Population structure and genetic diversity characterization of a sunflower association mapping population using SSR and SNP markers.

BACKGROUND: Argentina has a long tradition of sunflower breeding, and its germplasm is a valuable genetic resource worldwide. However, knowledge of the genetic constitution and variability levels of the Argentinean germplasm is still scarce, rendering the global map of cultivated sunflower diversity incomplete. In this study, 42 microsatellite loci and 384 single nucleotide polymorphisms (SNPs) were used to characterize the first association mapping population used for quantitative trait loci mapping in sunflower, along with a selection of allied open-pollinated and composite populations from the germplasm bank of the National Institute of Agricultural Technology of Argentina. The ability of different kinds of markers to assess genetic diversity and population structure was also evaluated. RESULTS: The analysis of polymorphism in the set of sunflower accessions studied here showed that both the microsatellites and SNP markers were informative for germplasm characterization, although to different extents. In general, the estimates of genetic variability were moderate. The average genetic diversity, as quantified by the expected heterozygosity, was 0.52 for SSR loci and 0.29 for SNPs. Within SSR markers, those derived from non-coding regions were able to capture higher levels of diversity than EST-SSR. A significant correlation was found between SSR and SNP- based genetic distances among accessions. Bayesian and multivariate methods were used to infer population structure. Evidence for the existence of three different genetic groups was found consistently across data sets (i.e., SSR, SNP and SSR + SNP), with the maintainer/restorer status being the most prevalent characteristic associated with group delimitation. CONCLUSION: The present study constitutes the first report comparing the performance of SSR and SNP markers for population genetics analysis in cultivated sunflower. We show that the SSR and SNP panels examined here, either used separately or in conjunction, allowed consistent estimations of genetic diversity and population structure in sunflower breeding materials. The generated knowledge about the levels of diversity and population structure of sunflower germplasm is an important contribution to this crop breeding and conservation.

Fusarium poae Pathogenicity and Mycotoxin Accumulation on Selected Wheat and Barley Genotypes at a Single Location in Argentina.

Fusarium poae is a relatively weak pathogen with increasing importance in cereal grains, principally due to its capacity to produce several mycotoxins. In this study, we evaluated the pathogenicity and toxin accumulation of individual F. poae isolates on wheat and barley under natural conditions for 3 years. Analysis of variance demonstrated significant differences for year-genotype, year-isolate, genotype-isolate, and year-genotype-isolate interactions for both incidence and disease severity. Based on contrast analysis, 'Apogee' was more susceptible than the other wheat genotypes, wheat genotypes were more susceptible than barley genotypes, durum wheat genotypes were more susceptible than bread wheat genotypes, and barley genotype 'Scarlett' had greater symptom development per spike than the other barley genotypes. Neither HT-2 nor T-2 toxins were detected in the grain samples. However, high levels of nivalenol were found in both wheat and barley samples. The increased reported isolation of F. poae from wheat and barley and the high capacity of this fungus to produce nivalenol underlie the need for more studies on F. poae-host interactions, especially for barley.

[Fusarium graminearum presence in wheat samples for human consumption]. / Presencia de Fusarium graminearum en muestras de trigo destinado al consumo humano.

One of the most important diseases in cereal crops is Fusarium head blight, being Fusarium graminearum the main etiological agent. This fungus has the ability to produce a wide spectrum and quantity of toxins, especially deoxynivalenol (DON). During the last crop season (2012-2013) the climatic conditions favored Fusarium colonization. The objective of this work was to determine the presence of this fungus as well as the DON content in 50 wheat grain samples. Our results showed that 80% of the samples were contaminated with Fusarium graminearum. Twenty four percent (24%) of the samples contained ≥ 1µg/g DON, 26% ranged from 0,5 and 0,99µg/g, and the remaining 50% had values lower than 0,5µg/g. Correlation was found between the presence of Fusarium graminearum and DON. It is necessary to establish DON limit values in wheat grains for human consumption.

Clinical evaluation of antiseptic mouth rinses to reduce salivary load of SARS-CoV-2.

