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- ArtículoEmbargadoQuality and endosperm storage protein variation in Argentinean grown bread wheat(2009) Lerner, S.E.; Kolman, M.A.; Rogers, John WilliamGenetic variability for endosperm storage proteins was analysed in 119 Argentinean grown bread wheat cultivars. For the HMW-GS, three, six and two alleles were observed at theGlu-A1,Glu-B1andGlu-D1loci, respectively, in 17 allelic combinations. The majority of these combinations were considered to be associated with good quality. For the LMW-GS, eight, seven and four alleles were provisionally observed at theGlu-A3,Glu-B3andGlu-D3loci, respectively, in 51 allelic combinations. Regarding quality, the alleles present atGlu-D3were mainly those previously shown to be associated with good quality, whereas atGlu-A3andGlu-B3, some alleles previously associated with poor quality were present at high frequency. Relatively few cultivars carried combinations for all the loci studied that would be expected to be associated with high quality. The mean genetic variation index (H) observed for the glutenin loci (0.589) was similar to values observed in other collections. Unweighted pair-group method using arithmetic averages (UPGMA) of the six loci plus the Chinese Spring-Cheyenne CSS–CNN difference showed that the 119 cultivars fell into 93 distinct combinations. For complete discrimination between all cultivars they would have to be analysed for additional loci. There remains scope for varietal quality improvement within this germplasm pool.
- ArtículoEmbargadoPseudocercospora griseola Causing Angular Leaf Spot on Phaseolus vulgaris Produces 1,8-Dihydroxynaphthalene-Melanin(2009) Saparrat, Mario; Fermoselle, Geraldine; Stenglein, Sebastián; Aulicino, Mónica B.; Balatti, Pedro AlbertoPseudocercospora griseolais the causal agent of angular leaf spot of common bean (ALS). It has undergone parallel coevolution with its host and two major groups have been defined, “Andean” (P. griseolaf.griseola) and “Mesoamerican” (P. griseolaf.mesoamericana). The aim of this study was to analyze the nature and the level of the dark pigment synthesized by the representatives of each group. After 21days of incubation on potato dextrose agar medium,P. griseolaf. griseolaisolate S3b developed colonies with diameters of 17.5±1.3mm and concentric rings of pigmentation. Isolate T4 ofP. griseolaf.mesoamericanapresented smaller colonies (9.9±0.3mm) with a uniform dark-gray color. Both isolates, S3b and T4, produced the same pigment, a 1,8-dihydroxynaphthalene-melanin, although different in quantity and structural features as suggested by the IR spectrum. TheP. griseolaf. griseolaisolate S3b had a higher growth rate and melanin content as well as smaller sensitivity to melanin synthesis inhibitors compared to the isolate T4 ofP. griseolaf.mesoamericana. These results suggest a possible link between melanin and growth inP. griseola.
- ArtículoEmbargadoPhylogenetic relationships of Fusarium poae based on EF-1 alpha and mtSSU sequences(2010) Stenglein, Sebastián; Rodriguero, M.S.; Chandler, E.; Jennings, P.; Salerno, G.L.; Nicholson, P.A molecular phylogenetic analysis ofFusarium poaeisolates from South America (Argentina) and Europe (mainly England, Germany, Italy) was performed using 98F. poae, fourFusarium culmorum, twoFusarium sporotrichioidesand oneFusarium langsethiaeisolates. Phylogenetic analyses were performed using nuclear (translation elongation factor 1-alpha,EF-1α) and mitochondrial (mitochondrial small subunit rDNA,mtSSU) sequences. Partitioned (each dataset separately) and combined (EF-1α+mtSSU) analyses did not reveal any clear correlations from the inferred branching topology, between the distribution of observed haplotypes and the geographic origin and/or host species. Results from the present study confirmed that isolates fromF. poaeform a monophyletic group, and the low variability within isolates from a broad geographic range suggests a common lineage history. AmongF. poaeisolates from Argentina, however, some were found to possess an insert withinmtSSUwith structural similarities to group IC2 introns.F. poaeisolates differing by the presence/absence of amtSSUinsertion were characterized further by analysis of a portion of theTri5gene, but this sequence was unable to reveal variability. The presence of this insert only within isolates from Argentina suggests that evolutionary events (insertions/deletions) are probably taking place within the ArgentinianF. poaeisolates, and that the acquisition of this insert occurred after geographic isolation of the Argentinian and European populations.
