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Garcia J.A.,Autonomous University of Madrid | Glasa M.,Slovak Academy of Sciences | Cambra M.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Candresse T.,French National Institute for Agricultural Research
Molecular Plant Pathology | Year: 2014

Summary: Taxonomic relationships: Plum pox virus (PPV) is a member of the genus Potyvirus in the family Potyviridae. PPV diversity is structured into at least eight monophyletic strains. Geographical distribution: First discovered in Bulgaria, PPV is nowadays present in most of continental Europe (with an endemic status in many central and southern European countries) and has progressively spread to many countries on other continents. Genomic structure: Typical of potyviruses, the PPV genome is a positive-sense single-stranded RNA (ssRNA), with a protein linked to its 5' end and a 3'-terminal poly A tail. It is encapsidated by a single type of capsid protein (CP) in flexuous rod particles and is translated into a large polyprotein which is proteolytically processed in at least 10 final products: P1, HCPro, P3, 6K1, CI, 6K2, VPg, NIapro, NIb and CP. In addition, P3N-PIPO is predicted to be produced by a translational frameshift. Pathogenicity features: PPV causes sharka, the most damaging viral disease of stone fruit trees. It also infects wild and ornamental Prunus trees and has a large experimental host range in herbaceous species. PPV spreads over long distances by uncontrolled movement of plant material, and many species of aphid transmit the virus locally in a nonpersistent manner. Sources of resistance: A few natural sources of resistance to PPV have been found so far in Prunus species, which are being used in classical breeding programmes. Different genetic engineering approaches are being used to generate resistance to PPV, and a transgenic plum, 'HoneySweet', transformed with the viral CP gene, has demonstrated high resistance to PPV in field tests in several countries and has obtained regulatory approval in the USA. © 2013 BSPP AND JOHN WILEY & SONS LTD.


De Boer S.H.,Canadian Food Inspection Agency | Lopez M.M.,Instituto Valenciano Of Investigaciones Agrarias Ivia
Annual Review of Phytopathology | Year: 2012

Accurate 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. © 2012 by Annual Reviews. All rights reserved.


Leida C.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Llacer G.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Badenes M.L.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Rios G.,Instituto Valenciano Of Investigaciones Agrarias Ivia
New Phytologist | Year: 2012

• Bud dormancy release in many woody perennial plants responds to the seasonal accumulation of chilling stimulus. MADS-box transcription factors encoded by DORMANCY ASSOCIATED MADS-box (DAM) genes in peach (Prunus persica) are implicated in this pathway, but other regulatory factors remain to be identified. In addition, the regulation of DAM gene expression is not well known at the molecular level. • A microarray hybridization approach was performed to identify genes whose expression correlates with the bud dormancy-related behaviour in 10 different peach cultivars. Histone modifications in DAM6 gene were investigated by chromatin immunoprecipitation in two different cultivars. • The expression of DAM4-DAM6 and several genes related to abscisic acid and drought stress response correlated with the dormancy behaviour of peach cultivars. The trimethylation of histone H3 at K27 in the DAM6 promoter, coding region and the second large intron was preceded by a decrease in acetylated H3 and trimethylated H3K4 in the region of translation start, coinciding with repression of DAM6 during dormancy release. • Analysis of chromatin modifications reinforced the role of epigenetic mechanisms in DAM6 regulation and bud dormancy release, and highlighted common features with the vernalization process in Arabidopsis thaliana and cereals. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.


Guidi L.,University of Pisa | Calatayud A.,Instituto Valenciano Of Investigaciones Agrarias Ivia
Environmental and Experimental Botany | Year: 2014

In Mediterranean areas, plants are concomitantly exposed to various abiotic stresses such as light intensity, water deficit, extremes in air temperature, air pollutants, etc. These environmental pressures adversely affect plant development. Changes in photosystem activity are an early response of plants to abiotic stresses. Therefore, chlorophyll (Chl) fluorescence and gas exchange, two non-invasive, rapid and inexpensive techniques for measuring photosynthesis in leaves, have been widely used by plant ecophysiologists to analyse plant responses to stressful conditions. Chl a fluorescence and gas exchange parameters can be indeed used to evaluate changes in photochemical and non-photochemical processes in photosystems associated with electron transport, CO2 fixation, and heat dissipation.In this review, we focus our analysis on the effects of different abiotic stresses on the photochemistry of Mediterranean plants using Chl a fluorescence and gas exchange measurements. Since changes in photosynthetic parameters are observed in the absence of visual injuries, these methodologies constitute fundamental tools to predict and evaluate the extent to which abiotic stresses damage photosynthesis. © 2014 Elsevier B.V.