Most public health measures to contain the COVID-19 pandemic are based on preventing the pathogen spread, and the use of oral antiseptics has been proposed as a strategy to reduce transmission risk. The aim of this manuscript is to test the efficacy of mouthwashes to reduce salivary viral load in vivo. This is a multi-centre, blinded, parallel-group, placebo-controlled randomised clinical trial that tests the effect of four mouthwashes (cetylpyridinium chloride, chlorhexidine, povidone-iodine and hydrogen peroxide) in SARS-CoV-2 salivary load measured by qPCR at baseline and 30, 60 and 120 min after the mouthrinse. A fifth group of patients used distilled water mouthrinse as a control. Eighty-four participants were recruited and divided into 12-15 per group. There were no statistically significant changes in salivary viral load after the use of the different mouthwashes. Although oral antiseptics have shown virucidal effects in vitro, our data show that salivary viral load in COVID-19 patients was not affected by the tested treatments. This could reflect that those mouthwashes are not effective in vivo, or that viral particles are not infective but viral RNA is still detected by PCR. Viral infectivity studies after the use of mouthwashes are therefore required. ( https://clinicaltrials.gov/ct2/show/NCT04707742 ; Identifier: NCT04707742).

Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis.

Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience.

Presencia de Fusarium graminearum en muestras de trigo destinado al consumo humano / Fusarium graminearum presence in wheat samples for human consumption

La fusariosis es una de las enfermedades más importantes de los cereales, Fusarium graminearum es su principal agente etiológico. Este hongo posee la capacidad de producir distintos tipos y niveles de toxinas, en especial deoxinivalenol (DON). En la campaña 2012-2013 se dieron condiciones ambientales predisponentes para el desarrollo de esta enfermedad. El objetivo de este trabajo fue evaluar la presencia del hongo y el contenido de DON en 50 muestras de trigo. Los resultados demostraron la presencia de Fusarium graminearum en el 80 % de las muestras analizadas. El 24 % de las muestras presentó valores de DON ≥ 1µg/g, el 26 % varió entre 0,5 y 0,99µg/g, mientras que el 50 % restante mostró valores inferiores a 0,5µg/g. Se observó correlación entre la presencia de Fusarium graminearum y de DON. Es necesario establecer valores límites de DON en granos de trigo destinados al consumo humano

One of the most important diseases in cereal crops is Fusarium head blight, being Fusarium graminearum the main etiological agent. This fungus has the ability to produce a wide spectrum and quantity of toxins, especially deoxynivalenol (DON). During the last crop season (2012-2013) the climatic conditions favored Fusarium colonization. The objective of this work was to determine the presence of this fungus as well as the DON content in 50 wheat grain samples. Our results showed that 80% of the samples were contaminated with Fusarium graminearum. Twenty four percent (24%) of the samples contained ≥ 1µg/g DON, 26% ranged from 0,5 and 0,99µg/g, and the remaining 50% had values lower than 0,5µg/g. Correlation was found between the presence of Fusarium graminearum and DON. It is necessary to establish DON limit values in wheat grains for human consumption

Sensibilidad cutanea a la Blomia tropicalis en pacientes alergicos de la ciudad de Medellin / Skin sensitization to Blomia tropicalis in allergyc patients of Medellin

La sensibilización a los ácaros del polvo juega un papel muy importante en el desencadenamiento de los padecimientos alérgicos. La alergia al ácaro Dermatophagoides se sitúa entre 45por ciento y 85por ciento según estudios publicados (3). Trabajos sobre el ácaro Blomia tropicalis, demuestran que es un importante alergeno en las zonas tropicales y especialmente costeras. Se propuso realizar un estudio para evaluar la prevalencia de sensibilidad cutánea a Blomia tropicalis en pacientes alérgicos de la ciudad de Medellín. Participaron 250 pacientes procedentes de esta ciudad y de los municipios que conforman el valle de Aburrá, remitidos al servicio de Alergología del Seguro Social. De los individuos estudiados, 184 tenían rinitis y 66 asma. De los pacientes con asma, el 69,6por ciento tuvieron pruebas positivas para Dermatophagoides farinae y Dermatophagoides pteronysinnus y 31,8por ciento a Blomia tropicalis. De los pacientes con rinitis el 56,5por ciento fueron positivos para Dermatophagoides y el 22,2por ciento lo fueron a Blomia tropicalis. Aunque se ha demostrado que existe muy baja reactividad cruzada entre las dos familias de ácaros porque sus alergenos son diferentes, en esta serie encontramos que todos los pacientes sensibles a Blomia tropicalis, lo fueron también a Dermatophagoides. Esto sugiere que aunque no sea tan frecuente, sí juega un papel importante en el desencadenamiento de la patología alérgica respiratoria