- ArtículoAcceso AbiertoComparison of low molecular weight glutenin subunits identified by SDS-PAGE, 2-DE, MALDI-TOF-MS and PCR in common wheat(2010) Liu, Li; Ikeda, Tatsuya M.; Branlard, Gerard; Peña, Roberto J.; Rogers, John William; Lerner, Silvia E.; Kolman, Maía de Los Angeles; Xia, Xianchun; Wang, Linhai; Ma, Wujun; Appels, Rudi; Yoshida, Hisashi; Wang, Aili; Yan, Yueming; He, ZhonghuBackground Low-molecular-weight glutenin subunits (LMW-GS) play a crucial role in determining end-use quality of common wheat by influencing the viscoelastic properties of dough. Four different methods - sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2-DE, IEF × SDS-PAGE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and polymerase chain reaction (PCR), were used to characterize the LMW-GS composition in 103 cultivars from 12 countries. Results At theGlu-A3locus, all seven alleles could be reliably identified by 2-DE and PCR. However, the allelesGlu-A3eandGlu-A3dcould not be routinely distinguished fromGlu-A3fandGlu-A3g, respectively, based on SDS-PAGE, and the alleleGlu-A3acould not be differentiated fromGlu-A3cby MALDI-TOF-MS. At theGlu-B3locus, allelesGlu-B3a,Glu-B3b,Glu-B3c,Glu-B3g,Glu-B3handGlu-B3jcould be clearly identified by all four methods, whereasGlu-B3ab,Glu-B3ac,Glu-B3adcould only be identified by the 2-DE method. At theGlu-D3locus, allelic identification was problematic for the electrophoresis based methods and PCR. MALDI-TOF-MS has the potential to reliably identify theGlu-D3alleles. Conclusions PCR is the simplest, most accurate, lowest cost, and therefore recommended method for identification ofGlu-A3andGlu-B3alleles in breeding programs. A combination of methods was required to identify certain alleles, and would be especially useful when characterizing new alleles. A standard set of 30 cultivars for use in future studies was chosen to represent all LMW-GS allelic variants in the collection. Among them, Chinese Spring, Opata 85, Seri 82 and Pavon 76 were recommended as a core set for use in SDS-PAGE gels.Glu-D3candGlu-D3eare the same allele. Two new alleles, namely,Glu-D3min cultivar Darius, andGlu-D3nin Fengmai 27, were identified by 2-DE. Utilization of the suggested standard cultivar set, seed of which is available from the CIMMYT and INRA Clermont-Ferrand germplasm collections, should also promote information sharing in the identification of individual LMW-GS and thus provide useful information for quality improvement in common wheat.
