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Pereira V.T.,Center for Biodiversity | Sousa L.,University of Lisbon | de Sousa A.T.,National Institute of Agricultural Research INIA | Pais M.S.,Center for Biodiversity
Agroforestry Systems | Year: 2015

Pyrus communis ‘Rocha’ is an economically important crop very susceptible to the pathogenic fungus Stemphylium vesicarium, the causal agent of brown spot disease. Knowledge on the complexity of mechanisms responsible for resistance to S. vesicarium infection is necessary for definition of strategies to improve defence responses in susceptible cultivars. To investigate the molecular mechanisms behind Pyrus communis defence responses to S. vesicarium, a 6624 (3312 × 2) cDNA microarray was constructed to identify genes differentially expressed between a resistant/tolerant cultivar (‘Ercolini’) and a susceptible cultivar (‘Rocha’). Both cultivars were compared to evaluate their genetic background differences prior to inoculation (T0h) and transcriptional changes along a time course infection with S. vesicarium (T6h and T24h). Two cDNA libraries, from ‘Rocha’ and ‘Ercolini’ pear cultivars, spotted in the microarray resulted on 146 differential expressed genes. Transcriptome analysis revealed several transcripts related to stress and defence, namely peroxidases, 3-dehydroquinate dehydratase/shikimate 5-dehydrogenase, thiazole biosynthetic enzyme, serpins, cytochromes P450, 2-methyl-6-phytylbenzoquinone methyltransferase, 6-phosphogluconate dehydrogenase, polyneuridine-aldehyde esterase precursor, lipoxygenases and PR proteins. The results suggest that resistance/tolerance of ‘Ercolini’ cultivar may result from the rapid activation of defence mechanisms while in ‘Rocha’ cultivar the defence mechanisms may be activated too late for inducing an efficient response to infection by S. vesicarium. Cell wall strengthening and biosynthesis of antifungal compounds may constitute efficient physical and chemical barriers to S. vesicarium infection and priming emerges as a putative mechanism of resistance/tolerance. The evidence gathered combined with knowledge on host/endophyte signalling in mycorrhiza leads us to suggest priming as a measure to brown spot disease control in ‘Rocha’ pear cultivar through symbiosis with mycorrhizal fungi in order to anticipate and induce a more efficient activation of defence mechanisms. Also the thiazole biosynthetic enzyme and the serpins appears as potential candidates for the development of molecular markers for resistance to infection. © 2015, Springer Science+Business Media Dordrecht. Source


Pereira V.T.,University of Lisbon | Sousa L.,University of Lisbon | de Sousa A.T.,National Institute of Agricultural Research INIA | Pais M.S.,University of Lisbon
Agroforestry Systems | Year: 2015

Pyrus communis ‘Rocha’ is an economically important crop very susceptible to the pathogenic fungus Stemphylium vesicarium, the causal agent of brown spot disease. Knowledge on the complexity of mechanisms responsible for resistance to S. vesicarium infection is necessary for definition of strategies to improve defence responses in susceptible cultivars. To investigate the molecular mechanisms behind Pyrus communis defence responses to S. vesicarium, a 6624 (3312 × 2) cDNA microarray was constructed to identify genes differentially expressed between a resistant/tolerant cultivar (‘Ercolini’) and a susceptible cultivar (‘Rocha’). Both cultivars were compared to evaluate their genetic background differences prior to inoculation (T0h) and transcriptional changes along a time course infection with S. vesicarium (T6h and T24h). Two cDNA libraries, from ‘Rocha’ and ‘Ercolini’ pear cultivars, spotted in the microarray resulted on 146 differential expressed genes. Transcriptome analysis revealed several transcripts related to stress and defence, namely peroxidases, 3-dehydroquinate dehydratase/shikimate 5-dehydrogenase, thiazole biosynthetic enzyme, serpins, cytochromes P450, 2-methyl-6-phytylbenzoquinone methyltransferase, 6-phosphogluconate dehydrogenase, polyneuridine-aldehyde esterase precursor, lipoxygenases and PR proteins. The results suggest that resistance/tolerance of ‘Ercolini’ cultivar may result from the rapid activation of defence mechanisms while in ‘Rocha’ cultivar the defence mechanisms may be activated too late for inducing an efficient response to infection by S. vesicarium. Cell wall strengthening and biosynthesis of antifungal compounds may constitute efficient physical and chemical barriers to S. vesicarium infection and priming emerges as a putative mechanism of resistance/tolerance. The evidence gathered combined with knowledge on host/endophyte signalling in mycorrhiza leads us to suggest priming as a measure to brown spot disease control in ‘Rocha’ pear cultivar through symbiosis with mycorrhizal fungi in order to anticipate and induce a more efficient activation of defence mechanisms. Also the thiazole biosynthetic enzyme and the serpins appears as potential candidates for the development of molecular markers for resistance to infection. © 2015 Springer Science+Business Media Dordrecht Source


