fruit quality of orchard-grown GM citrus trees. Results: The stability of the integration and expression of the transgenes was confirmed in 7-year-old, orchard-grown transgenic lines by Southern blot analysis and enzymatic assays (GUS and ELISA NPTII), respectively. Little seasonal variation was detected in the expression levels between plants of the same transgenic line in different organs and over the 3 years of analysis, confirming the absence of rearrangements and/or silencing of the transgenes after transferring the plants to field conditions. Comparisons between the GM citrus lines with their non-GM counterparts across the study years showed that the expression of these transgenes did not cause alterations of the main phenotypic and agronomic plant and fruit characteristics. However, when comparisons were performed between diploid and tetraploid transgenic citrange trees and/or between juvenile and mature transgenic sweet orange trees, significant and consistent differences were detected, indicating that factors other than their transgenic nature induced a much higher phenotypic variability. Conclusions: Our results indicate that transgene expression in GM citrus remains stable during long-term agricultural cultivation, without causing unexpected effects on crop characteristics. This study also shows that the transgenic citrus trees expressing the selectable marker genes that are most commonly used in citrus transformation were substantially equivalent to the non-transformed controls with regard to their overall agronomic performance, as based on the use of robust and powerful assessment techniques. Therefore, future studies of the possible pleiotropic effects induced by the integration and expression of transgenes in field-grown GM citrus may focus on the newly inserted trait(s) of biotechnological interest
Analysis of the production structure and crop costs of pomegranates in Spain
Get PDFThe importance of the pomegranate is growing with increasing worldwide consumer demand, which is stimulated due to this fruits are considered a functional food, its technological improvements in processing and conservation and a wide range of new industrial uses of the fruit (packed arils, juices and extracts). The increased significance of this fruit in world trade is stimulating improvements in farming techniques and commercialization. This paper reviews the production structure of pomegranates in Spain, highlighting both the more favorable and limiting aspects. An analysis of the costs of pomegranate production at representative farms in Alicante province has been performed in order to identify more direct inputs into the economy of the farms which can contribute to their viability and continuity in the medium term. The first finding to be emphasized is that variable costs alone account for over 80% of total costs. Labor is the largest cost (over 32% of total costs), mainly due to the operations of pruning, thinning and harvesting. The irrigation water cost is over 17% due to the high average price of this natural resource in the
area. The current average prices in the two main Spanish pomegranate varieties (‘Mollar de Elche’ and ‘Valenciana’) exceed the minimum threshold to offset the costs
Development of an irrigation scheduling recommendation for pomegranate trees (Punica granatum)
Get PDFPomegranate culture in Spain is concentrated in the south east, where water available is scarce. There is a need for providing growers with some irrigation recommendations for improving water use efficiency. For this purpose, information from indicators of the continuous soil-plant-atmosphere is being used in a commercial drip irrigated pomegranate orchard, for delivering to growers a weekly irrigation recommendation, taking into account the reference evapotranspiration, plant water status determined via stem water potential measurements and the soil water available to plant obtained from capacitance probes that measured soil water content at different depths. Watering recommendations are calculated in order to fulfil crop water requirements and also avoid water percolation. The average annual water application has been around 425 mm. The information obtained has been transferred by means of an experimental crop coefficient (Kc) integrated in a dissemination tool for calculating water crops requirements. Experimental Kc values increased from 0.32 in March to 0.74 in July, decreasing to 0.42 in November
Embriogénesis a partir del cultivo de anteras en níspero (Eriobotrya japonica Lindl.)
Get PDFEl níspero (Eriobotrya japonica Lindl.) es originario de China y se introdujo en Europa
desde Japón en el S. XVIII. El níspero se cultiva principalmente en países subtropicales y
mediterráneos, siendo España la zona de mayor producción en el Mediterráneo. Sin embargo,
la producción se basa en una estrecha gama varietal por lo que en el IVIA se inició un programa
de mejora varietal.