- Informe técnicoAcceso AbiertoCatalogue of gene symbols for wheat: 2011 Supplement(2010) McIntosh, R. A.; Dubcovsky, J.; Rogers, John William; Morris, C. F.; Appels, R.; Xia, X.C.The most recent version of the Catalogue, compiled for the 11th International Wheat Genetics Symposium held in Brisbane, Australia, and the 2009 and 2010 Supplements (Annual Wheat Newsletter 55 and 56) are available on the Komugi and GrainGenes websites. It was not included as part of the IWGS proceedings and therefore cannot be cited as part of them
- ArtículoEmbargadoFusarium proliferatum, a New Pathogen Causing Head Blight on Oat in Argentina(2010) Stenglein, Sebastián; Dinolfo, María Inés; Moreno, María Virginia; Galizio, R.; Salerno, G.L.Oat (Avena sativaL.) is widely grown (~200,000 ha) for livestock feed in Argentina.Fusariumspp. affect yield and commercial quality and can cause indirect losses because someFusariumspp. produce mycotoxins. In December 2008, a study of oat seeds (cv. Graciela INTA) from Trenque Lauquen, Buenos Aires, Argentina was conducted. Seeds (400) were surface sterilized by dipping successively into 70% ethanol for 2 min, 5% sodium hypochlorite for 2 min, rinsed twice in fresh sterilized distilled water, plated on 2% potato dextrose agar (PDA) pH 6, and incubated at 24 ± 2°C with 12-h photoperiods. Six isolates morphologically similar toFusariumspp. were observed after 6 days of incubation. For identification, monosporic isolates were transferred onto 2% PDA and carnation leaf agar (CLA) to grow with the conditions described above. Two isolates produced abundant, white, aerial mycelium and violet-to-dark (with age) pigments in the PDA. On CLA, macroconidia were abundant, slender, almost straight, thin walled, and usually three to five septate. Microconidia were abundant, usually single celled, oval or club-shaped in chains (less commonly in false heads) on monophialides and polyphialides. Chlamydospores were absent. The fungus was identified asFusarium proliferatum(Matsushima) Nirenberg on the basis of fungal morphology (1). To complete Koch's postulates, the pathogenicity of the fungus was tested by spraying five healthy inflorescences of oat (cv. Graciela INTA) with a 5-ml suspension (2 × 105conidia/ml). Another two healthy inflorescences were sprayed with sterile distilled water. Plants were placed in a growth chamber with a 12-h photoperiod at 22 ± 2°C and covered with polyethylene bags that were removed after 3 days and plants were moved to a glasshouse. This procedure was repeated. While control inflorescences were asymptomatic, inoculated inflorescences showed bleaching glumes that sometimes became necrotic with some grains that presented pale brown discoloration and necrotic areas. The fungus was reisolated from glumes and grains of inoculated plants and not from controls using the methodology described above. To confirm the morphological diagnosis, the genomic DNA of the isolates was extracted (3) and a PCR reaction with specific primers 5′-CTTTCCGCCAAGTTTCTTC-3′-forward and 5′-TGTCAGTAACTCGACGTTGTTG-3′-reverse was chosen (2) using the following cycling protocol: initial denaturation step at 95°C for 2 min; 30 cycles at 95°C for 30 s, 55°C for 30 s, 72°C for 45 s; final extension at 72°C for 2 min. Successful amplifications were confirmed by gel electrophoresis. Size of the DNA fragment was estimated using a 100-bp DNA ladder. The reaction was repeated three times. The expected size product (585 bp) was obtained, confirming the identification (2). To our knowledge, this is the first report ofF. proliferatumon oat in Argentina. This species is known to produce fumonisins, beauvericin, fusaric acid, fusarins, and moniliformin toxins, among others. SinceF. proliferatumcan infect different cereal grains, a large-scale survey in the same and different fields is in progress. A voucher culture has been deposited in the LPSC (Culture Collection of the La Plata Spegazzini Institute) No. 1058.
- ArtículoAcceso AbiertoCanaryseed (Phalaris canariensis L.) accessions from nineteen countries show useful genetic variation for agronomic traits(2010) Cogliatti, Maximiliano; Bongiorno, F.; Dalla Valle, H.; Rogers, John WilliamFifty-seven accessions of canaryseed (47 populations and 10 cultivars) from 19 countries were evaluated for agronomic traits in four field trials sown over 3 yr in the province of Buenos Aires, Argentina. Genetic variation was found for all traits scored: grain yield and its components (grain weight, grain number per square meter, grain number per head and head number per square meter), harvest index, percent lodging, and phenological characters (emergence to heading, emergence to harvest maturity and heading to harvest maturity). Although genotype×environment interaction was observed for all traits, the additive differences between accessions were sufficient to enable promising breeding materials to be identified. Accessions superior in performance to the local Argentinean population, which in general gave values close to the overall mean of the accessions evaluated, were identified. For example, a population of Moroccan origin gave good yield associated with elevated values of the highly heritable character grain weight, rather than with the more commonly observed grain number per square meter. This population was also of relatively short stature and resistant to lodging, and, although it performed best when sown within the normal sowing date, tolerated late sowing fairly well. Other accessions were also observed with high grain weight, a useful characteristic in itself, since large grains are desirable from a quality point of view. Regarding phenology, the accessions showed a range of 160 degree days (8 calendar days in our conditions) in maturity, which, while not large in magnitude, may be of some utility in crop rotation management. Some accessions were well adapted to late sowing. Grain yield in general was strongly correlated with grain number per square meter. Principal components analysis (PCA) carried out for all characteristics provided indications of accessions combining useful characteristics and identified three components that explained approximately 70% of the phenotypic variation. Furthermore, a second PCA plus regression showed that approximately 60% of the variation in grain yield could be explained by a component associated with harvest index and grain number per square meter. Pointers were provided to possible future breeding targets.