Gorbe E.,Wageningen UR Greenhouse Horticulture | Gorbe E.,Wageningen University | Calatayud A.,Instituto Valenciano Of Investigaciones Agrarias Ivia
Scientia Horticulturae | Year: 2012

Chlorophyll fluorescence is a rapid, non-destructive and inexpensive technique that has been used successfully in the evaluation of plant photosynthetic activity. However, this technique has been based on point measurements, and the habitual heterogeneity of photosynthetic activity over the leaf surface makes this approach highly error prone. The development of chlorophyll fluorescence imaging (CFI) overcomes this problem while including the advantages of non-imaging chlorophyll fluorescence. CFI permits the study of the spatial-temporal heterogeneities in the fluorescence emission pattern within cells, leaves or whole plants. In horticultural research, it has been mainly applied in the diagnosis of biotic or abiotic stresses in both preharvest and postharvest conditions. CFI has a useful potential to detect stresses before visual symptoms appear, which is ideal in screening of genotypes for the early identification of those with high tolerance to biotic and abiotic stress. This review provides an overview of the application of CFI in horticultural research, highlighting how CFI can be used for these purposes and in which subjects it can be applied in the future. © 2012 Elsevier B.V.


McClure B.,University of Missouri | Cruz-Garcia F.,National Autonomous University of Mexico | Romero C.,Instituto Valenciano Of Investigaciones Agrarias Ivia
Annals of Botany | Year: 2011

Background S-RNase-based self-incompatibility (SI) occurs in the Solanaceae, Rosaceae and Plantaginaceae. In all three families, compatibility is controlled by a polymorphic S-locus encoding at least two genes. S-RNases determine the specificity of pollen rejection in the pistil, and S-locus F-box proteins fulfill this function in pollen. S-RNases are thought to function as S-specific cytotoxins as well as recognition proteins. Thus, incompatibility results from the cytotoxic activity of S-RNase, while compatible pollen tubes evade S-RNase cytotoxicity. ScopeThe S-specificity determinants are known, but many questions remain. In this review, the genetics of SI are introduced and the characteristics of S-RNases and pollen F-box proteins are briefly described. A variety of modifier genes also required for SI are also reviewed. Mutations affecting compatibility in pollen are especially important for defining models of compatibility and incompatibility. In Solanaceae, pollen-side mutations causing breakdown in SI have been attributed to the heteroallelic pollen effect, but a mutation in Solanum chacoense may be an exception. This has been interpreted to mean that pollen incompatibility is the default condition unless the S-locus F-box protein confers resistance to S-RNase. In Prunus, however, S-locus F-box protein gene mutations clearly cause compatibility. ConclusionsTwo alternative mechanisms have been proposed to explain compatibility and incompatibility: compatibility is explained either as a result of either degradation of non-self S-RNase or by its compartmentalization so that it does not have access to the pollen tube cytoplasm. These models are not necessarily mutually exclusive, but each makes different predictions about whether pollen compatibility or incompatibility is the default. As more factors required for SI are identified and characterized, it will be possible to determine the role each process plays in S-RNase-based SI. © The Author 2011. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.


Navarro L.,Instituto Valenciano Of Investigaciones Agrarias Ivia
Acta Horticulturae | Year: 2015

The 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.


Perez-Hedo M.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Urbaneja A.,Instituto Valenciano Of Investigaciones Agrarias Ivia
Journal of Pest Science | Year: 2015

