ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Chlorophyll a fluorescence in transplants of Parmelia sulcata Taylor near a power station (La Robla, Leon, Spain)
No full textHealthy thalli of Parmelia sulcata Taylor were transplanted to 8 localities in the surroundings of a power station (La Robla, Leon, Spain), the sole pollution source in the region. Changes in chlorophyll a fluorescence were monitored in the transplants 12 months, 18 months and 24 months after transplantation. Statistically significant differences were observed in the ratio of variable to maximal fluorescence, non-photochemical fluorescence quenching and vitality index. The decrease in fluorescence parameters was higher in the localities of Cuadros and Rabanal de Fenar, which are situated a few kilometres away from the power station and in the same direction as the prevailing winds
Self- and cross-(in)compatibility between important apricot cultivars in northwest Iran
No full textKnowledge of the self-(in)compatibility trait in commercial apricot cultivars is of great importance for breeders and growers. Five commercial apricot cultivars, widely grown in Iran, were self- and cross-pollinated to determine their pollen and stylar compatibility. Fruit-set in the orchard and pollen tube growth in pistils, from flowers pollinated in the laboratory, were evaluated. In addition, specific primers previously designed to amplify fragments of the S alleles responsible for the incompatibility trait, were used to amplify DNA extracted from the five cultivars.All results agreed and confirmed that three out of the five cultivars studied were self-incompatible, two of which were cross-incompatible and therefore had the same genotype. The cultivars, ‘Ghorban-e-Marageh’ and ‘Ghermez-e-Shahroodi’ were self-compatible and, interestingly, shared a PCR band with all Spanish self-compatible apricot cultivars examined to date
Influence of ground predators on the survival of the Mediterranean fruit fly pupae, Ceratitis capitata, in Spanish citrus orchards
Get PDFA survey of predaceous ground arthropods was conducted in two citrus orchards in Valencia, Spain, and their role as predators of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) pupae was evaluated under field and laboratory conditions. A total of 2959 predaceous arthropods were collected in pitfall traps in the two orchards from July 2003 to September 2004. Ants (Hymenoptera) were the most abundant group (83.61%), followed by Staphylinidae (7.77%), Araneae (5.24%), Dermaptera (2.13%), Carabidae (0.64%) and Cicindelidae (0.61). Pupae disappearance rates were higher during the warmer months of the year, from May to October, and in the orchard with the largest ant population. In the warm season, the mean survival of C. capitata pupae was 35.7±6.2% and 14.3±6.7%, respectively, in both orchards. Patterns of predation, inferred from broken or abnormal pupae, were more frequently observed in the colder months, from November to April, when spiders, Staphylinidae and other predators were present. In the cold season, the combined effect of predation and low temperature led to an adult emergence rate of 26.7±9.9% and 13.0±7.5% in both orchards. In no-choice laboratory trials, all predator species tested fed at significantly different rates on C. capitata pupae. Preliminary data show that the Carabids, Pseudophonus rufipes (Duftschmid) and Harpalus distinguendus (Degeer), were the most voracious species, consuming more than one pupa per day. © 2006 International Organization for Biological Control (IOBC)
Global analysis of gene expression during development and ripening of citrus fruit flesh. A proposed mechanism for citric acid utilization
No full textMicroarrays of cDNA have been used to examine expression changes of 7000 genes during development and ripening of the fruit flesh of self-incompatible Citrus clementina, a non-climateric species. The data indicated that 2243 putative unigenes showed significant expression changes. Functional classification revealed that genes encoding for regulatory proteins were significantly overrepresented in the up-regulated gene clusters. The transcriptomic study together with the analyses of selected metabolites highlighted key physiological processes occurring during citrus fruit development and ripening such as water accumulation, carbohydrate build-up, acid reduction, pigment substitutions (carotenoid accumulation and chlorophyll decreases) and ascorbic acid diminution. Often, the combined analyses strongly suggested prevalence of specific metabolic alternatives. This observation has been exemplified with the proposal for a mechanism for citrate utilization, a process of much importance in citrus industry. Microarray data validated by real-time RT-PCR suggested that citrate was sequentially metabolyzed to isocitrate, 2-oxoglutarate and glutamate. Thereafter, glutamate was both utilized for glutamine production and catabolyzed through the gamma-aminobutirate (GABA) shunt (GABA -> succinate semialdehyde -> succinate). This last observation appears to be of special relevance since it links the proton consuming reaction glutamate + H+ -> GABA + CO2 with high acid levels. GG-MS determinations showed that glutamate was constant while GABA levels decreased at ripening in agreement with a feasible activation of the GABA shunt during acid catabolism. This suggestion provides a convincing explanation for the strong reduction of both citrate and cytoplasmatic acidity that takes place in citrus fruit flesh during development and ripening
Responses of citrus plants to ozone: leaf biochemistry, antioxidant mechanisms and lipid peroxidation
No full textThe effects of ozone upon 3-year-old trees of Clementina mandarin (Citrus clementina Hort. ex Tan.) cv. Marisol exposed for 12 months to ambient (10 nl l(-1)) and high (30 and 65 nl l(-1)) concentrations in open top chambers (OTCs) were investigated. The data showed that in leaves, ozone reduced total chlorophylls, carotenoid and carbohydrate concentration. and increased 1-aminocyclopropane-1-carboxylic acid (ACC) content and ethylene production. In treated plants, the ascorbate leaf pool was decreased, while lipid peroxidation and Solute leakaGe were significantly higher than in ozone-free controls. The data indicated that ozone triggered protective mechanisms against oxidative stress in citrus. (c) 2006 Elsevier SAS. All rights reserved
