ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Herbivore benefits from vectoring plant virus through reduction of period of vulnerability to predation
No full textHerbivores can profit from vectoring plant pathogens because the induced defence of plants against pathogens sometimes interferes with the induced defence of plants against herbivores. Plants can also defend themselves indirectly by the action of the natural enemies of the herbivores. It is unknown whether the defence against pathogens induced in the plant also interferes with the indirect defence against herbivores mediated via the third trophic level. We previously showed that infection of plants with Tomato spotted wilt virus (TSWV) increased the developmental rate of and juvenile survival of its vector, the thrips Frankliniella occidentalis. Here, we present the results of a study on the effects of TSWV infections of plants on the effectiveness of three species of natural enemies of F. occidentalis: the predatory mites Neoseiulus cucumeris and Iphiseius degenerans, and the predatory bug Orius laevigatus. The growth rate of thrips larvae was positively affected by the presence of virus in the host plant. Because large larvae are invulnerable to predation by the two species of predatory mites, this resulted in a shorter period of vulnerability to predation for thrips that developed on plants with virus than thrips developing on uninfected plants (4.4 vs. 7.9 days, respectively). Because large thrips larvae are not invulnerable to predation by the predatory bug Orius laevigatus, infection of the plant did not affect the predation risk of thrips larvae from this predator. This is the first demonstration of a negative effect of a plant pathogen on the predation risk of its vector
Effects of individual culture and volume of fertilization medium on in vitro bovine embryo development
No full textProduction of transgenic adult plants from clementine mandarin by enhancing cell competence for transformation and regeneration
No full textGenetic transformation of mature trees is difficult because adult tissues are recalcitrant to Agrobacterium tumefaciens infection and transformation and because transgenic mature events are less competent for regeneration. We have shown that reinvigoration allows manipulation of the vegetative phase to increase the potential for transformation and regeneration without loss of competence for flowering and fruiting. To produce transgenic plants from clementine mandarin (Citrus clementina hort. ex Tanaka), we optimized the conditions of the source material both ex vitro and in vitro. Grafting of mature buds on juvenile rootstocks in the spring and preventing multiple bud sprouting by removing all but one bud permitted selection of vigorous first flushes for in vitro culture. Use of additional virulence genes from A. tumefaciens to increase transformation frequency and optimization of culture media and conditions to enhance explant cell competence for T-DNA integration and organogenesis resulted in efficient and reliable transgenic plant production. Transformed regenerants from explants, cultured in media without antibiotics, were identified by a screenable marker (either beta-glucuronidase or green fluorescent protein (GFP)), creating the possibility of generating transgenic clementine plants without antibiotic resistance marker genes. Stable integration of foreign genes was demonstrated by Southern blot analysis, and expression of these foreign genes was confirmed by detection of GFP fluorescence in leaves, floral organs and fruits of the transgenic plants
Estudio preliminar sobre la separación física sólido-líquido de purines para su reutilización
Get PDFCon la finalidad de obtener un efluente líquido apto para su reutilización en granja, bien para
limpieza bien para irrigación, se ha diseñado un sistema de manejo y tratamiento de purines que
consta de una serie de dispositivos de separación sólido-líquido. En dicho sistema el purín es
sometido a la separación física producida por una prensa de tornillo que puede trabajar de forma
individual o como tratamiento previo a una centrífuga horizontal. La parte líquida se deja sedimentar
en un depósito, desde el que es dirigida, a través de un depósito de regulación, a nueve filtros lentos
de arena (3 repeticiones de 3 tipos de arenas), donde termina el proceso de separación y queda
dispuesta para su reutilización
Modificación de las propiedades del suelo provocada por diferentes modalidades de gestión de los restos de cultivos hortícolas bajo producción ecológica e integrada
Get PDFEn dos agroecosistemas de hortalizas al aire libre, que se cultivan siguiendo las
correspondientes técnicas de Agricultura Ecológica y Producción Integrada, ubicados
en el Centro Experimental de la Fundación Ruralcaja en Paiporta (Valencia), se viene
realizando desde el año 2003 una experiencia a largo plazo con la finalidad de evaluar
los efectos derivados de distintas modalidades de gestión de los restos de cultivo.