In recent years, biological control strategies to control many major horticultural pests have been successfully implemented in the Eastern Mediterranean basin. However, the management of some pests, such as aphids in sweet pepper crops, can still be improved. The goal of this study was to examine the potential of the omnivorous predatory mirids Nesidiocoris tenuis, Macrolophus pygmaeus, and Dicyphus maroccanus as biocontrol agents of aphids in sweet pepper crops. First, the capacity to detect Myzus persicae-infested and un-infested plants was studied in a Y-tube olfactometer. Females of the three species of predatory mirids were strongly attracted to the odor of infested M. persicae plants. Second, the prey suitability of young and mature nymphs of M. persicae for these three mirid species was studied. The three species actively preyed on M. persicae, although D. maroccanus resulted the most voracious species preying both young and mature nymphs. Finally, the capacity of the three omnivorous predators to reduce M. persicae in heavily infested plants was determined in semi-field conditions. The three species of mirids could reproduce on aphids and establish on sweet pepper plants. Mirids significantly reduced the number of M. persicae per leaf, reaching levels of aphid reduction close to 100 % when compared to the untreated control. These results suggest that mirids might play a major role in aphid management in sweet peppers. The potential implementation methods of predatory mirids for the biological control in sweet peppers are discussed. © 2014, Springer-Verlag Berlin Heidelberg.


Sanchez-Torres P.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Tuset J.J.,Instituto Valenciano Of Investigaciones Agrarias Ivia
Postharvest Biology and Technology | Year: 2011

The continuous use of chemical fungicides on citrus postharvest has led to the development of resistant strains against the fungicides in use, representing a considerable threat because the control systems are no longer effective. Evaluation of the sensitivity of 75 Penicillium digitatum strains to seven different fungicides revealed the presence of a significant number of TBZ- (84%) and IMZ-resistant (77%) strains, i.e., those fungicides most used in citrus postharvest. Molecular characterization of different P. digitatum genes involved in fungicide resistance was carried out. All P. digitatum genes were selected based on particular mechanisms of resistance due to fungicide target or mode of action. TBZ-resistance was characterized by a unique point mutation in the β-tubulin gene sequence corresponding to amino acid 200, confirming previous work on this subject. Moderate to low resistance to strobilurins did not reveal any mutation in the cytochrome b gene. DMI-resistance was evaluated by examining the CYP51 gene and four different ABC transporters PMR1, PMR3, PMR4 and PMR5. The CYP51 gene did not exhibit any mutation relating to DMI-resistance, but a five tandem repeat sequence previously described was found in the CYP51 promoter in 3 of the 75 isolates examined, whereas DMI-sensitive isolates and the other DMI-resistant isolates of P. digitatum had only one tandem repeat. Of all the ABC transporters studied, only PMR1 and PMR5 appear to be involved in fungicide resistance and several mutations were found in the promoter and the coding region for PMR5 in resistant strains compared to sensitive ones. In all cases, the resistance mechanism was consistent in both orchard or packing-house isolates and no differences conferred by either origin or fungicide pressure were observed.Consequently, since different processes have been described that confer fungicide resistance to the same compounds, such as DMIs, the hypothesis that multiple mechanisms could be acting simultaneously gains strength. © 2010 Elsevier B.V.


Molla O.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Gonzalez-Cabrera J.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Urbaneja A.,Instituto Valenciano Of Investigaciones Agrarias Ivia
BioControl | Year: 2011

Since Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was first detected at the end of 2006 in the Mediterranean Basin, several endemic natural enemies have been reported to prey on this exotic pest. The predator Nesidiocoris tenuis Reuter (Hemiptera: Miridae) can regulate T. absoluta populations, because it is able to prey efficiently on T. absoluta eggs. Furthermore, previous studies have demonstrated that first-instar larvae of T. absoluta are highly susceptible to Bacillus thuringiensis (Bt) treatments. In this work, we tested the combination of both approaches under greenhouse conditions. B. thuringiensis formulations were sprayed weekly for two months, three months or throughout the growing cycle, and in all cases, one N. tenuis per plant was also released. Control plants were completely destroyed by the infestation levels reached by T. absoluta. In contrast, all treatments based on B. thuringiensis treatments and releases of N. tenuis reduced leaf damage by more than 97% when compared to the untreated control, with no significant differences among them. Furthermore, yield in the control plants was significantly reduced when compared with all Bt-N. tenuis treatments. Our results demonstrate that when B. thuringiensis treatments are applied immediately after the initial detection of T. absoluta on plants, they do not interfere with N. tenuis establishment in the crop because T. absoluta eggs are available. According to our data, treatments with B. thuringiensis later in the growing season would no longer be necessary because mirids alone would control the pest. © 2011 International Organization for Biological Control (IOBC).

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