Isolation of cellulolytic bacteria from the intestine of Diatraea saccharalis larvae and evaluation of their capacity to degrade sugarcane biomass

As a strategy to find efficient lignocellulose degrading enzymes/microorganisms for sugarcane biomass pretreatment purposes, 118 culturable bacterial strains were isolated from intestines of sugarcane-fed larvae of the moth Diatraea saccharalis. All strains were tested for cellulolytic activity using soluble carboxymethyl cellulose (CMC) degrading assays or by growing bacteria on sugarcane biomass as sole carbon sources. Out of the 118 strains isolated thirty eight were found to possess cellulose degrading activity and phylogenetic studies of the 16S rDNA sequence revealed that all cellulolytic strains belonged to the phyla γ-Proteobacteria, Actinobacteria and Firmicutes. Within the three phyla, species belonging to five different genera were identified (Klebsiella, Stenotrophomonas, Microbacterium, Bacillus and Enterococcus). Bacterial growth on sugarcane biomass as well as extracellular endo-glucanase activity induced on soluble cellulose was found to be highest in species belonging to genera Bacillus and Klebsiella. Good cellulolytic activity correlated with high extracellular protein concentrations. In addition, scanning microscopy studies revealed attachment of cellulolytic strains to different sugarcane substrates. The results of this study indicate the possibility to find efficient cellulose degrading enzymes and microorganisms from intestines of insect larvae feeding on sugarcane and their possible application in industrial processing of sugarcane biomass such as second generation biofuel production.Fil: Dantur, Karina Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; Argentina. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Enrique, Ramón Atanasio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; Argentina. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Welin, Bjorn. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; Argentina. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Castagnaro, Atilio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; Argentina. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentin

Genetic Transformation of Sugarcane, Current Status and Future Prospects

Sugarcane (Saccharum spp.) is a tropical and sub-tropical, vegetative-propagated crop that contributes to approximately 80% of the sugar and 40% of the world’s biofuel production. Modern sugarcane cultivars are highly polyploid and aneuploid hybrids with extremely large genomes (>10 Gigabases), that have originated from artificial crosses between the two species, Saccharum officinarum and S. spontaneum. The genetic complexity and low fertility of sugarcane under natural growing conditions make traditional breeding improvement extremely laborious, costly and time-consuming. This, together with its vegetative propagation, which allows for stable transfer and multiplication of transgenes, make sugarcane a good candidate for crop improvement through genetic engineering. Genetic transformation has the potential to improve economically important properties in sugarcane as well as diversify sugarcane beyond traditional applications, such as sucrose production. Traits such as herbicide, disease and insect resistance, improved tolerance to cold, salt and drought and accumulation of sugar and biomass have been some of the areas of interest as far as the application of transgenic sugarcane is concerned. Although there have been much interest in developing transgenic sugarcane there are only three officially approved varieties for commercialization, all of them expressing insect-resistance and recently released in Brazil. Since the early 1990’s, different genetic transformation systems have been successfully developed in sugarcane, including electroporation, Agrobacterium tumefaciens and biobalistics. However, genetic transformation of sugarcane is a very laborious process, which relies heavily on intensive and sophisticated tissue culture and plant generation procedures that must be optimized for each new genotype to be transformed. Therefore, it remains a great technical challenge to develop an efficient transformation protocol for any sugarcane variety that has not been previously transformed. Additionally, once a transgenic event is obtained, molecular studies required for a commercial release by regulatory authorities, which include transgene insertion site, number of transgenes and gene expression levels, are all hindered by the genomic complexity and the lack of a complete sequenced reference genome for this crop. The objective of this review is to summarize current techniques and state of the art in sugarcane transformation and provide information on existing and future sugarcane improvement by genetic engineering.Fil: Budeguer, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Enrique, Ramón Atanasio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Perera, María Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Racedo, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Castagnaro, Atilio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Noguera, Aldo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Welin, Björn. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentin

The Endophytic Strain Klebsiella michiganensis Kd70 Lacks Pathogenic Island-Like Regions in Its Genome and Is Incapable of Infecting the Urinary Tract in Mice