En esta comunicación se exponen y comentan los resultados de producción de
los cultivos implantados, así como los de las características físico-químicas (pH y
conductividad eléctrica), químicas (nutrientes asimilables, materia orgánica) y
biológicas (actividades enzimáticas)
ACTA HORTICULTURAE
No full textUnlike artificial turf, natural turf does not cause injuries to skin when sportsmen slide on it. Nowadays, this is an important limitation for extending the use of artificial turf and a considerable effort in research is being made. IVIA has started a research project to characterize the mechanical properties of natural turf that may provide its excellent behaviour for sports practice. In this work, leaves of four different species of natural turf were subjected to tensile and friction tests. Differences among species and the relationship between mechanical properties and microstructure are studied
Micromechanical behaviour of apple tissue in tensile and compression tests: Storage conditions and cultivar effect
Get PDFThe micromechanical behaviour of apple tissue was studied using a miniature tensile stage positioned underneath a microscope that allowed for simultaneous acquisition of force-displacement curves while the deformation of the individual cells was followed and recorded. Tensile and compression tests were performed on small samples of apple parenchyma of two different cultivars (Jonagored and Braeburn) and two storage conditions (control and shelf-life). Tests on the repeatability of the methods has provided satisfactory results and will allow the reduction of samples in further experiments. Under tensile loading, no differences for any of the mechanical parameters were found between cultivars, while a significant storage effect was observed for both cultivars. This opens the possibility of developing new sensors for quality assessment. Differences were found when studying the relationship of mechanical properties at the micro- and macro-level, which requires further investigation. The insights gained in this research will be useful when developing mathematical models based upon the mechanical behaviour of apple tissue
Changes in carotenoid content and biosynthetic gene expression in juice sacs of four orange varieties (Citrus sinensis) differing in flesh fruit color
No full textThe contribution of carotenoid composition to the color range of the fruit juice sacs of four orange varieties (Citrus sinensis) differing in flesh color, namely, Shamouti (normal orange color), Sanguinelli ("blood cultivar" purple color), Cara Cara navel (pink-reddish), and Huang pi Chen (yellowish color), Was investigated. To this end, qualitative and quantitative analyses of carotenoid contents were first performed by high-performance liquid chromatography (HPLC) using a C-30 Column and a photodiode array detector in February, at a late developmental fruit stage. Concomitantly, transcript levels of Dxs, the gene controlling the first step of the MEP pathway, and six genes involved in,P-xanthophyll biosynthesis (Psy, Pds, Zds, Lcy-b, Hy-b, and Zep) were determined in August, November, and February. Transcript level measurement was carded out by real-time RT-PCR on total RNA from juice sacs. The four orange varieties displayed different carotenoid profiles. Shamouti and Sanguinelli oranges accumulated mainly beta,beta-xanthophylls as expected in typically colored oranges, whereas Cara Cara navel orange accumulated linear carotenes in addition to cis-violaxanthin. Huang pi Chen fruit flesh orange was characterized by a strong reduction of total carotenoid content. Whereas gene expression was relatively low and similar in August (before color break) in all four varieties, in November (during color break), Dxs, Zds, Hy-b, and Zep expression was higher in Cara Cara and Huang pi Chen oranges. The P,P-xanthophyll accumulation observed in February in Shamouti and Sanguinelli oranges was apparently related to the increase of transcript levels of all measured genes (i.e., Dxs, Psy, Pds, Zds, Hy-b, and Zep) except Lcy-b. At this time, however, transcript levels in Cara Cara were rather similar to those found in Sanguinelli, although both showed different carotenoid compositions. The Huang pi Chen phenotype correlated with lower expression of Dxs and Psy genes. These results revealed a general pattern of transcript change in juice sacs of citrus fruit, characterized by an apparent coordination of Dxs and Psy expression and a general increase in mRNA levels of carotenoid biosynthetic genes. These transcript changes correlated well with the,P-xanthophyll accumulation, the normal carotenoid set, observed in Shamouti and Sanguinelli oranges and suggest that the preferential accumulation of linear carotenes in Cara Cara navel and the practical absence of carotenoids in Huang pi Chen oranges were not predominantly due to changes in regulation of Garotenoid biosynthetic genes at the transcriptional level
Development of a full-genome cDNA clone of Citrus leaf blotch virus and infection of citrus plants
Get PDFCitrus leaf blotch virus (CLBV), a member of the family Flexiviridae, has a similar to 9-kb single-stranded, positive-sense genomic RNA encapsidated by a 41-kDa coat protein. CLBV isolates are associated with symptom production in citrus including leaf blotching of Dweet tangor and stem pitting in Etrog citron (Dweet mottle disease), and some isolates are associated with bud union crease on trifoliate rootstocks, but Koch's postulates for this virus were not fulfilled. A full-genome cDNA of CLBV isolate SRA-153, which induces bud union crease, was placed under the T7 promoter (clone T7-CLBV), or between the 35S promoter and the Nos-t terminator, with or without a ribozyme sequence downstream of the CLBV sequence (clones 35SRbz-CLBV and 35S-CLBV). RNA transcripts from T7-CLBV failed to infect Etrog citron and Nicotiana occidentalis and N. benthamiana plants, whereas agro-inoculation with binary vectors carrying 35SRbz-CLBV or 35S-CLBV, and the p19 silencing suppressor, caused systemic infection and production of normal CLBV virions. Virus accumulation was similar in citron plants directly agro-infiltrated, or mechanically inoculated with wild-type or 35SRbz-CLBV-derived virions from Nicotiana, and the three sources incited the symptoms characteristic of Dweet mottle disease, but not bud union crease. Our results show that (1) virions derived from an infectious clone show the same replication, movement and pathogenicity characteristics as the wild-type CLBV; (2) CLBV is the causal agent of Dweet mottle disease but not of the bud union crease syndrome; and (3) for the first time an RNA virus could be successfully agro-inoculated on citrus plants. This infectious clone may become a useful viral vector for citrus genomic studies
Intraguild predation between 'Euseius stipulatus 'and the phytoseiid predators of 'Tetranychus urticae' in clementines, 'Neoseiulus californicus and 'Phytoseiulus persimilis
No full textThe current management of the two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) in clementines is based primarily on applications of acaricides. In recent years, emphasis has been placed on implementing more environmentally safe measures to
control T. urticae in Spain. To this end, inoculative releases of the predator phytoseiids Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot are currently being implemented. Indeed, phytoseiid releases have demonstrated to be successful in controlling T. urticae on clementine under laboratory and semi-field conditions.
Both phytoseiids are naturally present in the citrus agro-ecosystem although at low levels. However, Euseius stipulatus Athias-Henriot is the most abundant phytoseiid in citrus and its conservation is a key component in the citrus IPM, due to its positive action on different pests. Therefore, before using N. californicus and P. persimilis to control T. urticae in inoculative releases in commercial orchards, we need to clarify the relationship between these
phytoseiid species. With this aim, we conducted two experiments of intraguild predation between E. stipulatus and N. californicus, and between E. stipulatus and P. persimilis. First, we tested the aggressiveness (propensity of an individual to attack and kill another individual) of adult females on hetero-specific larvae. Second, we assessed survival and development of immature individuals in presence and absence of intraguild adult predators and alternative food