- ArtículoEmbargadoISSR markers detect high genetic variation among Fusarium poae isolates from Argentina and England(2010) Dinolfo, María Inés; Stenglein, Sebastián; Moreno, María Virginia; Nicholson, Paul; Jennings, Philip; Salerno, Graciela L.Fusarium poae is one of the Fusarium species isolated from cereal grains infected by Fusarium head blight (FHB), and in recent years it has been identified as a major FHB component. In this study, 97 F. poae isolates from Argentina (n=62) and England (n=35) were analysed by inter-simple sequence repeats (ISSR) to examine the genetic diversity and to determine whether intraspecific variation could be correlated with geographic and/or host origin. The molecular analysis showed high intraspecific variability within F. poae isolates, but did not reveal a clear relationship between variability and the host/geographic origin. Fusarium poae isolates from the same geographic region or host appeared in different subclusters. Conversely, isolates with the same haplotype were also collected from different geographic regions. However, we did observe subclusters consisting of isolates from Argentina only or from England only. Furthermore, a single seed sample was found to host different haplotypes. Analysis of molecular variance (AMOVA) indicated a high genetic variability in F. poae, with most of the genetic variability explained by differences within, rather than between Argentinean and English populations. This is the first report on genetic diversity of F. poae using ISSR markers. Moreover, ISSR fingerprinting generates highly polymorphic markers for F. poae and proved to be a useful and reliable assay for genetic variability studies.
- ArtículoAcceso AbiertoCommon Bean germplasm molecular analysis: a biotechnological approach for breeding(2010) Galván, M.; Stenglein, Sebastián; Balatti, Pedro AlbertoArgentina, which is a major producer of common bean (Phaseolus vulgaris L.), represents the southern most limit of the Andean diversification center of the species. The diverse environmental conditions of these places and human selection favored the development of a great variability of wild beans and landraces, which is endangered due to the destruction of habitats by forest exploitation and agriculture. Information on the variability of these resources is essential to set conservation strategies and design breeding programs aimed at enlarging the genetic base of commercial beans. This work is an overview of the marker-based studies on landraces and wild bean genetic diversity, with special emphasis on Argentinean beans, as a first step for the optimal exploitation of the naturally available bean genetic resources, to generate new traits and improve crop performance. The identification of diversity and hybridization between populations is enhanced by the application of the new tools and the information generated by bean genomic research. Gene flow, which appears to occur fairly frequently in bean, has to be studied in more detail in this region in order to facilitate the transfer of useful alleles from the unexploited germplasm to improved lines, broadening the genetic diversity available for breeding. Some resistance gene analogs (RGAs) have been described within the Andean gene pool and only a few have been functionally characterized or linked to a phenotype. Therefore, a strategy for the exploitation of bean germplasm variability based on the detection of RGAs is also mentioned, though more work should be devoted at identifying these sequences in Andean landraces and wild beans.
- ArtículoAcceso AbiertoDiversity of Pyrenophora tritici-repentis isolates from the Argentinian wheat growing area: morphocultural and pathogenic analysis(2011) Moreno, María Virginia; Arambarri, A.M.; Perelló, Analíaheat is currently considered as one of the most important crops world-wide. Among the fungal diseases of this crop, tan spot produced byPyrenophora tritici-repentisis one of the most important. Tan spot increased its incidence, prevalence and severity in Argentina and South America. The aim of this work was to generate information about the morphocultural and pathogenic variability on wheat cultivars from Argentina. The results showed that isolates ofP. tritici-repentis, originated from diverse localities of Argentina differed in their morphocultural characteristics and in their level of severity. The cluster analysis of morphocultural characteristics among 155 isolates of the pathogen defined 44 morphotypes according with the Jaccard’s coefficient (CCC=0.79). Pathogenicity tests determined on a set of eight wheat cultivars under greenhouse conditions showed the presence of physiological specialization in 33 isolates ofP. tritici-repentis. The efforts to link morphocultural and pathogenicity features to the geographical origin of the isolates were mostly unsuccessful. The isolates tested appeared in different groups and most of the isolates which shared the highest similarity coefficient were collected from different localities and different wheat cultivars.