Klebsiella spp. have been isolated from many different environmental habitats but have mainly been associated with nosocomial acquired diseases in humans. Although there are many recently published sequenced genomes of members of this genus, there are very few studies on whole genome comparisons between clinical and non-clinical isolates, and it is therefore still an open question if a strain found in nature is capable of infecting humans/animals. Klebsiella michiganensis Kd70 was isolated from the intestine of larvae of Diatraea saccharalis but genome analysis revealed multiple genes associated with colonization and growth promotion in plants suggesting an endophytic lifestyle. Kd70 cells labeled with gfp confirmed capability of root colonization and soil application of Kd70 promoted growth in greenhouse grown sugarcane. Further genomic analysis showed that the Kd70 genome harbored fewer mammalian virulence factors and no pathogen island-like regions when compared to clinical isolates of this species, suggesting attenuated animal/human pathogenicity. This postulation was corroborated by in vivo experiments in which it was demonstrated that Kd70 was unable to infect the mouse urinary tract. This is to the best of our knowledge the first experimental example of a member of a pathogenic Klebsiella spp. unable to infect a mammalian organism. A proteomic comparison deduced from the genomic sequence between Kd70 and several other K. michiganensis strains showed a high similarity with isolates from many different environments including clinical strains, and demonstrated the existence of conserved genetic lineages within this species harboring members from different ecological niches and geographical locations. Furthermore, most genetic differences were found to be associated with genomic islands of clinical isolates, suggesting that evolutionary adaptation of animal pathogenicity to a large extent has depended on horizontal gene transfer. In conclusion our results demonstrate the importance of conducting thorough in vivo pathogenicity studies before presupposing animal/human virulence of non-clinical bacterial isolates.Fil: Dantur, Karina Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Chalfoun, Nadia Regina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Claps, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Tórtora, Maria Laura. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Silva, Clara. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Jure, Angela. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Porcel, Norma. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Bianco, María Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ciencia y Tecnología "Dr. César Milstein". Fundación Pablo Cassará. Instituto de Ciencia y Tecnología "Dr. César Milstein"; ArgentinaFil: Vojnov, Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ciencia y Tecnología "Dr. César Milstein". Fundación Pablo Cassará. Instituto de Ciencia y Tecnología "Dr. César Milstein"; ArgentinaFil: Castagnaro, Atilio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Welin, Bjorn. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentin

Development of PSP1: A Biostimulant Based on the Elicitor AsES for Disease Management in Monocot and Dicot Crops

In this work we present a novel biostimulant for sustainable crop disease management named PSP1. PSP1 is based on the plant defense-elicitor AsES, an extracellular protease produced by the strawberry fungal pathogen Acremonium strictum. Fungal fermentation conditions and downstream processing were determined to maximize extracellular protein production, product stability and a high plant defense-eliciting activity, as monitored by anthracnose resistance in supernatant-treated strawberry plants subsequently infected with a viral strain of Colletotrichum acutatum. Fermentation batches were shown to reduce anthracnose development by 30 to 60% as compared to infected non-treated plants. Product formulation was shown to be stable for 6 months when stored at temperatures up to 45°C and toxicological tests showed that PSP1 was harmless to beneficial organisms and non-toxic to mammalian species at concentrations 50 times higher than those used in plant experiments. Furthermore, disease protection studies using dilutions of PSP1 indicated that there is a minimum threshold protease activity needed to induce pathogen defense in strawberry and that this induction effect is dose-independent. A significant characteristic of PSP1 is its broad-range protection against different diseases in various crop species. In soybean, PSP1 reduced the symptomatology by 70% of Corynespora cassiicola, etiological agent of the target spot. This protection effect was similar to the commercial inducer BION 500 WG based on BTH, and both products were shown to induce an oxidative burst and up-regulated PR1-gene expression in soybean. Furthermore, a double PSP1-treatment on greenhouse-grown sugarcane plants provided protection against bacterial red stripe disease caused by Acidovorax avenae and a double foliar application of PSP1 on field-grown wheat plants significantly increased resistance against Fusarium graminearum, causal agent of head blight disease, manifested mainly in an increased seed germination rate. In summary, these disease protection studies demonstrated an effective control against both bacterial and fungal pathogens in both monocot and dicot crop species, which together with its low production cost, effectiveness at low concentrations, long shelf-life, tolerance to high temperatures, harmlessness to non-target organisms and simple handling and application, make PSP1 a very promising candidate for effective and sustainable disease management in many crop species.Fil: Chalfoun, Nadia Regina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Sandra B. Durman. Bayer S.A., Argentina – Crop Science LATAM 2, Crop Science Research, Buenos Aires; ArgentinaFil: Budeguer, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Caro, María del Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Romina P. Bertani. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Pia d.l.A. di-Peto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Tecnología Agroindustrial del Noroeste Argentino;; Argentina. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Sebastian A. Stenglein. Laboratorio de Biología Funcional y Biotecnología, Universidad Nacional del Centro de la Provincia de Buenos Aires-Comisión de Investigaciones Científicas de la Provincia de Buenos Aires and Instituto de Investigaciones en Biodiversidad y Biotecnología – Consejo Nacional de Investigaciones Científicas y Técnicas, Azul; ArgentinaFil: Filippone, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Enrique R. Moretti. Annuit S.a; ArgentinaFil: Juan C. Díaz Ricci. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Bjorn Welin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Castagnaro, Atilio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina. Estación Experimental Agroindustrial Obispo Colombres; Argentin

