Vida pampeana: visión integrada del agro-ecosistema pampeano

El presente proyecto tiene como objetivo general, evaluar las interacciones entre los diversos componentes/actores involucrados en la producción agropecuaria regional y desarrollar protocolos de producción y manejo agropecuario sobre la base de índices modernos de monitoreo, que favorezcan la mitigación de los efectos adversos derivados de las actividades productivas que se desarrollan actualmente. Asimismo, el proyecto busca establecer una plataforma dinámica de evaluaciones y monitoreo de parámetros y prácticas productivas, y simultáneamente, proceder a la identificación y selección de nuevos parámetros que fundamenten el diseño de prácticas agropecuarias amigables con el medio ambiente

First report of Leptosphaeria biglobosa ‘brassicae’ as causal agent of phoma leaf spot in Brassica napus (Canola) in Argentina

Canola(Brassicanapus L.) is the second largest oilseed crop in the worldproviding 13% of the world´s oil supply. This crop has been grown in Argentinasince the 1930s, and the area devoted to its cultivation varies every year,reaching a maximum of 95000 Ha in the 2012/2013 growing season. Because of theoccurrence of optimal weather conditions and soils with high fertility, theaverage yield in this region is about 2000 kg/Ha. Phoma leaf spot and Phomastem canker are considered the most important and devastating diseases in Brassica napus andother Brassicaespecies [1]. In both cases, the causal agent is a complexof two closely related fungal species, Leptosphaeria maculans and L. biglobosa. In Argentina,the presence of L. maculans incanola plants was reported for the first time in 2004 [2], but the existence ofL.biglobosa has not been recorded so far. During the 2015/2016season, we collected several samples with typical Phoma leaf spot symptoms fromcanola plants growing in fields from the north and northeastern regions of the Buenos Aires province.The necrotic lesions were circular to irregularly oval, 8 to 15 mm in diameter,pale brown in the center, grayish green at the margin and characterized withthe presence of pycnidia. Several leaf pieces with lesions were rinsed twicewith deionized sterile water and placed in a humid chamber (90 mm diameterPetri dish with a layer of filter paper soaked in deionized sterile water) during2-3 days to induce the pycnidia to exude cirri of conidia. After this period,one cirrus per sample was transferred onto PDA plates supplemented withantibiotics (15 mg/L streptomycin, 15 mg/L gentamicin and 12 mg/L tetracycline)using an inoculation needle under stereoscopic microscope. Thus, severalisolates were obtained, some of them showing rapid mycelial growth rate andpigment production on PDA medium, as showed by the isolate Tapidor of L. biglobosa thatwe used as control (kindly provided by Professor Bruce Fitt, University ofHertfordshire-UK). In order to confirm the identity of these isolates, a PCRassay using genomic DNA as template was performed to distinguish L. maculans from L. biglobosa withthe species-specific primers LmacR, LmacF,and LbigF ina three-primers strategy described by Gaetan (2005)[3]. These reactions gave a444-bp amplicon as expected for L. biglobosa ´brassicae´.In addition, these results were confirmed by sequencing the nuclear ribosomalinternal transcribed spacer (ITS) region, which showed a 99% of identity withthe sequence of L. biglobosa ´brassicae´at the GenBank database (FO905468). L. biglobosa isolateswere then tested for pathogenicity on the canola cultivars Westar and Bioaureo2286 (Nuseed). With this purpose, cotyledons of 10-day-old seedlings werepricked with a needle, and each wound inoculated with 10 μl ofa conidial suspension (107 42conidia/ml). Sterilized distilled water was used as control. Developing primaryleaves were removed every 2-3 days in order to ensure that cotyledons continueto expand. Fourteen days after inoculation, irregular and brown necroticlesions were visible at the site of inoculation. These cotyledons were detachedand placed in a humid chamber to induce pycnidia formation. After three dayscirri of conidia were transferred to a plate with PDA supplemented with antibioticsas mentioned above. The identity of these isolates of L. biglobosa wereconfirmed by pigment production on PDA medium and by PCR assay usingspecies-specific primers. To our knowledge, this is the first report of L. biglobosa ´brassicae´as a pathogen of canola in Argentina. This finding shows that in Argentina´scanola cropping areas not 50 only L. maculans but alsoL.biglobosa are the causal agents of Phoma leaf spot disease.Fil: Rossi, Franco Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Romero, Fernando Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Garriz, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Ruiz, Oscar Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentin

Osmotic induction marking with Alizarin Red S on juveniles of pejerrey, <i>Odontesthes bonariensis</i> (Atherinopsidae)

Juveniles of pejerrey, Odontesthes bonariensis, were exposed to 0.1% Alizarin Red S (ARS) alone or with a previous immersion in 2.2% saline solution (Osmotic Induction, OI) to enhance the ARS marking method. Fish were marked in the field and immediately released in 1 m3 cages in "La Salada de Monasterio" lagoon, Chascomús, Buenos Aires , Argentina. After 73 days, clear marks were observed in the otoliths, caudal fin rays and scales with both treatments, being the intensity of the signal in the scales of OI+ARS treated fish higher. On the other hand, no marks were observed in the control group on the same structures. Approximately one year post-treatment (385 days), only marks in caudal fin rays were found clearly in OI+ARS treated fish. After this period, no significant differences in total length or weight between marked or control fish were observed and the mortality ranged between 30-40 % in all cages. These results provide strong evidence for the potential applicability of this cost-effective marking technique in differentiation of wild and hatchery-produced pejerrey. The success in the caudal fin rays marking is also important because it is easy to do and does not require the sacrifice of fish.Juvenis de pejerrey, Odontesthes bonariensis, foram expostos a Vermelho de Alizarina S (ARS) 0,1% de duas formas, sozinho ou com uma imersão anterior em 2,2% de solução salina (Indução osmótica, IO) para melhorar o método de marcação ARS. Os procedimentos foram realizados no campo e os peixes foram liberados em gaiolas (tanques-rede) de 1 m3 na lagoa "La Salada de Monasterio", Chascomús, Buenos Aires, Argentina. Após 73 dias, marcas claras foram observadas nos otólitos, raios da nadadeira caudal e escamas em ambos os tratamentos, sendo que a intensidade do sinal nas escalas de IO + ARS de peixe tratado foi superior. Por outro lado, não foram observados marcas no grupo controle sobre as mesmas estruturas. Aproximadamente um ano pós-tratamento (385 dias), apenas marcas nos raios da nadadeira caudal foram encontrados claramente nos peixes tratados com IO+ARS. Entre os peixes observados, após este período, não houve diferenças significativas no comprimento total ou peso entre o grupo controle e marcados, ademais, a mortalidade variou entre 30-40% em todas as gaiolas. Estes resultados fornecem fortes evidências e um grande potencial para aplicação desta técnica rentável de marcação que diferencia o pejerrey selvagem e o produzido em cativeiro. O sucesso na marcação dos raios da nadadeira caudal também é de grande importância, pois sua verificação é fácil e não requer o sacrifício de peixes.Instituto de Limnología "Dr. Raúl A. Ringuelet

LOTUS spp: BIOTECHNOLOGICAL STRATEGIES TO IMPROVE THE BIOECONOMY OF LOWLANDS IN THE SALADO RIVER BASIN (ARGENTINA)

The Salado River Basin region is the most important livestock breeding area inArgentina, wherethe Lotus species has been traditionally cultivated as forages.Nearly 60% of their land surface is dominated by salt-affected soils with severeconstraints for crop cultivation. In order to cope with that limitation, farmers haveutilized species such as non-native L. tenuis (ex- Lotus glaber), which shows a verygood adaptation. As a result, inter-seeding of L. tenuis has been proposed as astrategy of choice for improving forage production in marginal areas. The increasein soil quality by these means is achieved by an increment of the organic mattercontent, improvement of soil fertility as well as microbial biodiversity. Thus, theintroduction of L. tenuis and/or other Lotus genotypes could have enormousbenefits for similar constrained lands around the world. We are developing anintegrated analysis of the changes that occur in soils under legume production. Wewill not only analyze the microbial diversity associated, but also soil physical andchemical characteristics and the impact of different legume-microbes associationon mitigation of GHG emissions. In addition, we are identifying the main geneticdeterminants associated with interesting agronomic traits such as plant toleranceagainst biotic and abiotic stresses and the content of condensed tannins. Our futureand present research will build a solid base for the improvement of agronomicallyimportantspecies and the development of better strategies for the management ofconstrained lands such as the lowlands in the Argentinean Pampas