Millas P.,Austral University of Chile | Carrillo R.,Austral University of Chile | Carrillo R.,National Institute of Agricultural Research INIA
Austral Entomology | Year: 2014

Previous studies using white grub larvae have not found a relationship between scarabaeid larval growth and the quantity of total organic matter (OM) in the feeding soil. This is probably because it is the type or quality of the OM that is more important to larval nutritional requirements. The aim of this research was to study, under laboratory conditions, how the quality of OM, measured as the percentage of particulate OM (POM), affected the live weight and faecal production of Hylamorpha elegans (Coleoptera: Scarabaeidae) larvae. Results showed that live weight gain of second and third instar larvae increased with an increase in the amount of POM. The faecal production showed no differences. Therefore, the effect on second and third instar larvae was related to the quality of the resource and not to an increase in the quantity of soil ingested. Better understanding of the dynamics of POM and other labile fractions of the soil OM as microbial biomass could be fundamental to assessing and implementing out agricultural practices that can ameliorate the impact of this pest. © 2014 Australian Entomological Society. Source


Calvo-Salazar V.,International Maize and Wheat Improvement Center | Calvo-Salazar V.,Colegio de Mexico | Singh R.P.,Campo Experimental Valle de Mexico INIFAP | Huerta-Espino J.,Campo Experimental Valle de Mexico INIFAP | And 9 more authors.
Plant Disease | Year: 2015

The Kenyan wheat (Triticum aestivum L.) ‘Kenya Kongoni’ exhibits high levels of adult plant resistance (APR) to leaf rust (LR) and yellow rust (YR). We determined the genomic regions associated with LR and YR resistance in a population of 148 recombinant inbred lines generated from a cross between ‘Avocet-YrA’ and Kenya Kongoni. Field experiments to characterize APR to LR and YR were conducted in four and two Mexican or Uruguayan environments, respectively. A linkage map was constructed with 438 diversity arrays technology and 16 simplesequence repeat markers by JoinMap 4.1 software. Genetic analyses showed that resistance to both rusts was determined by four to five APR genes, including Lr46/Yr29 and Sr2/Lr27/Yr30. Quantitative trait loci (QTL) analysis indicated that pleiotropic APR loci QYLr.cim-1BL corresponding to Lr46/Yr29 and QYLr.cim-7BL that is a putative novel QTL accounted for 5 to 57% and 12 to 35% of the phenotypic variation for resistance to LR and YR, respectively. These loci, in combination with another three LR QTL and two YR QTL, respectively, conferred high levels of resistance to both LR and YR in wheat under Mexican and Uruguayan environments. Among other detected QTL, QLr.cim-1DS, QLr.cim-2BL, and QYLr.icm-7BL may be new loci for APR to both rusts in common wheat. © 2015 The American Phytopathological Society. Source


Carlomagno M.,Institute Higiene | Matho C.,Institute Higiene | Cantou G.,National Institute of Agricultural Research INIA | Sanborn J.R.,University of California at Davis | And 5 more authors.
Journal of Agricultural and Food Chemistry | Year: 2010

The environmental impact of rice agriculture is poorly studied in developing countries, mainly due to limitations of the analytical capacity. Here, we report the development of a clomazone enzyme-linked immunosorbent assay as a fast and cost-effective tool to monitor the dissipation of this herbicide along the harvest. Antibodies were prepared using different strategies of hapten conjugation, and the best hapten/antibody pair was selected. It proved to be a reliable tool to measure the herbicide in the 2.0?20 ng/mL range in field samples, with excellent correlation with high-performance liquid chromatography results. The assay was used to study the dissipation of the herbicide in the floodwater of experimental rice paddies in Uruguay. Large differences in the residual amounts of herbicide were observed depending on the flooding practices. Because of its robustness and simplicity, the assay may be useful to delineate and monitor management practices that can contribute to minimizing the release of the herbicide in the environment. © 2010 American Chemical Society. Source

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