Plant growth-promoting bacteria isolated from sugarcane improve the survival of micropropagated plants during acclimatisation

The plant microbiome plays an important role in nutrient acquisition and buffering plant hosts against abiotic and biotic stress. During in vitro propagation of sugarcane, pathogenic microorganisms are eliminated and most of the beneficial endophytic microorganisms. The objective of this study was to isolate and characterise potential plant growth-promoting bacteria (PGPB) from sugarcane and to analyse their ability to improve the survival of micropropagated sugarcane plantlets during the acclimatisation stage. First, bacterial isolates from sugarcane were identified by partial 16S rDNA sequencing and tested for plant growth-promoting (PGP) features, such as inorganic and organic phosphate solubilisation nitrogen fixation, siderophore synthesis, indole-3-acetic acid production, tolerance to abiotic stress and antibiotics production. Then three bacterial strains with multiple PGP traits were independently applied to micropropagated seedlings of the sugarcane variety TUC 03-12 when the plants were transferred to a nursery for ex vitro acclimatisation. The effect of selected PGPB on survival rates of micropropagated plantlets was evaluated in three independent assays, using different batches of seedlings. Thirty days after inoculation, 182-Bacillus and 336-Pseudomonas isolates significantly improved the transferred plants survival rate. High variability in plant survival among independent experiments was observed, but treatments with the 336-Pseudomonas strain showed a low mortality rate (20%) in all assays. This procedure constitutes a biological tool to improve the survival of micropropagated plants during greenhouse acclimatisation. Furthermore, it provides an initial tool for selecting bacteria with possible PGP effects in the field. Highlights - A total of 162 isolates obtained from the rhizosphere, rhizoplane, roots, and stems of sugarcane were characterised for plant growthpromoting features and identified by partial 16S rDNA sequencing. - Two PGPBs strains isolated from sugarcane (182-Bacillus and 336-Pseudomonas) significantly improved survival rates of micropropagated seedlings during the acclimatisation stage. - Under different stress conditions, the 336-Pseudomonas strain improved the survival of micropropagated plants during the acclimatisation stage

