ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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RNA2-encoded VP37 protein of Broad bean wilt virus 1 is a determinant of pathogenicity, host susceptibility, and a suppressor of post-transcriptional gene silencing
Get PDFBroad bean wilt virus 1 (BBWV-1, genus Fabavirus, family Secoviridae) is a bipartite,
single-stranded positive-sense RNA virus infecting many horticultural and ornamental
crops worldwide. RNA1 encodes proteins involved in viral replication whereas
RNA2 encodes two coat proteins (the large and small coat proteins) and two putative
movement proteins (MPs) of different sizes with overlapping C-terminal regions. In
this work, we determined the role played by the small putative BBWV-1 MP (VP37)
on virus pathogenicity, host specificity, and suppression of post-transcriptional gene
silencing (PTGS). We engineered a BBWV-1 35S-driven full-length cDNA infectious
clone corresponding to BBWV-1 RNA1 and RNA2 (pBBWV1-Wt) and generated a
mutant knocking out VP37 (pBBWV1-G492C). Agroinfiltration assays showed that
pBBWV1-Wt, as the original BBWV-1 isolate, infected broad bean, tomato, pepper,
and Nicotiana benthamiana, whereas pBBWV1-G492C did not infect pepper and tomato
systemically. Also, pBBWV1-G492C induced milder symptoms in broad bean
and N. benthamiana than pBBWV1-Wt. Differential retrotranscription and amplification
of the (+) and (−) strands showed that pBBWV1-G492C replicated in the agroinfiltrated
leaves of pepper but not in tomato. All this suggests that VP37 is a determinant
of pathogenicity and host specificity. Transient expression of VP37 through a potato
virus X (PVX) vector enhanced PVX symptoms and induced systemic necrosis associated
with programmed cell death in N. benthamiana plants. Finally, VP37 was identified
as a viral suppressor of RNA silencing by transient expression in N. benthamiana
16c plants and movement complementation of a viral construct based on turnip crinkle
virus (pTCV-GFP)
Effect of antioxidants and pH on browning and firmness of minimally processed eggplant
Get PDFMinimal processing of eggplants (Solanum melongena L.) generates a rapid onset of enzymatic browning,
tissue softening and water loss that limits their shelf life. The aim of this study was to evaluate the effect of 1%
ascorbic acid and 2% calcium ascorbate in aqueous solution at natural pH of the antioxidant (pH 2.6 and 7.8,
respectively), or adjusted to pH 5 with generally recognized as safe substances, to maintain the quality of
minimally processed eggplant stored at 5 °C for 6 d. Water was used as a control. The colour, firmness,
polyphenol oxidase activity, and visual quality was evaluated in the freshly cut fruit at 3 and 6 d of storage. No
effect of the treatments on firmness or polyphenol oxidase activity was observed. At 3 d of storage, a correlation
was observed between polyphenol oxidase activity and the visual evaluation of the cut product. Samples treated
with 2% calcium ascorbate and the rest of the treatments at pH 5 had a lower browning index than those treated
with 1% ascorbic acid and the control. At the end of the storage period, the visual quality of the eggplant
samples treated with 1% ascorbic acid at pH 5 was evaluated above the marketing limit, whereas those treated
with 1% ascorbic acid at pH 2.6 had the lowest quality indicators. An adjustment to pH 5 helps to preserve the
luminosity and visual quality of the eggplant, however firmness was not affected by calcium ascorbate or the
pH of the medium
Row orientation effects on potted-vines performance and water-use efficiency
Get PDFThe relation between water-use and intercepted solar radiation depends on many factors involved in vine canopy architecture and physiology. In addition, vine productivity is related to the efficiency with which the intercepted photosynthetically active radiation (IPAR) is used, which in turn depends mainly on water availability and transport. In hedgerow-managed vines it exists the possibility to modulate IPAR by orienting their rows, influencing water-use efficiency (WUE), defined as dry matter produced by water used. Aiming to unravel the effects of row orientation on WUE, a three-year experiment was carried out in Valencia (Spain) on potted Vitis vinifera (L.) cv. Bobal and Verdejo with vine rows oriented either north-south (NS) or east-west (EW), under no-water restrictions. Simulated radiation interception over the growing seasons at the experimental plot showed an average 39% reduction in daily IPAR when EW was compared to NS. Vine transpiration was quantified by water balance, decreasing by 16% in Bobal and 8% in Verdejo when comparing EW against NS. In both cultivars, this reduction was 18% when considered relative to the total leaf area. Carbon assimilation was not markedly affected by row orientation. Therefore, since in both cultivars minor differences in vine performance occurred between orientations, WUE tended to increase by orienting the rows to the EW compared to NS. This resulted in most of the seasons an increase in water productivity calculated as grape yield/water-use ratio. Leaf gas exchange measurements partially agreed with the radiation interception simulations, suggesting a more complex regulatory mechanism and highlighting the importance of canopy microclimatic conditions in the physiological processes of hedgerow-managed crops. These findings encourage further research under field conditions and different soil water availabilities, aiming to optimize grapevine water productivit