- ArtículoAcceso AbiertoFirst record of Fusarium verticillioides as an entomopathogenic fungus of grasshoppers(2011) Pelizza, S.A.; Stenglein, Sebastián; Cabello, Marta Noemí; Dinolfo, María Inés; Lange, Carlos ErnestoFusarium verticillioides(Saccardo) Nirenberg (Ascomycota: Hypocreales) is the most common fungus reported on infected corn kernels and vegetative tissues, but has not yet been documented as being entomopathogenic for grasshoppers. Grasshoppers and locusts represent a large group of insects that cause economic damage to forage and crops.Tropidacris collaris(Stoll) (Orthoptera: Acridoidea: Romaleidae) is a large and voracious grasshopper that in recent years has become an increasingly recurrent and widespread pest in progressively more greatly extended areas of some of in Argentina’s northern provinces, with chemical insecticides being currently the only means of control. During February and March of 2008-09, nymphs and adults ofT. collariswere collected with sweep nets in dense woodland vegetation at a site near Tres Estacas in western Chaco Province, Argentina, and kept in screened cages.F. verticillioideswas isolated from insects that died within 10 days and was cultured in PGA medium. Pathogenicity tests were conducted and positive results recorded. Using traditional and molecular-biological methods, an isolate ofF. verticillioideswas obtained fromT. collaris, and its pathogenecity in the laboratory was shown against another harmful grasshopper,Ronderosia bergi(Stål) (Acridoidea: Acrididae: Melanoplinae). The mortality caused byF. verticillioidesonR. bergireached 58 ± 6.53% by 10 days after inoculation. This is the first record of natural infection caused byF. verticillioidesin grasshoppers.
- Parte de libroAcceso AbiertoPyrenophora tritici repentis, the causal agent of tan spot: a review of intraspecific genetic diversity(2012) Moreno, María Virginia; Stenglein, Sebastián; Perelló, AnalíaIn some countries where the wheat is cultivated, the biological adversities are led by foliar disease. These diseases have emerged as a serious problem in many areas where the wheat is the principal crop. In the last few years, minimum tillage has been considered advantageous to soil conservation, but it leads to a loss of available nutrients and a potential increase in necrotic pathogens whose saprophytic stage lives in the straw of the crop (Annone, 1985). Establishment of the crop under this management can be affected by pathogens of this type. Leaf spotting diseases can be caused by one or a combination of leaf spotting pathogens (Table 1). Leaf spotting diseases affect wheat grown reduce the photosynthetic area of leaves resulting in reduced grain filling and lower yields; particularly when the top two leaves (penultimate and flag leaves) are severely infected. The most of these diseases are similar in host symptomatology, disease cycle, life cycles of pathogens and types of damage induced. Whitin of these pathogens the Ascomycota fungus, Pyrenophora tritici-repentis (Ptr) (Died.) Drechs. It is a facultative pathogen whose asexual stage is Drechslera tritici-repentis (Dtr) (Died.). This pathogen is the causal agent of tan spot of wheat.