Usefulness of diurnal trunk shrinkage as a water stress indicator in plum trees
No full textWe compared seasonal changes in maximum diurnal trunk shrinkage (MDS) with seasonal changes in midday stem water potential (Psi(s)) over three years in plum trees grown in differing drip-irrigated regimes. In well-irrigated trees, day-to-day variations in Psi(s) and MDS were related to evaporative demand. Reference equations were obtained to predict MDS and Psi(s) values for well-irrigated trees as functions of environmental conditions. A decrease in plant water status toward the end of the growing season occurred even in the well-irrigated trees, probably reflecting a reduced volume of soil wetted by the drip irrigation system. Thus, for the prediction of Psi(s), different reference equations are required for the fruit-growth and after-harvest phenological periods. A seasonal change in the relationship between MDS and Psi(s) was observed, which compensated for the decrease in plant water status such that well-irrigated trees had similar MDS values during both the fruit-growth and after-harvest periods. The influence of tree size on the relationship between MDS and Psi(s) was also investigated. For tree trunk diameters ranging between 8 and 13 cm, MDS increased 13% for each cm of increase in trunk diameter, as a result of the thicker phloem tissues of the larger trees. This finding may allow extrapolation of Psi(s) predictions based on empirical relationships with MDS to plum trees of different sizes
History and future of introduction of exotic arthropod biological control agents in Spain: A dilemma?
No full textThe first documented introduction of an exotic invertebrate biological control agent (IBCA) in Spain occurred in 1908. Sixty-four additional species have been introduced since then. Information, both previously recorded and original data, on the species introduced for pest control is summarized. Most of the introduced IBCAs focused on citrus pests and homopterans clearly predominate among target phytophagous species. Success has been more frequent for IBCAs used in seasonal inoculative strategies (50.0% of cases) than in classical biological control programs (17.1% of cases). Concerns about potential non-target effects of such species are increasing, but post-release evaluation has often been insufficient to draw any conclusions about them. Most of the beneficial species introduced in Spain were parasitoids (n = 53), and the remaining species were predators (n = 12). Only four parasitoids are considered specialized monophagous natural enemies. The mean number of host species parasitized by parasitoids is 15.2, whereas the mean number of prey species attacked by predators is 21.2. Therefore, polyphagy appears to be quite common among the IBCAs that have been introduced in Spain. The rationale guiding many of these introductions in the past would not be acceptable nowadays. Since classical biological control is such a valuable strategy for pest control, straightforward protocols to evaluate exotic candidate species are urgently needed
Acta horticulturae
No full textA strain of Erwinia amylovora (IVIA 1614-2a) was isolated in Segovia (central Spain) in 1996 from an outbreak of fire blight. E. amylovora was isolated from a Crataegus sp. which showed symptoms of the disease. The morphology of the colonies on several media (King’s B, SNA, CCT) was identical to that of reference strains. The strain was positive by ELISA using specific monoclonal antibodies, but not by PCR using primers designed from sequences of the plasmid pEA29. Nevertheless, the strain amplified with primers designed from chromosomic regions. The biochemical characterization using commercial strips API20E, API20NE, API50CH, and fatty acid profile gave the same results as the reference strain CFBP1430. On the other hand, strain IVIA 1614-2a resembled one E. amylovora strain cured from plasmid pEA29 in the slow growth in minimal medium without thiamine. The analyses of the plasmid content showed that it contains one plasmid of approx. 70 kb, with no homology with pEA29, reported as an ubiquitous plasmid present in pathogenic E. amylovora strains. This was demonstrated by comparing their restriction profiles using three enzymes and by hybridisation of the plasmid fragments obtained using the pEA29 as probe. Several virulence assays on pear and apple plants and fruits showed that this isolate had virulence levels similar to other pathogenic strains containing the pEA29 plasmid. As far as we know, this is the first report of the isolation from naturally infected plant material of a fully virulent strain of E. amylovora without plasmid pEA29
Field trials of plum clones transformed with the Plum pox virus coat protein (PPV-CP) gene
Get PDFTransgenic clones C2, C3, C4, C5, C6, and PT-6, of plum (Prunus domestica L.) transformed with the coat protein (CP) gene of Plum pox virus (PPV), PT-23 transformed with marker genes only, and nontransgenic B70146 were evaluated for sharka resistance under high infection pressure in field trials in Poland and Spain. These sites differed in climatic conditions and virus isolates. Transgenic clone C5 showed high resistance to PPV at both sites. None of the C5 trees became naturally infected by aphids during seven (Spain) or eight (Poland) years of the test, although up to 100% of other plum trees (transgenic clones and nontransgenic control plants) grown in the same conditions showed disease symptoms and tested positively for PPV. Although highly resistant, C5 trees could be infected artificially by chip budding or via susceptible rootstock. Infected C5 trees showed only a few mild symptoms on single, isolated shoots, even up to 8 years post inoculation. These results clearly indicate the long-term nature and high level of resistance to PPV obtained through genetically engineered resistance