Na+ transporter HKT1;2 reduces flower Na+ content and considerably mitigates the decline in tomato fruit yields under saline conditions
Get PDFGenes encoding HKT1-like Na+ transporters play a key role in the salinity tolerance mechanism in Arabidopsis and other plant species by retrieving Na+ from the xylem of different organs and tissues. In this study, we investigated the role of two HKT1;2 allelic variants in tomato salt tolerance in relation to vegetative growth and fruit yield in plants subjected to salt treatment in a commercial greenhouse under real production conditions. We used two near-isogenic lines (NILs), homozygous for either the Solanum lycopersicum (NIL17) or S. cheesmaniae (NIL14) allele, at HKT1;2 loci and their respective RNAi-Sl/ScHKT1;2 lines. The results obtained show that both ScHKT1;2- and SlHKT1;2-silenced lines display hypersensitivity to salinity associated with an altered leaf Na+/K+ ratio, thus confirming that HKT1;2 plays an important role in Na+ homeostasis and salinity tolerance in tomato. Both silenced lines also showed Na+ over-accumulation and a slight, but significant, reduction in K+ content in the flower tissues of salt-treated plants and consequently a higher Na+/K+ ratio as compared to the respective unsilenced lines. This altered Na+/K+ ratio in flower tissues is associated with a sharp reduction in fruit yield, measured as total fresh weight and number of fruits, in both silenced lines under salinity conditions. Our findings demonstrate that Na+ transporter HKT1;2 protects the flower against Na+ toxicity and mitigates the reduction in tomato fruit yield under salinity conditions
Peach Cultivar Presivac-1
Get PDFPeach (Prunus persica L. Batsch) is the primary stone fruit grown in Spain. The area devoted to this crop has increased over the past 20 years. Spain ranks third in world production after China and Italy, producing 30% of the total peach crop in the European Union. The diversity in climate of the peach production regions in Spain allows an unusually long peach season, from late April to early November. The chill hours in the peach production areas range from 200 to 400 in the south (Andalucía) to more than 1000 in inland northeast regions (Aragón and Cataluña). Current production is distributed among melting peach cultivars, nectarines, and nonmelting cultivars. Traditional and autochthonous cultivars in Spain are mostly nonmelting peaches. The aroma and quality of the nonmelting cultivars from the Mediterranean basin are very interesting. These nonmelting cultivars are grown in Spain and Italy either for fresh market or for the canning industry. However, these cultivars ripen during the mid or late season; no early cultivars with these characteristics are available in the native peach populations. The program of the Instituto Valenciano de Investigaciones Agrarias (IVIA) and Agromillora Iberia initiated several crosses between nonmelting cultivars that combined the quality of native varieties from the Mediterranean region and earliness of foreign cultivars. One selection from these crosses is the cultivar Presivac-1. ‘Presivac-1’ is an early-ripening peach cultivar with low-to-medium chilling requirements, good agronomic characteristics, very good productivity, and good fruit quality at its time of ripening. The cultivar has the characteristics of a nonmelting peach similar to ‘Jonia’ or ‘Egea’, but it ripens 1 month earlier. ‘Presivac-1’ is also well-adapted to the warm winters and dry summers of the Mediterranean area
Next-generation biological control: the need for integrating genetics and genomics
Get PDFBiological control is widely successful at controlling pests, but effective biocontrol agents are now more difficult to import from countries of origin due to more restrictive international trade laws (the Nagoya Protocol). Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genomic approaches. Although they have been underutilised in the past, application of genetic and genomic techniques is becoming more feasible from both technological and economic perspectives. We review current methods and provide a framework for using them. First, it is necessary to identify which biocontrol trait to select and in what direction. Next, the genes or markers linked to these traits need be determined, including how to implement this information into a selective breeding program. Choosing a trait can be assisted by modelling to account for the proper agro‐ecological context, and by knowing which traits have sufficiently high heritability values. We provide guidelines for designing genomic strategies in biocontrol programs, which depend on the organism, budget, and desired objective. Genomic approaches start with genome sequencing and assembly. We provide a guide for deciding the most successful sequencing strategy for biocontrol agents. Gene discovery involves quantitative trait loci analyses, transcriptomic and proteomic studies, and gene editing. Improving biocontrol practices includes marker‐assisted selection, genomic selection and microbiome manipulation of biocontrol agents, and monitoring for genetic variation during rearing and post‐release. We conclude by identifying the most promising applications of genetic and genomic methods to improve biological control efficacy