- ArtículoEmbargadoDevelopment of a PCR assay to detect the potential production of nivalenol in Fusarium poae(2012) Dinolfo, María Inés; Barros, Germán G.; Stenglein, SebastiánFusariumspecies can produce mycotoxins, which can contaminate cereal-based food producing adverse effects for human and animal health. In recent years, the importance ofFusarium poaehas increased within theFusariumhead blight complex.Fusarium poaeis known to produce trichothecenes, especially nivalenol, a potent mycotoxin able to cause a variety of toxic effects. In this study, a specific primer pair was designed based on thetri7gene to detect potential nivalenol-producingF. poaeisolates. A total of 125F. poae, fourF. cerealis, twoF. culmorum, oneF. langsethiae, oneF. sporotrichioidesand sevenF. graminearum, plusF. austroamericanum, F. meridionale, F. graminearum sensu strictoandF. cortaderiaefrom the NRRL collection were analysed, and onlyF. poaeisolates gave a positive result for the presence of a 296-bp partialtri7DNA fragment. Moreover, the primer set was tested from cereal seed samples whereF. poaeand otherFusariumspecies with a negative result for the specific reaction (F. graminearum, F. oxysporum, F. chlamydosporum, F. sporotrichioides, F. equisetiandF. acuminatum) were isolated, and the expected fragment was amplified. We developed a rapid and reliable PCR assay to detect potential nivalenol-producingF. poaeisolates.
- ArtículoAcceso AbiertoCanaryseed Crop(2012) Cogliatti, MaximilianoEl alpiste (Phalaris canariensis L.) es una gramínea con un ciclo de cultivo y prácticas de producción similares a las de otros cereales invernales, tales como el trigo (Triticum aestivum L. y la avena (Avena sativa L.). Actualmente, sus granos se destinan, casi con exclusividad, a la alimentación de aves, solos o en mezcla con otros como mijo, girasol y lino. El alpiste es un cereal genuino con una composición única que sugiere un potencial para uso alimentario. P. canariensis se cultiva en muchas zonas de climas templados. En la actualidad, su producción se concentra en las provincias del suroeste de Canadá (Alberta, Saskatchewan y Manitoba) y en menor escala en Argentina, Tailandia y Australia. A nivel mundial es considerado como un cultivo menor, con pertinencia regional, con una producción de alrededor de 250 mil toneladas al año, lo que restringe la inversión privada y la investigación pública en su mejoramiento genético y tecnológico. Por esta razón, el tipo de manejo del cultivo que se aplica a esta especie depende en gran medida a las innovaciones hechas en otros cultivos similares. Este trabajo ofrece una revisión actualizada de la información disponible sobre esta especie, sus necesidades, distribución, recursos genéticos, prácticas de cultivo, usos potenciales, comercialización y otros temas de interés para los investigadores y productores.
- ArtículoAcceso AbiertoRespuesta del trigo (Triticum spp.) y la cebada (Hordeum vulgare) a Fusarium poae.(2012) Stenglein, Sebastián; Dinolfo, María Inés; Bongiorno, Fabricio; Moreno, María VirginiaLa fusariosis de la espiga es una enfermedad importante que ataca al trigo (Triticumspp.), la cebada (Hordeum vulgare) y otros granos en el mundo. Entre las especies deFusariumque causan esta enfermedad,Fusarium poaees una de las menos frecuentes, pero es un hongo cuya importancia es cada vez más reconocida y se le asocia con la toxicosis en humanos y animales. El objetivo de este estudio fue examinar las respuestas de las variedades de trigo y cebada a la inoculación de diferentes aislamientos deF. poae, a fin de observar la contaminación producida por este hongo en los granos. Los análisis se realizaron durante 2008, 2009 y 2010 en condiciones naturales, en la Facultad de Agronomía de Azul-UNCPBA, provincia de Buenos Aires, Argentina. Se hicieron análisis estadísticos, y las identidades de los aislamientos re-aislados se probaron con reacciones de iniciadores específicos PCR y por comparación de amplificaciones de ADN-ISSR. Las diferencias entre variedades en los síntomas del hongo fueron significativas (p≤0.05) sólo en 2008. Aunque el número de aislamientos re-aislados en trigo fue mayor que el número de muestras con síntomas observables, las correlaciones no fueron significativas. Sin embargo, hubo correlaciones significativas en la cebada y los análisis de regresión lineal sugiriendo que por cada grano con síntomas visibles, dos granos de cebada podrían contener el hongo. Asi puede concluirse que el número de granos contaminados conF. poaees significativamente mayor que el de aquellos con síntomas observables de la enfermedad y, por tanto, el alcance real de la contaminación conF. poaees subestimado y se debiera considerar para el análisis de riesgos alimentarios en un futuro próximo.
