- ArtículoAcceso AbiertoVirulence and enzymatic activity of three new isolates of Beauveria bassiana (Ascomycota: Hypocreales) from the South American locust Schistocerca cancellata (Orthoptera: Acrididae)(2020)Schistocerca cancellata is a large-sized acridid, which has historically represented the greatest agricultural problem in southern South America, causing serious economic losses. Since 2015 S. cancellata entered in a state of outbreak condition of historical proportions, producing frequent and large swarms of up to 25 km² in the north and central region of Argentina and areas of neigh boring Bolivia and Paraguay. At present, chemical insecticides are still the only means available for the control of S. cancellata. We analyzed under laboratory conditions the effectiveness of three fungal strains of Beauveria bassiana isolated from S. cancellata and also determined the relationship between chitinase, protease, and lipase levels at different temperatures of these fungi and their insecticidal activities. The pathogenicity assays were carried out by the sprayed method with concentrations of 1 × 10⁴, 1 × 10⁶ and 1 × 10⁸ conidia/ml. We observed that isolate LPSc 1227 caused the highest mortality at each dose studied, ranging from 100% at a dose of 1 × 10⁸ conidia/ml to 33.3 ± 3.2% at the lowest dose of 1 × 10⁴ conidia/ml. Moreover, in this isolate the highest values of chitinolytic and proteolytic activity were recorded (2.31 ± 0.31 and 1.78 ± 0.04), respectively.
- ArtículoAcceso AbiertoMetabolic Profiling of Phloem Exudates as a Tool to Improve Bread-Wheat Cultivars(2018)In a proof of concept study aimed at showing that metabolites in bread wheat (Triticum aestivum L. ssp. aestivum), phloem exudates have potential as biochemical markers for cultivar discrimination, Argentinean cultivars from three quality groups (groups 1, 2, and 3 of high, intermediate, and low quality, respectively) were grown under two nitrogen (N) availabilities and analysed for metabolic profile by electrospray ionisation mass spectrometry. Data as signal strengths of mass/charge (m/z) values binned to a resolution of 0.2 Daltons were subjected to principal component analysis and orthogonal projections to latent structures discriminant analysis. Certain bins were influential in discriminating groups taken in pairs and some were involved in separating all three groups. In high N availability, group 3 cultivars clustered away from the other cultivars, while group 1 cultivars clustered tightly together; group 2 cultivars were more scattered between group 1 and group 3 cultivars. In low N availability, the cultivars were not clustered as tightly; nonetheless, group 1 cultivars tended to cluster together and mainly separated from those of group 2. m/z values also showed potential for discrimination between N availability. In conclusion, phloem exudate metabolic profiles could provide biochemical markers for selection during breeding and for discerning the effects of N fertiliser application.
- ArtículoAcceso AbiertoFusarium oxysporum, potencial agente de control biológico para Sorghum halepense en Argentina(2018)El sorgo de Alepo (Sorghum halepense (L.) Pers.) es una de las especies de malezas perennes más importantes en el mundo. Hasta el momento, no se ha podido disminuir su propagación e incidencia en los sistemas agrícolas. El biocontrol es una posible alternativa de manejo de malezas. El objetivo del trabajo fue evaluar por primera vez en Argentina, el efecto de diferentes técnicas de aplicación de Fusarium oxysporum sobre el crecimiento aéreo y subterráneo del sorgo de Alepo. Además, se estudió la acción del patógeno sobre la germinación de semillas de maíz, girasol, soja y sorgo granífero, teniendo en cuenta que podría afectar a estos cultivos. Se utilizaron dos técnicas de aplicación del patógeno. La aplicación de una suspensión de esporas de F. oxysporum en suelo (técnica liquida) mostró que a los tres meses se había producido la muerte del total de las plantas, mientras que con la técnica de infestación del suelo con un cultivo sólido del patógeno (técnica sólida) a los 90 días sólo había muerto el 65% de las plantas. F. oxysporum no disminuyó el porcentaje de germinación de los cultivos de soja, girasol, sorgo granífero y maíz, por lo que este hongo podría utilizarse como agente de biocontrol del sorgo de Alepo. Sin embargo, es necesario conocer el rango de hospedantes del patógeno para poder evaluar los riesgos de usar este antagonista.
- ArtículoEmbargadoPseudocercospora griseola Causing Angular Leaf Spot on Phaseolus vulgaris Produces 1,8-Dihydroxynaphthalene-Melanin(2009)Pseudocercospora 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.
- ArtículoEmbargadoQuality and endosperm storage protein variation in Argentinean grown bread wheat(2009)Genetic 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.