Development of the transgenic sugarcane event TUC 87-3RG resistant to glyphosate

La variedad comercial de caña de azúcar RA 87-3 se transformó mediante biobalística con una construcción genética que porta el gen epsps de la cepa CP4 de Agrobacterium tumefaciens, y el gen nptII que confieren resistencia a glifosato y resistencia a kanamicina/geneticina, respectivamente. Las líneas transformadas fueron multiplicadas en invernadero y se evaluó la resistencia al herbicida utilizando diferentes concentraciones de glifosato (3, 4 y 8 l/ha). Las líneas resistentes al herbicida (RH) se evaluaron en campo para confirmar la resistencia a glifosato (3 l/ha) y realizar un análisis preliminar del comportamiento de estas con respecto al cultivar parental. Todas las líneas transformadas mantuvieron la resistencia al herbicida pero muchas mostraron cambios fenotípicos. Las diez líneas RH que resultaron muy parecidas a la variedad RA 87-3 se analizaron fenotípica y genéticamente utilizando los nueve descriptores morfológicos obligatorios propuestos por la “International Union for the Protection of New Varieties of Plants” (UPOV) y con 339 marcadores moleculares, respectivamente. Seis líneas de las anteriores presentaron cambios morfológicos y genéticos menores y fueron seleccionadas para ensayos en campo durante dos ciclos vegetativos (caña planta y soca 1), en dos áreas de producción de Argentina. Las seis líneas RH presentaron características agronómicas, industriales y de composición química indistinguibles respecto del cultivar parental. La herencia estable del gen CP4 epsps fue confirmada mediante ensayos de RT-qPCR y Southern blot en diferentes generaciones clonales (caña planta y soca 1). Los estudios confirmaron la utilidad de la transformación genética como una herramienta complementaria a la mejora clásica, y destaca la ventaja del uso de los descriptores de UPOV junto con los marcadores moleculares para una selección temprana de eventos transgénicos que tengan un alto parecido con el genotipo parental. Tomando en cuenta los resultados, una de las seis líneas estudiadas se seleccionó para una posible liberación comercial, la cual debe ser sometida a evaluación por parte de los entes regulatorios (CONABIA, SENASA y DNMA).The commercial variety of sugarcane RA 87-3 was transformed by biobalistic with a genetic construct that carries the epsps gene of the CP4 strain of Agrobacterium tumefaciens, and with the nptII gene that confer resistance to glyphosate and resistance to kanamycin / geneticin, respectively. Transformed lines were multiplied in greenhouse and resistance to the herbicide was evaluated using different concentrations of glyphosate (3, 4 and 8 l / ha). Resistant lines to the herbicide (RH) were evaluated in the field to confirm resistance to glyphosate and to carry out a preliminary analysis of their behavior with respect to the parental cultivar. All transformed lines maintained resistance to the herbicide but many showed phenotypic changes. Ten RH lines that were very similar to the RA 87-3 variety were analyzed phenotypically and genetically using the 9 compulsory morphological markers proposed by The International Union for the Protection of New Varieties of Plants (UPOV) and with 339 molecular markers, respectively. Six lines of the previous ones presented minor morphological and genetic changes and were selected for field trials during two vegetative cycles (cane plant and ratoon 1), in two production areas of Argentina. The six RH lines presented agronomic, industrial and chemical composition characteristics indistinguishable from the parental cultivar. The stable inheritance of the CP4 epsps gene was confirmed by RT-qPCR and Southern blot assays in different clonal generations (growth cycles). Our studies confirmed the usefulness of genetic transformation as a complementary tool to classical improvement and highlight the advantage of the use of UPOV descriptors together with molecular markers for an early selection of transgenic events that have a high similarity with the parental genotype. Taking into account the results, one of the six lines evaluated was proposed for a possible commercial release, under the requirements of regulatory affairs offices (CONABIA, SENASA and DNMA).Fil: Noguera, Aldo Sergio. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Enrique, Ramón Atanasio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Ostengo, Santiago. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Perera, María Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Racedo, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Chayle Costilla, Diego Roberto. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Zozzi. Silvia. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Cuenya, María Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Filippone, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Welin, Bjorn. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; ArgentinaFil: Castagnaro, Atilio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial "Obispo Colombres" (p). Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentin

Use of AFLP markers to estimate molecular diversity of Phakopsora pachyrhizi

Background: Asian soybean rust (SBR) caused by Phakopsora pachyrhizi Syd. & Syd., is one of the main diseases affecting soybean and has been reported as one of the most economically important fungal pathogens worldwide. Knowledge of the genetic diversity of this fungus should be considered when developing resistance breeding strategies. We aimed to analyze the genetic diversity of P. pachyrhizi combining simple sampling with a powerful and reproducible molecular technique. Results: We employed Amplified Fragment Length Polymorphism (AFLP) technique for the amplification of P. pachyrhizi DNA extracted from naturally SBR-infected plants from 23 production fields. From a total of 1919 markers obtained, 77% were polymorphic. The high percentage of polymorphism and the Nei's genetic diversity coefficient (0.22) indicated high pathogen diversity. Analysis of molecular variance showed higher genetic variation within countries than among them. Temporal analysis showed a higher genetic variation within a year than between years. Cluster, phylogenetic and principal co-ordinate analysis showed that samples group by year of collection and then by country sampled. Conclusions: The study proposed combining a simple collection of urediniospore with a subsequent analysis by AFLP was useful to examine the molecular polymorphism of samples of P. pachyrhizi collected and might have a significant contribution to the knowledge of its genetic diversity. Also, AFLP analysis is an important and potent molecular tool for the study of genetic diversity and could be useful to carry out wider genetic diversity studies

Period-doubling and Hopf bifurcations in far-infrared driven quantum well intersubband transitions

The behavior of n-δ-doped wide quantum well (QW) heterostructures in the presence of intense far-infrared (FIR) radiation is studied using the semiconductor Bloch equations, in the time-dependent Hartree version and without the rotating-wave approximation. A QW is designed where one can either obtain a strong subharmonic (period doubling) or a strong incommensurate (Hopf) frequency response by varying the sheet density and field strength. These strong responses should be attainable with current technology, and the field amplitudes and frequencies of the drive are well within the range of FIR free-electron lasers. © 2003 The American Physical Society.Fil: Batista, Adriano A.. Georgia Institute of Techology; Estados UnidosFil: Welin, Bjorn. University of California; Estados UnidosFil: Tamborenea, Pablo Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Citrin, S.. Georgia Institute of Techology; Estados Unido