Effect of pollen provision on life‐history parameters of phytoseiid predators under hot and dry environmental conditions
Get PDFBiological control can be severely disrupted under climate change conditions. This is the case of the spider mite Tetranychus urticae in Spanish citrus orchards, where the omnivorous phytoseiid Euseius stipulatus, the most abundant predator in the system, was highly impacted by hot and dry conditions mimicking future warmer summers. Such a situation can often be compensated by the provision of alternative food to support generalist predators. As a first step to studying whether such a technique could be applied in this case, we studied at laboratory conditions whether pollen could mitigate the negative effects of hotter and drier conditions derived of climate change on three phytoseiids with different diet specializations. In addition to E. stipu-latus, these predators, which all together, are considered key for the biological con-trol of T. urticae in citrus, are Neoseiulus californicus and Phytoseiulus persimilis. Our results confirm the extremely fine-tuning of T. urticae to hot–dry conditions. They also provide evidence of the poor performance of E. stipulatus, especially in terms of reproduction, compared to the other two phytoseiids at these conditions, even when high-quality pollen was available. Moreover, access to pollen in combination with T. urticae eggs enhanced survival but reduced predation and oviposition relative to a T. urticae-only diet for N. californicus and P. persimilis. Therefore, whether the overall effect of pollen would justify its use in citrus to counteract the deleterious effects of a hotter and drier climate on the natural regulation of T. urticae is still controversial
Identification and Characterization of Diaporthe spp. Associated with Twig Cankers and Shoot Blight of Almonds in Spain
Get PDFTwo hundred and twenty-five Diaporthe isolates were collected from 2005 to 2019 in almond orchards showing twig cankers and shoot blight symptoms in five different regions across Spain. Multilocus DNA sequence analysis with five loci (ITS, tub, tef-1α, cal and his), allowed the identification of four known Diaporthe species, namely: D. amygdali, D. eres, D. foeniculina and D. phaseolorum. Moreover, a novel phylogenetic species, D. mediterranea, was described. Diaporthe amygdali was the most prevalent species, due to the largest number of isolates (85.3%) obtained from all sampled regions. The second most frequent species was D. foeniculina (10.2%), followed by D. mediterranea (3.6%), D. eres and D. phaseolorum, each with only one isolate. Pathogenicity tests were performed using one-year-old almond twigs cv. Vayro and representative isolates of the different species. Except for D. foeniculina and D. phaseolorum, all Diaporthe species were able to cause lesions significantly different from those developed on the uninoculated controls. Diaporthe mediterranea caused the most severe symptoms. These results confirm D. amygdali as a key pathogen of almonds in Spain. Moreover, the new species, D. mediterranea, should also be considered as a potential important causal agent of twig cankers and shoot blight on this crop
Regresión o continuidad del sector citrícola. Función de los costes
Get PDFLas dificultades en la citricultura española podría decirse que tienen un carácter estructural y que se agravan en campañas como la 2018/2019, donde acontece una situación de sobreoferta coincidente con el aumento de las importaciones derivado de los tratados firmados por la Unión Europea con los principales países competidores.
Cuando hay sobreproducción, la realidad indica que el sector, junto con las entidades oficiales, son incapaces de ordenar una campaña con excedentes, cuyos efectos desfavorables siempre han repercutido directamente en las explotaciones. El funcionamiento solo es correcto desde la demanda
La irrupción de las tecnologías electrónicas y de la información
Get PDFEntendemos por agricultura de precisión el conjunto de prácticas agrícolas que se centran en áreas
concretas del campo en momentos particulares del tiempo. Las prácticas de manejo agrícola tradicionales,
como por ejemplo el riego o la aplicación de fertilizantes o pesticidas, habitualmente se han realizado
de forma uniforme en todo el campo, sin tener en cuenta la heterogeneidad intraparcelaria, es decir, la
variación natural o las diferentes necesidades que puedan existir dentro de una parcela. Los avances
en nuevas tecnologías, así como el desarrollo de nuevos sensores cada vez más especializados y
económicos, permiten su incorporación en el sector agrícola (Cubero et al., 2016).
Uno de los principales usos y posibilidades de la agricultura de precisión es la detección temprana
de plagas y enfermedades o de deficiencias nutricionales e hídricas, a partir del análisis de los datos
proporcionados por los sensores sobre la energía reflejada o emitida por las plantas.
Los sensores utilizados en teledetección como las cámaras multiespectrales, hiperespectrales o térmicas
permiten estimar algunos parámetros relacionados con el estado del cultivo tales como escasez de
agua, clorosis e incluso la deficiencia de nutrientes como nitrógeno, fósforo o potasio, debido a la
relación entre los compuestos químicos y determinadas longitudes de onda donde se absorben