La producción de plantas haploides y doble haploides (DH) ofrece una valiosa herramienta
biotecnológica para la mejora de especies leñosas, reduciendo el tiempo necesario para la
obtención de líneas homocigotas en comparación con la mejora convencional. En el caso de
árboles frutales, que presentan un alto nivel de heterocigosidad, largo periodo juvenil, gran
tamaño de planta y en algunos casos autoincompatibilidad, no existe otra vía para la obtención
de estas líneas homocigotas que no implique la autofecundación de varias generaciones
(Germanà, 2009).
El uso del polen se ha convertido en una de las más importantes aplicaciones en el campo
de la mejora genética para la obtención de haploides y DH. La regeneración a partir de gametos
masculinos ha sido descrita en manzano, frutales de hueso y cítricos (Ochatt y Zhang, 1996;
Germanà, 2006).
El objetivo principal de este estudio se centra en la obtención de plantas haploides o
DH mediante la inducción a embriogénesis de las microsporas a través del cultivo in vitro de
anteras
Association of citrus psorosis B symptoms with a sequence variant of the Citrus psorosis virus RNA 2
No full textCitrus psorosis virus (CPsV), the type species of genus Ophiovirus, is the presumed causal agent of a bark scaling disease in citrus plants. CPsV virions are kinked filaments composed of three negative-strand RNA molecules and a similar to 48-kDa coat protein. The virus induces two different syndromes: psorosis A (PsA), characterized by limited bark scaling lesions in the trunk and main limbs, and a more aggressive form of the disease called psorosis B (PsB) with rampant bark lesions affecting even thin branches and chlorotic blotches in old leaves. In the greenhouse, the PsA and PsB syndromes can be induced by graft inoculating healthy citrus seedlings with non-lesion or with lesion bark inoculum from PsA-affected field trees. PsA- and PsB-inducing CPsV sub-isolates obtained by this procedure from the same tree showed identical single-strand conformation polymorphism (SSCP) profiles in homologous segments of the RNAs 1 and 3, whereas segments of the RNA 2 enabled discrimination between PsA- and PsB-associated sequence variants. SSCP analysis of the RNA 2 population present in different tissues of psorosis-infected plants showed that: (i) PsA-inducing isolates contain PsB-associated sequence variants at low frequency, (ii) the PsB-associated sequence variant is predominant in blistered twigs and gummy pustules affecting old leaves, characteristic of PsB isolates, and (iii) the PsB-associated sequence variant accumulates preferentially in bark lesions of the trunk and limbs. SSCP analysis of the RNA 2 population also enabled monitoring of interference between PsA- and PsB-associated variants in plants co-inoculated with both psorosis types
Murcott seedless: influence of gamma irradiation on citrus production and fruit quality
Get PDFSeedlessness is an important economic trait relating to fruit quality, and gamma irradiation is a common technique used to obtain seedless citrus fruits. Herein, we report a study of new seedless ‘Murcott’ mandarin clones obtained by bud irradiation from the self-compatible not parthenocarpic ‘Murcott’ mandarin. All irradiated clones examined presented lower seed numbers (from 0.23 to 2.47 seeds per fruit) and reduced pollen germination (from 1.40% to 8.55%) whereas the wild-type ‘Murcott’ showed an average number of 9.03 seeds per fruit and a pollen germination value of 47.15%. Fruit quality and nutritional bio-components were affected differently; some clones presented no changes compared to the control ‘Murcott’ mandarin, while other clones showed significant differences. High-performance liquid chromatographic methods were used to identify and quantify of these compounds, using photodiode array, mass and refractive index detectors. Our results indicated high contents in natural antioxidants as vitamin C (from 20.13 to 25.73 mg/100 mL) and phenolic compounds, as flavonoids, in these citrus varieties cultived under the Mediterranean climate. Some of these clones, which ripen late in the season and whose fruit quality is maintained or improved, are in the process of registration. In conclusion, budwood irradiation is a suitable technique to improve cultivars, produce seedless cultivars, adjust ripening time or raise the content of health-promoting compounds. Also this study investigates the influence of temperature during flowering on the number of seeds formed. Findings indicate that low temperatures during flower formation decreased pollen germination and seed number