- RevisiónAcceso AbiertoHeat stress effects on crop performance and tools for tolerance breeding(Facultad de Ciencias Agrarias (UNCuyo), 2012) Peverelli, María Cecilia; Rogers, John WilliamAbiotic stress is one of the most common causes of crop deficit and loss and hence an important area of study. Moreover, concerns regarding global climate change over past decades mean the study of different abiotic stresses appears to be essential if its effects are to be mitigated. The current review covers the effects of heat stress on crop performance, the response crops make when subjected to this stress and the development of tools designed to breed for stress tolerant crops. Distinct levels of the problem are considered, from the morphological/anatomical, through the physiological and to the biochemical/molecular. The study of heat shock proteins (HSPs), quantitative trait loci (QTLs) identification and the relationship between metabolomics (OMICS) and heat stress are given special consideration.
- ArtículoAcceso AbiertoPathogenic and enzyme activities of the entomopathogenic fungus Tolypocladium cylindrosporum (Ascomycota: Hypocreales) from Tierra del Fuego, Argentina(Universidad de Costa Rica, 2012) Scorsetti, Ana C.; Elíades, Lorena; Stenglein, Sebastián; Cabello, Marta Noemí; Pelizza, Sebastián; Saparrat, MarioTolypocladium cylindrosporum is an entomopathogenic fungi that has been studied as a biological control agent against insects of several orders. The fungus has been isolated from the soil as well as from insects of the orders Coleoptera, Lepidoptera, Diptera and Hymenoptera. In this study, we analyzed the ability of a strain of T. cylindrosporum, isolated from soil samples taken in Tierra del Fuego, Argentina, to produce hydrolytic enzymes, and to study the relationship of those activities to the fungus pathogenicity against pest aphids. We have made the traditional and molecular characterization of this strain of T. cylindrosporum. The expression of hydrolase activity in the fungal strain was estimated at three incubation temperatures (4ºC, 12ºC and 24ºC), on different agar media supplemented with the following specific substrates: chitin azure, Tween ® 20, casein, and urea for chitinase, lipase, protease, and urease activity, respectively. The hydrolytic-enzyme activity was estimated qualitatively according to the presence of a halo of clarification through hydrolase action, besides was expressed semi-quantitatively as the ratio between the hydrolytic-halo and colony diameters. The pathogenicity of the fungus was tested on adults of the aphid Rhopalosiphum padi at three temperatures of incubation (4ºC, 12ºC and 24ºC). The suspension was adjusted to a concentration of 1x10 7 conidia/ml. In pathogenicity assays at seven days post-inoculation, the fungus caused the mortality of adults of Ropalosiphum padi at different temperatures also showed a broad ability to grow on several agar-culture media, supplemented with different carbon sources at the three incubation temperatures tested. Although, the growth was greater with higher incubation temperatures (with maximum levels at 24°C), the fungus reached similar colony diameters after 15 days of incubation on the medium supplemented with Tween® 20 at the lower two incubation temperatures of 4°C or 12°C. In accordance with the results on colony diameters, the fungus revealed an ability to degrade casein, chitin derivatives, Tween® 20, and urea as evidenced by the appearance of a halo around the fungal colony. Because of its origin and temperature tolerance, this Argentine strain has great potential for use as a biocontrol agent for insect pest control in cold and temperate environments.
- Documento de conferenciaAcceso AbiertoOccurrence and distribution of soil Fusarium species under wheat crop in zero tillage(2013) Silvestro, Luciana; Stenglein, Sebastián; Forjan, H.; Dinolfo, María Inés; Arambarri, A. M.; Manso, L.; Moreno, María VirginiaThe presence of Fusarium species in cultivated soils is commonly associated with plant debris and plant roots. Fusarium species are also soil saprophytes. The aim of this study was to examine the occurrence and distribution of soil Fusarium spp. at different soil depths in a zero tillage system after the wheat was harvested. Soil samples were obtained at three depths (0-5 cm, 5-10 cm and 10-20 cm) from five crop rotations: I, conservationist agriculture (wheat-sorghum-soybean); II, mixed agriculture/livestock with pastures, without using winter or summer forages (wheat-sorghum-soybean-canola-pastures); III, winter agriculture in depth limited soils (wheat-canola-barley-late soybean); IV, mixed with annual forage (wheat-oat/Vicia-sunflower); V, intensive agriculture (wheat-barley-canola, with alternation of soybean or late soybean). One hundred twenty two isolates of Fusarium were obtained and identified as F. equiseti, F. merismoides, F. oxysporum, F. scirpi and F. solani. The most prevalent species was F. oxysporum, which was observed in all sequences and depths. The Tukey’s test showed that the relative frequency of F. oxysporum under intensive agricultural management was higher than in mixed traditional ones. The first 5 cm of soil showed statistically significant differences (p=0.05) with respect to 5-10 cm and 10-20 cm depths. The ANOVA test for the relative frequency of the other species as F. equiseti, F. merismoides, F. scirpi and F. solani, did not show statistically significant differences (p<0.05). We did not find significant differences (p<0.05) in the effect of crop rotations and depth on Shannon, Simpson indexes and species richness. Therefore we conclude that the different sequences and the sampling depth did not affect the alpha diversity of Fusarium community in this system.
- ArtículoEmbargadoFusarium cerealis Associated with Barley Seeds in Argentina(2013) Castañares, Eliana; Dinolfo, María Inés; Moreno, María Virginia; Berón, Corina; Stenglein, SebastiánFusarium head blight is a fungal disease caused by a complex ofFusariumspecies on cereals, such as barley and wheat. It has economic impacts due to yield reductions and mycotoxin contamination. As barley production has increased considerably in the last 5years in Argentina, a survey was conducted for identifyingFusariumspecies associated with barley grains.Fusarium cerealiswas isolated and identified based on morphological and molecular analysis. The potential production of nivalenol and zearalenone was assessed using specific PCR assays. Koch′s postulates were carried out to confirm the pathogenicity of the fungus.
- ArtículoEmbargadoIndigenous filamentous fungi on the surface of Argentinean dry fermented sausages produced in Colonia Caroya (Córdoba)(2013) Canel, Romina S.; Wagner, Jorge R.; Stenglein, Sebastián; Ludemann, VanesaSome producers of dry fermented sausages use fungal starter cultures with the aim to achieve a desirable surface appearance and avoid the growth of mycotoxigenic fungi. These commercial cultures are mainly composed ofPenicillium nalgiovensebiotype 6. In contrast, in the case of producers who do not use starters, sausages are spontaneously colonized by the house mycobiota, which generally consists of heterogeneous molds corresponding to different genera and species. In this work, the surface mycobiota of dry fermented sausages produced in Colonia Caroya (Córdoba, Argentina) was determined in both summer and winter seasons. All the sausages sampled had been made without the use of surface fungal starters. In the 57 sausages analyzed in the two winter seasons studied (2010 and 2012), we found a total of 95 isolates of filamentous fungi belonging to six genera (Penicillium,Aspergillus,Mucor,Cladosporium,ScopulariopsisandEurotium) and ten fungal species, whereas in the 36 sausages analyzed in the two summer seasons studied (2011 and 2012), we found 89 isolates belonging to five genera (Penicillium, Aspergillus,Mucor,CladosporiumandGeotrichum) and ten fungal species. Although 16 different species were found in both winter and summer seasons, only 2 of them predominated completely.P. nalgiovensewas found in almost 100% of the sausages analyzed, where biotype 4 was the most frequent. This species gives a whitish gray coloration to the sausages. Considering that the factories sampled do not use fungal starter cultures, this predominance is very interesting since mycotoxin production by this fungus has not been reported.Aspergillus ochraceuswas isolated with a frequency of 80–90% in the summer seasons, but in none of the winter samples. The presence of this fungus in sausages produced in the summer was attributed to the high environmental temperatures and the uncontrolled temperature in the ripening rooms during the night. In all cases,A. ochraceuswas responsible for the undesirable yellowish gold color of the casing. This fungus thus causes significant economic losses to the producers of Colonia Caroya during the months of high temperatures.